型钢混凝土异形柱框架结构平扭振动反应及地震内力分析

Analysis on lateral-torsional vibration responses and seismic forces of a steel reinforced concrete frame structure with special-shaped columns

通过对5层实腹式型钢混凝土异形柱空间框架结构模型进行三向地震模拟振动台试验,获得了结构平动、扭转、平扭耦合动力特性,并对结构的多维地震反应、耗能能力、损伤程度、地震内力及平扭振动规律进行了综合分析。结果表明:模型结构前4阶自振频率对应的振型形态依次为X向平动、Y向平扭、扭转和Y向平动;随着地震强度的增加,型钢混凝土异形柱框架结构的自振频率不断下降,加速度放大系数逐渐减小,结构塑性变形不断发展,结构内部损伤逐渐累积,地震能量耗散不断增加,整体累积滞回耗能时程曲线呈台阶势跃迁;在历经0.80g地震作用后,模型结构平扭耦合引起的层间位移角最大值为1/39,超过弹塑性层间位移角限值要求,模型结构的变形和能量双参数模型损伤指数达到0.56;对比模型结构扭转效应发现,偶然偏心平扭耦合作用对模型结构的抗震性能影响较小,其偶然相对偏心距小于0.1;分析计算模型抗扭刚度、地震内力可知,在加载后期,随着水平侧移的增大,楼层的等效抗扭刚度退化并不明显,表明结构具有良好的抗震性能和抗扭变形能力。

The lateral,torsional,and lateral-torsional coupled dynamic characteristics of a 5-floor solid web spatial frame structure model with steel reinforced concrete special-shaped columns were investigated via 3-dimensional seismic simulation shaking table tests.In addition,the multi-dimensional seismic responses,energy dissipation,structural damage,seismic forces and lateral-torsional coupled vibration behaviors of the structure were comprehensively analysed.The results show that:the corresponding vibration modes of the first 4 orders in turn are:X direction translation,Y direction lateral-torsional coupled,torsion,and Y direction translation.As the seismic intensity increases,the free vibration frequency of the frame structure and the acceleration amplification coefficient decline gradually,the plastic deformation of the structure develops continuously,the internal damage of the structure gradually accumulates,the energy dissipation of the earthquake increases continuously,and the cumulative hysteretic energy of the structure is rapidly increased with stepped characteristic.After the effect of 0.80 g PHGA earthquake,the maximum value of inter-story drift ratio caused by the coupling effect of lateral-torsional vibration is 1/39,which exceeds the limit requirement of elastic-plastic inter-story drift ratio,and the damage index of the frame structure based on the deformation and energy parameter model is 0.56.Comparing with the general torsional effect of the model structure,the impact of an accidental eccentric torsion on the seismic performance of the model structure is small,and its accidental relative eccentric distance is less than 0.1.According to the analysis of the model torsional stiffness and seismic force,at the later stage of loading,the inter-story equivalent torsional stiffness degeneration is not distinct,which shows that the structure has high seismic performance and torsional deformation capacity.