Live Load Model for Long Span Steel Cable Bridges Considering Traffic Congestion Scenarios

Current design live load model for bridges are mainly for short to medium span bridges. For these bridges, one very heavy truck or a few heavy trucks may give the maximum load effects. However, for long span bridges, due to long lengths of the effective influence line, different scenarios should be considered for the bridge design. Long span bridges mainly have cable- supported structures and steel girder and deck. This paper deals with the development and application of the live load model for long span steel cable bridges considering traffic congestion scenarios. New live load model was proposed based on long-term weigh-in-motion truck weight data and various traffic congestion scenarios. Weigh-in-motion data have been collected at the location near industrial complex so that the sufficient number of loaded trucks can be measured. For the accuracy of long-term data, temperature compensation had been applied by considering the front axle weights of trucks. Traffic congestion scenarios utilizes the normal sequences of trucks arriving at the bridge with the minimum headway distances between trucks and other vehicles. One, two and four lanes scenarios are developed and used in this study. Proposed new live load model consists of four-axle truck with total weight of 510 kN and uniformly distributed load in which its magnitude is decreased as the length of the effective influence line increases. The load effects of the proposed model are compared with other well-known load model in the world for long span steel cable bridges with different span lengths.