钢筋混凝土框架异型中节点抗震性能影响因素分析

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

通过6个钢筋混凝土框架异型中节点试件在低周反复荷载作用下的试验,分析节点核心区尺寸、轴压比等因素对异型节点抗震性能的影响。研究表明:上柱截面发生变化对异型节点抗震性能的影响不明显,当其变化量小于1/6柱高时,即Δhc<hc/6,可忽略其不利作用;小梁截面发生变化对组合体试件的抗震性能影响较大,当大小梁截面高差在1/6柱高到2/5梁高时,即hc/6<Δhb<2hbl/5,随着大小梁高差的增大,组合体的抗震性能将逐渐改善;当2hbl/5<Δhb<hbl/2时,随着大小梁高差的增大,组合体的抗震性能将逐渐劣化;当Δhb>hbl/2时,建议按中间层边节点考虑。此外,轴压比增大对异型节点通裂阶段后组合体试件的抗震性能产生不利影响,对该类节点进行抗震设计时,建议轴压比应小于0.3。

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 Δhc 〈 h 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 Δhb was between hc/6 and 2b1/5, the seismic behavior improved gradually with the increase of Δhb; When Δhb was between 2hb1/5 and hb1/2, the seismic behavior deteriorated with the increase of Δhb; When Δhb 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 beamcolumn 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.