STRUCTURAL BEHAVIOR OF STRENGTHENED CONCRETE BEAMS WITH BOLTED SIDE PLATES
R.K.L. Su 1* Z.W. Shan 2 and Ling-zhi Li 3
1 Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China
3 College of Civil Engineering, Tongji University, 1239 Siping Road, Shanghai, P.R. China
Existing reinforced concrete beams may need strengthening due to material deterioration, defective construction or induced higher loads than those anticipated in the initial design of a structure. Previous experimental and numerical studies conducted by the authors have demonstrated that the use of bolted side plates (BSPs) 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 face of a beam. However, relative movement between the plates and concrete beam are unavoidable due to the use of mechanical shear connectors. This movement, which is also known as bolt slippage, increases the deformation of the beam and reduces the interaction between the steel plates and concrete. In this paper, the primary factors that impact the failure mode and the flexural capacity of beams with BSPs, such as bolt slippage, bolt-plate configuration and plate buckling, will be discussed. The profiles of the longitudinal and transverse bolt slippages that are measured experimentally will also be presented. Strain and curvature factors are introduced to quantify the effect of bolt slippage and define the strain profile of the steel plates. A numerical parametric study is carried out to determine, the design values of the strain and curvature factors and the optimal size of the stiffeners for controlling plate buckling . Finally, design recommendations for beams with BSPs are proposed based on the test results and parametric study.
Steel plate; Anchor bolt; Concrete beam; Bolt slippage; Plate buckling; Plate depth