Dynamic Behavior Analysis And Experimental Investigation Of Simply-Supported Steel-Concrete Composite Small Box Girders With Accelerated Construction Technology

Aiming at the dynamic behavior study including natural frequencies,vehicle-bridge coupling vibration,etc.for steel-concrete composite small box girder with group studs(SCCSBG)by accelerated construction method,this thesis proposed theoretically analytical methods,experimental studies as well as numerical methods to efficiently explore more dynamic information of this innovative type of structure.The main work and some valuable conclusions are drawn as follows:(1)Considering the group studs' effects and special mechanic behavior,the thesis deduced the theoretically analytical methods for natural frequencies exploration of SCCSBG based on Timoshenko theory and numerical search was applied into the solution of the proposed equations.Two SCCSBG models by acceleration method and one traditional SCCSBG were designed and constructed.In addition,finite element model was also built to further verify the effectiveness of the proposed theoretical expressions.After that,the verified expressions were used to compare the dynamic differences between SCCSBG with group studs and traditional SCCSBG with even studs.Some parameters studies,then,were also conducted,such as the different adjacent group distance and shear stiffness of studs to find their effects on the dynamic performance of SCCSBG with group studs.(2)Dividing the vehicle-bridge system into vehicle sub-system(5 DOFs)and bridge sub-system and considering the slip effects of the SCCSBG with group studs,this thesis deduced two sub-systems motion equations and turned to ANSYS and Matlab platforms with the whole iteration method to solve sub-systems.Experimental models and one calculation example in other references were also used to verify the correctness of the proposed programs.And then,some parameters studies,such as vehicle's speed,vehicle's mass,vehicle's suspension stiffness,bridge's stud layouts,adjacent stud group space and the pavement roughness,were conducted to explore more influence on the SCCSBG's vehicle-bridge coupling response.(3)In order to study the effect of external prestressed cables on the free vibration frequency of the rapid construction steel-concrete composite small box girder with external prestressed cables,by considering the deformation and stress of the micro beam segment and the group studs,introducing the relation between the change of external prestressed cable's prestress and the vibration displacement,this paper deduced the theoretical expressions for natural frequency calculation of steel-concrete composite small box girders(SCCSBG)with group studs and external prestressed tendons.The finite element method was also used to check the effectiveness and correctness of the proposed method.Some of parameter studies were then finished.The results show that the prestress force does not make obvious difference in the vibration state of SCCSBG with group studs but the layout of the prestressed tendon will greatly influence the frequencies of this type of structure,especially for the lower vibration orders of SCCSBG.