竖转钢-混凝土组合拱桥PBH剪力件疲劳性能试验

针对钢箱预制、立柱拼装、转体成拱的快速施工竖转钢-混凝土组合拱桥，基于PBL提出了新型PBH剪力件。以PBH剪力件的疲劳力学性能为研究目标，开展了一组11个试件的高周疲劳试验。分析不同箍筋直径、开孔直径PBH剪力件的疲劳破坏模式和损伤演化规律，并与PBL剪力件进行比较。结果表明：PBH疲劳破坏模式为钢板开孔内混凝土在循环荷载作用下的损伤累积，裂缝发展过程中发生裂缝尖端钝化，混凝土榫局部粉末化并向下迁徙导致了钢箱与混凝土界面滑移累积并最终破坏。解剖发现孔内混凝土粉末化，与之对应的PBH静载破坏模式为混凝土榫处主裂缝在荷载增加过程中扩展延伸，混凝土榫劈裂，裂缝反射至表面导致试件破坏，二者区别明显；PBH疲劳损伤演化曲线可分为3个阶段：由黏结力和摩擦力损伤主导的损伤弹塑性阶段、由孔内混凝土裂缝积累破碎主导的损伤累积阶段以及变形累积失控后的损伤破坏阶段，损伤弹塑性阶段约占整个疲劳寿命的10%，损伤累积阶段占全部疲劳寿命的70%以上且滑移量增加缓慢，损伤破坏阶段累积滑移量急剧增加，裂缝发展，剪力件随即发生疲劳破坏，疲劳破坏表现出明显的塑性特征。PBH与PBL损伤演化规律总体相似，但PBH较PBL有更加显著的第2阶段，即疲劳破坏损伤累积过程，表明PBH剪力件在疲劳破坏过程中的塑性破坏性能更佳。

Experimental of Fatigue Behavior of PBH Connector in Vertically Rotating Steel-concrete Composite Arch Bridge

In view of the rapid construction of steel-box concrete composite arch bridges, a new type of Perfobond Hoop (PBH) shear connector is proposed based on the Perforbond Leiste (PBL). To study the fatigue mechanical properties of PBH, 11 specimens with high cyclic loading fatigue were tested. The fatigue failure model and damage evolution law of PBH with different stirrup diameters and hole diameters were analyzed and compared with PBL shear connectors. The results are as follows. The failure mode of PBH consists of damage accumulation of concrete under cyclic loading in the hole of the steel plate; crack tip passivation during crack development; and partial powderization of the concrete tenon and downward migration, leading to slip accumulation and eventually the destruction of the interface between the steel box and concrete. Anatomical observations show that the concrete powder in the hole is powdery, and in the corresponding static failure mode, the main crack in the concrete tenon expands and extends during load increase, and the concrete tenon cleavage and crack are reflected onto the surface reflect to the surface, leading to the destruction of the specimen. The PBH shear connector fatigue damage evolution curve can be divided into three stages:elastic-plastic stage, damage cumulative stage, and failure stage. The elastic-plastic stage accounts for approximately 10% of the whole fatigue life with rapidly accumulating slip. The damage accumulation stage accounts for more than 70% of the total fatigue life with slowly increasing slip. In the failure stage, the cumulative slippage increases dramatically and cracks develop, causing fatigue failure of the shear connector. The damage evolution law of PBH is generally similar to PBL, but each stage of development has obvious differences. PBH has a more significant second stage than that of PBL, which indicates that the plastic damage performance of PBH is better during the fatigue failure process.