正交胶合木-混凝土组合楼板连接节点受火后受拉性能研究OA北大核心

To investigate the tensile performance of connections in cross laminated timber(CLT)-concrete composite floor after fire exposure,twelve groups of connections(totally 36 replicates)of CLT-concrete composite floor were designed and tested at normal temperature and after fire exposure.Test variables included connection type,self-tapping screw configuration,geometry,fire exposure time,etc.Test results indicate that connection type plays an important role in the failure modes,concrete tensile failure occurs on the bonded specimens,withdrawal failure of the self-tapping screws occurs at the self-tapping screw connections.The nonlinearity of the curves of the bonded specimens is low,while such nonlinearity of the self-tapping screw specimens is relatively higher.The tensile ultimate capacity of the specimens with self-tapping screws drilled into CLT along the 90° direction exhibits the most significant degradation.After being exposed to fire for 90 minutes,the maximum drop of the tensile bearing capacity of the connection can be up to 74.1％.The charring rate of the CLT after fire exposure for 30 min is notably higher than the nominal linear charring rate of timber prescribed by GB 50005-2017'Standard for design of timber structures',while the charring rates of the CLT after fire exposure for 60 min and 90 min are close to the prescribed nominal linear charring rate.Meanwhile,FEM analysis of tensile performance of connections in CLT-concrete composite floor after fire exposure was conducted.The FEM model can reflect the failure modes of the self-tapping screw specimens,and the averaged modelling error of the tensile ultimate capacity of specimens is 5.8％,which can meet the engineering accuracy.