Truss Bridge Analysis Using Influence Line Diagram

Influence line diagram for truss bridge is different from that for girder bridge. First of all, due to the nature of truss, there is only one force i.e. axial force acting in members. For this reason, we only have one influence line diagram for each member, as opposed to two or three for a girder (shear and moment, and axial if exists).

Load cases are established based on the possible loading location on the truss bridge. For each case, unit load is applied, and the member forces are determined. This process goes on until all cases are analysed. Then, the axial force in members for under the load cases is plotted and eventually, an influence line diagram is produced.

The following shows the procedure to analyse truss bridge using influence line diagram. Watch the video above for full details.