Experimental and Numerical study of Stainless Steel Wire Mesh (SSWM) Strengthened T-Flange Beam for Shear and Bending

Abstract

Strengthening of RC structural elements using different retrofitting materials has a substantial growth in construction industry since last decade. Presently Fiber Reinforced Polymer (FRP) composites are emerging as an important strengthening material for increasing capacity of existing structural element. FRP materials are available in form of carbon, glass and aramid fiber. Mainly Carbon Fiber Reinforced Polymers (CFRP) and Glass Fiber Reinforced Polymer (GFRP) are being used as a material for external strengthening of structural elements due to its high tensile strength, light weight, ease of application and durability. The failure of FRP strengthened structural element are observed either brittle failure or debonding of FRP. Thus, it is necessary to find an alternative material for FRP, which is more ductile and have better bond characteristic. Locally available Stainless Steel Wire Mesh (SSWM) bonded on a concrete surface with an epoxy resin is explored as an alternative material for strengthening of structural element. Research in area of strengthening of Reinforced Concrete (RC) element using SSWM subjected to flexural load is not attempted at greater details. An attempt has been made to investigate the behavior of simply supported RC T-Flange beams with externally strengthened using SSWM. The major objective of present study is to improve the flexural and shear resistance of RC T-Flange beam strengthened with different configuration of SSWM. Five different types of locally available SSWM are selected to identify the suitability as a wrapping material. The tension test is performed on SSWM coupon of size 100 mm × 500 mm and bond test is carried out between SSWM and concrete surface to understand the bond behavior. From tensile test and bond test it is found that SSWM 40 × 32 is suitable for strengthening of RC T-beam. Experimental study is conducted in fourteen RC beam specimens. It is included strengthening of six T-beams deficient in flexure and six T-beams deficient in shear using SSWM. All T-Flange beam specimens are having flange width of 225 mm, thickness of flange 50 mm and width of web 100 mm , depth of web 150 mm and having 1800 mm length. Beams are designed using Indian Standard codal provision. Six beams are made deficient for flexure and six beams are made deficient for shear by reducing percentage of longitudinal reinforcement and increasing the spacing of shear reinforcement respectively. Control T-Flange beam is reinforced with 2-16 mm longitudinal reinforcement and transverse reinforcement of 8 mm diameter bar with 125 mm spacing c/c. Flexure deficient beam is reinforced with 2-12 mm longitudinal reinforcement and transverse reinforcement of 8 mm diameter bar with 125 mm spacing c/c. Shear deficient beam is reinforced with 2-16 mm longitudinal reinforcement and transverse reinforcement of 8 mm diameter bar with 500 mm spacing c/c. Different wrapping configurations adopted in this study for Flexure Deficient T-Flange beam strengthened with SSWM strip at bottom of beam (FDT) and Flexure Deficient T-Flange beam strengthened with SSWM U-shape strip (FDTU). Whereas Shear Deficient beam Strengthened with 100 mm wide SSWM strips (SDST100) and Shear Deficient beam Strengthened with 500 mm wide SSWM strips (SDST500). Two beams without SSWM strengthening are used as control specimen for each category. These beams are tested under four point flexural load test. Transverse load and deflection at first crack and at an ultimate stage as well as load-deflection behavior of SSWM strengthened specimens are compared with controlled specimens. Also the failure pattern and strains at different locations of the beams are observed. FDTU is most effective wrapping configuration for flexural deficient beam element and SDST500 is for shear deficient beam. The numerical simulation of SSWM strengthened RC T-beam under transverse load is carried out using finite element based software ABAQUS. Results of nonlinear finite element analysis are found in good agreement with experimental results.