新型组合桥墩承插式连接侧剪强度试验研究

Experimental Research on the Side Shear Strength of Novel Composite Pier with Socket Connections

研究目的:为适应桥梁下部结构绿色建造、快速建造需求,对7个新型承插式波纹钢-橡胶混凝土组合墩-基础连接试件进行竖向加载试验和有限元数值模拟,以探究连接方式、嵌入深度、栓钉和端承混凝土对装配连接节点侧剪强度的影响,在此基础上对连接节点的破坏机理和侧剪承载力展开研究。研究结论:(1)相同嵌入深度下,试件采用承插式连接较整体现浇侧剪承载力提高了36%,增加嵌入深度和增设端承混凝土有助于进一步增大侧剪承载力,增设栓钉能够增强环向抗剪区强度;(2)竖向荷载作用下装配区混凝土与波纹钢管形成“强机械咬合”使节点处于类三向受压状态,从而侧剪强度得到较大提升;(3)引入波纹增强系数K以考虑“强机械咬合”作用对节点侧剪强度的贡献,K值大小为0.12~0.18,波形是影响K值大小的关键指标,结合节点受力状态提出的侧剪承载力公式计算结果与试验值、模拟分析值吻合良好;(4)基于塑性应力分布法考虑水平荷载作用给出的端承混凝土最小厚度计算公式可为波纹钢组合墩承插式节点设计与应用提供技术支撑。

Research purposes: In order to meet the demand of green construction and rapid construction of bridge substructure, this paper carried out vertical loading tests and finite element numerical simulations on 7 novel corrugated steel-rubberized concrete composite pier-foundation specimens with socket connections to explore how connection types, embedment depths, shear studs, and end-bearing concrete affect their connect strength. Also, we studied the failure mechanism and side shear capacity of the proposed pier-foundation connections. Research conclusions:(1) Socket connections have a 36% higher side shear capacity than integrated connections with the same embedding depths. Side shear capacity is increased by increasing embedding depths and adding end-bearing concrete. Similarly, shear studs in joint areas may strengthen circumferential shear zones even more.(2) When subjected to vertical loads, the "quasi-three-direction" compression state greatly improves the joint’s side shear strength, which is achieved through the "strong physical interlock" of concrete and steel corrugates.(3) The coefficient K, named as the corrugation enhancement coefficient, is proposed to assess the contribution of "strong physical interlock" to side shear strength. K’s value ranges from 0.12 to 0.18, and the waveform is the primary indicator that influences K. Based on the stress state of the joints, a formula for shear capacity is proposed, and the calculation results agree well with the experiment and simulation analysis.(4) A formula for the minimum thickness of end-bearing concrete is proposed, based on the plastic stress distribution method and taking lateral load into account, which can provide technical support for the design and application of corrugated steel composite pier with socket connections.