A hybrid-sandwiching system for buckling-restraining of reduced beam sections

Abstract

The present study proposes a new system for preventing local buckling in reduced beam sections (RBSs). The proposed method is called the “hybrid-sandwiching system”. In this approach, high-strength grout sandwiches an RBS part of a beam with the help of steel strips and high-strength bolts. Two T-shape specimens representing a beam-to-column connection were tested under displacement-controlled cycling loading. One specimen includes the conventional RBS and the other includes the proposed hybrid-sandwiched RBS. The experimental results of the specimens showed that the specimen with hybrid-sandwiched RBS experienced a considerable rotation up to a drift angle of R = 7% without any buckling in the web and flanges. However, in the specimen with conventional RBS, the flanges were buckled, and consequently, a significant strength degradation was observed at a drift angle of R = 4%. The experimental results confirmed that the hybrid-sandwiching system not only provides great ductility for RBSs but also does not disturb the basic role of the RBSs in moving the location of the flexural plastic hinges away from the columns' faces. In addition to experimental investigations, the finite element models (FEMs) of the specimens were conducted and validated with experimentally-obtained results. A series of FEMs was also carried out to verify the influence of hybrid-sandwiching systems on RBSs with different sizes.