What effect does stress have on a steel arch deck truss bridge?
It depends on the structure added. If you reroute traffic to double capacity then how are you going to hold all that traffic? If you increase the road bed then you increase the ‘dead’ load; which is the load that has to be constantly held and thus increase the load on the bridge. If you put in another road deck on top then you are doubling the weight and inviting collapse. If nothing else the foundations wouldn’t be able to support the load and so would sink. If you are simply making tighter lanes and pushing more cars across then you have increased the ‘live’ load. In the case of bridges the live load is usually only a fraction of the ‘dead’ load so that may not be such a big problem. However, the added stress and shaking caused by the increased traffic could be a major problem. The Minnesota I-35W Bridge didn’t collapse because the loading was changed but because the bridge was allowed to wear out. The bridge, like many in the US was old and had too many cracks in it. The scary part
