IMPACT STUDY OF CABLE-STAYED BRIDGE UNDER RAILWAY TRAFFIC USING VARIOUS MODELS

In routine bridge designs, the dynamic effects of the moving vehicles on bridges are taken into account by increasing the static loads by an impact factor. This impact factor depends on many things, and various design codes indeed give different guidance on the impact factor. This paper describes a study on the impact effects on a cable-stayed bridge under railway train loading. The cable-stayed bridge is modelled as a planar system. The rail irregularities and the geometric non-linear behaviour of the cable-stayed bridge are taken into account. The train comprises a number of cars, and numerical models of various degrees of sophistication are investigated. They include the sophisticated model comprising a 4-axle system possessing 10 degrees of freedom (d.o.f.), and the simplified models comprising a series of 2-d.o.f. mass–spring–damper systems, moving masses or moving forces. The impact factors for various speeds are evaluated using a typical cable-stayed bridge with various models for the train. The models are then reviewed in the light of such results.