Structural behavior of bolted side plates strengthened concrete beams

Abstract

Existing reinforced concrete beams may need strengthening due to material deterioration, defective construction or having higher loads than those foreseen in the initial design of the structure. Previous experimental and numerical studies conducted by the authors have demonstrated that the use of bolted side plates (BSP) can effectively enhance the flexural and shear capacities of reinforced concrete beams. In this method, anchor bolts are used to fix steel plates to the side faces of beam. As mechanical shear connectors are utilized, relative movements between the plates and concrete beam are unavoidable. Such movements, also known as bolt slips, would increase the deformation of beam and reduce the interaction between the steel plates and concrete counterpart. In this paper, the primary factors controlling the failure mode and the flexural capacity of BSP beams, such as bolt slips, bolt-plate arrangement and plate buckling, will be discussed. The longitudinal and transverse bolt slip profiles measured experimentally will also be presented. Strain and curvature factors are introduced to quantify the effect of bolt slips and to define the strain profile of steel plate. Through numerical parametric studies, the design values of the strain and curvature factors and the optimal size of stiffener for controlling plate buckling are determined. Based on the test results and parametric studies, some design recommendations for BSP beams are proposed.