Seismic Behavior of Substandard RC Columns Retrofitted with Embedded Aramid Fiber Reinforced Polymer (AFRP) Reinforcement

Abstract

Many existing reinforced concrete structures were constructed with substandard characteristics. Low quality concrete, poor transverse reinforcement details and insufficient flexural strength are among the most common deficiencies. While substandard structures are in need of retrofitting, particularly in seismic areas, problems such as high costs and disturbance to occupants are major obstacles for retrofit interventions. Fiber reinforced polymers can provide feasible retrofit solutions with minimum disturbance to occupants. In this study, the basic aim is to investigate the flexural seismic performance of substandard reinforced concrete columns retrofitted with embedded longitudinal fiber reinforced polymer reinforcement without increasing the original dimensions of the columns. In the experimental study, the reference and retrofitted columns were tested under constant vertical and reversed cyclic lateral loads. Three different connection methods of aramid fiber reinforced polymer reinforcement to the footing were investigated experimentally. A significant enhancement was obtained in lateral flexural strength through the proposed retrofitting method. Furthermore, it was observed that the cyclic lateral drift capacities of the retrofitted columns were as high as 3%, which can be deemed as quite satisfactory against seismic actions. The comparison of the experimental data with analytical calculations revealed that a conventional design approach assuming composite action between concrete and fiber reinforced polymer reinforcement can be used for flexural retrofit design. Experimental results also demonstrated that strain limit for longitudinal fiber reinforced polymer (FRP) reinforcement should be remarkably lower in case of reversed cyclic loading conditions.

Strengthening and Repair of Reinforced Concrete Columns by Jacketing: State-of-the-Art Review

“…Researchers have been using different types of FRP composites in hybrid jacketing techniques. Seyhan et al [68] proposed the strengthening of deficient RC columns with embedded aramid fiber-reinforced polymer (AFRP) reinforcement in the longitudinal direction to increase the flexural strength and CFRP sheets in the transverse direction to enhance the ductility under cyclic lateral actions with constant axial compression. The proposed retrofitting method resulted in the significant enhancement of the flexural strength of the tested columns.…”

Reinforced Concrete Beams with Carbon-Fiber-Reinforced Polymer Bars—Experimental Study

“…As main advantages of FRP bars in comparison to the conventional steel bars can be considered the high corrosive-resistant behavior, the high tensile strength in the direction of the fibers and their lightweight non-magnetic characteristics. Due to these attractive characteristics, the application of FRP bars as internal reinforcement in RC structural members under monotonic or/and seismic loading has been examined recently [14][15][16][17][18][19].…”

Flexible Adhesive in Composite-to-Brick Strengthening—Experimental and Numerical Study

“…Fibre Reinforced Polymers (FRP) have been investigated intensively and applied in practice for structural strengthening over the last decade [1,2,3,4,5]. The stiff and brittle adhesives, as epoxy resin [6,7,8] or mineral mortars [9,10,11,12,13,14], are applied in composite strengthening systems composed of various high strength fibers, bonded to concrete and masonry substrates. Composite reinforcement textiles, made of various fibers, are divided into groups according to the fiber and matrix/adhesive type.…”