Examination of parameters impacting flexural and shear strengthening of RC beams

Abstract

Structural performance of reinforced concrete (RC) structures should be improved due to new design standards, strength reduction, and/or functional changes throughout their service life. To reach a sufficient level of structural performance, the following two options can be considered: reconstruction or strengthening of structures. Although reconstruction has some advantages in terms of using current technological developments, this option can lead to some negative consequences such as interruption of the building's service life, relatively high cost, and sustainability issues. Therefore, strengthening an existing structure mostly stands out as the first choice. The techniques used in strengthening applications can be grouped into two different methods: traditional (addition of new structural members) and non-conventional (seismic base isolation, local retrofitting, and jacketing). Among innovative methods, the fibre-reinforced polymer strengthening method attracts attention due to several advantages including practical applicability, as well as shear and bending capacity increase. Its application to the outer surface of structural members using resin reduces deterioration. Plus, fibres oriented in various directions spread stresses in different directions, therefore, provide effective force distribution. In this study, the effect of carbon fibre reinforced polymer (CFRP) orientation and RC material properties in the strengthening RC beams were investigated using MATLAB software. Accordingly, all stages of the design process are presented for RC beam strengthening considering both flexural and shear effects based on the American Concrete Institute (ACI) 440.2R standard. Through compiling MATLAB code, calculation time reduces, and material characteristics can be obtained more accurately. Plus, using curves obtained by MATLAB coding, shear and bending capacity increases can be observed. According to our findings, the application of one-layer CFRP plate to an RC beam increases the bending capacity by 50.6% and shear capacity by 33.6%. However, as the number of layers increases, the capacity increase rate reduces.