Shear Strength of Reinforced Concrete Columns Retrofitted by Glass Fiber Reinforced Polyurea

Abstract

Aged structures and structures constructed based on outdated non-seismic design codes should be retrofitted to enhance their strength, ductility, and durability. This study evaluates the structural performance of reinforced concrete (RC) columns enhanced via polyurea or glass fiber reinforced polyurea (GFRPU) strengthening. Four RC column specimens, including a reference specimen (an unstrengthened column), were tested to evaluate the parameters of the strengthening materials and the strengthened area. The tests were carried out under a combined constant axial compressive load and quasi-static cyclic loading. The experimental results show that the composite strengthening provides lateral confinement to the columns and leads to enhanced ductility, shear-resistance capacity, and dissipated energy. The shear strength provided by the composites depends on the degree of lateral confinement achieved by the composite coating. The specimens finally failed through the development of diagonal tension cracks within the potential plastic hinge regions. The specimen treated with GFRPU strengthening showed greater strength and dissipated more energy than the specimen treated with polyurea strengthening. Furthermore, by modifying ATC-40, this study proposed an equation to estimate the shear capacity provided by the composites.

Modeling of success factors of using PU coats in concrete construction projects

“…Using Kaiser's criteria (eigenvalue > 1) and scree plot analysis, the number of variables to extract was calculated. The first EFA performed on 21 variables [ 17 , 62 ]. Following an examination of the factor loadings and item-total correlations.…”

“… [ 5 , 60 ] F8 Polyurea coatings are fire-resistant, offering additional protection in a fire. [ 61 , 62 ] F9 Polyurea coatings are resistant to ultraviolet radiation, making them a viable option for concrete surfaces exposed to direct sunshine and located outside. [ 17 , 53 ] F10 Polyurea is a highly durable polymer resilient to impact, abrasion, and chemicals.…”

In-Plane Strengthening of Unreinforced Masonry Walls by Glass Fiber-Reinforced Polyurea

“…where 𝐹 𝑚 denotes the shear strength of the UMW and takes the minimum value of the shear strength calculated by the four failure modes of rocking, toe crushing, sliding, and diagonal tension failure specified in the Korean code [27]. 𝐹 𝐺 represents the shear strength carried by the GFRPU and is derived using the experimental results.…”

Out-of-Plane Strengthening of Unreinforced Masonry Walls by Glass Fiber-Reinforced Polyurea

“…Wu et al [19] investigated the reinforcing effect based on the coating thickness and compared the reinforcement effect for nonreinforced and polyurea-reinforced clay brick walls against blast loads. The reinforcement effect on concrete beams and columns reinforced by glass fiber-reinforced polyurea (GFRPU) mixed with milled glass fiber to improve the tensile strength of polyurea [20][21][22][23] was investigated. The authors reported that GFRPU was effective in enhancing the strength and ductility of structural members.…”