Developing a method of strengthening concrete structures: Precast Pre-stressed Concrete Braces

There are multiple methods for seismically retrofitting existing concrete structures, such as adding jackets, adding concrete shear walls, or using FRP, CFRP, HFRP sheets;applying steel braces and external Frames or even applying external precast concrete. Another method is RC INFILLING, external post-tensioned cables, et al. A newmethod for strengthening concrete structure is Precast Pre-stressed concrete braces (PPCB), which were introduced by Watanabe. This method applies an X-shapeconcrete brace to the existing RC frame; this brace is consist of four legs and a middle section. Watanabe successfully applied this method in the lab on a half-scale of a fourstoryframe. In our research, we provided a 3D-model in ABAQUS-FEA in order to Finite Element Analysis of the PPCB. The results of the numerical analysis were incompliance with the experimental work of Watanabe. Then we modified different properties to the concrete brace in order to study its behavior. Results indicated thatsince the compression strength of the brace was more than two times of the existing frame, it could significantly be effective in reducing lateral displacement. In thefollowing, we have introduced two new assemblies for concrete braces: single diagonal and V-shape braces. In The single diagonal brace, the middle section is omitted, andthe brace would be installed in two consecutive frames. Results of the Finite Elements Analysis indicated that this new assembly is effective. Also, we have proposed anotherassembly for the PPCB, V-shape, which could be more buckle resistance because it has less length, but it adds extra force to beam in the existing frame

Keywords:

Concrete braces , precast Concrete , pre-stressed Concrete , Retrofitting RC structures , strengthening concrete structures , Finite Elements Analysis