Research On Shear Performance Of New Embedded Nut Connector Of Assembled Composite Beam

The new embedded nut connector of assembled composite beam is an improved connector based on the general embedded nut connector.Its main structure is composed of embedded nut and bolt,which is mainly used to transfer the shear force of steel-concrete interface.By changing the geometric parameters of the embedded nut and screw,the mechanical properties can be changed.It has the advantages of good assembly performance,small slip and high shear strength.The preliminary research results show that the connector has good engineering application prospects and profound research significance.In this paper,push out test and three-dimensional nonlinear finite element analysis method were used,the research contents were as follows:（1）Through the first batch of 15 new connectors push out test,the shear performance change rule and failure process of connectors with different bolt diameter were studied.The results showed that: with the increase of bolt diameter,the shear capacity of the connector increased gradually,and the failure mode of the specimen was that the bolt rod was sheared,and the concrete was not cracked.（2）Based on the push out test and numerical simulation of 18 new connectors in the second batch,the influence of three factors,such as the area of bolt head,the length of embedded nut and the strength grade of concrete,on the shear performance of connectors and the change process were discussed.The results showed that with the increase of bolt head area,the shear capacity of the connector increased gradually;With the increase of embedded nut length,the shear capacity of the connector increased gradually;With the increase of concrete strength,the shear capacity of the connector increased gradually,and the failure mode of the specimen was that the bolt rod was not broken,and the concrete cracking was reduced.（3）Through the numerical simulation method,the development process of two failure modes of the above two batches of specimens were simulated,and the process was briefly analyzed.The numerical simulation results were in good agreement with the experimental results.（4）By summarizing the test data of 99 stud connectors and the calculation formula of shear bearing capacity of connectors in various national codes,the main factors affecting the shear bearing capacity of connectors were summarized,and a calculation formula of ultimate bearing capacity of the connector was fitted.