钢管初应力对哑铃型钢管砼拱桥承载力影响分析

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

钢管初应力对钢管砼拱桥承载力影响一直是工程界关注的问题。根据拱桥达到极限承载力时拱圈截面受力特点,为综合考虑钢管初应力及钢管与核心砼之间套箍效应的影响,提出综合应用了包含初应力的实体-空间梁单元和空间梁单元来计算哑铃型钢管砼拱桥承载力的新方法,并推导了相应的刚度矩阵,编制了计算程序。在此基础上,分析了不同初应力系数、不同含钢率和不同跨径等因素对哑铃型钢管砼拱桥承载力的影响规律,计算结果表明,钢管初应力使哑铃型钢管砼拱桥承载力降低,最大降低值可超过10%。为便于工程设计和施工参考,该文最后提出了考虑初应力影响时哑铃型钢管砼拱桥钢管初应力限值和承载力影响系数计算公式。

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.