Performance of Masonry walls Under In-Plane Seismic Loading

Abstract

This paper presents the results of in-planedynamic tests of masonry walls. Five half-scale walls were built, using half-scale hollow claybrick units. Two mo- ment/shear ratios (1.4 (slender) and 0.7 (squat)) and two mortar types (M2.5and M9) have been investigated. Four walls were tested as Un-Reinforced Masonry (URM) walls. Thefifth wall was specially designed to study the shear behavior of a slender masonry wall. This wasachieved by applying two vertical plates of carbon fiber reinforced poly- mers (CFRP) on a singleside of the test specimen. These CFRP plates increased the specimen’s flexural strength withminimal increment in its shear strength. The test specimens were subjected to a series of syntheticearthquake motions with increasing intensities on a uni-axial earthquake simula- tor. The testresults show that the walls behavior is highly dependent upon the moment/shear ratio and level ofthe normal force, with material properties playing a smaller role. For slender URM specimens, thebehavior was domi- nated by rocking. For other specimens, the behavior was dominated by mixed modesof failure (shear and flexural). The average cracking drifts were 0.06% for slender speci- mens and0.08% for squat specimens. Also, the maximum measured drifts were 0.76% for slender URM specimensand 0.33% for other specimens. The cracking load ranged from 65 to 77% of the ultimate load forslender and squat walls, respectively. In addition, the lateral resistances of the specimens werecompared with the prediction using exist- ing simple models. In the case of slender URM specimens,the measured lateral resistances were approximately 97% of the calculated flexural strengths. Incase of squat speci- mens, the measured lateral resistances ranged from 104% to 166% of thepredicted shear strengths and 85% of the predicted flexural strengths. For the slender specimenwith CFRP, the measured lateral resistance was approximately78% of the predicted shear strength.