正交胶合木-混凝土螺栓连接力学性能试验研究及参数分析

Experimental study and parametric analysis on mechanical performance of CLT-concrete bolted connection

为研究正交胶合木(CLT)-混凝土螺栓连接的力学性能,对12个顺纹连接试件和12个横纹连接试件进行了单调加载和低周往复加载试验,总结了连接典型的破坏模式,得到了连接的初始刚度、承载力及延性系数等力学性能;利用ABAQUS软件对连接进行非线性参数分析,研究螺栓直径、螺栓强度等级及CLT层板厚度等参数对连接力学性能的影响。结果表明:连接的破坏模式与厚径比(CLT厚度与螺栓直径之比)相关,当厚径比不大于6.56时,主要发生单塑性铰屈服、木材销槽承压及局部承压破坏;螺栓直径一定时,增加CLT层板厚度可有效提高连接承载力;当厚径比大于6.56时,主要发生螺栓双塑性铰屈服与剪断破坏;增加层板厚度对连接初始刚度、承载力和破坏模式无明显影响。针对螺栓屈服破坏模式,增大螺栓直径可提高连接的初始刚度与承载力;提高螺栓强度等级对初始刚度影响较小,但可提高连接承载力。

To study the mechanical performance of cross-laminated timber(CLT)-concrete bolted connection, both monotonic and low cyclic loading tests were conducted on 12 specimens using parallel-to-grain CLT and 12 specimens using perpendicular-to-grain CLT. The typical failure modes of the connection were summarized. The basic mechanical properties of the connection including initial stiffness, bearing capacity and ductility coefficient were obtained. Parametric nonlinear analysis was then performed using ABAQUS, and the influences of the bolt diameter, bolt strength grade and CLT laminate thickness on mechanical properties of the connection were evaluated. The results show that failure modes of the connection are related to the ratio of CLT thickness to bolt diameter. With the ratio no larger than 6.56, single plastic hinge yielding mode of the bolt, dowel-bearing and local bearing failure modes of CLT tend to occur. The bearing capacity of the connection can be effectively increased by increasing the thickness of the CLT laminate with constant bolt diameter. With the ratio larger than 6.56, yielding mode with two plastic hinges and shear failure mode of the bolt tend to occur. Increasing the laminate thickness will not change the connection failure mode, and with no evident effects on the initial stiffness and bearing capacity. When the failure mode of the connection is controlled by the bolt, increasing the diameter of the bolt can increase the initial stiffness and bearing capacity. Further, the increase of bolt strength grade has little effect on the initial stiffness, but it can improve the bearing capacity of the connection.