This document presents a study that aims to simplify the process of determining train load effects on bridges. It analyzes simply supported bridges with spans ranging from 5m to 40m under IRC Class A, AA and 70R train loadings. Equivalent uniformly distributed loads are used to calculate maximum bending moments and shear forces at different span locations. Charts are developed showing variations in bending moment and shear force with span length. These charts allow bridge engineers to easily determine design forces for different load cases, improving efficiency over traditional load placement calculations. In conclusion, the charts make it simple to identify critical sections and ensure structural adequacy under shifting single train loads.

1. 744 International Journal of Earth Sciences and Engineering
ISSN 0974-5904, Volume 04, No 06 SPL, October 2011, pp. 744-747
#020410364 Copyright © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved
Simplification for train loading on bridges
Akash Agrawal
Student College of Engineering Pune-411005,Email:akassh90@gmail.com
Sreyashrao S
Student College of Engineering Pune-411005, Email:sreyash05@gmail.com
B. M. Dawari
Assistant Professor College of Engineering Pune-411005, Email: bal_dawari@yahoo.co.in
ABSTRACT: While designing bridge - deck, placing of the live load i.e. to obtain maximum value of design forces
becomes quite tedious for different class of loading. It is not always possible to spend that much time for such a
calculation. Hence, there is a need to develop some design tables which may become quite handful tool for bridge
engineer. In the present work simply supported span varying from 5m to 40m are considered for single and two lane
bridges. IRC loading of class A, class AA and class 70R are used during analysis. The impact factor on these loadings is
not considered as the same that can be applied on the final calculations. The maximum bending moment and shear force
vale are computed using equivalent uniformly distributed load concept. Finally, charts are prepared to obtain maximum
design forces for various load cases enumerated as per IRC.
KEYWORDS: - Live load, Design forces, IRC loadings, Equivalent loading.
INTRODUCTION: The actual loads are
considered to be axle load from engine and
bogies.. The Equivalent UDL Values depend upon the
span length. However, in case of rigid frame,
cantilever and suspension bridges, it is necessary for
the designer to proceed from the basic wheel loads.
Normally, bridges on national IRC Class AA loading
consists of either a tracked vehicle of 70 tonnes or a
wheeled vehicle of 40 tonnes with dimensions. The
units in the figure are mm for length and tonnes for
load. Normally, bridges on national highways and
state highways are designed for these loadings.
Bridges designed for Class AA should be checked for
IRC Class A loading also, since under certain
conditions, larger stresses may be obtained under
class A loading. Class A loading consists of a
wheel load train composed of a driving vehicle and
two trailers of specified axle spacings.
The loadings for the various classes are as follows:
Class 70 R Loading
Class A Loading
The cases used in the design consideration when the
loads are applied at the given position. The loadings
consist of series of loads and these point loads must be
shifted to verify the maximum bending moments and
the shear forces. The cases imply:
Case 1: The first load in the series.
Case 2: The second load in the series.
Case 3: The third load in the series.
Case 4: The fourth load in the series.
Case 5: The fifth load in the series.
Case 6: The sixth load in the series.
The graphs obtained for the various spans at the given
sections are as given below

2. 745Simplification For Train Loading On Bridges
International Journal of Earth Sciences and Engineering
ISSN 0974-5904, Volume 04, No 06 SPL, October 2011, pp. 744-747
THE SHEAR FORCE VARIATION CHARTS
Class 70 R Loading
For Class 70 R loading the shear force variation with
span at 0.1 L
For Class 70 R loading the shear force variation with
span at 0.2 L
For Class 70 R loading the shear force variation with
span at 0.3 L
For Class 70 R loading the shear force variation with
span at 0.4 L
For Class 70 R loading the shear force variation with
span at 0.5 L
THE SHEAR FORCE VARIATION CHARTS FOR
CLASS A LOADING
For Class 70 R loading the shear force variation with
span at 0.1 L
For Class 70 R loading the shear force variation with
span at 0.2 L
For Class 70 R loading the shear force variation with
span at 0.3 L

3. 746 Akash Agrawal, Sreyashrao S, B. M. Dawari
International Journal of Earth Sciences and Engineering
ISSN 0974-5904, Volume 04, No 06 SPL, October 2011, pp. 744-747
For Class 70 R loading the shear force variation with
span at 0.4 L
For Class 70 R loading the shear force variation with
span at 0.5 L
THE BENDING MOMENT CHARTS
For Class A loading the bending moment variation with
span at 0.1 L
For Class A loading the bending moment variation with
span at 0.2 L
For Class A loading the bending moment variation with
span at 0.3 L
For Class A loading the bending moment variation with
span at 0.4 L
For Class A loading the bending moment variation with
span at 0.5 L
BENDING MOMENT VARIATION FOR CLASS
AA LOADING
For Class AA loading the bending moment variation
with span at 0.1 L

4. 747Simplification For Train Loading On Bridges
International Journal of Earth Sciences and Engineering
ISSN 0974-5904, Volume 04, No 06 SPL, October 2011, pp. 744-747
For Class AA loading the bending moment variation
with span at 0.2 L
For Class AA loading the bending moment variation
with span at 0.3 L
For Class AA loading the bending moment variation
with span at 0.4 L
For Class AA loading the bending moment variation
with span at 0.5 L
CONCLUDING REMARKS
With the help of above charts it becomes very easy to
determine the bending moments and shear forces acting
on the various spans of the bridges in case of a single
train loading for Class 70 R, Class A, Class AA. The
bridge can hence be designed for the maximum bending
moments and shear forces acting on the various points
as the load keeps on shifting and hence the critical
sections can easily be indentified and precautions can
be taken to avoid the load failure in such cases. In the
present work simply supported span varying from 5m
to 40m are considered for single and two lane bridges.
IRC loading of Class A, Class AA and Class 70R are
used during analysis. The impact factor on these
loadings is considered here the same that can be
applied on the final calculations. The maximum
bending moment and shear force value are computed
using influence line diagram. Finally, charts are
prepared to obtain maximum design forces for various
load cases enumerated as per IRC.
REFERENCES
[1] Standard Specifications and Code of Practice for
Road Bridges Section:II Loads and Stresses
(4th
Revision) Indian road Congress:21-2000
[2] Standard Specifications and Code of Practice for
Road Bridges Section:IIICement Concrete
Plain and Reinforced 3rd
Revision Indian
road Congress:6-2000
[3] Design Criteria for Prestressed Concrete road
Bridges Post Tensioned Concrete III Revision
Indian Road Congress:18-2000
[4] Indian Standard Code Of Practice For Prestressed
Concrete(First Revision)-IS:1343-1980
(Reaffirmed 2004) Edition 2.1
[5] Design of Prestressed Concrete Bridges –N
Krishna Raju – Oxford and Hill Publications,
4th
Edition.
[6] The Design of Prestressed Concrete Bridges –
Robert Benaim-Francis and Taylor
Publication,4th
Edition
[7] Prestressed Concrete Bridges –C Menn-Springer-
Verlag,Wien,Publication-1986
[8] Design of Bridge Structures-T. R. Jagadeesh, M.
A. Jayaram-PHI Learning Pvt. Ltd., 2004