Flexural behavior of RC beams strengthened by enlarging the member size using cementitious grout: experimental and theoretical study

This paper presents an experimental and theoretical investigation of the flexural strengthening of undamaged reinforced concrete beams by enlarging the member size using cementitious grout. Four-point bending tests were conducted on nine beams, namely, one control beam, four beams strengthened in the compressive zone, and four beams strengthened in the tensile zone. The main test parameters include the strengthening position, strengthening thickness, and ratio of the new reinforcement. The test results emphasize the effect of enlarging the member size using cementitious grout in terms of flexural capacity (58.1–116.9% increase in ultimate load), and the ductility of the beam strengthened in the compression zone is better than that of the beam strengthened in the tension zone. In addition, a theoretical calculation formula was developed to predict the flexural capacity of the strengthened beams based on the plane section assumption. A comparison of the experimental and theoretical results indicated that the formula is accurate.