Torsional Strengthening Of RC Rectangular Beam Using Stainless Steel Wire Mesh(SSWM)

Abstract

Generally in Reinforced Concrete (RC) structures, local elements are designed for axial force, shear force and bending moment but torsion moment is completely neglected. But in some cases like curved beam in water tank, spreader beam etc. torsional moment cannot neglected. This torsional moment in structural element may be large enough that it can increase the principle diagonal tensile stress and this tensile stress can develop cracks which cause catastrophic character of the torsional failure of members. Strengthening of structural elements are necessary in case of increase in loading, deterioration/damage of structure, modification in structural systems, error in construction etc. Stainless Steel Wire Mesh (SSWM) is locally available strengthening material. SSWM is a cost effective strengthening material compare to other available strengthening materials in market. Research in area of strengthening of RC elements using SSWM is not attempted in greater details. Most of the experimental studies on torsional strengthening of RC element using SSWM have been published recently. In order to gain a better understanding of the torsional behaviour of SSWM strengthened RC beam, the main objective of the study is to evaluate numerically response of SSWM strengthened RC element with difference wrapping schemes. The numerical simulation is performed using finite element (FE) based software ABAQUS. The three dimensional nonlinear FE anlaysis based on concrete damaged plasticity (CDP) model is used for numerical simulation of SSWM strengthened RC element under pure torsional loading. The type of specimen on which FE analysis carried out on RC rectangular beam having cross section dimensions are 150 mm × 250 mm with 4-10 mm diameter longitudinal bars and 2 leg 8 mm diameter stirrups at 75 mm c/c at support and 150 mm c/c at mid span. The length of the specimens is 1.2 m. Total 2 beams are designated as control specimens and 8 beams are strengthened using SSWM wrapping with 5 different wrapping configuration such as full wrapping (FW), strips above stirrups wrapping (SAS), strips in between stirrups wrapping (SIS) and corner and diagonal strips (CoDS). Comparison of different strengthening configuration is made to find out effectiveness of wrapping on RC rectangular beam. It is also found that full wrapping (FW) type wrapping configuration shows better ultimate twist compare to other wrapping patterns, it can be recommended for retrofitting of RC rectangular element under torsional loading.