负弯矩区PBL剪力连接件剪切性能试验研究  

Experimental study on shear performance of PBL shear connector in negative moment region

作　　者：邹杨[1,2] 彭洪波[1,2] 张中亚 蒋金龙 余坤 Zou Yang;Peng Hongbo;Zhang Zhongya;Jiang Jinlong;Yu Kun(State Key Laboratory of Mountain Bridge and Tunnel Engineering,Chongqing Jiaotong University,Chongqing 400074,China;School of Civil Engineering,Chongqing Jiaotong University,Chongqing 400074,China)

机构地区：[1]重庆交通大学山区桥梁及隧道工程国家重点实验室,重庆400074 [2]重庆交通大学土木工程学院,重庆400074

出　　处：《土木工程学报》2023年第10期52-66,共15页China Civil Engineering Journal

基　　金：国家自然科学基金青年基金(52008066);海南省重大科技计划项目(ZDKJ2021048);西藏自治区科技计划项目重点研发计划(XZ202001ZY0054G)。

摘　　要：当PBL剪力连接件应用于连续组合梁负弯矩段等拉应力区时,拉应力场是影响其抗剪性能的关键因素。为明晰拉应力对组合结构桥梁负弯矩段中圆孔形PBL连接件的影响规律,该文设计并开展5组共12个PBL连接件推出试验,研究当混凝土板处于拉应力场时连接件的剪切性能和承载机理。试验结果表明:与压应力场下的连接件相比,处于拉应力下的连接件开裂荷载更小且裂缝发展得更快,这是由于拉应力场降低了混凝土榫的约束程度,加快了混凝土的损伤发展。当试件处于拉应力场时,无贯穿钢筋连接件的极限承载力、抗剪刚度分别是压应力场连接件的0.78倍、0.89倍,有贯穿钢筋连接件的极限承载力是压应力场连接件的0.93倍,两者抗剪刚度较为接近,说明贯穿钢筋的存在能一定程度上缓解拉应力对连接件力学性能的“削弱”作用。对于处于拉应力场的连接件,当纵向钢筋配筋率从0.75%增加到1.88%时,其抗剪承载力增幅为9.57%,抗剪刚度增幅为40.12%,同时试件的横向裂缝显著减少。原因是更加密集的纵向钢筋增强了混凝土榫的约束程度,抑制了混凝土在拉应力作用下的损伤和开裂,进而提高连接件的抗剪承载力和抗剪刚度。最后,基于试验结果和有限元分析,提出考虑拉应力场和纵向钢筋配筋率影响的混凝土榫抗剪承载力折减系数,并对现有各抗剪承载力公式进行修正。When the PBL shear connector is applied to tensile stress field such as the negative moment region of a continuous composite beam,the tensile stress field is the key factor affecting its shear resistance.To clarify the effect of the tensile stress on the circular hole-shaped PBL connectors in the negative moment region of the composite structure bridge,the push-out tests on 12 PBL of 5 groups were designed and carried out to investigate the shear performance and load-bearing mechanism of PBL shear connectors when the concrete slab is in the tensile stress field.The test results show that the cracking loads of PBL shear connectors under tensile stress shall be smaller and the cracks may develop faster than those of PBL shear connectors under the compressive stress field,because the tensile stress field reduces the confinement of the concrete dowel and accelerates the damage development of concrete.When the specimens are in the tensile stress field,the ultimate bearing capacity and shear stiffness of connectors without perforating rebar are 0.78 times and 0.89 times those of the connectors in the compressive stress field,respectively.The ultimate bearing capacity of the connectors with perforating rebar is 0.93 times that of the connector in the compressive stress field.The shear stiffness of the two types of connectors is relatively close,indicating that the presence of perforating rebar can alleviate the‘weakening'effect of tensile stress on the mechanical properties of the PBL shear connectors to some extent.For the PBL connectors in the tensile stress field,when the longitudinal reinforcement ratio was increased from 0.75%to 1.88%,the shear load capacity of the PBL connectors was increased by 9.57%,and the shear stiffness was increased by 40.12%.During the process,the number of transverse cracks of the specimens was significantly reduced,because the denser arrangement of longitudinal reinforcement may enhance the confinement of the concrete dowel,inhibit damaging and cracking of the concrete under tensile str

关 键 词：桥梁工程 钢-混凝土组合结构 PBL连接件 负弯矩区 推出试验 

分 类 号：TU398.9[建筑科学—结构工程]