scholarly journals An Anchorage Technique for Shear Strengthening of RC T-Beams Using NSM-BFRP Bars and BFRP Sheet

2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Hesham M. Diab ◽  
Ahmed M. Sayed
Keyword(s):  
Reinforced Concrete ◽  
Basalt Fiber ◽  
Shear Capacity ◽  
Fiber Reinforced Polymer ◽  
Experimental Program ◽  
Shear Strengthening ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Anchorage System ◽  
Near Surface Mounted

Abstract This study presents a detailed experimental program for reinforced concrete T-beams strengthened in shear with near-surface mounted (NSM) basalt fiber-reinforced polymer (BFRP) bars. This paper aims to introduce and evaluate a nonmechanical anchorage technique for shear strengthening using NSM-BFRP bars. T-beams were strengthened using manually manufactured closed or U-shaped hybrid BFRP stirrups (BFRP bars and BFRP sheets). The experimental program was developed to study the effects of these anchorage techniques. The results showed that the shear capacity increased by 8%–46% for beams strengthened with NSM-BFRP bars without anchorage. However, the presence of the proposed anchorage system increased the shear capacity of the strengthened beams by 39.6%–81.6%. Moreover, the maximum strains induced in the BFRP bars ranged from 27 to 59% of their ultimate strains according to the spacing between the NSM and the presence of the anchorage. The proposed anchorage technique prevented the premature debonding of the NSM-BFRP bars.

scholarly journals Numerical Modeling of Earthquake-Damaged Circular Bridge Columns Repaired Using Combination of Near-Surface-Mounted BFRP Bars with External BFRP Sheets Jacketing

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 258 ◽  
Author(s):  
Xing-Gui Zeng ◽  
Shao-Fei Jiang ◽  
Xin-Cheng Xu ◽  
Hai-Sheng Huang
Keyword(s):  
Numerical Modeling ◽  
Numerical Models ◽  
Basalt Fiber ◽  
Fiber Reinforced Polymer ◽  
Experimental Program ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Near Surface Mounted ◽  
Damage Accumulation Model ◽  
Good Agreement

This paper reports the numerical simulation of earthquake-damaged circular columns repaired with the combination of near-surface-mounted (NSM) basalt fiber reinforced polymer (BFRP) bars with external BFRP sheets jacketing at quasi-static loading. The numerical modeling was carried out with the nonlinear OpenSees software platform by using the BeamWithHinges element. In the simulations, the effect of the previous earthquake damage on the behavior of the repaired columns was taken into account, and a simple and effective material damage-accumulation model is proposed to modify the constitutive of materials in the unrepaired regions of the repaired columns. The developed numerical models were validated by comparing their quasi-static findings with those obtained from a previous experimental program, and a good agreement can be observed. Furthermore, the efficiency of the repair technique used in tests is evaluated via the developed numerical model.

Experimental investigation of seismic strengthening of reinforced concrete short columns using externally bonded reinforcement, near surface mounted, and hybrid techniques

2019 ◽  
Vol 54 (9) ◽  
pp. 1177-1195 ◽  
Author(s):  
A Kargaran ◽  
A Kheyroddin
Keyword(s):  
Reinforced Concrete ◽  
Fiber Reinforced Polymer ◽  
Dissipated Energy ◽  
Fiber Reinforced ◽  
Near Surface ◽  
Short Columns ◽  
Reinforced Polymer ◽  
Shear Rupture ◽  
Externally Bonded ◽  
Near Surface Mounted

Nowadays, the existence of short columns is a major factor in the failure and collapse of structures during the earthquake. In this article, 10 reinforced concrete short columns are prepared and experimentally investigated under cyclic lateral displacements. Since failure in short columns under earthquake was in the form of diagonal cracks and shear rupture, two new techniques are proposed to strengthen short columns against seismic loads. These techniques include externally bonded reinforcement with carbon fiber-reinforced polymer sheets and near surface mounted with glass fiber-reinforced polymer bars in the form of transverse, diagonal, and hybrid strengthening techniques. The experimental results demonstrated that the above-mentioned strengthening techniques in short columns lead to a change in the type of failure from shear to flexural, and the change of crack patterns and columns failure. The mentioned strengthening methods lead to an increase of ductility, increase of load carrying capacity and increase of dissipated energy.

Retrofitting of reinforced concrete columns using near-surface-mounted steel rebars and fiber-reinforced polymer straps under eccentric loading

2019 ◽  
Vol 23 (4) ◽  
pp. 687-701 ◽  
Author(s):  
Sayed Behzad Talaeitaba ◽  
Ehsan Barati ◽  
Abolfazl Eslami
Keyword(s):  
Reinforced Concrete ◽  
Concrete Columns ◽  
Fiber Reinforced Polymer ◽  
Small Scale ◽  
Fiber Reinforced ◽  
Reinforced Concrete Columns ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Near Surface Mounted ◽  
Steel Rebars

This experimental study focuses on the retrofitting of reinforced concrete columns subjected to axial compression loading with different eccentricities. The proposed hybrid retrofitting technique incorporates two components: near-surface-mounted longitudinal steel rebars and transverse carbon-fiber-reinforced polymer straps. The latter was implemented to preclude buckling of the near-surface-mounted steel rebars under compression, to postpone debonding of near-surface-mounted steel rebars, to increase shear capacity of columns, and to improve the confinement level of concrete. The efficiency of the adopted retrofitting technique was evaluated through experimental testing of undamaged and damaged columns. Toward this, a total of 20 small-scale reinforced concrete circular columns including 5 control, 5 repaired, and 10 strengthened specimens were tested. All specimens were built to be identical with a diameter of 150 mm and a height of 500 mm. The specimens were tested under pure compression, combined axial–flexural (with eccentricities of 30, 60, and 90 mm), and four-point flexural loadings. Comparison of the results showed the efficacy of the proposed retrofitting strategy in enhancing the structural performance of both the undamaged and damaged columns in terms of loading capacity, ultimate displacement, and ductility factor. Finally, the axial load–bending moment interaction curves were discussed for all the tested columns.

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