ANALYSIS OF EFFECT FACTOR ON SEISMIC BEHAVIOR OF ABNORMAL INTERIOR JOINTS IN REINFORCED CONCRETE FRAME STRUCTURES

Six specimens of abnormal interior joints were tested under reversed cyclic loading.Experimental studies were carried out to investigate the effect of joint core dimensions and axial compression ratio on seismic behaviour of abnormal joints.Test results indicated that column section abrupt had little effect on seismic behavior of the specimen.When the reduced height of column section was less than 1/6 column section height,that is h_ch_c/6,the negative effect of that could be neglected.The test results also indicated that beam section abrupt had an obvious effect on seismic behavior of the beam-column subassemblage. When h_b was between h_c/6 and 2h_(bl)/5,the seismic behavior improved gradually with the increase of h_b;When h_b was between 2h_(bl)/5 and h_(bl)/2,the seismic behavior deteriorated with the increase of h_b;When h_b was greater than 1/2 high beam section depth,a exterior joint model would be better for this case analysis.In addition,the axial load level of the column had a negative effect on seismic behavior of abnormal joints after the beam-column subassemblage reached to critical crack stage,it was suggested that the axial compression ratio shoulds be less than 0.3 for the seismic design of this sort of abnormal joint.