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

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 the elastic 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.