Study On Performance Of Connection Joints Of Assembled Square Steel Pipe Column-Truss Beam

The assembled steel structure system has the advantages of short construction period,low labor intensity,energy saving and environmental protection,and good comprehensive benefits.With the continuous development of China's economy and the vigorous promotion of national policies,the fabricated steel structure system has shown a good development momentum and has become an important direction for the development of steel structure.The beam-column joint is a key part of the steel structure system,and it is the transmission hub of the structural member.The quality of the joint is directly related to the safety and stability of the structure.The quality of the nodes is reflected in the connection mode,ultimate strength,node stiffness,ductility and energy consumption of the nodes.When the node is working normally,it can resist its own constant load,wind load,etc.,and avoid large deformation and displacement of the structure when it is used.The square steel pipe column in the assembled square steel tubular column-truss beam system has better torsional resistance,and the smaller column section can behidden in the wall,which increases the use space of the building,and the internal space of the truss beam facilitates the insertion of the pipeline and installation.In the study of nodes at home and abroad,there are few studies on this system.Therefore,the mechanical properties of seven fabricated square steel tubular column-truss beam systems are studied and analyzed.In this paper,the design of the node and the content that needs to be studied are designed.The failure mode of the test piece is analyzed by the data collected and collected by the test site,and the yield point of the node is determined according to the hysteresis curve.The six commonly used methods for determining the yield point are compared,and the engineering mechanics method is most suitable.Secondly,according to the determined bearing capacity,the ductility and energy consumption of the assembled square steel tubular column-truss beam are analyzed.When the column is damaged,the ductility is better,which satisfies the seismic design principle of “strong column weak beam”,and then analyzes the stiffness degradation law during the loading process of the specimen based on the curve.Based on the finite element software ABAQUS,the finite element model is established for the test piece,and compared with the failure mode and bearing capacity of the test,the correctness of the finite element model is checked,and the specific process of node damage is analyzed.Based on the above finite element model,the thickness of the square steel pipe column of the test piece,the thickness dimension of the truss beam chord,the thickness dimension of the truss girder,the axial compression ratio and the loading mode are changed for the assembled square steel tubular column-truss beam.The displacement and beam end reaction force under each parameter were extracted,and the failure mode,hysteresis performance,bearing capacity,ductility and energy consumption of the test piece under each parameter were analyzed.From the test results,the following conclusions are drawn: In the method of determining the yield point,after the calculation error comparison,the method error determined by the engineering mechanics method is the smallest,and the node is applied.When the damage point is determined,the second method is adopted;In view,the yield points of the first group of test pieces J1-4-C and J1-6-C are significantly lower than those of the second group and the third group,and the corresponding yield load is also lower than that of the second group of the third group;In terms of maximum load,the maximum bearing capacity of the first group is the lowest,the second group is the second,the maximum bearing capacity of the third group is the highest,and the displacement of the maximum value of the reaching load is not much different.The wall thickness of the column is related.The larger the thickness,the higher the bearing capacity.From the point of view of failure,the value of the firstgroup of failure points is the smallest,the second group is the second,the third group is the largest,and the displacement of the failure point is reached.Less than the displacement of the second group and the third group reaching the failure point,but the displacement of the second group reaching the failure point is not much different from the displacement of the third group reaching the failure point;from the initial stiffness to Ki,KJ1-4-C < KJ1-6-C < KJ2-2-C < KJ2-4-C < KJ3-2-C;energy consumption factor,energy dissipation coefficient of the third group of test pieces The largest,the second group is the second,the first group is the smallest,and except for the test piece J1-6-C,the energy consumption coefficients on both sides of the other test pieces are not much different,basically the same;on both sides of the test piece,the test piece J3 The stiffness of-2-C is the largest.The J2-2-C of the second set of test pieces is the second and the test piece J2-4-C.The stiffness of the first set of test pieces is the smallest;the ductile coefficient of the first set of test pieces is the lowest.The ductility coefficient of the two sets of test pieces is second,and it is stable at about 2.0.The ductile coefficient of the third set of test pieces is the highest;the established finite element model has been verified and can be used for subsequent calculation and analysis;In the parameter analysis,from the economic consideration of the test piece,the column is 20 mm,the chord is 8mm,the web is 8mm,and the loading mode is higher.The bearing capacity of the monotonic loading is higherthan that of the specimen under cyclic loading.