PBL剪力连接件粘结滑移性能的静载推出试验研究

PBL剪力连接件是组合梁桥中波纹钢腹板和混凝土上下翼缘板连接的关键构造,研究PBL剪力连接件的粘结滑移性能是连接件设计的关键环节。该文简要介绍了PBL剪力连接件的发展和研究现状,结合波形钢腹板PC组合箱梁桥工程背景,进行了4个PBL连接件的静载推出试验,分析了腹板厚度和孔径大小对连接件粘结滑移性能、极限承载能力和破坏机制的影响。实验结果表明,各个试件有相似的滑移趋势并表现出一定的延性,随着腹板厚度和连接件孔径的增大,极限承载能力增强。同时,通过对荷载和水平位移关系的分析,得到连接件的受力机理为:在受力初期,混凝土受到剪力件的力传递发生变形向外膨胀;随着荷载的增大,剪力件发生明显滑移,混凝土发生向外侧的位移。剪力连接件腹板、翼缘和钢腹板上的应变发展趋势符合加载受力的传递机理。最后,对比和分析了连接件极限承载力的理论结果和试验结果,阐述了影响极限承载力的主要因素,并且在考虑安全实用意义的基础上,提出了一个新的估算公式,可以较好地估算本次试验结果。

PUSH-OUT EXPERIMENTAL STUDY ON BOND-SLIP BEHAVIORS OF PBL SHEAR CONNECTOR UNDER STATIC LOADING

PBL shear connector is a key structure as the connection of corrugated web and flange up and down in composite bridges.The bond-slip behavior of PBL connector is significantly important for connector design.In this paper,the development of PBL shear connector is presented,and four PBL shear connector push-out tests under static loadings are conducted based on its practical application in pre-stressed concrete box-girder with corrugated steel web,in such a way the influence of the web’s thickness and the hole’s dimension is investigated on the bond-slip behavior,ultimate bearing capacity and failure mechanism.The results show that,every specimen shows similar bond-slip trend and ductility;thicker web and bigger diameter of the hole yield greater ultimate bearing capacity.Meanwhile,the relationship between the load and horizontal displacement shows that,during the preliminary loading stage,the concrete slabs expand outwards under the transferred shear load,and then distinct slip happens to shear connectors and the concrete slabs move outwards a little with the load increasing.The strain development accords with the load transformation rules from the records of strain gauges on the web,the flange of shear connectors and the steel slab.Finally,the experimental and analytical results are compared and the main influence factors on the ultimate capacity are presented,as a result,a new formula is proposed.