Long-term Mechanical Properties Of Steel-concrete Connector Subjected To Corrosion And Load Coupling

Steel-concrete composite structures are composed of steel girders and concrete slabs connected through shear connectors.These structures have numerous advantages,such as their stiffness,light weight,and easy construction.Steel-concrete composite structures can fully utilize the tensile properties of steel and the compressive performance of concrete with significant technical and economic effects,which has made them popular for use in modern bridge construction.But the effects of environmental corrosion and load can easily lead to the degradation of the mechanical behaviors of the critical component of steel-concrete composite beams,that is,the degradation of the mechanical behaviors of connector.The existing researches of structural durability mainly target for concrete structures or steel structures under the coupling action of corrosion and load,while the study on structural durability of connector hasn't been touched upon.Therefore,there is a gap on the research of long-term mechanical behaviors of steel-concrete composite structures under the coupling action of corrosion and load.As a key component of the steel-concrete composite structure,the durability and mechanical properties of the connector directly affects the durability and service life of the steel-concrete composite structures.Therefore,it is necessary to carry out the long-term mechanical properties of the connector under corrosion and load coupling.And it has important engineering application value and theoretical significance that reflect the true stress state of the composite structures and understand the law of its degradation.In this paper,based on the current application and research status of composite structure,accelerated corrosion with applied current was used to simulate the corrosion of studs of connectors when the long-term load test was carried out on the steel-concrete connector at the same time.The main research work include:(1)The corrosion test of concrete,studs and other materials was carried out by accelerated corrosion method.And then the mechanical properties test of concrete and studs were performed under different corrosion conditions to establish mechanical performance degradation model.(2)A self-designed loading device were used to perform the long-term test of steel-concrete connectors and the corrosion of studs carried out at the same time by accelerated corrosion method.The effects of long-term load and the corrosion of studs on the mechanical properties of the connectors were investigated,and the degradation law of mechanical properties was studied.(3)The push-out test of the unloaded steel-concrete connectors was carried out to investigate the law of the ultimate shear strength,load-slip relationship and stress-strain relationship of steel-concrete connectors.By analyzing the influence factors such as the corrosion rate of the studs and the long-term load,the mechanism and the degradation law of the static performance of the steel-concrete connectors are analyzed.(4)Through the theoretical analysis,the experimental data statistics and the experimental comparison methods and so on,the calculation model of the corrosion behavior of mechanical properties of the concrete and the studs is established;the practical calculation method of the long-term elastic modulus of the steel-concrete composite structure is established;and the calculation model of shear capacity,load-slip relationship and other mechanical properties of Steel-concrete connectors under the corrosion and load coupling.