UHPC锚固区传力性能试验与拉压杆模型分析

Experimental Study on Load Transfer Behavior of UHPC Anchorage Zone and Analysis of Strut⁃and⁃Tie Model

针对公路桥梁中应用2300 MPa级超高强钢绞线可能导致锚固区劈裂的问题,以预应力混凝土小箱梁的梁端锚固区为研究对象,开展超高性能混凝土(Ultra-High Performance Concrete,UHPC)和普通混凝土锚固区传力性能试验并对比二者的抗裂性能,建立三维有限元模型分析锚固区的应力分布,构建静定拉压杆模型分析UHPC超高强预应力锚固体系的劈裂效应。结果表明:应用UHPC超高强预应力锚固体系是可行的;与普通混凝土相比,UHPC锚固区的开裂荷载更高,裂缝发展更缓慢,抗裂性能好;基于静定拉压杆模型,计算得到小箱梁UHPC超高强预应力锚固区内的劈裂力为873 kN,结果偏安全,可用于指导梁端的配筋设计。

Aiming at the problem that the application of 2300 MPa ultra-high strength steel strands in highway bridges may lead to cracking in the anchorage zone,a three-dimensional finite element model was established to analyze the stress distribution in the anchorage zone of prestressed concrete small box girders by conducting load transfer behavior test on the anchorage zones of ultra-high performance concrete(UHPC)and ordinary concrete.A strut-and-tie model was constructed to analyze the splitting effect of UHPC ultra-high strength prestressed anchor system.The results show that the application of UHPC ultra-high strength prestressed anchor system is feasible.Compared with ordinary concrete,UHPC anchorage zone has higher cracking load,slower crack development,and better crack resistance.Based on the statically determined strut-and-tie model,the splitting force in the UHPC ultra-high strength prestressed anchorage zone of the small box girder is calculated to be 873 kN,which is relatively safe and can be used to guide the reinforcement design of the girder end.