Bridge Design and Building

Modelling forces on a bridge

 

The forces pushing and pulling on parts of a bridge when a load is placed on the bridge are called compression (pushing) and tension (pulling). These forces can be modelled using software.

 

Different truss designs have advantages and disadvantages when it comes to the distribution of forces on parts of the bridge.

 

Task

 

Your task is to model the distribution of forces on different kinds of trusses (shown below).

 

pratt truss                                                     warren truss

 

 

 

 

 

 

 

K truss                                                          howe truss

 

 

 

 

 

 

Use the modelling java applet at at the Johns Hopkins University Engineering Department and instructions to help you.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Keep the span and load the same if you can.

 

Which type of truss do you think is the most stable when a load is applied in the centre of the bottom chord? Why?