钢-UHPC轻型组合桥面板局部修补技术试验

Experimental on Partial Repair Technology of Light-weight Composite Bridge Deck Composed of Steel and UHPC Layer

为了解决在修补钢-UHPC轻型组合桥面结构的UHPC层破损区域时遇到的UHPC层局部拆除和接缝处理难题,提出了一种通过拉拔UHPC层内钢筋来拆除UHPC破损区域的方法,设计了一种将受力钢筋焊接于钢顶板的新型局部修补接缝形式。为了证明拆除方法的可行性,利用足尺试验模型进行了指定区域UHPC层的拆除试验;为了验证新-旧UHPC接缝的受力性能,完成了纵向接缝、横向接缝的强度试验。结果表明:该拆除方法可以快速完成UHPC破损区域的拆除;新型修补接缝方法通过将接缝位置处的受力钢筋焊接于钢面板,有效提高了接缝的抗拉强度;试验测得接缝在纵桥向、横桥向的开裂应力分别为21.8,17.4MPa,接缝开裂应力分别为现浇段开裂应力的73.4%、63.9%,且明显大于传统接缝9.8MPa的开裂应力;通过对洞庭湖大桥进行有限元计算分析得到UHPC层纵桥向、横桥向的最大拉应力分别为15.4,5.4 MPa,小于接缝的实测抗拉强度,新型修补接缝完全满足该桥UHPC层最大拉应力要求。

In order to solve problems of the partial demolition and the joint treatment in repairing the damaged area in the UHPC layer of composite bridge deck,a method of dismantling damaged area by pulling out the rebar in the UHPC layer was proposed.A new design with welding tensioned bar on the steel plate as joint was provided.To prove the feasibility of the demolishing method,demolition experiments of UHPC layer in designated areas were carried out using the full-scale test model.In order to verify the mechanical performance of the old-new UHPC joint,strength tests of horizontal joints and vertical joints were completed.The results show that the method is used to dismantle the damaged area of UHPC layer quickly.The new repair joint effectively boosts the tensile strength through welding tensioned bars in the position of joint on the steel plate.The cracking stresses of horizontal joints and vertical joints are 21.8 MPa and17.4 MPa respectively,obviously larger than 9.8 MPa,the cracking stress of traditional joints.The cracking stresses of joints are 73.4% and 63.9% of cracking stresses of cast-in-place section respectively.The finite element analysis of Dongting Lake Bridge indicates that the maximum horizontal tensile stress and the maximum vertical tensile stress are 15.4 MPa and 5.4 MPa respectively,less than measured values.The new repair joint completely meets the requirement of tensile stresses in the UHPC layer.