钢管混凝土箱形叠合超高墩设计与静力性能分析

Design of CFST-RC High-Rise Piers and Static Performance Analysis

为了解钢管混凝土箱形叠合超高墩的设计理念和结构静力性能,以金阳河特大桥为背景,分析该类桥墩各部分作用和受力特性,并开展静力性能研究。该类桥墩内部的钢管混凝土格构柱为主要受力结构,并作为外包钢筋混凝土施工的劲性骨架;各柱肢钢管外包薄层钢筋混凝土以提高桥墩承载力;连接各柱肢的钢筋混凝土腹板参与抗剪。采用MIDAS Civil软件分析对比钢管混凝土箱形叠合超高墩和钢筋混凝土薄壁空心超高墩的静力性能。结果表明:最大悬臂施工阶段和成桥阶段,钢管混凝土箱形叠合超高墩的一阶弹性稳定系数大于钢筋混凝土薄壁空心超高墩;从墩顶向墩底分段增大钢管管径和壁厚,可使钢管和外包混凝土应力沿墩高方向不变;外包混凝土应力远小于钢筋混凝土薄壁空心超高墩,可采用较薄的低强度混凝土。

To examine the design concept and structural performance of the high-rise pier with CFST reinforced concrete box section(the CFST-RC high-rise pier for short),the Jinyang River Bridge is cited as an example to analyze the function and load bearing behavior of each part of the pier of this type and to study the static performance as well.The lattice column inside the pier that is formed of concrete-filled steel tubes is the main load bearing structure and also acts as the stiffening skeleton in the construction of the external reinforced concrete.Each steel tube is encased with a thin layer of reinforced concrete to improve the load bearing capacity of the pier and the reinforced concrete webs of each pier column also contribute to the overall anti-shearing capacity.The software MIDAS Civil was used to compare the static performance of the CFST-RC high-rise pier and that of the RC thin-walled hollow high-rise pier.The results indicate that the elastic stability coefficient of first mode vibrations of the CFST-RC high-rise pier is bigger than that of the RC thin-walled hollow high-rise pier in the longest cantilever construction state and the completed bridge state.When the diameter and wall thickness of the steel tubes are increased from pier top to pier base section by section,the stresses in the steel tubes and the concrete can keep the same along the pier height.The stresses in the encased concrete are far less than the stresses in the RC thin-walled hollow high-rise pier.Therefore,it is feasible to employ the thin layer of low-strength concrete.