剪切型破坏模式的配筋砌块砌体剪力墙恢复力模型

HYSTERETIE MODEL FOR REINFORCED BLOCK MASONRY SHEAR WALLS DOMINATED SHEAR FAILURE MODE

利用25片足尺全灌芯配筋砌块砌体剪力墙的低周往复荷载试验,研究了此种墙体在发生剪切型破坏模式下的恢复力模型。选取截面宽度包含190mm、240mm和290mm三种块型的墙体试验,研究了不同砌块孔洞率、竖向压应力、竖向和水平配筋率、墙体高宽比等参数对墙体破坏模式的影响。利用试验记录提出骨架曲线,其归一化骨架曲线符合带下降段的三折线模型。对试验数据进行回归分析,得到满足指数衰减规律的刚度衰减方程。提出适用于发生剪切型破坏模式的配筋砌块砌体剪力墙的滞回规则,此规则在卸载阶段用两折线表示,两折线采用不同的刚度值,第一卸载段采用初始刚度,第二卸载段采用本文提出的刚度衰减方程。该文提出的滞回模型能够较好模拟配筋砌块砌体剪力墙捏拢现象,模拟出的滞回曲线与试验记录到的曲线吻合良好。

A hysteretic model of the reinforced block masonry shear wall dominated by shear failure is presented according to tests of 25 full-scale fully grouted reinforced block masonry （FGRM） shear walls subjected to low cyclic reversed lateral loads. The block masonry used to build these walls includes three different cross-section width, 190mm, 240mm and 290mm. In the meantime the effects of hollow ratio of different masonries, vertical compressive stress, vertical and horizontal reinforcement ratio and aspect ratio on the failure mechanism of these walls were studied. The skeleton curve was extracted according to test records, whose normalized version complies with the tri-linear model with a descending section. The stiffness degradation equation suitable to exponential decay law was integrated by the test data. A new hysteretic rule applied to shear failure mode of FGRM shear walls was proposed, and this rule may be expressed as two polylines in unloading phase. The two polylines use different stiffness, i.e. the first and second unload section are associated with theelastic initial stiffness and the stiffness attenuation equation proposed in this paper respectively. The hysteretic model proposed in the paper can simulate the pinching phenomenon of FGRM shear walls, especially the hysteretic curve obtained from this model conforms to one of the experimental records.