The Behavior And Performance Of Self-insulating Reinforced Concrete Masonry Shear Walls Under In-plane Loading

Masonry has been used as a common building material worldwide for many centuries.Masonry is a composite of block units bonded together with mortar.Nowadays,many developed countries applied the energy conservation concept in the building technology to achieve alternative building materials which have a low impact on the environment.The use of thermal insulation materials in the production of masonry is one of the most effective ways for green building technology.In this study a new type of self-insulating concrete masonry unit(SCMU)has been developed to be used for low and medium height residential buildings in seismic area zones with severe ambient conditions.This study has been divided into two main parts to cover all the aspects related to developing a new type of self-insulating concrete masonry shear wall.The first part of this study aimed at investigating the mechanical behavior of the new type of self-insulating concrete masonry units(SCMUs).A total of twelve full grouted wall assemblages were prepared and tested for compression and shear strength.In addition,different axial stress ratios(0.1 N/m12 and 0.3 N/mm)were used in the shear test,Furthermore,numerical models using simplified micro modeling technique were developed to predict the behavior of grouted specimens.The mortar joints were modeled with zero thickness and their behavior was applied using the traction-separation model of the cohesive element.The experimental results revealed that the shear resistance increased form 104.9 kN to 127.2 kN as the level of pre-compression stress increased from 0.1 N/rrumm to 0.3 N/mm.Moreover,the cohesive stress and the friction angle for SCMUs were obtained from linear regression model based on the test results and were applied in the finite element models.A good agreement between the experimental results and the numerical models was observed.It was concluded that the proposed models can be used to deduct the general behavior of grouted specimens.On the other hand,the second part of this study aimed to investigate the inelastic behavior for fully-grouted masonry shear walls which were built from the new type of self-insulating concrete masonry units(SCMUs)under in-plane cyclic loading.A total of six fully-grouted self-insulating concrete masonry shear walls(SCMSW)were prepared with four aspect ratios(1.0,2.0?2.6 and 3.6),three magnitudes of axial compressive stresses(0,0.5 and 1.0 N/mm2)and three vertical reinforcement ratios(0.46,0.67 and 0.72).In addition,one wall was strengthened by two concrete columns at the wall ends.The performance of S CMSW was established from the test results considering predicted load capacities,wall drift,displacement and curvature ductility,plastic hinge length,amount of energy dissipation,and equivalent hysteretic damping.In addition,the relationship between the key design parameters such as the amount of axial loading,aspect ratio and the amount of reinforcement of self-insulating concrete masonry shear walls(SCMSW)were defined to facilitate better understanding of the inelastic behavior under seismic loading.Generally,the SCMSW exhibited predominantly flexural behavior.Results showed that the yield displacement increased as the SCMSW aspect ratio increased but the sliding deformation decreased.Moreover,the application of moment curvature assumptions to predict the flexural capacity of SCMSW is an acceptable procedure with an average accuracy of 94%.Also,the results revealed that the lateral load capacity of SCMSW increases with the amount of applied axial load and the amount of vertical reinforcement.However,the lateral load capacity decreases inversely in relation to an increase in wall aspect ratio.The existence of the boundary elements at the SCMSW ends increases the ductility and the lateral load capacity.Moreover,the wall test results in this study were also compared to results obtained by finite element program(ABAQUS 6.10 software)to gain a better understanding of how the parameters influence wall behavior.Finally,a design example of eighteen storey building under an earthquake excitation was provided to give a practical application of the self-insulating concrete masonry shear walls.These findings are in good agreement with those reported in previous researches for ordinary concrete shear walls.