Seismic retrofit of reinforced concrete structures without adhesive anchors

摘要

The Japanese Building Standard Act was revised in 1981 considering limit states after yielding of structural members, on a basis of the lesson learned from Miyagi earthquake in 1978. It was found that poor seismic behavior of the buildings built before 1981 were exhibited due to inadequate horizontal retained forces and shortage of shear reinforcement of RC framed structures. Adhesive anchors are generally used to connect steel braces to the existing structure on the conventional way of seismic retrofitting. As the adhesive anchor requires drilling holes in the concrete structure, the retrofitting work causes hazards such as vibration, noise and dust particles. These hazards make retrofitting work difficult and become one of the reasons which obstructs wide spread of seismic retrofitting. It is important to emphasize that seismic retrofitting using no anchors would resolve those problems. We carried out cyclic loading tests and analysis of a framed specimen strengthened with steel braces to confirm the effect of the retrofit method without anchors.