Investigation On The Mechanical Properties And Seismic Performance Of Bolted Connections Between Steel Beams And CLT Wall Panels

Prefabricated steel structures have been vigorously promoted by our government due to their advantages such as rapid and efficient construction,green and environmentally friendly materials,excellent performance,and industrialization.As an important component of steel structure buildings,the enclosure wall panel is one of the important factors restricting the industrialization of steel structure housing development.The internal wall forms in steel structure buildings are mainly divided into block,lightweight strip board,and composite wall panels,all of which generally have problems such as low strength,wet operation,and poor performance at joints.Cross-laminated timber(CLT)is a new type of green building material with good overall integrity,high strength,and stiffness,making it an ideal wall material in steel structure housing systems.The connection between CLT wall panels and the main structure is mainly through angle steel and antipull anchor bolts,requiring a secondary connection when connecting to steel structures,which wastes the assembly performance of steel and wood materials,and exposed joints can reduce fire resistance.Therefore,improving the connection between wall panels and steel structures is of great significance for the application of cross-laminated timber in steel frame systems.Regarding the above issues,this article proposes a bolt connector suitable for connecting CLT wall panels and steel beams,and conducts experimental research and finite element analysis on the force performance of the nodes.The feasibility of bolt connection in filling CLT wall panels in steel frames is also explored.The main work content and research results are as follows:(1)Based on the characteristics of bolted connection nodes,seven sets of CLT wall panels and steel beam connection specimens were designed,and their bending and shear performance tests were conducted.The mechanical properties,failure characteristics,and influencing factors of the nodes under lateral load were studied,and the theoretical calculation of the failure load of the nodes was carried out using code formulas.The research results show that the bolted connection between CLT wall panels and steel beams is feasible,with good assembly performance.The main failure mode of the specimens is groove compression failure,wood shear deformation at the screw hole,and bolt deformation.Changing the sizes of the bolt can significantly improve the bending and shear performance of the nodes.The calculated results of the failure load of the nodes using code formulas are in good agreement with the experimental values.(2)Based on the size of the bolt connector,three sets of CLT wall panel and steel beam bolted connection specimens were designed,and their seismic performance was tested.The mechanical properties,failure characteristics,and influencing factors of the bolted connection nodes under low-cycle reciprocating loading were studied.The research results show that the failure mode of the specimens under reciprocating load is more fully developed.The hysteresis curves of the three sets of specimens have a similar overall shape,and the skeleton curves all show an "S" shape.With the increase of the bolt length,the lateral stiffness and energy consumption of the nodes increase,but the energy consumption capacity of the nodes changes little.(3)To further study the factors affecting the mechanical properties of bolted connection nodes,a finite element model of CLT wall panel and steel beam bolted connection specimens was established in ABAQUS software.The rationality of the material parameter settings,contact surface interaction,and boundary condition settings in the model were verified.The influence of the strength of the bolted connection,the thickness and number of CLT layers on the mechanical properties of the nodes was studied,and reasonable suggestions were given.(4)To explore the feasibility of using cross-laminated timber(CLT)wall panels as internal walls in steel frame structures,the construction of CLT wall panels and nodes was added to traditional steel structure residential building designs.The dynamic response of the overall structure under earthquake loading and the stress state of the CLT wall panels were analyzed.The research results show that CLT wall panels can improve the seismic performance of the overall structure,and under small seismic loads,the mechanical properties of the CLT wall panels is stable.Bolted connections can be used to connect CLT wall panels to steel beams.