Analysis of Long-term Deflection of Steel-concrete Composite Beams

The theoretical model to compute the long-term deflection of simply supported steel-concrete composite beam was deduced. The model includes the effects of steel bars in concrete slab, concrete shrinkage and creep. The computed results agreed well with the test results. On this basis, the effects of factors such as concrete age to loading, longitudinal reinforcement ratio in concrete slab, concrete slab width, steel beam height, environmental yearly average relative humidity, external load value and concrete strength on the long-term deflection were discussed. The results show that the ratio of steel beam height to concrete slab thickness, as well as the concrete strength can not be ignored. The concrete age to loading, environmental yearly average relative humidity, concrete slab width, external load value have relatively bigger effect as well. But the longitudinal reinforcement ratio in concrete slab has less impact. The fruits are useful to the design and deflection control of steel-concrete composite beams.