SHEAR CAPACITY PREDICTION FOR STIRRUP-CORRODED RC BEAMS STRENGTHENED WITH FRP

Ahmed K El-Sayed

doi:10.3846/est.2019.8885

Abstract

Corrosion of steel reinforcement represents one of the main causes of deterioration and degradation of reinforced concrete (RC) structures. Shear reinforcements (stirrups) as an outer reinforcement in RC beams are more susceptible to corrosion problems and damage. This paper describes an analytical procedure for predicting the shear capacity of stirrup-corroded RC beams strengthened in shear using FRP laminates. The procedure shows how to incorporate the effects of the damages due to corrosion of stirrups into the design equations. An experimental investigation has been conducted to provide experimental data on the shear capacity of RC beams with corrosion-damaged stirrups strengthened using carbon fiber reinforced polymer (CFRP) sheets. The experimental study comprised three beams of 200 mm wide, 350 mm deep, and 2800 mm long. The steel stirrups in the beams were corroded using an accelerated corrosion technique. After CFRP strengthening, the beams were tested in four-point bending under a simply supported span of 2400 mm. The shear capacity of the strengthened beams was predicted using the proposed procedure and compared with the experimental ones. Good correlations were found between the predicted and experimental shear strength of the beams.

Highlights

Corrosion of steel reinforcement reduces the cross-sectional area of the bars which in turn reduces their capacity in resisting applied forces
Reinforcing steel coupons that had a length of 200 mm were extracted from both legs of corroded stirrups for mass loss measurements
This paper presented an analytical procedure for assessing the shear capacity of reinforced concrete (RC) beams with corrosion-damaged stirrups strengthened using carbon fiber reinforced polymer (CFRP) sheets

Summary

Introduction

Corrosion of steel reinforcement reduces the cross-sectional area of the bars which in turn reduces their capacity in resisting applied forces. Few studies have been directed to examine the feasibility of using FRP strengthening for upgrading RC elements with corrosion-damaged stirrups (Li, Wu, & Wang, 2016; Qin, Dirar, Yang, Chan, & Elshafie, 2015; El Maaddawy & Chekfeh, 2013; Kage, Abe, & Lee, 1997). The outcomes of these studies were encouraging; none of these studies provided practical procedure for evaluating the shear strength of FRP strengthened beams with corroded stirrups. The experimental data is used for verifying the assessment procedure

Shear capacity for FRP strengthened RC beams

Shear capacity for FRP strengthened RC beams with corroded stirrups

Experimental investigation

Comparison of predictions and experimental results

Conclusions