Experimental Research On Seismic Performance Of Abnormal Frame Joints With Concrete-filled Square Steel Tube Columns And H-shaped Steel Beams

The structural forms complexity and the space use functions diversification of large industrial and civil buildings have inevitably resulted in many unconventional nodes with variable cross-sections in which the left and right beams are not equal,and under the external load,such unconventional joints are in the composite stress state of compression,bending and shear,and the force is more complicated than ordinary nodes,making the joints of beams and columns are often vulnerable parts under the action of earthquakes.At present,there is still a lack of necessary experimental research and theoretical analysis on this kind of special-shaped joints at home and abroad,and based on this,the test on seismic performance of the concrete filled steel tube(CFST)column-H type unequal high steel beam frame joints was studied.The main research contents were as follows:(1)According to the scale ratio of 1/3 and the principle of "strong joints weak member",10 strong joints models with unequal cross section of left and right beam were designed and made,and the quasi-static test of the joints models was carried out by applying constant axial load and low cyclic horizontal load.The specimen CFSTJ-1~CFSTJ-8 were made to study the effect of beam height ratio(beam height ratio was 0.089,0.179,0.268,0.357,0.445,0.536,0.625,0.714 respectively,and the axial compression ratio was 0.4).The specimen CFSTJ-2,The CFSTJ-9 and specimen CFSTJ-10 were made to study the effect of axial compression ratio change on seismic performance(axial pressure ratio was 0.4,0.3,0.5 respectively,and the beam height difference ratio was 0.179).(2)The hysteresis performance,energy dissipation capacity,stiffness and strengthdegradation and ductility performance of the CFST joints models were obtained bymeans of the quasi-static test,and the influences of beam height ratios and axial compression ratios on the seismic performance of the joints were analyzed.(3)Based on the test model,this paper analyzed the flexural bearing capacity and the shear bearing capacity of the CFST column-H type unequal high steel beam frame joints,and established the formula for calculating the bending moment of the end in unequal high beam and the formula for calculating the shear bearing capacity of the core area ofthe joint,and compared the calculation values and shear value of the jonits.