Study On Structure And Mechanical Of New Shear Connectors For Box Girder With Corrugated Steel Webs

Box-girder bridge with corrugated steel webs is a new type of steel-concrete composite bridge structure,which has been vigorously promoted and applied in China due to its numerous structural and economic advantages,such as its economic cost,reasonable mechanical performance,environmental protection character,light structure weight,beautiful appearance and remarkable seismic performance.Shear connectors play a vital role for transferring forces between the steel and concrete materials in the composite construction.Therefore,a comprehensive research of shear connectors suitable for the box girder with corrugated steel webs will show a positive significance in promoting the application of box girder with corrugated steel webs.This study proposed a new type of shear connectors.The static and fatigue behavior of the new type of shear connectors and traditional S-PBL shear connectors was studied by test study and refined finite element model analysis.The test results were analyzed through the multi-segment linear equivalent models,the failure forms of the two kinds of shear connectors under static and fatigue loads were revealed,and the main factors affecting the static and fatigue properties of the new type of shear connectors are identified.Finally,new formulas for calculating the static bearing capacity and fatigue life of the new type of shear connectors were established.The main research contents and conclusions of the study are as follows:?Based on the characters of existing shear connectors,the study presented a new type of improved embedded shear connectors,which is mainly enhanced with stiffened angle steel in comparison with the traditional embedded shearing connectors to improve the stiffness of embedded shearing connectors.Subsequently,the increase of static and fatigue behavior was analyzed by refined finite element model.?In view of the two types of shear connector comparison schemes in the project,the static and fatigue performance experimental research was carried out through 12 test pieces belonging to 2 groups.A series of finite element refinement models were established for verification analysis,revealing the force transmission path,stress performance and failure form of the two types of shear connectors.The static loading of the new type of shear connectors can be divided into elastic stage,strengthening stage and failure stage,while the static loading of S-PBL shear connectors can be divided into elastic stage,yielding stage,strengthening stage and failure stage.The results showed that the static performance and fatigue performance of the new embedded shear connectors are significantly improved than those of the S-PBL shear connectors based on the same structural parameters,which provides support for the determination of the engineering shear connector design scheme.?Through the multi-segment linear equivalent method,the trilinear elastoplastic model of improved embedded shear connectors and the bilinear elastoplastic model of S-PBL shear connectors were established.Methods for determining mechanical properties such as the yield point were determined,and the equivalent stiffness,strength and ductility before and after yielding as well as other important mechanical performance indicators are obtained.The differences in the mechanical properties and mechanical behavior of the two types of shear connectors are revealed:the yield of S-PBL shear connectors is due to the yield of a single material,while the yield of improved embedded shear connectors is caused by the cooperative yielding of multiple materials.?Based on the study of 5 test pieces and a large number of finite element parametric models,the influence of various parameters on the static performance of the improved embedded shear connects were analyzed,including the concrete strength,bar strength,diameter of the hole,number of holes,thickness of corrugated web,strength,thickness and width of the stiffened angle steel.The major influence factors were also obtained.Then,maximum hyperplane method is used to fitting formula of the static bearing capacity of shear members considering multiple materials,structural parameters and porous reduction effects.?Based on a large number of finite element parametric models,the influence of lots of parameters on the fatigue performance of the improved embedded shear connects were analyzed,including the concrete strength,bar strength,hole diameter,number of holes,thickness of corrugated web,strength,thickness and width of the stiffened angle steel.The major influence factors were also obtained.Finally,the fatigue life of the improved embedded shear connectors was obtained by the maximum hyperplane method.