Abstract

In this paper, which focuses on the fiber-reinforced polymer (FRP) sheet bonding method for improving the impact resistance of RC beams, low-velocity impact load tests are performed on RC beams strengthened with FRP sheets. Both aramid FRP (AFRP) and carbon FRP (CFRP) sheets are used to experimentally investigate the flexural strengthening effect of the sheet materials. The impact force is created by dropping a 300-kg steel weight from various heights. The experiments are conducted using a single loading method for each beam, and the drop height of the weight is increased until the sheet debonded. The results obtained from this study are as follows: the impact-resistance capacities of the beams are improved by flexural strengthening with FRP sheets; the strengthening effects of the sheets are similar, regardless of the sheet materials, when the axial stiffness values of the sheets are equal; and the maximum and residual deflections are approximately linearly distributed with increasing input impact energy until the FRP sheets debonded.

Highlights

  • Steel plate bonding and/or section enlargement methods are generally applied to strengthen existing RC members

  • For Beam NS, which was not strengthened with an Fiber-reinforced polymer (FRP) sheet, the load gradually increased after the rebar yielded due to the plastic hardening effect of the rebar; the load was applied until the beam deflected to approximately 90 mm

  • To investigate the strengthening effects of FRP sheets on the impact resistance of RC beams, low-velocity impact load tests are performed on beams strengthened by bonding FRP sheets to tension-side surfaces

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Summary

Introduction

Steel plate bonding and/or section enlargement methods are generally applied to strengthen existing RC members. Fiber-reinforced polymer (FRP) composite materials, which are mainly developed for use in the aviation and space industries, are lightweight, noncorrosive, and have high strength-to-weight ratios, and they are relatively easy to install. Due to these characteristics, research and development on FRP applications in the field of civil engineering have been encouraged since the 1990s. Triantafillou (1998) experimentally studied the applicability of carbon FRP (CFRP) laminates as shear strengthening materials for RC beams and analytically investigated the contributions of FRP materials to the shear loadcarrying capacities of beams. Design guidelines for strengthening RC members with externally bonded FRP laminates have been established, such as in the case of ACI 440.2R-17 (ACI 2017), and have been widely applied in practice

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