不同洞口位置节能砌块隐形密框墙体抗震性能

为了研究节能砌块隐形密框复合墙体的破坏形态及滞回性能、刚度退化、延性和耗能能力等抗震性能,以门洞位置为变化参数,设计制作了6个缩尺比例为1/2的墙体试件,进行了低周往复加载试验.首先,通过对比、总结的方法,得出了试件的破坏形态并分析了其滞回性能;其次,采用切线刚度计算方法,对比分析了各试件刚度退化规律;然后,通过图解法确定屈服位移,并利用公式计算位移延性系数,从而分析判断各试件的延性性能;最后,采用等效粘滞阻尼系数的计算方法研究试件的耗能能力.研究结果表明:在低周往复加载下,配筋合适的开洞复合墙体往往会发生剪压破坏,其破坏过程可分为弹性、弹塑性和破坏3个阶段;墙体试件的滞回曲线形状较为饱满,能表现出开洞的墙体会有良好抗震性能;中开洞墙体其骨架曲线下降段更为平缓,比偏开洞墙体的抗震性能更好;开洞位置越接近墙体的中间部位,墙体在弹塑性阶段刚度的有利贡献就越大,其变形能力也会越强;6个试件的延性系数均大于3,满足抗震规范要求,开洞位置越接近墙体中间的试件延性越好,其等效粘滞阻尼系数也越大,其耗能性能也越好;确定了墙体在不同性能目标时的变形容许值,为设计该类墙体提供理论基础.

Seismic Behavior of Energy-Saving Block & Invisible Multi-ribbed Frame Composite Walls with Different Opening Positions

In order to study the failure modes and seismic performance of energy-saving block & invisible multi-ribbed frame composite wall (EBIMFCW) in terms of hysteretic behavior, stiffness degradation, ductility, energy dissipation capacity, etc., low cyclic reversed loading tests were conducted on six test specimens of EBIMFCW designed in a scale of 1/2 and manufactured with varied opening positions. First, the test results of the specimens were compared and analyzed to determine their failure modes and hysteretic behaviors. Then, the stiffness degradation of each specimen was analyzed using the tangent stiffness calculation method and compared with others, the yield displacement was determined by the graphic method, and the displacement ductility coefficient was calculated using a formula to judge the ductility of each specimen. Finally, the energy dissipation capacity of specimens was studied using the equivalent viscous damping coefficient. Results show that under the horizontal low cyclic reversed loading, a shear-compression failure often occurs to the EBIMFCW with appropriate reinforcement and the failure process can be divided into elastic, elastoplastic and failure stages. The shape of hysteretic loop curve of specimens is relatively full, suggesting that the wall with holes has good seismic performance. Besides, the skeleton curve of the wall with a central opening is descending more slowly and the wall has better seismic performance than those with a non-central opening; a closer opening position to the wall center results in a more favorable contribution of the wall stiffness in the elastoplastic stage and thus a bigger deformation ability of the wall. In addition, the ductility coefficients of the six specimens are all greater than 3, meeting the requirements of the seismic design code; when the opening position is closer to the wall center, the specimen has a better ductility, a larger equivalent viscous damping coefficient, and better energy dissipation performance. Based on the test data, the allowable deformation values of the wall under different performance targets are determined, which provides a theoretical basis for design of EBIMFCWs.