SIMULATION OF INTERNAL FORCE''''S ENVELOPE DIAGRAM FOR HIGHWAY''''S BRIDGES
公路桥梁内力包络图的仿真计算

The calculation of internal force's envelope diagram for a bridge under moving loads is a typical problem which can be solved by the computer simulation. In this paper, a computer simulation is made for the vehicle load moving on a highway's bridge with a small step length. For each step, the internal force diagram is plotted. When the vehicle load moves through the bridge, these internal force diagrams will fill in a region. The up-lower boundary of the region is just the internal force envelope diagram. The algorithm in this paper does not depend upon the concept of the influence line, hence the calculation is simple.