CE 72.32 (January 2016 Semester): Lecture 1b: Analysis and Design of Tall Buildings using Commercial FE Programs

Dr. Pramin Norachan
Manager, Structural Engineering Unit, AIT Consulting
Affiliated Faculty, Structural Engineering, AIT
CE72.32 Tall Buildings
Modeling, Analysis and Design Tall
Buildings using Commercial Finite
Element Programs

1. Introduction
2. Commercial Finite Element
Software
3. Basic Concepts of Finite
Element Software
4. Modeling, Analysis and Design
of Tall Buildings
5. Sequential Construction Cases
6. Wind Loads
7. Seismic Loads
8. Piles, Spring Supports and
Foundations
9. Design
Presentation Outline

To introduce commercial finite
element programs used for
analysis and design of tall
buildings.
To provide an understanding of the
concepts, techniques and
technologies in modeling, analysis
and design of RC tall buildings
using FE programs.
Objectives

Dr. Pramin Norachan 5
Structural Mechanics
Statics Dynamics
Rigid Body Deformable Body
Statics
(Rigid Body)
Mechanics of
Materials
Structural Analysis
Matrix Structural
Analysis
Continuum or
Advanced
Mechanics of
Materials
Advanced Structures
Dynamics
(Rigid Body)
Structural Dynamics
Earthquake EngineeringWind EngineeringFinite Element
Commercial FE programs (SAP2000, ETABS, STAAD Pro, ANSYS, ABAQUS, etc.)
Rigid Body Deformable Body
UndergraduateGraduate
RC,PC, Timber, and
Steel Designs
Adv. RC,PC, and
Steel Designs

STRUCTURAL ENGINEERING IS
THE ART OF USING MATERIALS
That Have Properties Which Can Only Be Estimated
TO BUILD REAL STRUCTURES
That Can Only Be Approximately Analyzed
TO WITHSTAND FORCES
That Are Not Accurately Known
SO THAT OUR RESPONSIBILITY WITH RESPECT TO
PUBLIC SAFETY IS SATISFIED.
Adapted From An Unknown Author
Edward L. Wilson
Professor Emeritus of Structural Engineering (The original developer of CAL, SAP and ETABS series of computer programs)
University of California at Berkeley
Three-Dimensional Static and Dynamic Analysis of Structures
A Physical Approach With Emphasis on Earthquake Engineering

Tall Building
2 Story House
Stadium
Offshore Structure
Warehouse
Bridge

Architectural
Functional Plans
Structural System
Trial Sections
Modeling
Analysis
Revise Sections
Member Design
Acceptable
Connection Design
Detailing
Final Design
Yes
No
Conceptual Design
Modeling and Analysis
Design and Detailing

MahaNakhon Tower (314 m)Baiyoke Tower II (304 m)

Dr. Pramin Norachan Dr. Pramin Norachan
Researches Structural Analysis and Design
ABAQUS SAP2000, ETABS, PERFORM3D,
CSIbridge
ANSYS STAAD Pro
ADINA MIDAS
DIANA ROBOT
NASTRAN SASC
15

Structural and Earthquake Engineering Software
Computers and Structures, Inc. (CSI)
www.csiamerica.com

Integrated software for structural analysis and design

Integrated software for structural analysis and design
Ferris wheel

Integrated analysis, design and drafting of building systems

Integrated 3D bridge design software

Nonlinear analysis and performance
assessment for 3D structures

Integrated design of flat slabs, foundation and spread footing

Design of simple and complex reinforced concrete columns

How do the FE programs work?
Creating the model
(Pre-process)
Reporting results
(Post-process)
Analysis of the
Structure (FEM)
A, E
A, E
Displacements
Stresses
1 2 3
36

1) Line Elements : Truss and Beam Elements (1D, 2D, 3D)
2) Surface Elements : Plane Stress, Plane Strain, Plate and
Shell Elements (2D, 3D)
3) Solid Elements (3D)
37
Element Types

Real Structures
Solid Model 3D Shell-Frame 3D Frame
2D Frame
There are various ways to model a real structure
2D
3D
38
Concepts of Structural Modeling

Cable Structures
Line Structures
Surface Structures
Solid Structures
- Cable Stayed
- 2D/3D Trusses
- 2D/3D Frames
- Plate, Shell
- Plane Stress
39
Structural Types

Tall Buildings Columns : Frame elements
Which types of elements will we choose to
model structures?
Floors : Plate or Shell elements
Suspension
bridges
Main Towers : Frame elements
Decks : Frame, Plate or Shell elements
Cables : cable elements
(Line structures)
(Surface structures)
(Line structures)
(Line structures)
(Line or surface structures)
Beams : Frame elements
(Line structures)
40

EXCITATION STRUCTURE RESPONSES
Loads
- Gravity (DL, LL)
- Wind
- Earthquake
Vibrations
Settlements
Thermal Changes
(Static of Dynamic) (Elastic or Inelastic)
F = K × Δ
Displacements
Strains
Stresses
Stress Resultants
(Internal Forces)
- Axial Force
- Shear
- Moment
(Linear or Nonlinear)
DESIGN

EXCITATION STRUCTURE RESPONSES
(Loads) (Stiffness)
F = K × Δ
(Deformation)
F
F
K
K
Δ
Δ
F K 
F
K
 

Dr. Pramin Norachan Dr. Pramin Norachan
Gravity Load Lateral Load
Moment
Shear
Moment
Shear
F
F
F
F
F
F
F
F
43

46
Create the structure Assign Supports Assign Material
Properties and
Section
Assign Loads
Hinge Roller
6.00

47
Assign Supports Perform Analysis Perform Design
3.00 3.00
3.00
3.00
3.00
3.00
stress
strain
E, v
Concrete
Steel
(Concrete,
Steel, Others)
W
W
W
W
F
F
F
F
Fix Fix Fix
M(+) M(+)
M(-)M(-) M(-)
Draw Grid Line Define Material
Properties
Define Sections Draw the Structure
Assign Loads
1 2 3 4
5 6 7 8
1 2,3 4 5,6 7 8

50
E, v
Define Material
Properties
2

53
Line Element Area Element
Draw the Structure4

55
Point Load
Line Load
Area Load
Assign Loads6

61
• Static Load Cases
- Dead Load (Sequential Construction : D)
- Live Load (L)
- Wind Load (W)
- Equivalent Static Load Cases (E)
Load cases are defined by the user and used for
analysis purpose only
• Dynamic Load Cases
- Response Spectrum Load Cases (E)
- Time History Load Cases (E)
Load Cases

62
Sequential Construction Cases

Deflection
63
Moment
89.843.5
Linear Sequential

64

65

66
- Live Load (L)
- Wind Load (W)
Load Cases

Severe damage to an office building caused by Hurricane Andrew (1992)

Torsional Flutter of the Tacoma Narrows Bridge (1940)

Vertical variation of external wind pressure coefficient Cp with respect to plan aspect
ratio L/B.

- Live Load (L)
- Wind Load (W)
77
Load Cases

Pressure loads on
Surrounding areas
Point loads at the
center of diaphragms
Wind Pressure Point loads at
column nodes
1 2 3

79
Point loads at the
2

80
Point loads at the
2

81
Pressure loads on
Surrounding areas
3

82
Pressure loads on
Surrounding areas
3

83
Pressure loads on
Surrounding areas
3

84
Pressure loads on
Surrounding areas
3

A reinforced concrete house in Chiang Rai
collapsed due to a strong earthquake event.

The other wood house which is
located nearby the first RC
house can stand over the
earthquake event.
There was no structural
damage which could be
observed.
The first reason is possible due
to the light weight (mass) of the
wood building, which produced
the less seismic force. The
second reason is due to the
wood structure is very flexible,
which can perform with large
deformation.

m
2
k
u
gu
2
k c
(a) Moving Base
m
2
k
u
( ) ( )eff gp t mu t 
2
k c
(b) Stationary Base
( ) ( )eff gp t mu t 
Effective Earthquake Force, ( )effp t
0 ?m 
0 ?gu 

89
Seismic Load
1) Equivalent Statics 2) Response Spectrum 3) Time History
- Static approach
- Simple regular structures
- Low-to-medium-rise
building
- Dynamic approach
- All structures
- Suitable for structural
design
- Dynamic approach
- All structures
- The most accurate analysis
- Both linear and nonlinear
- Based on fundamental
mode
- Linear analysis
- Linear analysis - Take time for analysis
- Difficult to combine the
results

- Live Load (L)
- Wind Load (W)
90
Load Cases

- Live Load (L)
- Wind Load (W)
92
Load Cases

- Live Load (L)
- Wind Load (W)
96
Load Cases

Piles, Spring Supports
and Foundations

100
The fist model is used for finding number of piles and preliminary
designing the foundations based on loads at the supports.
The model with Normal Supports

The Model with Piles
The second model is included both piles and
foundations. The internal forces of piles which are used
to design pile detailing can be known by perform the
linear analysis for this model. 101

Equivalent Spring Supports
Actual pile
embedded in soil
102
𝐾𝑣 = 𝐹𝑣 ∆ 𝑣
𝐾ℎ = 𝐹ℎ ∆ℎ
𝐹𝑣
𝐹ℎ
∆ 𝑣
∆ℎ
𝐾𝑣
𝐾ℎ
Soil represented
by lateral spring
Pile modeled
with lateral
spring
Pile deformation
under applied
loads
𝐾 = 𝐾𝑠 × 𝐴ℎ
𝐾

The Model with Spring Supports
This model can be used for foundation design by
exporting the foundation floor to SAFE, and it will be
used for analysis and design in the remaining works.
103

Programs for Structural Design
- Beams
- Columns
- Shear Walls
- Arbitrary shape
Columns
- Composite Columns
- Slabs
- Post tension
Slabs
- Foundations

Structural Modeling
Siri@Sukhumvit

Design for Parts of the Structures
Water tank
Mat
Foundation
Floor
Transfer
beam
Roof
Structures

Swimming
pool
Guard house
Project road
Fence
Design for Parts of the Structures

Demand Force (D) ≤ Structural Capacity (C)
u nF F
1.0u
n
FD
C F
 
Strength Design Method (SDM)

No. Load Combinations Description
1 1.4 DL Dead load
2 1.2 DL + 1.6 LL Gravity load
3 1.2 DL + 1.0 LL + 1.6 WL Wind load (compression)
4 0.9 DL + 1.6 WL Wind load (tension)
5 1.2 DL + 1.0 LL + 1.0 EQ Seismic load (compression)
6 0.9 DL + 1.0 EQ Seismic load (tension)
ACI 318-08 (Strength Design Method) : SDM
Load factor on the live load LL in No. 3 and 5 shall be permitted to be reduced
to 0.5 except for all areas where LL is greater than 500 kg/m2.

No. Load Combinations Description
1 DL Dead load
2 DL + LL Gravity load
3 DL + 0.75 LL + 0.75 (0.6 WL) Wind load (compression)
4 0.6 DL + 0.6 WL Wind load (tension)
5 DL + 0.75 LL + 0.75 (0.7 EQ) Seismic load (compression)
6 0.6 DL + 0.7 EQ Seismic load (tension)
ASCE 7-10 (Allowable Stress Design)

Member Items Demand (D) Capacity (C) Design Concept
Pile Number of
piles
Service load
combinations
(including footing
weight)
Ultimate pile load → Calculate from
soil report
Safe load =
Ultimate load
SF
SF ≈ 2.0 – 2.5
RC Design Ultimate load
combinations
(including footing
weight)
D
n
C

( )n
n
n
PMM
F
V



 

  


Compression
Tension 1.0u
n
FD
C F
 
F
uF

Footing RC design Ultimate load
combinations
(including footing
weight)
Column
above
footing
RC design Ultimate load
combinations
(including footing
weight)
n
n
n
M
F
V





 


1.0u
n
FD
C F
 
uF
uF
1.0u
n
FD
C F
 One-way shear
Punching shear
n
n
PMM
F
V



 

  


Compression
Tension

Beam/
Stair
combinations
Column/
Shear
wall
combinations
One-way
slab
combinations
Two-way
slab
combinations
n
n
n
M
F
V




 

1.0u
n
FD
C F
 
uF
uF
1.0u
n
FD
C F
 
n
n
PMM
F
V



 

  


Compression
Tension
uF
n
n
n
M
F
V




 

1.0u
n
FD
C F
 
uF
n
n
n
M
F
V





 


1.0u
n
FD
C F
 One-way shear
Punching shear

2
n s y
a
M A f d 
 
  
  0.85 '
s y
c
A f
a
f b

• Flexural Design
• Shear Design
n c sV V V   
'
0.53c cV f bd 
v y
s
A f d
V
s
 
 
  
 

Dr. Pramin Norachan
Manager, Structural Engineering Unit, AIT Consulting
Affiliated Faculty, Structural Engineering, AIT
Thank You

CE 72.32 (January 2016 Semester): Lecture 1b: Analysis and Design of Tall Buildings using Commercial FE Programs

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CE 72.32 (January 2016 Semester): Lecture 1b: Analysis and Design of Tall Buildings using Commercial FE Programs