Mechanical Behavior Of Glued-in Steel Plate Joints In Single-layer Reticulated Timber Domes

The large-span single-layer reticulated shell made of wood is not only beautiful in shape,efficient in force,but also environmentally friendly.There have been many engineering examples abroad.Although there are individual cases of large-span wooden reticulated shells in China,there are few related studies and the analysis and design techniques are not yet perfect.The key to the design of wooden reticulated shells is the connection of joints.Therefore,it is of great significance to study the structural form and mechanical performance of wooden reticulated shells.Based on the basic form of glued-in steel plate connection,a new type of reinforced single-layer wood reticulated shell joint is developed in this paper.The design of the form is based on the principle of clear force transmission and avoiding brittle failure.Simplified finite element models of single-layer spherical wooden reticulated shells with spans of 50 meters,100 meters,and 160 meters were established,eigenvalue analysis and nonlinear stability analysis were performed using ABAQUS,and internal forces at key joints were extracted.Based on the hypothesis of linear elastic wood and flat section,the theoretical model of joint bending capacity was derived.According to the internal force level of the joint and the theoretical model,the dimensions of each component of the developed joint were designed.In order to ensure the sufficient strength of the glued-in steel plate connection in the joint,a monotonic loading test was performed on the test pieces of the glued-in steel plate connection to study the influence of various parameters on its bonding and anchoring performance.The tests show that sandpaper sanding and chemical etching on the surface of the steel plate are beneficial to the improvement of the bonding and anchoring performance of the glued-in steel plate connection,especially the chemical etching completely removes the weak bonding layer on the surface of the steel plate,which makes the bonding and anchoring performance large increased.Increasing the anchorage length and width of the steel plate is also conducive to the improvement of the pull-out bearing capacity,but after the anchorage length and width reach a certain level,the growth rate slows down and the pull-out capacity almost never increases.The force transmission form at the end of the steel plate also has an important effect on the bonding and anchoring performance.According to the experimental data,the empirical formula for the pull-out bearing capacity of the glued-in steel plate connection is fittedin this paper.Experiments were conducted on the mechanical performance of the designed joints under axial force conditions of 0k N,250 k N,and 500 k N.The mechanical performance and failure modes of wooden reticulated shell joints at different axial force levels were studied to obtain their bending moment-rotation curves.The designed joint achieves the design intent well.After the chemical etching of the steel plate,sufficient anchoring strength can be achieved to ensure the expected ductile failure mode.A control specimen without a chemically etched steel plate shows the adverse effects of brittle failure of the glued-in steel plate connection,and the important role of the safety bolt in this case.The test results show that the ultimate bearing capacity of the specimens destroyed in the tensile zone increases with the axial force.The bending stiffness of the joint increases with the axial force.Based on the analysis method of the component method,the ultimate bending capacity and the initial rotational stiffness of the test piece were evaluated.The theoretical values obtained are basically consistent with the test results,which proves the rationality and feasibility of the component method.