Predicting the Strength of Rectangular Reinforced Concrete Columns Confined with FRP Sheets

A complete reorganization about the behavior of rectangular RC columns confined with FRP sheet is very important to predict the axial compressive strength values of the strengthened rectangular RC columns. That is because the process of strengthening RC rectangular column depending on several parameters that role this type of strengthening. These parameters include the characteristics of the used fiber, the grade of concrete and the geometry of the cross section including the rectangularity aspect ratio, corner radius, and size of specimens. Besides that, using a wide scope of experimental data may affect positively to generalize a model that considers the whole parameters affect the value of the axial strength. So, in this paper a review about parameters that affect the axial compressive strength values of rectangular RC columns was conducted. After that, based on the test results regarding FRP-confined rectangular RC columns available in the literature or conducted by the author, some existing confinement models for rectangular RC columns were assessed. Further, a new model is proposed through regression analysis of the database. A new model is proposed through regression analysis of the database. The proposed model was found to be in good agreement with the test results in the database. Finally, based on the results conclusions were drawn.

Structural Behavior of RC Column Confined by FRP Sheet under Uniaxial and Biaxial Load

Various researches have been performed to find an effective confining method using FRP sheet in order to improve the structural capacity of reinforced concrete column. However, most of these researches were undertaken for the columns subjected to concentric compressive load or fully confined RC columns. To date, it remains hard to find studies on partially FRP-confined RC columns under eccentric load. In this manner, an experimental investigation was carried out to assess the performance of rectangular RC column with different patterns of CFRP-wrap subject to eccentric loads in this paper. The experiment consists of fourteen mid-scale rectangular RC columns of 200 mm × 200 mm × 800 mm, including five controlled columns and nine CFRP-strengthened ones. All CFRP-strengthened columns were reinforced with one layer of vertical CFRP sheet with the main fiber along the axial axis at four sides, then divided into three groups according to confinement purpose, namely unconfined, partially CFRP-confined, and fully CFRP-confined group. Two loading conditions, namely uniaxially and biaxially eccentric loads, are considered as one of the test parameters. From the test of uniaxial eccentric load, partial and full CFRP-wraps provided 19% and 33% increased load-carrying capacity at an eccentricity-to-column thickness ratio (e/h) of 0.125, respectively, compared to controlled columns, and 8% and 11% at e/h = 0.25, respectively. For the partially CFRP-confined columns subjected to biaxial eccentric load with e/h = 0.125 and 0.25, the load-carrying capacities were improved by 19% and 31%, respectively. This means that the partial confinement with CFRP effectively improves the load-carrying capacity at larger biaxial eccentric load. It was found that the load-carrying capacity could be properly predicted by using code equations of ACI 440.2R-17 and Fib Bulletin 14 Guideline for the full CFRP-confined or partially CFRP-confined columns under uniaxial load. For partially CFRP-confined columns under biaxial loading, however, the safety factors using the Fib calculation process were 20% to 31% lower than that of uniaxially loaded columns.

Seismic Performance of LRS-FRP–Concrete–Steel Tubular Double Coupling Beam

To improve the ductility and seismic performance of a double coupling beam, the authors applied a polyethylene terephthalate (PET) sheet and steel tube to form fiber-reinforced polymer (FRP)–concrete–steel double-skin tubular (DST) composite coupling beams. A low-cyclic reversed experimental program was carried out which factored in the member form, steel tube diameter, and construction methods. The results indicate that the ductility and energy dissipation performance of double coupling beams—whether wrapped with a PET-FRP sheet or surrounded by an FRP–concrete–steel DST composite system—is a substantial improvement over the traditional reinforced-concrete double coupling beam (RC-DCB). The ductility coefficient and accumulated energy dissipation of the DST-DCB members improved above 170% and 2300%, respectively. These percentages compare to the RC-DCB and are based on the rupture of a PET-FRP sheet. The results are similar to those of the large rupture strain double coupling beam (LRS-DCB). Meanwhile, the external wrapped PET-FRP sheet does not affect the initial stiffness and peak strength of the RC-DCB. Relatively, the inner steel tube will improve the initial stiffness, yielding strength, and peak strength. DST-DCB members still have considerable deformability after 85% of peak strength since the external PET-FRP sheet provided an effective constraint effect on the core concrete and the inner steel tube could bear excellent shear deformation.

FINITE ELEMENT MODELING TO PREDICT FLEXURAL PERFORMANCE OF STEEL I-SECTION BEAM EXTERNALLY BONDED BY VARIOUS FRP FABRICS: A REVIEW .

Use the fiber reinforced polymers fabric (FRP) in repair and strengthening of bridges, steel structure, etc. This article is review of literature available on flexural behavior of I-section steel beams with externally attached with FRP fabrics. It can be useful to decide which FRP sheet is best to use with steel beam to enhance flexural strength. Also this study comprises of cost comparison of Steel I beam strengthened by various FRP i.e. Basalt-FRP, Glass-FRP and Carbon-FRP. This can be achieved by bonding various FRP sheet at bottom flange, top flange & two faces of web to steel I section beam. It was studied through experimental, analytical, numerical investigation. Most of work is done on carbon-FRP fabric attached to steel beam as compared with Basalt-FRP. Some literature studied properties of FRP, adhesive bond, and fatigue behavior. In experimental method, four point bending test was performed and model were analyzed using FE analysis. From this review, Carbon-FRP gives better performance of Steel I beam as compared with other FRPs.

Experimental Study on FRP-to-Concrete Bonded Joints with FRP Sheet Anchor System

Fiber-reinforced polymer (FRP) has been widely used for retrofitting and strengthening concrete structures over the past two decades. Because concrete members retrofitted by externally bonded FRP sheets can fail prematurely in debonding because of the fracture between FRP and concrete, FRP tensile strength cannot be fully utilized in engineering practices. Numerous useful investigations have been conducted to develop effective anchor systems to restrict FRP debonding. Thus, an FRP sheet-anchor system was developed and observed to be one of the most effective and convenient anchor systems. The FRP sheet-anchor system is applied to reinforced concrete beams strengthened with U-wrapping and side-bonded FRP configurations in few design guidelines. However, only a few investigations have focused on the failure mechanism of the FRP sheet-anchor system in the existing literature. Therefore, the main objective of this study is analyzing the effect of the carbon FRP (CFRP) sheet-anchor system on the bonding behavior of the CFRP-concrete interface, particularly the effect of the width and stiffness of the CFRP sheet-anchor system. In addition, the anchor-strengthened stage is defined by the load-slip response, which is different from that of specimens without the CFRP sheet-anchor system. Based on the experimental results, three linear stage models of the bond-slip constitutive relationship are proposed in this study.

Desain balok beton menggunakan penulangan lembaran continue fiber reinforced polymer (FRP)

Fiber Reinforced Polymer (FRP) sudah banyak dipergunakan untuk perkuatan konstruksi beton bertulang maupun untuk penulangan internal beton. Namun penggunaan FRP sebagai penulangan internal pada struktur beton, masih didominasi dengan penggunakan tulangan Bar (FRP Bars). Sementara penggunaan FRP tipe lembaran (FRP Sheet) masih terbatas dikarenakan kesulitan dalam pemahaman metode desain dan juga permasalahan debonding antara lembaran FRP dan beton. Tulisan ini membahas cara mendesain balok beton dengan menggunakan penulangan lembaran FRP, baik berupa lembaran FRP tipe pelat, maupun lembaran FRP yang kontinyu yang dapat dipergunakan sebagai kombinasi penulangan lentur dan geser. Hasil penelitian yang sudah diseleksi juga ditampilkan dalam tulisan ini sebagai perbandingan dengan teori yang dikembangkan.