Study On Mechanical Properties Of Beam-Column Joints With Flush End Plates Connected With Single Direction Bolts Based On High Strength Steel

In recent years,rectangular steel tubular columns are increasingly used in industrial plants and steel structure residential areas due to their excellent bearing capacity and seismic resistance.Because rectangular steel tube columns belong to closed sections,if welding is used,the contact part between the end plate and the column wall is prone to brittle damage,making it difficult to ensure the welding quality of the weld.If ordinary high-strength screws are used for node assembly,there will be places where the hands cannot pass through.This problem can be effectively overcome by using the one-sided locking function.Using the newly developed STUCK-BOM type reinforced concrete rectangular steel tubular column beam column joint in China,the mechanical behavior of the joint was deeply investigated using a combination of experimental and numerical simulation methods.So far,many scholars at home and abroad have done a lot of research work on single direction bolt beam-to-column connections,but these work mainly focuses on finite element research to study the mechanical properties of single direction bolt beam-to-column connections,and there is no method or calculation formula that can be directly applied in practical engineering to predict the moment-rotation curve of single direction bolt flush end plate connections.In response to this problem,this study took STUCK-BOM as an example and carried out a series of experiments and simulations.Using three parameter theory and methods,it was verified theoretically and experimentally,and the approximate expressions of its initial rotational stiffness,ultimate bending moment,shape factor,etc.were given.From this,the variation law of its bending moment to rotation angle was obtained,providing a basis for practical application.The main research work of this article includes:(1)The effect of chemical elements in steel materials on their mechanical properties was studied.(2)A set of flush end plate single direction bolt joints was subjected to monotonic static loading tests,and the failure modes and moment rotation curves of the specimens were obtained.(3)Using ABAQUS finite element software,a mathematical model of flush end plate joints with single direction bolts was established,and the results were compared with the calculated results to verify the correctness of the method.After confirming the model,parametric analysis was conducted to obtain the main factors affecting the initial stiffness and ultimate bending moment of one-way bolt flush end plate beam-column joints.(4)On this basis,the finite element numerical simulation method is used to establish an approximate calculation formula of the shape coefficient of single direction bolt connection based on the three-parameter constitutive relation.The formula is compared with the bending moment-angle curve and Angle curve obtained by using the three-parameter constitutive relation to test the accuracy of the three-parameter model.(5)A frame model was established using MIDAS software to compare the mechanical properties of single direction bolt flush end plate connections with ordinary high-strength bolt connections.According to the structural analysis results,the mechanical properties of single direction high-strength bolts are similar to those of conventional high-strength bolts.