钢-UHPC组合梁斜拉桥多尺度有限元分析与试验研究

Multi-scale Finite Element Analysis and Experimental Study on Cable-stayed Bridge with Steel-UHPC Composite Beams

为确保富龙西江特大桥的新型钢-UHPC桥面板具有足够的抗裂性能和极限承载力,首先通过多尺度有限元分析计算出最不利工况下的应力状态,包括采用全桥杆系有限元模型计算第1体系应力和采用局部精细有限元模型计算第2体系应力。然后,开展了一系列钢-UHPC组合桥面板及其湿接缝的足尺模型试验,验证了桥面板系统在上述应力状态下的可行性。试件包括1块简支整浇钢-UHPC组合板、1块两跨连续整浇钢-UHPC组合板、1块带燕尾榫湿接缝的简支钢-UHPC组合板。有限元分析结果表明:第1体系和第2体系的应力叠加后,钢箱梁的最大纵向应力为156.04 MPa,最大横向应力为48.18 MPa;UHPC的最大压应力为21.67 MPa,最大拉应力为3.88 MPa。足尺模型试验的结果表明:湿接缝是桥面板的薄弱部位;燕尾榫湿接缝的名义开裂应力为10.2 MPa,比整浇UHPC低41.4%,但仍达到了有限元分析所得最大拉应力的2.6倍,表明抗裂性能有足够的富余度;所有试件均发生延性良好的弯曲破坏,由于开裂后的承载能力储备充足,在一定限度内的超载工况下不会发生破坏。综合有限元分析和试验的结果可知,富龙西江特大桥在运营阶段的受力状况良好,不存在桥面板开裂风险,钢箱梁处于弹性受力状态。

In order to ensure the steel-UHPC composite deck of Fulong Xijiang bridge has sufficient crack resistance and ultimate capacity,multi-scale finite element analysis is conducted first to calculate the stress state under critical load case,including the global stresses analysis by using a line-element-based global model and the local stresses analysis by using an elaborate local model.Subsequently,in order to further verify the feasibility of deck system under the aforementioned stress state,a series of full-scale tests on the steel-UHPC composite slab and its wet joint is carried out.The tested specimens include a simply-supported integrally-cast steel-UHPC composite slab,a two-span continuous integrally-cast steel-UHPC composite slab and a simply-supported steel-UHPC composite slab with a dovetail-shaped wet joint.The finite element analysis result shows that(1)after the superposition of the global and local stresses,the maximum longitudinal and transverse stress of steel box girders are 156.04 MPa and 48.18 MPa respectively;(2)the maximum compressive and tensile stresses of UHPC are 21.67 MPa and 3.88 MPa respectively.Full-scale experimental result shows that(1)the wet joint is the weak position of deck slab;(2)the nominal cracking stress of dovetail-shaped wet joint is 10.2 MPa,which is 41.4%lower than that of cast-in-situ UHPC,but it still reaches 2.6 times of the maximum tensile stress obtained by finite element analysis,indicating that there is enough surplus in cracking resistance;(3)all specimens experience ductile flexural failure,which will not fail under some overloading cases because of sufficient ultimate capacity after cracking.The combination of finite element analysis results and experimental data demonstrates that Fulong Xijiang bridge works well under service loads.The deck slabs have no risk of cracking,and the steel box girders are under the elastic stage.