Study On Flexural Performance Of Prefabricated Composite Beams With Grouped Bolt Shear Connectors

Prefabricated steel-concrete composite beams(PSCCBs)have the advantages of disassembly,the convenience of installation and construction,and the recyclability of related components.The grouped arrangement of shear connectors facilitates efficient installation,but at the same time affects the flexural performance of the PSCCBs.In this paper,prefabricated steel-concrete composite beams with grouped bolt shear connectors and segmented precast concrete(PC)slabs were proposed.In this paper,we used experimental and finite element methods to investigate their flexural performance,the main research contents include:(1)Flexural tests under static loading were carried out by fabricating three composite beams with segmented PC slabs and one beam with a monolithic PC slab.Experimental results show that all the specimens failed due to concrete crushing in the pure bending regions,presenting typical characteristics of flexural failure;Compared to the PSCCB with a monolithic PC slab,the PSCCBs with segmented PC slabs experienced a short fast increasing stage of mid-span deflection after the steel girders yielded,and the initial flexural stiffness and ductility coefficient decreased by 47.8% and 44.1% at most,respectively;The ultimate flexural capacity increased with the shear connection degree,but the ductility of the beams decreased instead.(2)The finite element software ABAQUS was used to analyze the PSCCBs.Numerical results demonstrate that the failure mode of PSCCBs was flexural failures,and the existence of gaps did not lead to an essential change in their failure modes;For the PSCCBs with GW of greater than 2 mm and LM of less than 1680 mm,the load-deflection curves experienced a short fast increasing stage of mid-span deflection;The influence of the distance from the grouped bolt to the gap on the flexural performance of the PSCCBs can be ignored.It is recommended to use a longer middle PC slab and a higher height of the steel girder web,which is beneficial for improving the initial flexural stiffness,ultimate flexural capacity,and ductility of the PSCCBs;Appropriate bolt shear connectors should be arranged in the pure bending regions to maintain the flexural performance of the PSCCBs.(3)Repeated loading tests were conducted on three beams,followed by flexural tests under monotonic static load.Research shows that: the failure modes of three beams in the static test after repeated loading were similar to the specimens only subjected to static load,they exhibit typical flexural failure modes;Repeated loading has little effect on the ultimate flexural capacity of the PSCCBs,but the maximum decrease in ductility coefficient of the PSCCBs that had undergone repeated loading exceeded 46.9%;The steel of the PSCCB was strengthened during repeated loading.The Finite element models of PSCCBs were established based on experiments,taking into account the reinforcement effect of steel caused by repeated loads.The analysis shows that for PSCCBs subjected to repeated loading,setting the gaps near the loading points can significantly improve the ductility of the composite beam;For composite beams with full shear connection and steel girder web height between 150 mm and 300 mm,the repeated loading increased the initial flexural stiffness and ultimate flexural capacity of the PSCCB by 105.9% and7.0% respectively but decreased the ductility coefficient by 20.5% at most.The research results of this paper can provide a reference and basis for the design and calculation of PSCCBs with grouped bolt shear connectors and segmented PC slabs.