超高性能混凝土桥面板湿接缝受力性能试验研究

Experimental study on mechanical behavior of wet joints in ultra-high-performance concrete decks

沾临黄河特大桥是山东省沾化至临淄高速公路在建的一座主跨480m的斜拉桥,采用钢箱梁+超高性能混凝土(UHPC)桥面板构成的组合梁。针对UHPC桥面板的湿接缝,开展了两系列足尺模型试验,包括一组简支板试件和一组两跨连续板试件。重点研究了燕尾榫湿接缝、带钢板增强的燕尾榫湿接缝和梳齿湿接缝的受力性能,测试并分析其荷载-挠度响应、开裂行为、破坏模式,以及应变的发展与分布。结果表明,含钢板增强的燕尾榫湿接缝抗裂性能最优,与整浇板相当,较传统的燕尾榫湿接缝有显著提升;无增强的湿接缝的抗裂性能较整浇UHPC有明显削弱,名义开裂应力劣化一半以上。此外,钢板增强构造可有效加强燕尾榫湿接缝,甚至实现高于整浇板的承载性能和延性。将梳齿湿接缝布置于连续板中支座会导致承载力有一定降低,这对于内力较小的横桥向是可接受的。提出了含湿接缝的UHPC板的抗弯承载力计算方法,与文献中已有的方法相比具有更高的准确性。

Yellow River Bridge of Zhanhua-Linzi Highway,a cable-stayed bridge with span length of 480 m,adopted the composite girder composed of steel box beams and ultra-high-performance concrete(UHPC)deck slabs.Two series of full-scale tests were conducted on the wet joints of UHPC deck slabs,including a group of simply supported slabs and a group of double-span continuous slabs.Experimental investigations mainly focused on dovetail-shaped wet joints,dovetail-shaped wet joints with reinforcing steel plates and comb-shaped wet joints.The load-deflection response,cracking behavior,failure mode,the development and distribution of strain were tested and analyzed.Results indicate that the dovetail-shaped wet joints with reinforcing steel plates have the good crack resistance,which is close to that of integrally cast slabs and is much better than that of conventional dovetail-shaped wet joints.Compared with integrally cast UHPC,wet joints without reinforcing steel plates possess much worse crack resistance with their nominal cracking stresses decreased by over 50%.Moreover,the reinforcing steel plates can effectively strengthen the dovetail-shaped wet joints,even achieving better capacity and ductility compared with integrally cast slabs.Placing a comb-shaped wet joint at the intermediate support of continuous slab will result in a certain decrease of capacity,but it is acceptable for the transverse direction with relatively small internal forces.The method for calculating the bending capacities of UHPC slabs with wet joints is proposed,which has higher accuracy compared with the existing methods.