Research on Reinforcement Technology of Existing Frame Structure with Externally Attached U-Shaped Steel Plate Sub-Structure

With the improvement of building technical requirements and the updating of standards, the demand for the reinforcement of existing buildings is increasing. In order to solve the problem regarding the low economic applicability of the traditional seismic retrofit method, this paper proposes a seismic retrofit method for an externally attached U-shaped steel plate sub-structure that follows the concept of “reinforcing while using”, is composed of a U-shaped steel plate and herringbone channel steel, and can meet the needs of multiple retrofits. Based on the results of a pseudo-static test, the mechanical properties of one unreinforced frame and three reinforced frames with different specifications for the U-shaped steel plate sub-structure were comparatively studied, and the effectiveness and rationality of the reinforcement method were analyzed. The results show that the externally attached U-shaped steel plate sub-structure has good deformation and energy dissipation capacity and can effectively improve the horizontal bearing capacity of an existing frame without changing the original failure mode. The bearing capacity of the three reinforced frames was 1.43, 1.89, and 2.57 times that of the unreinforced specimen. The initial lateral stiffness of the frame also increased significantly, namely, to 1.41, 2.02, and 2.08 times that of the unreinforced specimen, and the stiffness degradation rate decreased. The seismic performance of the original frame was greatly improved.

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