1. Recommendation for Update of
Nepal National Building Code
Final Report
July, 2009
Submitted by:
MULTI Disciplinary Consultants (P) Ltd.
P.O. Box 5720, Kathmandu, Nepal
Tel: (977)-1-5525076/5529304, Fax: (977)-1- 5523103
E-mail: mdc@multinepal.com.np, Web Site: www.MultiNepal.com/mdc
in associaton with
K.D. Associates (P) Ltd.
P.O. Box 686
Tel: 425263, Fax: 4215341
E-mail: kdapl@info.com.np,
Web: www.hurarah.com.np
and
Khwopa Engineering College
Libali, Bhaktapur-2
P.O. Box 84, Bhaktapur, Nepal
Tel: 6614794, 6614798
E-mail: khec@wlink.com.np
The Government of Nepal
Ministry of Physical Planning and Works
Earthquake Risk Reduction and Recovery Preparedness
Programme for Nepal
(UNDP/ERRRP-Project: NEP/07/010)

2. Recommendation for Update of Nepal National
Building Code: Final Report
Contents
Executive Summary ........................................................................................................................ 6
1 Introduction......................................................................................................................... 10
1.1 General ................................................................................................................................... 10
1.2 The Project ............................................................................................................................. 10
1.3 The Assignment...................................................................................................................... 10
1.4 Objectives of the Assignment ................................................................................................ 10
1.5 Scope of Works ...................................................................................................................... 11
1.6 Methodology .......................................................................................................................... 11
1.7 The Project Team, Inputs and responsibilities ....................................................................... 11
1.8 Interaction with the Target Groups ........................................................................................ 12
1.9 Major Findings ....................................................................................................................... 12
2 Current Practices................................................................................................................ 14
2.1 National Policy....................................................................................................................... 14
2.2 Implementation of NNBC by Municipalities......................................................................... 14
2.3 Building Permit Process in LSMC......................................................................................... 14
2.4 Building Permit Process in KMC........................................................................................... 15
2.5 Data and information on building code implementation........................................................ 15
2.5.1 Government Buildings by DUDBC ........................................................................ 15
2.5.2 Practice in Municipalities........................................................................................ 16
2.6 Institutional Arrangements for Implementation of NNBC .................................................... 16
2.7 Jurisdiction of Application of NNBC..................................................................................... 17
2.8 Subscribed methods (PWD) of Seismic design consideration............................................... 17
3 Consideration of Problems and Issues of NNBC Application and Construction ......... 18
3.1 The Codes............................................................................................................................... 18
3.2 Hierarchy of Act, Bylaws, Codes and Standards, and References......................................... 19
3.3 Building bylaws...................................................................................................................... 19
3.4 Code Structure and Nepal Standards...................................................................................... 19
3.5 Need for Unified Code ........................................................................................................... 19
3.6 Criticism of NNBC................................................................................................................. 19
3.7 Family of Codes ..................................................................................................................... 20
3.8 Frequency of Update .............................................................................................................. 20
3.9 Commentary on Codes and Standards ................................................................................... 20
3.10 Conservation of Historic Building, Aesthetics, Planning Codes ........................................... 20
3.11 Relationship between Aesthetics and Structural Safety......................................................... 21
3.12 Change in Occupancy............................................................................................................. 21
3.13 High Rise Buildings ............................................................................................................... 21
3.14 Detailing of Joints .................................................................................................................. 21
3.15 Quality Monitoring and Advertisement Market..................................................................... 21
3.16 Supervision of Construction Works ....................................................................................... 21
3.17 Building Material Handling, storage and use......................................................................... 22
3.18 Specification of other Materials not mentioned in NNBC..................................................... 22
3.19 Mechanism for addressing Technical issues and data bank................................................... 22
3.20 Participation of masons, stakeholders, owners....................................................................... 22
3.21 Info dissemination and Interactions ....................................................................................... 22
3.22 Construction Safety................................................................................................................ 22
3.23 Ownership of Design and Intellectual Property rights ........................................................... 22
3.24 Education................................................................................................................................ 23

3. 3.25 Capacity of personnel, qualification....................................................................................... 23
3.26 Licensing of Skill Labor......................................................................................................... 23
4 Implementation of Codes and Standards ......................................................................... 23
4.1 Water Supply and Sanitation.................................................................................................. 23
4.2 Electrical Code ....................................................................................................................... 23
4.3 Fire Safety Code..................................................................................................................... 23
4.4 Use of NNBC 205: MRT ....................................................................................................... 24
5 Review of NNBC ................................................................................................................. 24
5.1 Review of NBC 000: 1994 State-Of-The Art Design And NBC 105: 1994 Seismic Design
Of Buildings In Nepal ............................................................................................................ 24
5.1.1 General .................................................................................................................... 24
5.1.2 NNBC 000: 1994 Requirements For State-Of-The Art Design .............................. 25
5.1.3 NNBC 105: 1994 Seismic Design Of Buildings In Nepal ...................................... 27
5.2 Review of NNBC 101, 102, 103, 104, 106, 108, 109 (Loads, Occupancy, Site
Consideration, Unreinforced Masonry) ............................................................................. 35
5.2.1 NNBC 101:1994: Materials Specifications............................................................. 35
5.2.2 NNBC 102:1994: Unit Weight of Materials ........................................................... 36
5.2.3 NNBC 103:1994: Occupancy Load (Imposed Load).............................................. 36
5.2.4 NNBC 104:1994: Wind Load ................................................................................. 37
5.2.5 NNBC 106:1994: Snow Load ................................................................................. 38
5.2.6 NNBC 108: 1994 Site Consideration...................................................................... 40
5.2.7 NNBC 109: Masonry (Unreinforced) ..................................................................... 41
5.3 Review of NNBC: 107 (Fire Code)...................................................................................... 42
5.3.1 General .................................................................................................................... 42
5.3.2 Main Objectives and Purpose of Building Codes ................................................... 42
5.3.3 Compliance to the Fire Code of Nepal.................................................................... 43
5.3.4 Major Drawback...................................................................................................... 43
5.3.5 Requirement of Fire Safety in Building Codes ....................................................... 43
5.4 Review of NNBC: 110, 111, 112, 113, 114 (Masonry, PCC, Materials, Construction
Safety).................................................................................................................................... 44
5.4.1 NNBC 110: Plain and Reinforced Concrete..................................................................... 44
5.4.2 NNBC-111: 1994: Steel....................................................................................................... 44
5.4.3 NNBC-112: Timber 1994.................................................................................................... 45
5.4.4 NNBC-113: Aluminum 1994.............................................................................................. 45
5.4.5 NNBC 114:1994 CONSTRUCTION SAFETY ................................................................ 46
5.5 Review of NNBC: 201, 202, 203, 204, 205 (MRT, Low Strength and Earthen Buildings)
................................................................................................................................................ 46
5.5.1 General .................................................................................................................... 46
5.5.2 NNBC 201: Mandatory Rules Of Thumb - Reinforced Concrete Buildings with
Masonry Infill.......................................................................................................... 47
5.5.3 NNBC 202: MRT-LOAD BEARING MASONRY................................................ 47
5.5.4 NNBC 203: 1994 - Guidelines For Earthquake Resistant Building Construction:
Low Strength Masonry............................................................................................ 48
5.5.5 NNBC 204: 1994 - Guidelines For Earthquake Resistant Building Construction:
Earthen Building (EB)............................................................................................. 49
5.5.6 NNBC 205: 1994 - MRT Reinforced Concrete Buildings without Masonry Infill 49
5.6 Review of NNBC 206: 2003 - Architectural Design Requirements ................................. 50
5.6.1 General .................................................................................................................... 50
5.6.2 High Rise Buildings ................................................................................................ 50
5.6.3 Other aspects ........................................................................................................... 50
5.7 Review of NNBC 207: 2003- Electrical Code..................................................................... 51

4. 5.8 Review of NNBC 208: 1994 - Plumbing and Sanitation ................................................... 51
5.8.1 Water Supply........................................................................................................... 51
5.8.2 Waste Water Disposal ............................................................................................. 51
5.8.3 Rain Water Disposal................................................................................................ 52
6 Conclusion............................................................................................................................. 53
7 Recommendation.................................................................................................................. 54
Appendix-1: List of NNBC...................................................................................................... 57
Appendix-2: Check list of activities for the study................................................................. 57
Appendix-3: Interaction with Target Groups and National Workshop............................. 57
Appendix-4: Review of NNBC: 000, 105 (State of Art, Seismic Design) ............................ 57
Appendix-5: Review of NNBC 101, 102, 103, 104, 106, 108, 109 (Loads, Occupancy, Site
Consideration)..................................................................................................................... 57
Appendix-6: Review of NNBC: 110, 111, 112, 113, 114, (Materials) .................................. 57
Appendix-7: Review of NNBC: 107 (Fire Code)................................................................... 57
Appendix-8: Review of NNBC: 201, 202, 203, 204 and 205 (MRT).................................... 57
Appendix-9: Review of NNBC: 206 (Architectural Code)................................................... 57
Appendix-10: Review of NNBC: 207 (Electrical Code)...................................................... 57
Appendix-11: Review of NNBC: 208 (Water Supply and Sanitation).............................. 57
Reference Materials ...................................................................................................................... 57

5. Abbreviations:
ADRC Asian Disaster Reduction Center
ADPC Asian Disaster Preparedness Center
ASTM American Society for Testing of Materials
AASHTO American Association of State Highway and Transport Officials
AREMA American Railway Engineers and Maintenance-of-way Association
ACI 318 American Concrete Institute
AISC American Institute of Steel Construction
AFPA American Forest and Paper Associations
BPU Building Permit Unit
BCPR Bureau of Crisis Prevention and Recovery
BSI British Standards Institution
DDC District Development Committee
DIN German Standards
DUDBC Department of Urban Development and Building Construction
ERRRPP Earthquake Risk Reduction and Recovery Preparedness Programme
ESS Earthquake Safety Section
FSCN Fire Safety Code of Nepal (NNBC 107)
HFA Hyugo Framework for Action (2005-2015)
GON Government of Nepal
IRC Indian Road Congress
ISI Indian Standards Institution
ICC International Code Council
IFC International Fire Code,
IBC International Building Code
IRP International Recovery Platform
JSI Japanese Standard Institute
KMC Kathmandu Metropolitan Corporation
KVTDC Kathmandu Valley Town Development Committee
LSMC Lalitpur Sub-Metropolitan City
LSGA Local Self-Governance Act 1999
LSGA Local Self Governance Act of Nepal, 1996 and Regulations 1997
LSGR Local Self-Governance Regulations 1999
LSM Low Strength Masonry
NBCI National Building Code of India,
NFPA National Fire Protection Act
NNBC Nepal National Building Code
OBC Ontario Building Code
PWD Public Works Directives
SAARC South Asian Association for Regional Cooperation
UNDP United Nations Development Program
VDC Village Development Committee
UKBC UK Building Regulations 2000
UDB Urban Development Byelaws of 2007, KVTDC, GON

6. Executive Summary
Introduction
The assignment for preparation of the recommendation report for Updating the National Building
Code of Nepal is entrusted to MULTI Disciplinary Consultants (P) Ltd in association with KD
Associates (P) Ltd. and Khwopa Engineering College through a contract agreement signed
between the consultant and Earthquake Risk Reduction Recovery Preparedness Programme for
Nepal - UNDP/ERRRP-Project: NEP/07/010 (The Project) on December 15, 2008.
The Project
The “Earthquake Risk Reduction and Recovery Preparedness Programme for South Asian
Region” is supported by the Government of Japan under a grant assistance for disaster prevention
and disaster reconstruction contributed through the United Nations Development Programme
(UNDP). The Project is designed to seek regional cooperation through sharing of knowledge and
experience in Disaster Management and to utilize the knowledge of recent Earthquake
Engineering.
Objectives of the Assignment
The objectives of the Assignment are to: a) review and recommend technical additions, alterations
and modifications, to be made in the current code, b) study, analysis and justify for update of the
Code, c) review general practice of NNBC [implementation] in some municipalities (Kathmandu
and Lalitpur), and d) study the effectiveness of implementation of NNBC in construction.
Scope of Works
The scope of works related to above mentioned Objectives is to: a) interact with major
stakeholders and experts, b) study linkages with current building bylaws, c) analyze the problems
faced by Kathmandu and Lalitpur in implementation of NNBC, d) study technical issues raised by
designers and professionals, e) compare NNBC with other codes, e) review the specific
Earthquake Safety specifications, f) specify the technical details in the code to be updated for
overall revision of NNBC, g) specify the names of codes to be urgently updated, and h) prepare
final recommendation report for updating of NNBC.
Interaction with the stakeholders
The interaction with the stakeholders such as UNDP/ERRRP, NEA, SEEN, SCAEF, SONA,
SEANEP, Licensed Designers of LSMC and KMC was carried out in four different meetings. A
national level workshop was organized on June 29, 2009 by ERRRP to discuss on the Draft Final
Report. The outcome of the interaction and comments obtained during the workshop covered
various aspects of NNBC and presented in Appendix-3 and summarized in Section 2.8. The
comments and suggestions relevant to the current assignment had been incorporated in the report
whereas certain queries which are not related to the Terms of Reference were included in
Appendix-3 for consideration during the actual revision of the Codes.
Apart from the details on the provisions of NNBC, the important aspects raised were:
 Confusion of Hierarchy and Priority of Acts, Bylaws, Codes, Standards, Directives,
specifications, manuals, and References and Priority of the documents;
 Need for mechanism to implement the codes as part of the Building Bylaws
 Need for application of the code all over the country including VDC and small settlements
 Need of Unified Code and other codes as Architectural Code, Residential Code, Historical
Building Code, High Rise Building Code, Fire Code, Plumbing Code, Construction Safety
Code, Retrofitting and Building Strengthening Code, Disabled Accessibility Code, Mechanical
Code, Fuel and Gas Code, Environmental Code and Commentary on Codes.

7.  Anomalies of NNBC
 Frequency of Updates of Codes and Responsibilities
 Aesthetics, Change in Occupancy and Structural Safety, and annual Audit for compliance
with codes
 Use of MRT
 Regulation of Advertisement of construction materials
 Safety during handling and storage of materials
 Audit of Performance of Code implementing organisations,
 Ownership and Intellectual Property Right
 Education, Training, Qualification, Licensing of skilled labor.
NNBC and NS Series
There are two sets of documents available which are known as Nepal National Building Code or
Nepal Standard. Actually, both of the series address the same issues. NNBC is presented as
amendment to IS whereas NS are adaptation of IS or other standards into NS with relevant
amendments.
Normally, the codes and standards are revised and updated every 3 years. But for Nepalese case,
this may not be pragmatic and frequency of updating may be adopted differently. The
International Code Council or other institutions dedicated for code development and updating
review the codes at a regular interval, for example say 3 years. A regular process for recording of
occurrence is carried out and forwarded to the standing committees for code updating. Nepal does
not have a dedicated office for record of occurrence in relation to the need for updating of Codes
and Standards.
More detailed deliberations on specific codes are provided in Section 5 and Appendices.
MRT not to be a part of NNBC
Strong voices were noted for treating MRT as non-Code document since it is just an example of
design of various types of buildings and details following the provisions of NNBC. This document
is incomplete and do not include the requirements of other codes as Fire Code, Plumbing Code,
Environmental Code etc. The quality assurance and construction complexities are not considered.
Lalitpur Municipality from the very day of application of NNBC adopted certain changes in MRT.
This document should be developed as model examples that fulfill the requirement of all codes
and should be served as guide for proper design and shall not be a part of the Building Code.
Implementation of NNBC by Municipalities
The implementation of NNBC is made mandatory by issue of instructions by the Ministry of Local
Development but the Building Act and Building Byelaws do not include NNBC provisions and
hence remains ineffective and practically not applied in Building Permit Process. Lalitpur
Municipality initiated the application of NNBC in the Building Permit Process in voluntary
manner since 2003. Kathmandu Municipality started implementation of NNBC only since 2007.
The implementation of NNBC could not be initiated in other municipalities since the Building
Byelaws has not incorporated NNBC as part of it. It will be fundamental to include the NNBC and
other relevant Family of Codes as described in Section 3 to be included in Building Bylaws.

8. Mandatory Application of Bylaws through out the country
The Building Byelaws are by legislation applicable in the areas of jurisdiction of the
municipalities. Most of the areas in country side and rural areas are not covered by Building Act
and Building Bylaws making the rural areas more vulnerable for Construction Safety. This loop
hole in Building Act has prompted many builders and owners to shift to VDC areas for
construction for avoiding the need for obtaining Building Permits and avoiding application of
NNBC. This provision has defeated the purpose of NNBC in general.
Implementation of Architectural Design Requirements and Planning Guidelines
Though the Architectural Design Requirements (NNBC 206:2003) had been introduced in 2003,
the actual design had not been checked for compliance with this code and coordination with
Planning Guidelines and zoning plans been very week. The effect of coordination is clearly visible
in the haphazard development of the urban areas.
Institutional Arrangements for Implementation of NNBC
There is no single institution responsible for all earthquake related matters in Nepal. Various
institutions and agencies are responsible for various earthquake related matters, and the
coordination among them is practically not provided. For this reason, the issues related to NNBC
remain unattended and keeps waiting for a particular project to start. There is a dire need for
establishing Nepal Code Council that will address the development issues of Codes and their
implementation.
Code Structure, Nepal Standards and Family of Codes
There is a gross confusion about the hierarchy and priority of the documents in relation to Act,
Bylaws, Codes (NNBC), Standards (NS), and Directives (PWD), Specifications, Manuals
Instructions and administrative circulars. This aspect needs to be clarified and clear demarcation
and definition is required.
NNBC is a collection of individual codes. May be it would be more effective when compiled into
a unified code that takes into account the family of various other codes as Urban Planning Code,
Fire code, Plumbing Code, Electrical Code, Construction Code, Construction Safety Code etc (See
list in Section 3.6 Box 2) including provision for adoption of administrative procedures for
implementation.
Criticism on NNBC
A series of positive criticism on NNBC was spelt out during the interaction with the stakeholders.
The major issues are highlighted in Section 3.5 and details are provided in Appendix-3. Most
important of all criticism is that since the code is presented as amendment to Indian Code, it has
lost its value since there is no need to refer to an incomplete code when Indian Code is handy. The
dependency of other code has to be eliminated otherwise the international codes shall be adopted
as reference codes only. The Code requires technical and literature editing to eliminate errors and
misprints.
Review of NNBC 000 to 208 and Comparison with other Codes
The review of NNBC has been carried out and a number of issues had been identified that would
required to be considered while updating the Building Code. Comments and suggestions to every
Section of the Code are provided in Appendices. Particular attention is drawn on major issues
pointed out and few disasters that have occurred recently due to the lack of provisions in the code.
They are:

9.  The provisions in the Codes have several ambiguous statements, Incomplete sentences,
reference to the Indian Standard Codes of Practice, absence of the Commentary, design
earthquake level is too un-conservative,
 Fire Hazard in rural settlements induced by poor planning of the settlements and inadequate
consideration of Fire Safety measures
 Changes in occupancy of buildings without confirming to Safety requirements,
 Electrical hazards associated with lack of adherence to Electrical Code
 Lack of coordination between Architectural Design Requirements and Planning and Zoning
Guidelines
 Lack of Data base on Wind and Snow Loads
 Lack of Data base on Building permits granted that will highlight the use of NNBC.
The updating of NNBC requires utilization of technological advancements and development of
international codes as IBC and Eurocode.
Family of Codes
Apart from the NNBC series and NS serious, the need for a numerous other codes is identified
which will be required to fulfill the purpose of achieving the safety of life and property and
enhancing comfort of living. These additional codes are listed in Section 3.5.
Environmental Code
This Code is very specific and needs to be addressed while updating the Code. The important of
this code is obvious since it affects the quality of life and its comfort. The code should introduce a
separate section for the Environmental Pollution Control covering following:
 Air Pollution (Indoor and Outdoor)
 Emission Control
 Sound Pollution
 Water Pollution
 Solar pollution
 Solid waste management
 Visual Pollution in Urban and rural Areas
 Landscaping
 Public Information for Safety of Life, Property and Peaceful Living
Mandatory Rules of Thumb (MRT)
The main objective of MRT is to provide ready-to-use dimensions and details for various
structural and non-structural elements for up to three-storey reinforced concrete (RC), framed,
ordinary residential buildings commonly being built by owner-builders in Nepal that include a)
RCC framed with using brick infill walls, b) load bearing brick masonry, c) low strength rural
construction and earthen buildings.
The details in MRT designs are provided without consideration of construction requirements for
quality assurance (limitation of concrete placing from less than 1 m, allowing consolidation of
concrete, preventing honey comb in concrete and smaller dia reinforcement (10mm and 12 mm in
foundation and columns).
The designs provided in MRT should serve as good illustrations of compliance to the requirements
of all codes (family of Codes) for the designers and owners. Hence, it is considered that MRT
should not be a part of the Code.

10. Recommendation for Update of Nepal National
Building Code: Final Report
1 Introduction
1.1 General
The current assignment of preparation of recommendation report for Updating the National
building Code of Nepal is entrusted to MULTI Disciplinary Consultants (P) Ltd in
association with KD Associates and Khwopa Engineering College through a contract
agreement signed between the consultant and Earthquake Risk Reduction Recovery
Preparedness, Programme for Nepal - UNDP/ERRRP-Project: NEP/07/010 (The Project) on
December 15, 2008.
1.2 The Project
The Government of Japan has decided to provide a grant assistance for disaster prevention
and disaster reconstruction, with a view to contributing to the “Earthquake Risk Reduction
and Recovery Preparedness Programme for South Asian Region” through the United
Nations Development Programme (UNDP).
The UNDP/BCPR, the leading agency of the International Recovery Platform (IRP, Office:
Kobe City, Hyogo Prefecture), and Japan have extended cooperation in this programme to
fulfill the requirement of the Hyugo Framework for Action (HFA 2005-2015) to reduce the
degree of damage and quickly restore earthquake damage by promoting quake-proof
capacity of buildings, taking into consideration the strengthened capability in the field of
disaster prevention of the South Asian Association for Regional Cooperation (SAARC) for
the South Asian region, including India, Nepal, Pakistan, Bangladesh and Bhutan.
The Project is designed to seek regional cooperation through sharing of knowledge and
experience in best practice on Disaster Management and utilize the knowledge of recent
Earthquake Engineering.
1.3 The Assignment
The assignment is related to preparation of recommendation report for updating of the
National Building Code of Nepal. The report will serve as base for updating of the Building
Code by the Government.
1.4 Objectives of the Assignment
The objectives of the Assignment are:
To review and recommend technical additions, alterations and modifications, to be made in
the current code
 To study, analysis and justify for update of the Code
 To review general practice of NNBC [implementation] in some municipalities (
Kathmandu and Lalitpur)
 To study the effectiveness of implementation of NNBC in construction

11. 1.5 Scope of Works
The scope of works related to above mentioned Objectives is:
 Discussion and interaction with ERRRP/DUDBC, stakeholder municipality and other
experts
 Study linkages with current building bylaws prepared by DUDBC/Town Development
Committees
 Study and analyze the technical complications and problems faced by some
municipalities (Kathmandu and Lalitpur) in the implementation process of NNBC
 Study Technical Issues raised by the designers and the professionals regarding the
revision of the NNBC
 Study and Compare NNBC with other codes that are being practiced in Nepal such as
IS Code and others
 Study other International Codes that are correlations with NNBC
 Study and review the specific Earthquake Safety specifications in building codes and
guidelines already available in Nepal
 Specify the technical details in the code to be reviewed and updated for overall revision
of NNBC
 Specify the names of codes that have to be urgently updated
 Prepare final recommendation report for updating of NNBC
 Presentation of draft final report to ERRRP, UNDP,DUDBC, Municipalities and other
stakeholder organizations for comments and suggestions
 Preparation of Final Report
1.6 Methodology
The methodology adopted for meeting the requirement of above scope of works is:
 Collection and Study of data/information, documents on NNBC. The comprehensive list
is given in Appendix-1;
 Collection and Study of data, information and documentation on building code
implementation for government buildings by DUDBC
 Collection and Study of data, information and documentation on building code
implementation in municipalities;
 Interaction with the users of the Codes as licensed designers of municipalities,
professional consultants involved in the Earthquake engineering, municipal and
government authorities, professional organizations;
 Preparation of Recommendation for update of NNBC with detail information on
amendments, revisions, alterations to be made.
1.7 The Project Team, Inputs and responsibilities
The proposed team members are listed below in Table-1 along with the proposed task
assignment
Table-1: Proposed Team Members
SN Position Name Firm Input,
MM
Task Assignment
1 Project
Director
Mr. BL
Nyachhyon
Multi 1 Administration, Quality Management
Coordination
Review of Fire Code NNBC 107

12. SN Position Name Firm Input,
MM
Task Assignment
2 TL
Structural
Engineer
Dr. Prem
Nath
Maskey
Multi 1 Discussion and interaction
Review of Building Codes 000, 105
Compare NNBC with other codes
Study Codes correlations with NNBC
Specify the codes to be urgently updated
Prepare final recommendation report
3 Structural
Engineer
Mr. PM
Pradhan* /
Dr.
Govinda
Lamichhane
Khec 1 Discussion and interaction
Study linkages with building bylaws
Analyze the problems faced by some
municipalities
Review NNBC 110, 111, 112, 113
Specify details to be updated for overall
revision of NNBC
4 Civil
Engineer
Dr. Rekha
Shrestha
Multi 1 Discussion and interaction
Study Issues raised by the designers
Review NNBC 101, 102, 103, 104, 108,
109, 114, 201, 202, 203, 204, 205
Review Earthquake Safety specifications
in building codes and guidelines already
available in Nepal
5 Architect
Planner
Devendra
Nath Gongal
Multi Discussion and interaction
Review NNBC 206
Architectural Code
6 Sanitary
Engineer
Shankher
Agrawal/
Kul Deep
Tuladhar
KDA 1 Discussion and interaction
Review NNBC 208
System Protection and Safety
Uninterrupted Supply
7 Electrical
Engineer
Shambhoo
Bahadur
Shrestha
Multi 1 Discussion and interaction
Review NNBC 207,
Electrical Safety, System Protection, ,
Uninterrupted Supply
* Mr. PM Pradhan could not contribute to the study since he has resigned from Khopa Engineering College.
1.8 Interaction with the Target Groups
The Appendix -3 lists the Target Groups for interaction for brain storming on updating of
NNBC. The interaction sessions were carried out as follows:
 Dec 28, 2008 - Brief interaction with UNDP/ERRRP National Program Coordinator
 Feb 5, 2009 – Institutional Target Groups
 Feb 9, 2009 – Licensed Designers registered with Lalitpur Sub-Metropolitan City
 Feb 27, 2009 – Licensed Designers registered with Kathmandu Metropolitan City
The notes on the Interaction programs are presented in Appendix-3.
1.9 Major Findings
The NNBC, described in 20 independent volumes, is mostly comprises of editing of certain
terminology of IS Codes and as such requires intensive revision and updating. Practically,
this updating cannot be done at this stage in view of availability of resources for review and
updating.

13. The revision and updating of NNBC are not done in a regular basis since there is no
dedicated institution for this job. The revision and updating of Building Codes are very
complex and cumbersome process that requires huge resources in terms of knowledge
accumulation, institutional memory, time, research and development and statistics. The code
updating assignment even for rich countries like USA and UK is very huge and requires
considerable investment. They have started standarisation at international level and today
most of them use International Building Code. Those codes which are not included in the
IBC are included by reference and used as a set of document agreed at international level.
Each country or local governments are given rights to amend the parts which are not relevant
to the local area and needs revision.
There are no statistical records on the application of NNBC in recent construction of both
Government and Private Sectors. But it is evident that mostly used documents are MRT,
which has good stories mentioned above and does not warrantee the safety of the Building
design under it. With these facts in mind, it is required that MRT is taken away from the
family of Building Codes but a separate standard design could be developed which could be
readily used by anybody without requiring to go through the Safety review procedures in
Municipalities.
The provisions of NNBC are currently applicable within the Municipality boundaries and
there is no formal need to apply NNBC in rural areas. This weakness has to be changed and
all buildings and infrastructures in the rural areas are also required to fulfill the requirements
of NNBC.
It is recommended that as a priority MRT should be urgently discarded as part of the code
and replaced with standard design of typical buildings that complies with requirement of the
Family of Codes.
The revision and updating of NNBC should replaced by adaptation of IBC with specific
changes of certain provisions that are relevant to the country and locality.
A dedicated Institution as National Code Council shall be established urgently and entrusted
the task of development and implementation of NNBC and help to protect life and property
from various risks of Natural and manmade disasters.
The provision for implementation of NNBC shall be included in the Building bylaws which
govern the external and internal design aspects of individual buildings and infrastructure and
warrant the least effect to the neighborhood.
Though the building permit process according to Building Bylaws has granted certain
purpose to the buildings constructed in the urban areas, but there are considerable cases
when the occupancy loads were changed without proper justification and without design
revision. They pose huge risks in terms of safety.
Similarly, the case of high rise buildings needs to be looked very seriously and provide
specific guidelines for comprehensive design.
The Conclusion and recommendation are provided in Chapter 6 and 7.

14. 2 Current Practices
2.1 National Policy
Nepal is considered one of most vulnerable country for earthquakes. The recent earthquakes
(1988 in Udayapur, Nepal) have prompted serious concerns for the earthquake safety of
infrastructure. Following the major earthquake event in 1988, the Ministry of Housing and
Physical Planning undertook a policy initiative jointly with UNDP and UNCHS to address
need for changes in current building design and construction methods. The UNDP / UNCHS
(Habitat) Project and the Ministry undertook “Policy and Technical Support to Urban Sector
Project” under which national housing survey, shelter sector training needs assessment, draft
national housing policy formulation, draft national building code preparation etc. were
undertaken. The ‘Building Act’ was adopted to facilitate the regulation of building design /
construction practice in Nepal. The ‘Engineering Council Act’ was formulated to facilitate
self regulation of the profession by professionals themselves. The Nepal National Building
Code was prepared in 1994. At the same time The Bureau of Standards and Metrology had
developed the NNBC as Nepal Standards under various Standard Codes. But in the absence
of the Parliament the Codes and Standards remained unimplemented. The Gujarat
Earthquake of Jan 2001 prompted the Society of Consulting Architectural and Engineering
Firms (SCAEF, Nepal) initiated joint collaboration with NBSM for implementation of
NNBC and NS. The collaboration prompted to form the National Forum of Earthquake
Safety that facilitated the Declaration by Lalitpur Sub-Metropolitan City for implementation
of NNBC and initiation of Master’s Degree Course in Earthquake Engineering by Khwopa
Engineering College.
2.2 Implementation of NNBC by Municipalities
LSMC is the First Leading Municipality in Nepal to implement NNBC in the Building
Permit Process through a declaration on the occasion of Earthquake Safety Day celebration
on January 16, 2003 (2059 BS).
The Implementation of NNBC was initially facilitated by the Technical Cell (Group of
Municipal Engineers & Engineers from DUDBC, NSET, NFES, NEA) which worked for 6
months prior to the establishment of the Earthquake Safety Section 27th November 2003
(2060 BS).
2.3 Building Permit Process in LSMC
The Building Permit Application in LSMC is processed in following steps (ref….):
 Registration by the Building Permit Unit of Municipality
 Checking for compliance with Building Bye-Laws
 Review the design by the Earthquake Safety Section (Technical Cell in initial stage) for
compliance with NNBC
 Presentation of the design by the Licensed Designer in a public forum organized by
LSMC, ESS for sharing experience, knowledge, methodology of application of NNBC,
confirmation of compliance to NNBC. This process was dropped at later stage and not
continued any more.
 Building Permit is granted in two stages:
 Initial Permit for construction upto Plinth Level
 Final Permit after inspection of construction upto Plinth Level

15.  Inspection of Construction Progress by Municipality Staff
 Certification of Completion jointly by the Licensed Designer who supervised the
construction and Building Permit Unit who inspected the construction.
The general Building Permit process is provided in Section 2.4.2 below.
2.4 Building Permit Process in KMC
The Building Permit process in KMC differs significantly. The compliance with NNBC for
upto 3 storeys or 1000 sqft in area is reviewed by Building Permit Section and for Buildings
over 6 floors, it is checked by the National Building Code Implementation committee
(NBCIC). The detailed procedure is described below. Kathmandu Metropolitan City (KMC)
has started implementing building code-2060 from August 21, 2005, for the construction of
buildings within the city. In October 2005 a National Building Code Implementation
Committee was set up within KMC, it is comprised by six specialists who act on voluntary
basis.
The general building permit process is as follows:
 Step 1: The Application for Building permit is checked for compliance with planning
guideline as Guided Land Development, particularly for adequacy of accessibility;
 Step 2: For Buildings less than 3 storeys and less than 1000 Sqft, Computer checking by
Junior Engineer for compliance with requirements of NNBC and Planning Bylaws;
collection of revenue
 For Buildings more than 3 storeys and more than 1000 Sqft, checking by Engineer for
compliance with requirements of NNBC and Planning Bylaws; collection of revenue
 Step 3: Initial Registration and Computer Entry
 Step 4: Forward to Ward Office for Field Verification and Neighborhood Consent
 Step 5: Forward to Building Permit Section for Final Registration
 Step 6: Checking by Engineer and Issue of Building Permit for Construction upto DPC
Level
 Step 7: Checking of Construction upto DPC Level
 Step 8: Issue of Building Permit for Construction of Superstructure
 Step 9: Checking of Completion of Construction and Issue of Completion Certificate
 Step 10: Apply for water and sewerage service connections, Electricity and
Telecommunication
 Step 11: The drinking and sewerage office sends their recommendation to the Roads
Department for permission to dig the road for the water and Sewerage connection.
 Step 12: The Department of Roads grants its permission to dig the road.
 Step 13: Inspection by water and sewage offices and Water and sewer connection is
carried out
 Step 14: Wiring Inspection before obtaining electrical power connection and telephone
connection
 Step 15: Connection of Electrical Power Supply and Telephone connection
2.5 Data and information on building code implementation
2.5.1 Government Buildings by DUDBC
DUDBC carries out implementation of certain government buildings through its
construction and Maintenance divisions. It is not known how far they comply with the

16. requirement of NNBC and who does certify the compliance since design and construction
supervision documents and As-Built Drawings are not readily available.
2.5.2 Practice in Municipalities
Building permit system started after the endorsement of ‘Building By-Laws in 1994
(2050)’. Simply a set of Architectural drawings consisting of plans, four side elevations,
section, location plan and site plan were required for submission and this was dealt by the
Drawing Cell. This cell was also responsible for checking the compliance with other
aspects such as coverage, FAR, GLD, zoning etc. After the introduction of NNBC, a set of
structural drawing was added to the list of requirements.
From 2003, the requirement for architectural, structural design analysis, electrical etc
drawing sheets was introduced for SOA type of buildings (Class A) while the requirement
was limited to architectural and structural drawings for Class B type buildings and Class C
type building does not require any structural design. In some cases where the area is
designated as heritage conservation area, additional design for preservation of traditional
style and vernacular architecture is emphasized and permission from the Department of
Archeology is required.
Initially, the building permit process included the technical committee for review of
designs by a panel of external experts comprising of the representatives from DUDBC,
KMC, IOE, NSET and SCAEF. This process gained very essential lessons that benefited
the crystallizing the Building Permit Process and was a learning stage for many Licensed
Designers and Building Owners. But soon, the review process felt lot of resistance since
the Licensed Designers were unable to defend their designs and the process was felt as a
burden to the Municipality. Certainly, a thorough and detailed scrutiny required excellent
preparation of the design and drawings.
There are two certificate systems one is temporary which is given after DPC check, but this
temporary certificate is postponed now. The other is the Permanent completion certificate
as obvious from the name is given after the completion check of the building construction.
Now the number of structural drawing sheets has increased from one to three and pillar
from 9”x 9” to 12”x12”. All engineered building for residential purpose which is more
than 1000sq. ft and 3 storeys require analysis report. For commercial buildings there is a
further requirement of soil test report and other drawings such as electrical, sanitation,
plumbing.
NNBC was enforced through the endorsement of Building Act 1999, but formally it was
implemented only in 2003 because the Building Bylaws did not make any reference to the
implementation requirements of the Building Code. NNBC has categorized buildings into
four categories namely type A, B, C and D.
2.6 Institutional Arrangements for Implementation of NNBC
There is no single institution responsible for all earthquake related matters in Nepal. The
following agencies are responsible for various earthquake related matters:
 Department of Mines and Geology is responsible for earthquake instrumentation
network in the country and preparation of the seismic zone map of the country.

17.  National Bureau of Standards and Metrology is responsible for the certification of
standards and constituents of codes and guidelines on various public works including
earthquake matters.
 National Building Council is envisaged as an apex body to deal with the creation and
updating of the National Building Code of Nepal.
 Department of Urban Planning and Housing is responsible for the creation and
implementation of Nepal National Building Codes including earthquake matters.
 Kathmandu Valley Town Development Committees are responsible for formulation of
Formulation of urban development plans, planning and building byelaws.
 Local bodies (VDCs, DDCs and Municipalities) are responsible for formulation and/or
adoption of bylaws, codes, norms, regulations and enforcing / policing their
implementation in the areas of their jurisdiction.
 Professional Societies as NEA, SCAEF, SONA, SEANEP, SEEN, ESI, NSET and other
Non-Government Organisations are responsible for information dissemination,
awareness campaigns, upgrading the knowledge and skill of their members to comply
with these codes in their professional practice and occasionally provide training.
 Donor agencies involved in the area of earthquake safety include UNDP, UNCHS,
UNESCO and JICA.
There is no dedicated institutional arrangement for dealing with the Earthquake Safety
matters, follow up and updating of NNBC, for expert advice, and pursuance for application
of NNBC by local Governments including Municipalities and VDCs.
2.7 Jurisdiction of Application of NNBC
The Local Self-Government Act Part 2-VDC Clause 28 (f) (2) has made provision of the
criteria for construction of Buildings and Infrastructure. LSGA Part 3-Municipality Clause
96 (b) (6) has made provision for approval of Building Construction. These provisions could
be rationally utilized for application of NNBC in VDC and Municipality areas effectively.
More specific and elaborate guidelines may be required.
Building Act 2055 (amendment 1998) has given authority to all municipalities to implement
the NNBC for providing Building Permits. However, the Act do not specify a particular
organization that is authorized to follow up and monitor the compliance to NNBC by the
Municipalities.
2.8 Subscribed methods (PWD) of Seismic design consideration
PWD Part II Chapter has provided certain guideline for Earthquake Consideration in
Infrastructure Project Sector. The guidelines for earthquake considerations apply to the
following categories of structures:
 All buildings having a plinth area greater than 20 m2 or height ranging from 5 m to 90
m.
 All masonry and concrete walls having a height of greater than 1.5 m.
 All elevated water tanks and silos with capacity up to 200 m3.
 All public buildings having general public access.
 All civil engineering structures such as bridges, dams, earth structures, silos, water tanks,
chimneys etc.
 All towers and electric or telecom or radio pylons.

18. The requirements of these guidelines shall be followed at minimum. The designer is
however free to exercise more stringent procedures if considered necessary considering the
merit of the case.
3 Consideration of Problems and Issues of NNBC Application and
Construction
The problems and issues related to the application of NNBC and construction quality are
largely discussed in various interaction programs with major stakeholders and brief notes on
the discussion points are described in Appendix-3. These issues are briefly highlighted
herewith:
3.1 The Codes
A code is a set of technical specification and standards that control major details of analysis,
design, construction and equipment. The purpose of the code is to produce safe and
economic design so that people are protected from poor and inadequate design and
construction.
Two types of codes exist. One type of code is called “Structural Code” and is written by
Structural Engineers and other specialists who are concerned with a particular class of
structures (e.g., buildings, bridges, nuclear plants) or who are interested in proper use of
materials (Steel, Aluminum, Reinforced Concrete, Plastics or Wood). Typically, structural
codes specify design loads, allowable stresses of various parts of structures, design
assumptions and requirements of material. Examples of Codes frequently used by structural
engineers include following:
 AASHTO – Standard specification of Highway Bridges
 AREMA- Manual for Railway Engineering
 ACI 318 – Building Code requirement of reinforced concrete
 AISC – Manual for Steel Construction
 AFPA- National design Specification for Wood Construction
The second type of code, called Building Code, is established to cover construction in a
given region (a state, city or country). A building code contains provisions pertaining to
architectural, structural, mechanical, electrical, requirements. The objective of a building
code is toprotect the public by accounting for the influence of the local conditions on
construction. Those conditions of particular concern to the structural engineers cover such
topics as soil conditions, live loads, wind pressure, snow load, and earthquake forces. Today
many building codes adopt the provisions of Standard minimum design loads for Buildings
prepared by ASCE or more recent International Building Code by ICC.
As new systems evolve, as new materials or new technology becomes available, or repeated
failures of accepted design occur, the cont3ent of codes are revised and updated. In recent
years, a large volume of research on structural behavior and materials has resulted in
frequent changes in both types of codes. For example, the ACI committee issues annual
addendum and produces revised codes every 6 years.
Most codes make revision to depart from the provisions in the standard provision if the
design can prove by the test or analytical studies that such changes can produce a safe
design.

19. 3.2 Hierarchy of Act, Bylaws, Codes and Standards, and References
There is a gross confusion about the hierarchy and priority of the documents in relation to
Act, Bylaws, Codes (NNBC), Standards (NS), and Directives (PWD), Specifications,
Manuals Instructions and administrative circulars. This aspect needs to be clarified and clear
demarcation and definition is required.
The reference to other international codes as IS, IRC, JSI, DIN, ASTM, Eurocode and others
shall be provided.
3.3 Building bylaws
The building byelaws of municipalities do not include several codes which are considered
very essential for enhancing safety and quality of Life. The safety of Neighborhood
buildings such as supermarkets, high rise buildings, hospitals, schools, institutional building,
water towers, electrical towers, communication towers etc requires special treatment and
deserves specific consideration. The existing bylaws do not deal with hazardous buildings as
abandoned and dangerous houses. The Building Permits process shall include all codes
relevant to the safety of buildings and infrastructure. Apart from this, the bylaws shall
include provisions for innovativeness in planning and design.
3.4 Code Structure and Nepal Standards
There are two sets of similar documents: One published by DUDBC under NNBC 000 to
NNBC 208, and another set published by NBSM under NS series. NNBC is basically refers
to IS with corrections made for internalizing with Nepal Requirements. So, NNBC is a
dependent code and requires intensive reference with IS. In the other hand, NS has adapted
the NNBC provisions and replaced the references of NNBC with relevant clauses adapted
from respective international codes. This duplication of NNBC and NS has created
confusion among the users of Nepal Codes. NNBC requires to be made more users friendly,
warrantee safety compared to other codes and build confidence among the professionals and
community as a whole.
3.5 Need for Unified Code
NNBC is a collection of individual codes. May be it would be more effective when compiled
into a unified code including provision for adoption of administrative procedures for
implementation.
3.6 Criticism of NNBC
Several experts and professionals have reported that NNBC contains several anomalies
which make it unreliable and confidence on it could not be developed. These factors are
related to:
 The Safety factors,
 Importance factors,
 Response spectra,
 Worse case of load combination
 Low Load factors, Load reduction provision, Load distribution of non-orthogonal plan
 Lateral earth pressure in basement
 Load distribution for high rise and low rise
 Time period < 0.1 N

20.  Design Parameters as:
- Settlement, deformation, strength, crack opening
- Static and dynamic analysis
- Retrofitting of existing buildings by laws / codes
- Repair and maintenance of old existing buildings/ code
- Disaster mitigation – building stock inventory
3.7 Family of Codes
The International Code Council has adopted
a series of codes that comprehensively
provide safety of life and property, and
enhance the quality and comfort of the
people. This aspect has not been covered by
Building Act of Nepal and Byelaws of any
municipalities and the building codes
prepared have limited provisions. The list of
International Codes used is listed in Box-2.
These codes are part of Building By-Laws
and required to be followed as the minimum.
3.8 Frequency of Update
The Bylaws, codes and Standards required
to be updated within a certain period in
order to address the dynamic technological
development and requirement of the
consumers.
3.9 Commentary on Codes and Standards
Inclusion of Commentary on Codes and
Standards is most important since it
develops the confidence of the users, and
provides evidence of authenticity. The
commentary shall be included in the same
code and standard where it is required to be
provided.
3.10 Conservation of Historic Building, Aesthetics, Planning Codes
NNBC includes a code on Architectural
Design Requirement (NNBS 206:2003),
but the important aspects of urban areas as
conservation
of historic buildings, aesthetics and context of urban areas affecting the neighborhood safety
are missing which has a huge toll on the urban safety. The building permit process in the
vicinity of historic buildings and in the World Heritage Sites or Preservation areas are not
subject to the requirements of Department of Archeology which is the governing body for
conservation of buildings and heritage sites.
Box-2: List of International Codes in Use
1. Building Code *,
2. Residential Code,
3. Mechanical Code,
4. Plumbing Code *,
5. Fuel Gas Code,
6. Fire Code *,
7. Property Maintenance Code,
8. Private Sewage Disposal Code,
9. Electrical Code
10. Energy Conservation Code,
11. Existing Building Code,
12. Utility Codes (Lifts and Escalators, Lighting and
ventilation, Prefabrication and System buildings,
Acoustics, Noise control, Air Conditioning and
Heating, Communication and Networking)
13. Urban Wild land Interface Code,
14. Performance Code,
15. Planning and Zoning Code
16. Code and Commentary
17. Elevator Safety Construction Code
18. Historical Building and Conservation Code
19. Reference Standards Code
20. Disabled Accessibility Guidebook
21. National Green Building Standard
22. Nonstructural elements code
23. Code for Special Buildings as high rise
buildings, water towers, bridges.
24. Construction Safety
25. Environmental Codes (Indoor and Outdoor
Ambience)
26. Retrofitting and Building Strengthening Code
* Codes included in NNBC

21. 3.11 Relationship between Aesthetics and Structural Safety
In several cases, the architectural shape and size artificially dictate the type of structures to
be used which violates the structurally safety provisions. The codes shall make a distinction
of the relationship between the architectural shape and structural safety requirement.
Similarly, the building shape and configuration have effect on ductility of the building and
overall safety against Earthquake Hazard.
3.12 Change in Occupancy
There are several occasions of change of occupancy category of the buildings that threaten
the safety of life and property. Recently, several of hotel buildings have changed occupancy
to supermarkets and office buildings. The residential buildings are easily used for
accommodating lower class schools, warehouses, and offices. Such changes in occupancy
required to be monitored and shall be governed by the provisions in Building Bylaws and
codes.
3.13 High Rise Buildings
The requirement of high rise buildings in terms of overall safety is different than that of low
rise buildings. The quality of materials and reliability of technology is much stringent and
operation and maintenance of the service require higher degree for reliability. This
requirement should be covered by NNBC.
3.14 Detailing of Joints
The use of facede materials as granite, glass panels and traditional decorative bricks (Dachi
Apa) requires inclusion of detailing of joints with main structure in order to warrantee the
safety during Earthquake. The details of connection of infill walls, parapet walls, sunshades
and main frames shall be considered.
3.15 Quality Monitoring and Advertisement Market
The current practice of quality assurance of materials and their use in construction is getting
in mess. There is no uniform method of quality monitoring exits except for the voluntary
application of quality standards at the large scale project level. The materials in the market
are dominated by commercial advertisement irrespective of applicability of the products to
the specific job and requirement of quality parameters. More the advertisement materials are
misleading to the consumers since the information provided in the advertisements are not
correct or not applicable to the situation at the particular job. The business community
exploits the consumers for their lack of knowledge understanding and ignorance, and lack of
institutional approach towards monitoring the advertisement materials.
3.16 Supervision of Construction Works
This is one of the weakest parts of implementation of NNBC and NS. The qualification of
Human resources being engaged in supervision and quality of materials and equipment
required to be addressed.

22. 3.17 Building Material Handling, storage and use
The Safety of public and labor during material handling, storage and use is not taken care of.
Use and handling of hazardous materials as fuel and electricity and other inflammable
materials shall be considered with special care. The sales of cement, steel, brick and sand at
public places are harmful to health.
3.18 Specification of other Materials not mentioned in NNBC
There are several other building materials that are commonly used in the market whereas
these materials are not included in the Codes or Standards. There should be a mechanism
where these new materials and technology could be permitted for use under the code
provisions.
3.19 Mechanism for addressing Technical issues and data bank
The mechanism for addressing technical issues on provision of codes, standards,
specification and construction technology is lacking. Similarly, data on experts on
Earthquake Safety and Building Code matters are not consolidated. A data bank on Code
and Earthquake Safety matters will be extremely helpful including the development of a
library for collection of important reports and research works.
3.20 Participation of masons, stakeholders, owners
The participation of stakeholders directly involved in the project as masons, owners and
other stakeholders in code making and updating is lacking.
3.21 Info dissemination and Interactions
Information dissemination on code related issues are not adequately made. The information
rarely reaches the concerned stakeholders as professional societies and entities. The
information on the codes and standards shall be discussed with the stakeholders at length for
making the codes more effective and popular.
3.22 Construction Safety
The Construction safety is dealt in NNBC 114: 1994. However, it is limited to certain items
and major safety issues as responsibility and accountability of safety is not considered. At
the same time several items as formwork, reinforcement, concreting, equipment operation
and many more are not included.
3.23 Ownership of Design and Intellectual Property rights
The ownership of the designer over the design and intellectual property right of the designer,
the contractor and major technology suppliers is not covered by NNBC. This will be an
important aspect to be included in the Building Code.

23. 3.24 Education
The education in Engineering Colleges is based on course books and seldom referred to the
NNBC or other codes and remained more academic and not pragmatic. The use of code
provisions shall b encouraged for practical classes. The colleges are the best places for
building awareness on need for use of codes and standards.
3.25 Capacity of personnel, qualification
The qualification of the administrators of the codes at municipality level is another issue.
The application of codes is ignored since there is lack of adequate human resources with
knowledge of Codes. Equally, important is the qualification of the designers who are
basically responsible for compliance with the codes. This qualification requirement shall be
applicable to the contractor’s staff as well.
3.26 Licensing of Skill Labor
Licensing of Skilled construction workers, inspectors, supervisors and professionals should
be adopted with provision of appropriate training addressing the requirement of quality
monitoring.
4 Implementation of Codes and Standards
The current practice of implementation of codes and standards is very poor. Particularly, this
is correct since there is no institution that is responsible for monitoring the implementation of
the Codes and the roles and responsibilities of various entities involved are not defined in
context of application of NNBC and NS. Appropriate Institutional Arrangement for
continuity of follow up for upgrading NNBC will be required. NNBC has certain provision
of Water Supply, Sanitation and Plumbing (NNBC208:2003), Electrical Safety (NNBC
207:2003), and Fire Code (NNBC 107:1994) but these codes are seldom used for granting
the Building Permit.
4.1 Water Supply and Sanitation
There is no code related to water supply.
4.2 Electrical Code
Electrical Safety Code (NNBC 207:2003) provides certain guideline for electrical details to
be made. However the need for detailed electrical diagram including wiring details is not
strongly spelt out and monitoring of safety shall be considered. Nepal Electricity Authority
makes certain verification of the house wiring prior to providing connection to the city
supply.
4.3 Fire Safety Code
The Fire Safety Code as provided by (NNBC 107:1994) is limited in application of certain
provisions as fire alarm and other appurtenances. The requirement for design consideration
and selection of building material based on Fire Grading of the Building category is not
included.

24. 4.4 Use of NNBC 205: MRT
The municipality licensed designers widely use these codes for all construction beyond the
limit of MRT for building of larger sizes as well.
Equally, MRT is extensively used for rural construction. It shall be said that this document is
a very useful one but need to be very cautious since the designers in urban areas particularly
are misusing this document and threatening the safety. The minimum size of column of
9”x9” recommended in NNBC is considered inappropriate for construction and LSMC is
adapting 9”x12”, and changed the concrete grade from M15 to M20.
It was referred that while better examples of standard typical designs to be made available
for replication where permitted, MRT itself should not be a part of the Bylaws, Codes and
Standards.
5 Review of NNBC
5.1 Review of NBC 000: 1994 State-Of-The Art Design And NBC 105: 1994
Seismic Design Of Buildings In Nepal
5.1.1 General
Seismic design of buildings constitutes the principal component of the building codes. The
purpose is to reduce or mitigate the damage due to future earthquakes. It has been well
recognized that the single most important development in reducing earthquake losses in the
world has been the incorporation of seismic design provisions into the building codes. The
seismic codes of various countries are in a state of continuous evolution in research and
changes in construction practice.
The history of building code and hence the seismic design of buildings in Nepal is at
tender age compared to the same of other countries. The need for national building code in
Nepal was first strongly felt following the substantial loss and damage due to Udayapur
earthquake of 1988. The preparation of the building code was initiated in early nineties and
published officially only in 1994. The general response to the code has been lukewarm
since its inception, and is in a state of model building code rather than a national building
code in terms of legal status.
Substantial advance have been achieved in the knowledge related to seismic resistant
design of buildings and structures during the past 15 years since the publication of the
National Building Code of Nepal. Changes in seismic design provisions in seismic codes
of different countries from 1994 to the present date are many and far reaching in their
impact. Part of the reasons for such changes has been to incorporate the lessons learned
from the devastating large earthquakes. Inclusion of the lessons learnt from 1994
Northridge and the 1995 Kobe earthquakes have been the major highlights of 1997 edition
of Uniform Building Code with a considerable change in 1994 edition of UBC. Since then
the large earthquakes of Gujarat (2001 January), Sumatra-Andaman (2004 December),
Kashmir-Kohistan (2005 October) and China (2007) have resulted into devastating loss
and damage, imparting the new lessons to be incorporated in the next future seismic codes.
The lessons learnt from the past earthquakes, rapid development in the technology and

25. researches in the area of Earthquake Engineering have resulted into sophisticated seismic
codes in developed countries. The recent editions of National Earthquake Hazards
Reduction Program (NEHRP) Provisions following the custom of updating in a cycle of
three years substantiate the fact. The recommended provisions incorporated in ‘The
NEHRP Recommended Provisions for Seismic Regulations for New Buildings’ have
increasingly been adopted in recent times by model codes and standards. If in United
States, there is a custom of revising the codes every three years, it may be not that easy in
case of developing countries like Nepal. The revised edition of the Indian standard Criteria
for earthquake resistant design of structures IS 1893(Part 1) 2002 came into light replacing
IS 1893: 1984 only after a period of 18 years. However, it should be recognized that the
updating of design documents like the codes is a dynamic process, and shall be
materialized as soon as possible to further reduce and mitigate the possible losses in future
earthquakes. In view of this, it is urgently needed that the present code on seismic design
of buildings in Nepal is carefully reviewed with an objective of removing any deficiencies,
errors or scope for misinterpretation. Moreover, development of commentaries or
explanatory handbook on the code to explain the provisions with solved examples is of
utmost importance to solicit a favorable response from users.
5.1.2 NNBC 000: 1994 Requirements For State-Of-The Art Design
NNBC 000: 1994 basically describes the preface of the building code preparation and
philosophy behind the need for seismic design of buildings in Nepal. It describes and
advocates for, in general, four different levels of sophistication of design and construction,
namely, International state-of-art, Professionally engineered structures, Buildings of restricted
size designed to simple rules-of-thumb, and Remote rural buildings where control is
impractical. Accordingly, the NNBC 000: 1984 contains four separate parts describing the
requirements for each category of the design sophistication. The categorization of the design
and construction is highly influenced by the typology of buildings prevalent then in Nepal and
appears highly overwhelmed by the fact that the first ever building code should be generous to
accommodate the unsophisticated and un-engineered design. It implies the poor status of
design capability and exposure to building codes and standards. It calls for a need to not only
to revise regularly but also ascertains that the provisions are drafts standards for adoption by
NBSM. The content of NNBC 000: 1994 could have been a set of good guidelines
incorporated in local building regulations or byelaws. Since a national building code also
represents the status and sophistication of design and construction embracing latest research
and technological developments, it should not only emphasize but also concentrate only on the
International state-of-art.
A building code is a set of rules that specify the minimum acceptable level of safety for
buildings and other constructed objects. The main purpose of the building code is to protect
public health, safety and general welfare as they relate to the construction and occupancy of
buildings and other structures. The Building Code becomes the law of a particular
jurisdiction when formally enacted by the appropriate authority. Generally the codes are
meant for regulating building activity which may be recommendatory or mandatory
depending upon the authorities issuing these. Compliance to the building code is
mandatory when it is covered in Building Byelaws, Regulations, Acts, Rules, etc. issued
by the National Government and various regional or local authorities.
Building Codes are generally intended to be applied by architects and engineers, but are
also used for various purposes by safety inspectors, environmental scientists, real estate
developers, contractors, manufacturers of building products and materials, insurance
companies, facility managers, disaster management personals, and others.

26. The practice of developing, approving, and enforcing Building Codes is different from one
country to another. In some nations Building Codes are developed by the governmental
agencies or semi-governmental standards organizations and then enforced across the
country by the national government. Such codes are the National Building Codes, and they
enjoy a mandatory nation-wide application. In the countries, where the power of regulating
construction is vested in local authorities, a system of Model Building Codes is used.
Model Building Codes have no legal status unless adopted or adapted by an authority
having jurisdiction. In some countries, each municipality and urban development authority
has its own building code, which is mandatory for all construction within their jurisdiction.
Such buildings codes are variants of a National Building Code, which serves as model
code proving guidelines for regulating construction activity. The degree to which national
building codes and standards are enforced by law varies from country to country, as stated in
the Foreword of the Code, however it was intended that its implementation be enforced
through the Parliamentary Bill Act and concerned, local authority by-laws. In the above
scenario, it has become very important to establish the status of the building code. It is to be
noted that Building Byelaws, in relation with Building Codes, are mandatory rules and
guidelines for construction activities, issued normally by governmental agencies or
authorities with jurisdiction. Byelaws reflect the legal status of the document, and are
regulatory in nature. National Building Code or Model Building Code may be included as
an essential part of Building Byelaws; however, building codes may not contain the
byelaws. In view of this the philosophy of various levels of requirements depending upon
the design sophistication are more relevant to the byelaws to be enforced by the central or
local authorities. It is always preferable to maintain the distinct boundaries between
existing building byelaws/building regulations and building codes to avoid the confusion.
The sanctity of the building code, different from building byelaws and building
regulations, and in its turn, the seismic design of buildings shall be retained by focusing on
the international state-of-art.
It is important to understand the expressed or implied purpose of a particular design
document in order to fully appreciate its provisions. Although the basic purpose of any
seismic code is to protect life, the way that this purpose as well as any additional purposes,
presented can provide additional insight into the reasons for the presence of specific
provisions in the body of the document and its intended audience. The document shall be
free, as far as possible, of ambiguous or confusing statements or provisions. The following
paragraph describes some of issues to be resolved under NNBC 000: 1994:
 The background of the development of the building code and the philosophy of seismic
design could be reasonably incorporated in the introductory part of Seismic Design of
Buildings or even in that of National Building Code itself. The requirements for the
Professionally engineered structures (Part II), Buildings of restricted size designed to
simple rules-of-thumb (Part III), and Remote rural buildings where control is impractical
(Part III) along with minimum design requirements based on the flow chart (Figure 1) shall
be left out for building regulations or building byelaws. The requirements for the
International state-of-art is the main part, based on which the Seismic Design of
Buildings evolves. The need for a separate code on the remaining issues is not
justifiable.
 Labeling the Building Code or part of it as draft standards belies the purpose of the
document, and weakens the position of the code executing agencies in the
enforcement of the building code.

27.  Ambiguous statements shall be removed unless a necessary clarification is provided to
avoid the scope for misinterpretation. The return periods mentioned for the onset of
damage of a typical building and for the strength of building as 50 years and 300 years
respectively, in 1.2 Seismic Design under Part 1, need a clarification or rephrasing.
 Incomplete sentences in the document of importance shall be avoided. The sentence
starting with “The basic philosophy for…” and ending in blanks, in 1.2 Seismic Design
under Part 1, fails to express the principal objective of the seismic design.
 The language and the format of clauses and provisions in a building code deserve a
formal/legal style rather than those of a technical report. The paragraphs following the
subheading 1.3 Other Loads under Part 1 appear like parts of a report with a little
regard for other Nepalese Standards.
 Mere referring the Indian Standard Codes of Practice for design in materials like
concrete, steel and masonry does not serve the purpose of popular use and enforcement
of Nepal National Building Code. IS 456: 1978 Indian Standard Code of Practice for
Plain and Reinforced Concrete has been revised into the Fifth revision IS 456: 2000
Indian Standard Code of Practice for Plain and Reinforced Concrete. Similarly the
detailing requirements included in IS 4326: 1993 Indian Standard Code of Practice for
Earthquake Resistant Design and Construction of Buildings have been modified and
incorporated in a separate detailing code IS 13920: 1993 Indian Standard Code of
Practice for Ductile Detailing of Reinforced Concrete Structures subjected to Seismic
Forces. Since the present building code of Nepal is not explicit about which Indian
Standard Codes, referred ones or revised ones, to be adopted, the designers along with
other stake holders obviously will be in dilemma.
 Due reference to Nepalese Standards without using the adjective – draft, and without
the background of their development, is most preferable. The Nepalese Standards, such
as for Wind Loads (NNBC 104: 1994), Steel Design (NNBC 111: 1994), Un-
reinforced Masonry (NNBC 109: 1994) and others shall be reviewed and improved, no
matter assistance from which international codes or publications has been derived, so
that these could be treated with respect as Nepal’s own Standards and essential
components of the National Building Code.
 Due weightage needs to be given to international coordination among the standards and
practices prevailing in different countries in addition to relating it to the practices in the
field in Nepal.
5.1.3 NNBC 105: 1994 Seismic Design Of Buildings In Nepal
Background and purpose of the code
The important information regarding the preparation of the code including its history of
development, need of the document development/improvement and the purpose of seismic
design shall be described under Foreword. Due credit shall be given to the documents and
codes, which have been used and referred in the development of the code.
The present form of Foreword needs to be enhanced with changes in terms of content and
description. The name of sub-heading - design procedure and its content stating as the
minimum design requirements for the seismic design of structures do not match; referring just
to the section under the scope does not say any thing about the design procedure nor about the
minimum requirements.

28. The special emphasis on the need for application of the code in conjunction with IS 4326 –
1993, under sub-heading – Related Codes is not appreciable for two reasons. Firstly, the status
of IS 4326 – 1993 in India has been changed with most of the contents being separately
transferred into newly developed codes. The statement in the para implies that NNBC 105:
1994 can not be used without referring IS 4326 – 1993. In principle, emphasis should be on the
need of developing such basic standards or codes. Alternatively, the relevant provisions shall
be incorporated, separately as clauses, in the seismic design code itself. Naming recent editions
of IS 4326 – 1993 or other relevant national and international codes or documents as reference
materials will be more appreciated. Moreover, details of the Standards, preferably developed
for Nepal, which are necessary adjuncts to the Seismic Design of Buildings in Nepal shall be
listed elsewhere in the code.
The absence of the Commentary, forming an accompanying volume to the code, makes it
difficult to substantiate the requirement of using the code in association with the Commentary
as given under sub – heading- Commentary.
Scope
The requirements presented under the section of scope of the present code sound conservative.
Instead, the scope of the code should be general and broad in terms of seismic load assessment
on various structures and seismic resistant design of buildings. The basic provisions shall be
applicable to buildings, elevated structures, industrial structures, dams, bridges and other
structures. The scope may not include the construction features of those buildings for which
separate standards will have to address.
Terminology
The terms used in the seismic design and their definitions given in the present code should be
extended. Since the code is the sole principal document for earthquake resistant design of
buildings it will be preferable to include basic terms and their definitions related with
Earthquake Engineering in general to shed light on basic seismological aspects, as well as
Earthquake Engineering related with buildings. Basic terms related with damping, modes,
spectra, PGA, importance factor, intensity and magnitude of earthquake, liquefaction,
maximum considered earthquake, normal modes and modal characteristics, seismic weight,
zone factor and others related with basic Earthquake Engineering shall be included. It is also
necessary to incorporate more terms related with building such as base, center of mass and
rigidity, design eccentricity, base shear, bracing systems, lateral load resisting elements,
principal axes, P- effect, storey drift, storey shear, soft storey and others.
Symbols
The symbols used in the present code may be retained with the extension or revision as the
method improved or altered. However, some terms used in the symbols may be changed, for
example, fundamental time period is more suitable than translational period Ti. There is
perhaps a typographical error in meaning the symbol Fp –design seismic force for elements
and components designed in accordance with 8.
General Principles of Design
The general principles described under the present section 3 of the code could be elaborated
with the important features of seismicity and basic assumptions of seismic design.

29. It is necessary to include the general principle adopted regarding the ground motion, its
features in relation with the earthquake source characterizations including the sizes of the
earthquake.
It will be favorable to describe the seismic design approach adopted in the code. The generally
accepted principle of seismic resistant design of buildings is that structures should be able to
withstand minor earthquakes without damage, withstand moderate earthquakes without
structural damage but with some non-structural damage, and withstand major earthquakes
without collapse but with some structural as well as non-structural damage. These widely
quoted objectives, however, are unstated in many codes including the current NNBC 105:
1994. Instead, the principal objectives are stated, for example, the Uniform Building Code
UBC 1997 states an overall objective of safeguarding life or limb, property and public welfare.
Although the definitions of minor, moderate and major earthquakes are variable, they
generally relate to the life of the structure, and the consequences of failure. The major
earthquake level defined in most of the codes of the world has a recurrence interval of 475
years, which corresponds to a 10% probability of exceedence in 50 years that is commonly
accepted to be the expected life of a building. The corresponding service level earthquake for a
typical building would have a recurrence interval of 10 years and a 99.3% probability of being
exceeded in 50 years.
There is also a need to mention about the design approach in relation with consideration of
lateral force in each of the two orthogonal horizontal directions, and approach regarding
consideration of earthquake load in vertical direction. It shall also include the approach and
corresponding provision regarding simultaneous occurrence of wind or flood, soil-structural
interaction and change in usage of the building.
Design Methods and Load Combinations
There must be a valid logical reason for need of Limit State Method of design for reinforced
concrete design and recommending Working Stress Method for other structural materials. At
this juncture of improvement, it will be preferable to explore the design methods available and
recommended in other codes and adopt the design method most appropriate for the country. In
general, most of the countries have adopted Limit State Method or Strength Method replacing
Working Stress Method for Concrete as well as Steel, the two principle structural materials.
The provision regarding the increase in allowable soil bearing pressure by up to 50 percent
when earthquake forces are considered along with other design forces according to 4.3 of the
present code may be too un-conservative and ambiguous in application. Elaboration of the
clause is required about in what condition 50% increase can be considered, and in what
condition lower values, which are to be mentioned, of increment can be considered. IS 1893
(Part 1) : 2002 recommends the increase in allowable soil bearing pressure from 25 to 50%
depending upon the soil type (hard, medium or soft ) and the type of foundations (piles, raft,
combined, isolated and well).
The design load combinations included in the present code for Working Stress Method as well
as for Limit State Method seriously require reworking. It is well recognized that the load
factors, recommended are based on the reliability levels assumed in the structures. For
example, it appears too un-conservative to have load factor for dead load as 1 and for live load
1.3 in case of Nepal. The uncertainties due to non-uniformity of materials, workmanship,
quality control seem to be ignored in the load factor for dead load. The uncertainties in
overloading is covered by maximum 1.3 may not be practical in the condition of Nepal. IS 456
: 2000, for example, considers 1.5 for both the dead load and the live load. Similarly the
maximum load factor value for seismic load considered is just 1.25, both in combination with

30. 0.9 times dead load, as well as in combination with dead load and 1.3 times live load. The
value of 1.25 is too low in view of the large uncertainties involved in assessment of the
seismic load. Furthermore, the recommendation for adoption of partial safety factors as per
Table 12 of NNBC 110: 1994 contradicts the provision of 4.5 of Seismic Design Code.
Method of Seismic Design
The present seismic code recommends two methods of earthquake analysis, namely, Seismic
Coefficient Method and Modal Response Spectrum Method.
The bulk of seismic resistant buildings are designed using equivalent static lateral forces to
represent the effects of ground motion due to earthquake on buildings. It is from the
assumption that equivalent static forces can be used to represent the effects of an earthquake
by producing the same structural displacements as the peak earthquake displacement response.
The application of this method is limited to reasonably regular structures. The present code
restricts the use of this method for structures up to 40 m height, and should also mention the
condition of regularity.
The dynamic analysis shall not be confined to the response spectrum method. There must be
an optional provision for Time History Analysis also. The conditions for need of using Modal
Response Spectrum Method (Dynamic Analysis) are listed, which are basically related with
irregular configuration. Due to absence of definition and classification of irregularity, the users
of the code will be confused. It is desirable to include clauses that define and describe different
types of irregularity (horizontal, vertical, stiffness, mass, geometric and others). By such
definitions a clearer picture and effect of soft storey and weak storey will be available.
The formula for determination of seismic coefficient has been changing in the seismic codes of
the world. However, the base shear due to ground motion has all the time been the product of
the seismic coefficient and the mass of the structure. The principal code factors used in
deriving static lateral forces, for a long time, have basically been:
Z A numeric value representing the seismic zoning
I An importance factor representing the importance of the structure,
especially in terms of use following a major earthquake.
C A factor representing the appropriate acceleration response spectrum value.
S A factor representing the effect of local soil conditions on the spectral
response of the ground
W The mass of the structure, including an assessment of live load
K A factor representing the performance of the structure depending on the
brittleness or ductility of the structure These values are combined in general
form for base shear:
V = ZICKSW
This formula for base shear has been for a long time popular. However in course of
evolution the formula for the seismic coefficient has been changing. The formula for the
seismic coefficient presented in the present NBE 105: 1994 considers all the above factors
except S-the factor representing the effect of local soil conditions on the spectral response
of the ground. This effect has been considered, like in other codes, in the response spectra
drawn for different (basically three) types of soil. Thus the expression for the seismic
coefficient is given in equation 8.1. Similarly, the equation 8.2 for the expression for the

31. design response spectrum, in which the ordinate of the basic response spectrum for the
natural time period, is multiplied by ZIK.
It has been a trend in the codes of the world to drop the performance factor K and replace it
by reciprocal of R, response reduction factor, a factor dependant on the building type and
its ductility level. The adoption of the response reduction factor leads to a realistic values
of acceleration from which the design forces are obtained by dividing the elastic forces by
it. It implies that the design force is much lower than what can be expected in the event of
a strong earthquake (Jain 2003).
The replacement of the factor K by the factor 1/R may result into a logical estimation of
the seismic coefficient, and alternate expressions derived in recent editions of codes or
documents like NEHRP shall be given a thought for the new edition of the code.
Computing dynamic response instead of using static forces is becoming increasingly
common as higher powered computing facilities are being available in design offices.
Since there is no restriction of building height and irregularity the dynamic analysis
appears to be simpler in application and yields more logical and accurate results. However,
special care shall be taken into consideration about conservative provision in some
international codes. Some codes require checking of the dynamic analysis results by
seismic coefficient method. Some documents like IS 1893 (Part 1) : 2002 require
comparing the base shear with the base shear calculated using the fundamental time period
calculated using the empirical formula recommended for static approach, and if the base
shear from dynamic analysis is less than the base shear calculated using the time period
from the empirical formula, all the dynamic responses shall be up-scaled multiplying by
the ratio of the two base shears. It again implies the dominance of the seismic coefficient
method over the dynamic analysis.
Seismic Hazard Level and Response Spectrum
Estimate of the design ground motion is the most important and complicated part of the
seismic design code development. Estimates of the design ground motion are necessarily
controversial and uncertain. It is more important to the structural designer that this is
understood than for him to attach some particular significance to any ground motion
parameter used in his design. However there is a strong argument for conservatism in the
assessment of ground motion input, and the use of high confidence level.
NNBC 105: 1994 does not present any elaborate information on the seismicity of the
country. It would be favorable to include at least maps showing epicenters of past
earthquakes, principle tectonic features, geological features including principal lithological
groups, and seismic zones, all of which are well documented by the Department of Mines
and Geology, Nepal. Pandey et al. (2002) has presented seismic hazard map of Nepal as a
result of probabilistic seismic hazard analysis The document presents the contour of
seismic hazard at the bedrock of Nepal for a return period of 500 years, indicating 10%
probability of exceedence in 50 years.
The design values of ground motion parameter such as Peak Ground Acceleration (PGA)
for different regions of the country are presented either in a tabular form (GB 50011-2001)
or attaching relevant maps like in IBC 2006 in the codes. It is necessary to do the same in
NNBC 105: 1994 also since the seismic hazard for the code was determined based on the
probabilistic seismic hazard analysis. The seismic codes adopting probabilistic approach of
hazard estimation use the hazard levels in terms of Maximum Considered/Capable
Earthquake (MCE) as in NEHRP (2003) and IBC (2006), and Design Basis Earthquake
(DBE) as in ATC (1978) and UBC (1997). The MCE and DBE represent 2% probability of

32. exceedence in 50 years with a return period of 2500 years and 10% probability of
exceedence in 50 years with a return period of 475 years respectively.
The seismic hazards considered in earlier editions of NEHRP and UBC 97 (1997) had a
recurrence interval of 475 years (Design Basis Earthquake) corresponding to a uniform 10
percent probability of exceedance in 50 years, which is commonly accepted to be expected
life of a building. The NEHRP(1997) and IBC2000(2000) had changed the Design Basis
Earthquake(DBE), and since then have been using the Maximum Considered Earthquake
(MCE) to represent the seismic hazards in the provisions.. The MCE represents the seismic
hazard that has a recurrence interval of 2500 years corresponding to a uniform 2%
probability of exceedence in 50 years. The design earthquake according to the provisions
of NEHRP(2003) and IBC 2006 (2006) is two-thirds of the MCE. Comparison of the
provisions of 1994 or older editions with 1997 or later editions of the NEHRP Provisions
reveals that, a structure designed by the 1994 or older editions of NEHRP Provisions is
believed to have a low likelihood of collapse under an earthquake that is one and one-half
times (reciprocal of two-third) as large as the design earthquake of those documents. The
same change has taken place from UBC 97 (1997) to IBC 2000 (2000). This major change
in association with other provisions indicates the newer versions of the documents tend to
be more conservative.
The seismic loading in NNBC 105: 1994 is set at a seismic hazard level having a return
period of 50 years, which corresponds to a probability of exceedence less than 45% in 30
years, which had been estimated as the economic life of a structure in Nepal, as presented
by Beca Worley International et al.(1993), The document as well reveals that the seismic
hazard level was set to be at a level approximately equal to that defined in the Indian
Standard, that is, IS 1893: 1984. The design earthquake level set hence is too un-
conservative and strongly needs a major revision for the following reasons:
i. The service life of buildings in Nepal estimated as 30 years is far from reasonable,
instead it must be 50 years.
ii. It is unfair to set the seismic hazard level for Nepal heavily banking upon the
earthquake level stipulated in IS 1893: 1984, which has already been revised into IS
1893 (Part 1): 2002 with a different value of design earthquake value. The Indian
Standard has yet to adopt probabilistic format of seismic hazard analysis.
iii. The provisions in the present code have been developed in reference with mainly low
rise buildings with short natural periods, where as long period structures are
increasingly becoming prevalent.
iv. The seismic design lateral load calculated for short period structures as 0.08, when
compared with the basic horizontal seismic coefficient for zone V of IS 1893: 1984,
found the same as 0.08. But the value according to the revised IS 1893 (Part 1): 2002
will be 0.09 against 0.08.
The response spectra and the zoning factors largely depends on the design earthquake
levels, and hence will be different as the seismic hazard levels change.
The broad classification of soil conditions into three types is universally accepted.
However, the definition and requirements of each type of them shall be more practical and
recognizable.
Static Method (Seismic Coefficient Method)
The seismic base shear V along any principal direction is determined by the expression: