To understand the behaviour of structure due to live load or moving load, it is necessary to understand the concept of influence line.

An Influence line represents the variation of structural response function (support reaction, shear force, bending moment or deflection etc.) due to change in the position of a concentrated load on the span (such as bridges, cranes, conveyor etc.). A plot of the influence line vs the load position is known as influence line diagram.

It is important to understand the difference between influence line diagram and the shear or moment diagram. Influence line represent the effect of moving load only at a specified loaction on a member, while shear and moment diagrams represent the effect of dead load (fixed load) at all point along the axis of the structural member.

Please watch our following video lecture about moving load analysis

Video Lecture on Analysis of Moving Loads
This video lecture is about developing influence line diagram for shear force and bending moment to do analysis of structures in case of moving loads.

Video Lecture on Maximum Shear Force at a section due to a series of moving loads
This video lecture explains the trial and error procedure for determining the value of maximum shear force at a section due to a series of moving loads. It includes a solved example also.

Video Lecture on Maximum Bending Moment at a given section due to a series of moving loads
This video lecture is about determining maximum bending moment at a given section and the absolute maximum bending moment due to a series of moving loads on a simple beam

It is also noticed that all statically determinate beams will have influence lines which are linear. Click on the following links to know more about influence line.

Procedure for developing influence line diagrams

Applications of influence line diagram

You can also use the following calculators for Moving Load Analysis

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Solved Examples on Application of equilibrium equations to find support reactions; truss member forces by method joints and method of sections.

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Solved examples on shear force and bending moment diagrams for cantilever, simply supported beam and overhanging beams.

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Solved examples on deflection of beam and truss by different methods like doble integration, Macaulay's method, energy method (unit load method).

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Solved examples on indeterminate structures by slope-deflection equation, moment distribution method, consistent deformation(compatibility)

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Solved examples for determination of strength of reinforced concrete beams (singly reinforced and doubly reinforced).