Steel - Concrete Composite Structure In The Steel Truss Reinforcement Applied Research,

In last century 50s, our country have built many steel-truss bridges and most of them have still been used. But they all need to strengthening in order to improve their load-carrying ability to fit the modern communication. It is a core topic which many engineers want to solve it. According to the feature of them, the paper think can use steel-concrete composite structure to strengthen steel-truss bridges. So ,the author had done the followings:The paper generalize the two method of design steel-concrete beam, including two ways: one is elastic theory, the other is plastic theory and also compare the two from principle, scope of use, analytical method. The former fit to calculate the structures' regular service absolute state, and the next can used in calculating limit bearing capacity.The paper discusses shear key's species, test of bearing capacity and elastic theory and plastic theory. It shows that there is not difference in shear key's distribute when the key's numbers is equality.For steel-concrete composite continuous beam, the section at fulcrum is infirmness. This paper make emphasis on that we must ignore the concrete board when you calculate the beam's stiffness at the 0.15/ scope.At last, the thesis describes Wubao Huanghe steel truss bridge's loading test and strengthening program. The author analyzed the effect after strengthening through the Madis/civil finite element program. We know the main member bar's force, the section's biggest deflection and amplitude of vibration will decrease after strengthening by analyzing(the maximum deflection can be 45%). These can proof the program's effects are significant and can give the engineers reference.