In Situ Test of School Buildings Retrofitted with External Steel-Framing Systems

Abstract

In situ push-over experiments and analytical assessments were conducted in this study to investigate the seismic capacity of RC school buildings at the Guan-miao Elementary School in Tainan City, Taiwan. Both prototype and external steel-framing specimens were constructed and compared. Reinforcements with steel channels were adhered to the captive columns and their adjacent beams in the weak direction, to retrofit the school building through the creation of external steel-framing systems. The design and construction procedures of the beam-column connection are introduced, as well as detailed drawings of the column-base anchorage system, both of which are key to the effects of the proposed retrofitting method. The experimental results show that the steel-framing system can be firmly bonded to the retrofitted specimen, providing continuous stress transference from the beam-column joints to the steel channels. The failure mode of the retrofitted captive columns was shifted from shear failure, as seen with the prototype specimen, to flexural-shear failure, with the retrofitted one. Both the experimental and analytical results show the following: The maximum total base shear strength increases 2.11 times, the total enclosed area of the stored energy increases 2.20 times, and ductility capacity increases 1.31 times. The external steel-framing systems proposed in this work can thus effectively enhance the base shear strength and the ductility of the specimens.