Effect of small openings on strength and stiffness of shear walls in reactor buildings Original Research Article

A total of 26 wall specimens were tested to examine the effect of small openings on the strength and stiffness of shear walls in reactor buildings. The parameters tested were the shape, number and local arrangement of the openings, and the reinforcing method around the openings. Reversed cyclic loads were applied to the specimens, and their strengths and restoring force characteristics were compared with each other to understand the effects of these parameters. Based on the test results, two methods for predicting the shear strength of walls with numerous small openings are examined. One is a method to calculate directly the strength along assumed failure lines, and the other method allows estimation of the strength reduction factors for design, taking account of the effect of openings. Both methods are found to be useful to estimate roughly the strength of such shear walls. It is also shown that the stiffness of such walls could be evaluated using a combined multi-spring model. For the reinforcing methods around openings, a simplified reinforcing method is proposed and the effectiveness of the method is discussed by checking the contribution of the reinforcement to the wall strength.