兰张高铁十八里堡特大桥56 m UHPC组合简支梁设计研究

Design and Research of 56 m UHPC Composite Simple Supported Beam of ShiBaLiBao Super Large Bridge of Lanzhou-Zhangye High Speed Railway

UHPC材料是一种新型纤维增强水泥基复合材料,利用其力学性能高的特点建造桥梁后可以实现桥梁结构轻型化。国内公路和市政桥梁中均已有应用先例,而铁路桥梁主体结构未见应用。兰州至张掖高速铁路十八里堡特大桥拟建造56 m UHPC组合简支梁桥,以解决大跨度混凝土桥梁地震响应大这一技术难题,十八里堡特大桥UHPC简支梁的建造应用将拓宽国内铁路桥梁建设中主体结构只有钢和混凝土两种建筑材料的限制。该桥已完成设计研究分析,研究结果表明:(1)拟建造应用的56 m UHPC简支梁仅为同等跨度普通混凝土梁梁重的72%;(2)提出UHPC组合薄壁简支梁剪力键的主要构造形式;(3)提出UHPC组合简支梁的主要施工方法;(4)建立UHPC组合简支梁双层梁有限元计算模型,分析UHPC薄壁箱梁受力特征,计算分析UHPC与普通混凝土组合梁相对收缩效应和相对徐变效应。

UHPC is a new fiber enhancement cement-based composite material.The light weight of bridge structure can be realized by using the high mechanical properties of the material.There have been precedents in domestic highway and municipal bridges,but not yet in the main structure of railway bridges.In order to solve the technical problem of large-span concrete bridge with large seismic response,a 56 m UHPC composite simply supported beam bridge is proposed for the Shibalibao Super Large Bridge of Lanzhou-Zhangye High Speed Railway.The construction and application of this bridge will widen the limitation that only steel and concrete can be used in the main structure of railway bridges in China.The design research and analysis of the bridge have been completed.The research results show that:(1)The 56m UHPC simply supported beam to be constructed and applied is only 72%of the weight of the ordinary concrete beam of the same span;(2)The main structure of the shear connector of UHPC composite thin-walled simply supported beam is put forward;(3)The main construction method of UHPC composite simply supported beam is proposed;(4)The finite element model of UHPC composite simple supported double-layer beam is established to analyze mechanical characteristics of UHPC thin-walled box beam,and the shrinkage effect and relative creep effect of UHPC and ordinary concrete composite beam are calculated and analyzed.