新型UHPC-NC组合盖梁的结构设计与试验分析

Structural design and experimental analysis of new UHPC-NC composite bent cap

为了实现城市高架桥或高速公路改扩建工程超大规模盖梁的装配化、快速化施工,提出由钢板和超高性能混凝土(UHPC)制作的外壳及现浇核心混凝土(NC)组成的新型UHPC-NC组合盖梁.为了探究外壳UHPC和钢模板厚度对受力性能的影响,对不同UHPC和钢板厚度进行参数分析.分析结果表明,在自重作用下,外壳的刚度受UHPC和钢板厚度及其比例的共同影响.当张拉预应力和浇筑混凝土时,UHPC和钢板越厚,外壳的受力性能越好,但是经济性会降低,建议采用UHPC厚70 mm,钢板厚6 mm的方案.为了验证该方案的可行性和安全性,设计1∶2.5的缩尺模型,开展静力加载试验.结果表明,新型UHPC-NC组合盖梁的受力性能好,安全储备较高,可以为盖梁的装配化施工提供参考.

A new composite bent cap consisting of a shell made of steel plate and ultra-high-performance concrete(UHPC)and cast-in-place core normal concrete(NC)was proposed in order to realize the assembly and rapid construction of ultra-large-scale bent cap for urban viaducts or highway reconstruction and expansion projects.Parametric analysis of different UHPC and steel plate thickness was conducted in order to analyze the influence of the thickness of UHPC and steel mold plate on its stress performance.Results showed that the stiffness of the shell was affected by the thickness of UHPC and steel plate and their ratio together under the action of self-weight.The thicker the UHPC and steel plate are,the better the stress performance of the shell is,but the economy will be reduced when tensioning prestress and casting concrete.It is recommended to use UHPC thickness of 70 mm and steel plate thickness of 6 mm.A piece of 1∶2.5 scaled-down model was designed and static loading test was conducted in order to verify the feasibility and safety of this scheme.Results show that the new UHPC-NC composite bent cap has good force performance and high safety reserve,which can provide reference for the assembly construction of bent cap.