FLEXURAL STRENGTHENING OF NORMAL STRENGTH SELF COMPACTED RC BEAMS

Abstract

Abstract Strengthening of the damaged or weak reinforced concrete structures is critical to ensuring the safety of residents or users. Beams are essential structural elements for withstanding of loads, so it is very necessary to find the efficient strengthening and repair methods to maintain the structures safety. Several materials and strengthening methods have been introduced, but the research for perfect material and method is still ongoing. This chapter introduces the difference between repairing, maintenance and strengthening. Also, it explains the different techniques in flexural strengthening for beams. The most common used material in strengthening beams are fiber reinforced polymers (FRP). The main goal of this thesis is to study the flexural behavior of flexural strengthened self-compacted RC beams Several materials and strengthening methods have been introduced, but the research for perfect material and method is still ongoing. Two techniques, externally bonded materials and near surface mounted used as a flexural strengthening for normal strength RC beams. Also, to examine the effect of different types of materials as carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) wraps and CFRP plates as externally bonded materials for strengthening self-compacted concrete beams in flexure. Basalt, glass, and carbon fiber rods were used for strengthening using near surface mounted technique (NSM). Fifteen beams were cast and strengthened with the change of strengthening technique (NSM and externally boned material) When using NSM technique the parameters were strengthening materials, number of fiber rods and study the effect of these variables in increasing flexural load capacity and ductility. When using externally bonded material technique, the parameters were strengthening materials, sheets dimensions (strips width) and study the effect of these variables in increasing flexural load capacity and ductility. From the study the used techniques (Near surface mounted and externally bonded material) has a great effect on improving load capacity and ductility for strengthened beam. The beam strengthened with basalt fiber reinforced polymer (BFRP) rods showed the best results. The increase in load capacity and ductility in beam that strengthened with BRB rods was up to 85% and 308.271% respectively. Also the beams strengthened with GFRP wraps was better than beam strengthened with CFRP wraps in load capacity and ductility. Also beams strengthened with carbon fiber plates were better than beams strengthened with GFRP wrap an CFRP wrap in load capacity and ductility