书夹型钢-混组合结构在桥梁加宽中的应用研究

Application of C-Clamp Shaped Steel-Concrete Composite Structure in Bridge Widening

为避免桥梁加宽时下部结构拓宽,减少新旧桥面纵向裂缝及铺装层损伤,提出一种以钢结构立柱及护栏、书夹式钢板、高强度螺栓为主要构件,超高性能混凝土(UHPC)为铺装层的书夹型钢-混组合结构进行桥梁加宽。为评估该组合结构在运营条件下的安全性,以厦门官浔溪大桥加宽工程为背景,通过实桥现场静载试验研究水平荷载作用下书夹型钢-混组合结构的力学性能,并与数值仿真结果进行对比,验证试验结果的可靠性。结果表明:实测结果与数值仿真结果吻合良好;书夹型钢-混组合结构关键部位荷载~位移曲线、荷载~应力曲线呈线性变化,钢结构最大拉应力约为材料屈服强度的75%,整体结构处于弹性工作阶段;螺栓预紧力有效减少了高强度螺栓的直剪作用,降低了剪切疲劳破坏风险;采用书夹型钢-混组合结构进行桥梁加宽可有效避免下部结构拓宽,改善新旧桥面纵向裂缝及铺装层损伤,具有较好的加宽效果。

This paper presents a C-clamp shaped steel-concrete composite structure for bridge widening projects,which consists of the primary components of steel baluster railing,steel C-clamp and high-strength bolts as well as the UHPC pavement,aiming to avoid the expansion of substructure while widening the bridge deck and to reduce the longitudinal cracks and pavement damages in both the new and old decks.The presented structure has been utilized in the deck widening of the Guanxunxi bridge in Xiamen.First,on-site static tests were performed to study the mechanical property of the C-clamp shaped steel-concrete composite structure under horizontal loads,and numerical modelling was carried out to verify the reliability of the test results.As per the analysis,the test results well agreed with the numerical simulation.The displacements and stresses in the key locations of the C-clamp shaped steel-concrete composite structure varied linearly with the applied loads,with the maximum tensile stress in the steel plates reaching 75% of the steel yielding strength,and the overall composite structure was in elastic stage.The pre-tightening force effectively alleviated the direct shear effect on the high-strength bolt,thereby reducing the risk of shear fatigue damage.The engineering practice proves that when the deck of an existing bridge is widened by using the presented C-clamp shaped steel-concrete composite structure,there is no need to widen the substructure of the bridge,at the same time,the longitudinal cracking and pavement damages in the new and old decks can be effectively treated and controlled,and the widening effect is sound.