| In the global trend of reducing carbon emissions,modern timber structure building had become one of the construction industry’s low-carbon emission reduction solutions.Cross-laminated timber（CLT）,as a new engineering wood material,had gradually become an indispensable part of modern wood structure building system,and had been widely used in the field of high-rise wood structure in recent years.At the same time,as a choice of low-carbon life,tiny house was developing rapidly in North America and Europe,in which the tiny timber structure house was the main form of tiny house.This paper focuses on the application requirements of CLT tiny timber structure buildings in multi-seismic and humid environments,and studies the connection mode and side seismic resistance of thin CLT shear walls with single layer thickness of 16 mm and three layers of whole panel thickness of 48 mm.In this paper,the failure mode and the difference between the shear strength and shear stiffness of the 48mm thin CLT shear wall were studied.Based on the comparison results,the lateral and seismic properties of the 48mm CLT shear wall with the bolt double shear connection at the bottom were studied.The influence of opening size on lateral stiffness failure mode and seismic performance of CLT shear wall was analyzed.The finite element modeling of thin CLT shear wall was also carried out and verified with the experimental results.Finally,the paper made a theoretical analysis of the thin CLT shear wall,established the calculation formula of the horizontal displacement and shear strength of the wall top,and verified the comparison with the test data.The main conclusions of this paper are as follows:（1）In the test of screw connection and bolt connection of 48 mm thin CLT panel,the bolt connection specimens showed better shear bearing capacity and elastic stiffness in general.The elastic stiffness and ductility coefficient of the bolt connection were larger than those of the screw connection,indicating that the bolt connection had small elastic deformation,good ductility after yielding,and had a certain safety reserve.In terms of failure mode of CLT panels and metal connectors,bolt connection was obviously better than screw connection.Compared with the failure of metal connectors,it can be found that the bolt had no obvious deformation and can be reused,while the screw had a lot of bending deformation and even shear failure.In terms of the failure of CLT panel itself,the screw connection specimen also presented the characteristics of more complicated failure and more serious tear.These phenomena indicated that the bolt connection was reliable in force transmission,easy to disassemble and repair,and compared with the screw connection,the bolt connection had small deformation under the same load,which can improve the comfort of the building.（2）The experimental results of the lateral resistance of 48 mm thin CLT shear wall showed that the sliding deformation can be ignored for the CLT shear wall with double shear bolt connection,and the lateral displacement is mainly composed of bending deformation,shear deformation and rotational deformation,which indicated that the bolt connection can play the advantage of good shear resistance of CLT panel.The lateral bearing capacity and stiffness of CLT shear wall will decrease obviously due to the opening of the hole,and the stiffness will decrease more obviously,which was also proved by the cyclic test.In addition,the experimental results showed that the shear strength and stiffness of CLT shear wall with larger opening width decrease more obviously when the opening area was the same.The results of the comparative study on the opening reinforcement of the specimen with the opening showed that the shear stiffness of the CLT shear wall after the opening reinforcement increased by 44.4%,indicating that the opening reinforcement was effective.According to the energy dissipation effect in the cyclic test,since the bottom of the shear wall was connected by bolts,the wall panel can recover well after load removal,so the energy consumption loss was smaller than that of the screw connection,and the energy dissipation accumulation of the CLT shear wall panel with no opening was larger than that with an opening hole.On the other hand,according to the stiffness degradation curve,the CLT shear wall panel with no opening had a large stiffness but its stiffness degraded quickly and decreased much,while the CLT shear wall panel with the opening had a small stiffness and less stiffness degradation.（3）Through finite element simulation of CLT shear wall specimens,it can be found that the simulation results of FW specimen show that the failure mode of CLT panel was consistent with that of the FW specimen in lateral static load test.The displacement of the CLT shear wall consists of the displacement caused by bending deformation,shear deformation and rotation.The slope of the load displacement curve was basically the same as that of the actual test,and the stiffness difference was8.5%.Stress concentration was found at the four corners of the opening in specimen with opening,which is consistent with the failure mode in lateral static load test.The displacement was also composed of bending deformation,shear deformation and rotation.The differences between the simulated stiffness and the test stiffness of the specimen OW-1,OW-2 and OW-3 were 6.3%,11.0%and 2.1%,respectively,showing good coincidence.The size of the opening had a great effect on the bearing capacity and anti-deformation ability of the CLT shear wall,and the larger the opening,the smaller the bearing capacity and stiffness.When the size of the openings were the same,the smaller the distance between the opening position and the top surface of the wall was,the less stiffness the CLT shear wall was,and it was easier to produce larger deformation under the action of horizontal force.The stress of the CLT panels on the left and right sides of the opening also increased,which made the bearing capacity of the CLT shear wall decrease.（4）In the theoretical research,the lateral stiffness,displacement calculation and shear bearing capacity of CLT shear wall were analyzed and studied.Combined with the shear bolt connection test,the plastic deformation control value and the bearing capacity calculation formula were given.Due to the fact that there was no gluing on the sides of the wooden strips in each layer and the material was in the elastic stage when stressed,the influence of the transverse plate in the middle layer on the lateral deformation and bearing capacity was ignored.The deformation of CLT wall panel under lateral load was composed of bending deformation and shear deformation,namely the elastic deformation of the CLT wall panel.The displacement caused by the elastic deformation of the CLT shear wall also includes the rotational displacement caused by the compression deformation（plastic deformation）of wood under the bolt hole caused by the rotation of the CLT wall panel.So,the wall top displacement includes the lateral displacement?(（7）caused by the elastic deformation of the wall and the rotational displacement?′of the elastic support.When studying the calculation of lateral bearing capacity,the plastic deformation stage in the load displacement curve was the deformation caused by the continuous compression of the wood below the bolt hole.Therefore,according to the shear performance test of the bolt connection at the bottom of the wall panel,the corresponding load(（8） of the hole wall compression deformation was taken as the limit value of the shear bearing capacity of the bolt connection.Under lateral load,it was determined that the wall rotates around the outermost bolt of the bottom bolt group,and the shear strength calculation formula of the wall was determined by calculating the shear strength of the innermost bolt. |
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