Research On Calculation Of The Bearing Capacity Of The New Full-Bolt Connections For Steel Frames

The new type of full bolt connection is a new type of connection which is for the steel pipe column and H type steel,this connection way give up the traditional bolt nut,by tapping directly in the position of the corresponding column wall,and then the H type steel beam and square steel tubular column with end plates connected by high strength bolts.This connection method effectively solved the problem that the square steel tube is closed cause it is not easy to bolt.In this paper,take this new connection as an object.The anti loosening performance,tensile bearing capacity,calculation method of joints and the seismic performance of the frame are studied in detail in this paper.The main research contents and results are as follows:(1)The transverse load Juncker vibration test was carried out on the three groups of 33 specimens.The test phenomena and the pretension attenuation rate were analyzed and compared,and the anti loosening performance of the new type full bolt connection method was determined to meet the requirements.(2)Through the test of the tensile capacity of 6 square steel tubes,the main factors affecting the tensile strength of the bolts are analyzed.Then,reference the European standard used in EC3 "T connection method",proposed the new type connection failure mode,combined with the knowledge of mechanics proposed new type full bolt tensile bearing capacity formula.Based on the data of tensile tests,it is found that the actual tensile bearing capacity is basically the same with the theoretical value.(3)A total of 11 cross joints were designed for Pseudo-static Test.Use calculation method of end plate suitable for new full bolted connection mode and formula for calculating the bolts tensile capacity,calculate the joint and determine the theoretical failure mode of all joints.It is found that the failure mode of the joints are basically consistent with the theoretical failure mode.Finally,the calculation method of the bearing capacity of the joint is determined and the design method suitable for the new type of full bolt joint is put forward.(4)In order to study the structural performance of new type of full bolt connection,two steel frames with a model ratio of 1:2 are designed.One of them is a new type of full bolt connection frame,and the other is a frame connected by the traditional bolt welding.Two steel frames are tested under low cyclic loading.By comparing and analyzing the seismic performance of two frames,such as test phenomena,hysteretic curves,skeleton curves,stiffness degradation,ductility and energy dissipation capacity,etc.Found the load capacity and seismic performance of new type full bolted steel frames are better than the traditional steel frames.