Wang Yan, Hu Long, Li Wei, Zhang Guangshuai, Han Bin, Di Jin, Fei Peng, Duan Xiaofeng, Dong Jinying, Qin Fengjiang
Shandong Expressway Qingdao Construction Management Co., Ltd., Qingdao 266300, China.
Key Laboratory of New Technology for Construction of Cities in Mountain Area, School of Civil Engineering, Chongqing University, Chongqing 400000, China.
Materials (Basel). 2024 Dec 21;17(24):6252. doi: 10.3390/ma17246252.
According to the mechanical characteristics of joints in steel-concrete composite bridge decks under the combined bending and shear, improved joint details with simple structure and convenient construction were studied, including lapped U-bars, lapped headed bars, and lapped hook bars. In order to test the mechanical properties of the three joint details and compare them with the existing lapped/welded linear bars, the tests of five specimens were carried out. The cracking load, ultimate load, failure mode, crack pattern, and reinforcement strain were analyzed. The test results showed that the joint with lapped U-bars and hook bars exhibited ductile failure, while the joint with lapped headed and lapped/welded linear bars exhibited brittle failure. The cracking load of the five specimens was basically the same. The crack first occurred at the interface of pre-cast concrete and wet joints. When the ultimate bearing capacity was reached, the vertical main cracks were generated near the interface of the lapped U-bars, lapped hook bars, and welded linear bars specimens. The diagonal cracks were generated at the wet joint of the lapped headed bars specimen and lapped linear bars specimen. The lapped U-bars specimen had the highest bearing capacity, which was 22.8%, 14.2%, 50.4%, and 32.1% higher than the capacities of the lapped headed bars, lapped hook bars, lapped linear bars, and welded linear bars specimens, respectively. The load-deflection curves and crack mode obtained from the FEM of the lapped U-bars joint specimen were consistent with the test results. The bearing capacity of the FEM (351.3 KN) was 1.8% less than the test result (357.6 KN), which indicates that the bearing capacity calculated by the finite element model is reliable. There are 80 models with varying lap lengths and concrete strengths. The self-organizing migrating algorithm was used to fit the coupling effect of lap length and concrete strength. Based on doubly reinforced beam flexural capacity formulas, a bearing capacity calculation for lapped U-bars joint was proposed. The mean value of the formula calculation result and the finite element result ratio is 1.03, and the variance is 0.0004.
针对钢 - 混凝土组合桥面板在弯剪共同作用下节点的力学特性，研究了结构简单、施工方便的改进节点构造，包括搭接U形筋、搭接带帽钢筋和搭接弯钩钢筋。为测试这三种节点构造的力学性能并与现有的搭接/焊接直线钢筋进行比较，进行了5个试件的试验。分析了开裂荷载、极限荷载、破坏模式、裂缝形态和钢筋应变。试验结果表明，搭接U形筋和弯钩钢筋的节点呈现延性破坏，而搭接带帽钢筋和搭接/焊接直线钢筋的节点呈现脆性破坏。5个试件的开裂荷载基本相同。裂缝首先出现在预制混凝土与湿接缝的界面处。当达到极限承载力时，搭接U形筋、搭接弯钩钢筋和焊接直线钢筋试件界面附近产生竖向主裂缝。搭接带帽钢筋试件和搭接直线钢筋试件的湿接缝处产生斜裂缝。搭接U形筋试件的承载力最高，分别比搭接带帽钢筋、搭接弯钩钢筋、搭接直线钢筋和焊接直线钢筋试件的承载力高22.8%、14.2%、50.4%和32.1%。搭接U形筋节点试件有限元模拟得到的荷载 - 挠度曲线和裂缝模式与试验结果一致。有限元计算的承载力（351.3kN）比试验结果（357.6kN）小1.8%，表明有限元模型计算的承载力可靠。有80个不同搭接长度和混凝土强度的模型。采用自组织迁移算法拟合搭接长度和混凝土强度的耦合效应。基于双筋梁抗弯承载力公式，提出了搭接U形筋节点的承载力计算方法。公式计算结果与有限元结果的比值平均值为1.03，方差为0.0004。
