EFFECT OF INITIAL STRESS ON BEARING CAPACITY OF DUMBBELL CONCRETE-FILLED STEEL TUBE ARCH BRIDGE

The problem of the effect on the initial stress to the bearing capacity of the concrete-filled steel tube (CFST) arch bridge are constantly concerned by bridge engineers. According to the section mechanical characteristic of an arch bridge when the ultimate capacity reached, for the comprehensive consideration of the initial stress of the steel tube and the confined effect between the steel tube and the core concrete, a new method which included both the spatial solid-beam element and the general spatial beam element with the initial stress to analyze the effect on the initial stress to the bearing capacity of the dumbbell CSFT arch bridge was introduced. Based on this method, the both element stiffness matrices were given and a computing program was developed. On basis of these, the influences of the initial stress ratio, sectional steel ratio and spans and so on were comprehensively studied. The analytical results show that the bearing capacity of dumbbell CSFT arch bridge will reduce due to the existence of the initial stress of the steel tube. The maximum reduction is large than 10%. At last, a limitation to the initial stress of the steel tube and a formula of the influence factor of the bearing capacity of the dumbbell CFST arch bridge have been put forward; these are useful for engineering design and construction.