scholarly journals Flexural Strengthening of RC Structures with TRC—Experimental Observations, Design Approach and Application

2019 ◽  
Vol 9 (7) ◽  
pp. 1322 ◽  
Author(s):  
Silke Scheerer ◽  
Robert Zobel ◽  
Egbert Müller ◽  
Tilo Senckpiel-Peters ◽  
Angela Schmidt ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Design Model ◽  
Textile Reinforced Concrete ◽  
Bending Tests ◽  
Rc Structures ◽  
Flexural Strengthening ◽  
Reinforced Concrete Slabs ◽  
Open Questions ◽  
Basic Behavior ◽  
Strengthening Method

Today, the need for structural strengthening is more important than ever. Flexural strengthening with textile reinforced concrete (TRC) is a recommendable addition to already proven methods. In order to use this strengthening method in construction practice, a design model is required. This article gives a brief overview of the basic behavior of reinforced concrete slabs strengthened with TRC in bending tests as already observed by various researchers. Based on this, a design model was developed, which is presented in the main part of the paper. In addition to the model, its assumptions and limits are discussed. The paper is supplemented by selected application examples to show the possibilities of the described strengthening method. Finally, the article will give an outlook on open questions and current research.

scholarly journals Strengthening of Concrete Element with Precast Textile Reinforced Concrete Panel and Grouting Material

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3856
Author(s):  
Young-Jun You ◽  
Hyeong-Yeol Kim ◽  
Gum-Sung Ryu ◽  
Kyung-Taek Koh ◽  
Gi-Hong Ahn ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Bending Test ◽  
Strengthening Effect ◽  
Textile Reinforced Concrete ◽  
Concrete Element ◽  
Rc Structures ◽  
Flexural Strengthening ◽  
Grouting Material ◽  
Rc Slab ◽  
Rc Slabs

Textile reinforced concrete (TRC) has widely been used for strengthening work for deteriorated reinforced concrete (RC) structures. The structural strengthening often requires accelerated construction with the aid of precast or prefabricated elements. This study presents an innovative method to strengthen an RC slab-type element in flexure using a precast panel made of carbon TRC. A total of five RC slabs were fabricated to examine the flexural strengthening effect. Two of them were strengthened with the precast panel and grouting material and another set of two slabs was additionally strengthened by tensile steel reinforcement. The full-scale slab specimens were tested by a three-point bending test and the test results were compared with the theoretical solutions. The results revealed that the ultimate load of the specimens strengthened with the TRC panel increased by at least 1.5 times compared to that of the unstrengthened specimen. The application of the precast TRC panel and grouting material for the strengthening of a prototype RC structure verified its outstanding constructability.

scholarly journals Reinforced Concrete Slabs Strengthened with Carbon Textile Grid and Cementitious Grout

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5046
Author(s):  
Hyeong-Yeol Kim ◽  
Young-Jun You ◽  
Gum-Sung Ryu
Keyword(s):  
Plastic Deformation ◽  
Reinforced Concrete ◽  
Test Data ◽  
Concrete Slabs ◽  
Test Results ◽  
Structural Elements ◽  
Textile Reinforced Concrete ◽  
Rc Structures ◽  
Reinforced Concrete Slabs ◽  
Rc Slabs

A textile reinforced concrete (TRC) system has been widely used for repair and strengthening of deteriorated reinforced concrete (RC) structures. This paper proposes an accelerated on-site installation method of a TRC system by grouting to strengthen deteriorated RC structures. Four RC slabs were strengthened with one ply of carbon textile grid and 20 mm-thick cementitious grout. The TRC strengthened slab specimens were tested under flexure and the test results were compared with those of an unstrengthened specimen and theoretical solutions. Furthermore, the TRC strengthened specimens experienced longer plastic deformation after steel yield than the unstrengthened specimen. The TRC strengthened specimens exhibited many fine cracks and finally failed by rupture of the textile. Therefore, TRC system with the proposed installation method can effectively be used for strengthening of deteriorated RC structural elements. The theoretically computed steel yield and ultimate loads overestimate the test data by 11% and 5%, respectively.

scholarly journals Cyclic Shear Performance of Reinforced Concrete Columns Strengthened by External Steel Rods

2021 ◽  
Vol 13 (23) ◽  
pp. 13224
Author(s):  
Hyeong-Gook Kim ◽  
Yong-Jun Lee ◽  
Kil-Hee Kim
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Analytical Approach ◽  
Concrete Columns ◽  
Loading Test ◽  
Rc Structures ◽  
Cyclic Shear ◽  
Flexural Failure ◽  
Shear Performance ◽  
Strengthening Method

This study presents a strengthening method for reinforced concrete (RC) columns. The proposed method, which consists of a pair of steel rods, two reverse-threaded couplers, and four corner blocks, is feasible and straightforward. A quasi-static cyclic loading test was performed on the columns externally strengthened by the steel rods. It was found that the corner blocks and the external steel rods with a low prestress level effectively confined the concrete on the compression side of plastic hinges, which eventually induced flexural failure with a ductility higher than three in the strengthened columns. In addition, an analytical approach to predict the shear strength and ultimate flexural strength of the externally strengthened columns was applied. The comparison of analytical and experimental results showed that the analytical approach provided highly accurate predictions on the maximum strength and the failure mode of the externally strengthened columns. It is expected that the application of the proposed method will improve the seismic performance of damaged or deteriorated RC structures, thereby increasing their lifespan expectancy and sustainability.

scholarly journals Flexural Strengthening of Concrete Slab-Type Elements with Textile Reinforced Concrete

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2246 ◽  
Author(s):  
Hyeong-Yeol Kim ◽  
Young-Jun You ◽  
Gum-Sung Ryu ◽  
Kyung-Taek Koh ◽  
Gi-Hong Ahn ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Tensile Test ◽  
Tensile Properties ◽  
Surface Coating ◽  
Strengthening Effect ◽  
Test Results ◽  
Short Fibers ◽  
Textile Reinforced Concrete ◽  
Flexural Strengthening ◽  
The Matrix

This paper deals with flexural strengthening of reinforced concrete (RC) slabs with a carbon textile reinforced concrete (TRC) system. The surface coating treatment was applied to a carbon grid-type textile to increase the bond strength. Short fibers were incorporated into the matrix to mitigate the formation of shrinkage-induced cracks. The tensile properties of the TRC system were evaluated by a direct tensile test with a dumbbell-type grip method. The tensile test results indicated that the effect of the surface coating treatment of the textile on the bonding behavior of the textile within the TRC system was significant. Furthermore, the incorporation of short fibers in the matrix was effective to mitigate shrinkage-induced crack formation and to improve the tensile properties of the TRC system. Six full-scale slab specimens were strengthened with the TRC system and, subsequently, failure tested. The ultimate load-carrying capacity of the strengthened slabs was compared with that of an unstrengthened slab as well as the theoretical solutions. The failure test results indicated that the stiffness and the ultimate flexural capacity of the strengthened slab were at least 112% and 165% greater, respectively, than that of the unstrengthened slab. The test results further indicated that the strengthening effect was not linearly proportional to the amount of textile reinforcement.

Flexural Strengthening of Reinforced Concrete Beams with Prestressed CFRP Plates

2011 ◽  
Vol 255-260 ◽  
pp. 3077-3081 ◽  
Author(s):  
Lang Ni Deng ◽  
Hua Chen ◽  
Kan Kang
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Bending Tests ◽  
Control Beam ◽  
Flexural Strengthening ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Anchorage System

Four medium -scale reinforced concrete beams were constructed and tested to investigate the effectiveness of external poststrengthening with prestressed carbon fiber reinforced polymer (CFRP) plates. The various variables included the strengthening method and the amount of prestressing. The experiments consisted of one control beam, one nonprestressed CFRP-bonded beam, and two prestressed CFRP-bonded beams, all the beams were subjected to four-point bending tests. In comparison to the control beam and the nonprestressed CFRP-bonded beam, the cracking load, yield load, ultimate load and stiffness of the beams with bonded prestressed CFRP plates were increased. The failure mode of the prestressed CFRP-plated beams was not debonding, but concrete crushing. After the debonding of the CFRP plates, the behaviour of the bonded CFRP-plated beams changed to that of unbonded CFRP-plated beams due to the effect of the anchorage system. The ductility of the beams strengthened with CFRP plates having the anchorage system was considered high if the ductility index was above 3.

Combined effect of sustained load and freeze–thaw cycles on one-way concrete slabs reinforced with glass fibre – reinforced polymer

2013 ◽  
Vol 40 (11) ◽  
pp. 1060-1067 ◽  
Author(s):  
Hizia Bellakehal ◽  
Ali Zaidi ◽  
Radhouane Masmoudi ◽  
Mohamed Bouhicha
Keyword(s):  
Reinforced Concrete ◽  
Shear Capacity ◽  
Concrete Slabs ◽  
Thermal Cycles ◽  
Bending Tests ◽  
Freeze Thaw ◽  
Reinforced Concrete Slabs ◽  
Reinforced Polymer ◽  
Significant Difference ◽  
Fibre Reinforced Polymer

Flexural behaviour of reinforced-concrete slabs has been widely investigated to characterize properties and behaviour of fibre-reinforced polymer (FRP) materials as reinforcement for concrete structures. However, the short- and long-term thermal effects on FRP bars owing to the significant difference between the bars’ coefficients of thermal expansion in the transverse and longitudinal directions are still to be evaluated and may affect the bond properties and the concrete cover thickness after multiple exposures to freeze–thaw cycles. This paper presents the thermostructural behaviour of one-way concrete slabs reinforced with glass FRP (GFRP) that have previously been subjected to mechanical loads of 20% and 30% of the ultimate flexural capacity of reinforced-concrete slabs, simultaneously with short freeze–thaw cycles. Series tests were conducted on FRP-reinforced concrete slabs 500 mm wide, 195–215 mm thick, and 2500 mm long. The thermal cycles were varied from −30 to 60 °C. Four-point bending tests were conducted up to failure of the slabs. The results show that the thermomechanical load applied before bending tests increases the performance of reinforced-concrete slabs, particularly the concrete shear capacity. The deflection predicted from CSA code and ACI guidelines are very close to those obtained from experimental tests; however, the CSA code overestimates the deflection at the service load. The applied thermal cycles have no big influence on the behaviour before shear failure of concrete slabs reinforced with GFRP bars.

scholarly journals NGHIÊN CỨU THIẾT KẾ TĂNG CƯỜNG KHẢ NĂNG CHỊU UỐN SÀN BÊ TÔNG CỐT THÉP BẰNG VẬT LIỆU TẤM SỢI FRP DÁN NGOÀI

2021 ◽  
Vol 5 (1) ◽  
pp. 2330-2341
Author(s):  
Nguyễn Thị Thanh ◽  
Phạm Việt Hùng ◽  
Ngô Quý Tuấn ◽  
Lê Minh Đức ◽  
Nguyễn Trường Giang
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Concrete Strength ◽  
Fiber Reinforced Polymer ◽  
Concrete Slabs ◽  
Fiber Reinforced ◽  
Flexural Strengthening ◽  
Reinforced Concrete Slabs ◽  
Reinforced Polymer ◽  
Calculation Results

Phương pháp tăng cường khả năng chịu uốn của kết cấu sàn bê tông cốt thép sử dụng vật liệu tấm sợi FRP (Fiber Reinforced Polymer) dán ngoài đã trở nên phổ biến, vì những ưu điểm của chúng mang lại như cường độ chịu kéo cao, trọng lượng nhẹ, cách điện, cách nhiệt tốt, bền theo thời gian. Bài báo trình bày quy trình thiết kế tăng cường khả năng chịu uốn của sàn bê tông cốt thép gia cường bằng tấm sợi FRP dán ngoài để đảm bảo yêu cầu khai thác và khảo sát hiệu quả tăng cường tương ứng với các cấp cường độ chịu nén của bê tông theo hướng dẫn ACI 440.2R-17. Kết quả tính toán theo trình tự đề nghị giúp chọn và kiểm tra được diện tích tấm FRP tăng cường cần thiết. Ngoài ra, kết quả tính toán chỉ ra rằng mức độ tăng cường khả năng chịu uốn của sàn tỷ lệ thuận với cường độ chịu nén của bê tông, tương ứng với cường độ bê tông tăng từ 11,5 MPa đến 19,5 MPa, sức kháng uốn tính toán tăng từ 91%  đến 144%. Đồng thời, kết quả cũng cho thấy rằng sự phá hoại của sàn bê tông cốt thép xảy ra do mất dính bám giữa lớp FRP gia cường khỏi bề mặt cấu kiện là chủ yếu. ABSTRACT The method of the flexural strengthening of reinforced concrete slabs using the externally bonded FRP (fiber reinforced polymer) laminates has become popular because of their advantages as high tensile strength, large modulus of elasticity, lightweight, high abrasion resistance, electrical insulation, good heat resistance and durable over the time. The paper presented the design procedure for the flexural strengthening of reinforced concrete slabs with FRP laminates to ensure the mining requirements and investigation of the reinforcement efficiency corresponding to the compressive strength levels of concrete based on ACI 440.2R-17. Calculation results in the suggested sequence helped select and check the required reinforcement FRP areas. In addition, the calculation results showed that the degree of increased flexural strengthening of the slabs was proportional to the compressive strength of the concrete, corresponding to the concrete strength increased from 11,5 MPa to 19,5 MPa, flexural strengthening increases from 91% to 144%. Moreover, the damage to the reinforced concrete slabs was caused by the debonding between the FRP and the surface of the structures.

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