scholarly journals Behavior and Analysis of Self-Consolidated Reinforced Concrete Deep Beams Strengthened in Shear

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Kh. M. Heiza ◽  
N. N. Meleka ◽  
N. Y. Elwkad
Keyword(s):  
Load Capacity ◽  
Fiber Reinforced Polymers ◽  
New Technique ◽  
Deep Beams ◽  
Carbon Fiber Reinforced Polymers ◽  
Shear Strengthening ◽  
Reinforced Polymers ◽  
Near Surface ◽  
Externally Bonded ◽  
Strengthening Technique

In this study, a new shear strengthening technique for reinforced self-compacting concrete (RSCC) deep beams was suggested and compared with some traditional techniques. An experimental test program consists of sixteen specimens of RSCC deep beams strengthened by different materials such as steel, glass, and carbon fiber reinforced polymers (GFRP and CFRP) was executed. Externally bonded layers (EBLs) and near-surface mounted reinforcement (NSMR) were used as two different techniques. The effects of the new technique which depends on using intertwined roving NSM GFRP rods saturated with epoxy were compared with the other models. The new technique for shear strengthening increases the load capacity from 36% to 55% depending on the anchorage length of GFRP rods. Two-dimensional nonlinear isoperimetric degenerated layered finite elements (FEs) analysis was used to represent the SCC, reinforcement, and strengthening layers of the tested models. The analytical results have been very close to the experimental results.

scholarly journals Experimental Study of a New Strengthening Technique of RC Beams Using Prestressed NSM CFRP Bars

2019 ◽  
Vol 11 (5) ◽  
pp. 1374 ◽  
Author(s):  
Vicente Alcaraz Carrillo de Albornoz ◽  
Eva García del Toro ◽  
M. Isabel Más-López ◽  
Alfredo Luizaga Patiño
Keyword(s):  
High Performance ◽  
Fiber Reinforced Polymers ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Near Surface ◽  
Environmentally Sustainable ◽  
Sustainable Solutions ◽  
Reinforced Beams ◽  
A New Technique ◽  
Strengthening Technique

The reinforcement of structural elements subjected to bending with carbon fiber reinforced polymers (CFRP) located on the underside of the element to be reinforced (known as near surface mounted or NSM) is an effective technique that provides environmentally sustainable solutions in the field of civil engineering. Introducing preloads on the reinforcing elements allows us to maximize the high performance of CFRPs, besides recovering deformations. A new technique to perform the pre-stressing of CFRP bars in NSM configuration is described in this paper. The technique introduces the preload on the rods after they have been placed in the grooves, and with a system that acts and reacts against the beam itself. We also present the results of a testing campaign conducted to determine the effectiveness of said technique. Breakage of the control beams (without reinforcement) was ductile, while breakage of reinforced beams was explosive. Pre-stressing the reinforcing elements allowed us to increase the bearing capacity of the beams 170% compared to the control beams, also resulting in an increase in the rigidity of the reinforced elements and a decreased cracking of the beam. The results however are only slightly better than those of a conventional CFRP NSM reinforcement, due to the appearance of cavities in the groove where the adhesive didn’t manage to penetrate.

scholarly journals Shear and Flexural Behavior of Reinforced Concrete Deep Beams Strengthened with CFRP Composites

2017 ◽  
Vol 11 (10) ◽  
pp. 110 ◽  
Author(s):  
Hana Al-Ghanem ◽  
Aya Al-Asi ◽  
Mu’tasim Abdel-Jaber ◽  
Maha Alqam
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Strength ◽  
Flexural Behavior ◽  
Fiber Reinforced Polymers ◽  
Deep Beams ◽  
Carbon Fiber Reinforced Polymers ◽  
Shear Strengthening ◽  
Cross Sectional ◽  
Flexural Strengthening ◽  
Cfrp Composites

The current research studies the shear and flexural behavior of reinforced concrete (RC) deep beams strengthened with externally bonded carbon fiber-reinforced polymers (CFRP). Using two types of CFRP composites including sheets and laminates, different configurations for shear and flexural strengthening of deep beams were experimentally investigated. In total, twenty specimens of deep beams with cross-sectional dimensions of 190 mm width, 400 mm depth and an overall length of 1 900 mm were casted and tested to failure. Concerning the cracks’ formation, failure’s modes, ultimate strength and overall stiffness, the performance of the strengthened beams compared to the control beams were evaluated. From the test results, the effectiveness of CFRP technique on enhancing both the shear and flexural capacity of deep beams is verified; however, the efficiency differs variedly depending on the material and the strengthening scheme. Regarding the shear strengthening, using the continuous wrap of two sheets records the highest increase in the ultimate strength with a value exceeds 86% compared only to 36% with the inclined laminates. On the other hand, an enhancement of about 51% is achieved through the flexural strengthening with two layers of sheets and 26% when the laminates are used; both are accompanied by a divergent in the failure mode from flexure to shear. 

scholarly journals Behaviour of Segmental Concrete Beams Reinforced by Pultruded CFRP Plates: An Experimental Study

2019 ◽  
Vol 25 (8) ◽  
pp. 62-79 ◽  
Author(s):  
Ali Adel Abdulhameed ◽  
AbdulMuttalib Issa Said
Keyword(s):  
Carbon Fiber ◽  
Design Procedure ◽  
Interface Condition ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Externally Bonded ◽  
Design Values ◽  
Carbon Fiber Reinforced

The research aims to develop an innovative technique for segmental beam fabrication using plain concrete blocks and externally bonded Carbon Fiber Reinforced Polymers Laminates (CFRP) as a main flexural reinforcement. Six beams designed and tested under two-point loadings. Several parameters included in the fabrication of segmental beam were studied such as; bonding length of carbon fiber reinforced polymers, the surface-to-surface condition of concrete segments, interface condition of the bonding surface and thickness of epoxy resin layers. Test results of the segmental beams specimens compared with that gained from testing reinforced concrete beam have similar dimensions for validations. The results display the effectiveness of the developed fabrication method of segmental beams. The modified design procedure for externally bonded carbon fiber reinforced polymers ACI 440.2R-17 was developed for designing segmental beams. The experimental test values also compared with design values, and it was 93.3% and 105.8% of the design values, which indicates the effectiveness of the developed procedure.  

CFRP strengthening system to increase fatigue resistance of bridges

2019 ◽  
Author(s):  
Roman Sedlmair ◽  
Lothar Stempniewski
Keyword(s):  
Strain Distribution ◽  
Fatigue Behavior ◽  
Dynamic Loads ◽  
Fiber Reinforced Polymers ◽  
Stress Concentrations ◽  
Carbon Fiber Reinforced Polymers ◽  
Cfrp Laminates ◽  
External Reinforcement ◽  
Externally Bonded ◽  
Strengthening Technique

<p>Carbon fiber reinforced polymers (CFRP) laminates externally bonded with epoxy resins are an often used strengthening technique of aged and overloaded structures, e.g. bridges. A well-known, though not commonly discussed, problem is the stiff bond behavior of the used adhesives. Their use leads to stress concentrations in the CFRP and concrete at the location of cracks and an uneven strain distribution of internal and external reinforcement. On that basis, the usage of such a strengthening technique for components subjected to dynamic loads is limited or almost impossible due to premature debonding of the CFRP.</p><p>The present paper focuses on numerical analysis of reinforced concrete bending beams strengthened with CFRP using the finite element method. In our analysis we focus on contact modelling techniques. The effect of differing adhesives on the overall behavior of the strengthened beams and strain distribution of internal and external reinforcement is shown. Numerical investigations demonstrate the relevance of the used adhesive on the static and fatigue behavior of the strengthened component. Modified and optimized material properties of the adhesive lead to a strengthening system which is even capable of carrying dynamic loads.</p>

scholarly journals Advancements in shear strengthening of prestressed concrete I-girders using fiber reinforced polymers

2021 ◽  
Author(s):  
Muhammad Arslan Yaqub ◽  
Stijn Matthys ◽  
Christoph Czaderski
Keyword(s):  
Prestressed Concrete ◽  
Failure Modes ◽  
Rational Solution ◽  
Fiber Reinforced Polymers ◽  
Shear Reinforcement ◽  
Shear Strengthening ◽  
Reinforced Polymers ◽  
The Past ◽  
Externally Bonded ◽  
Fibre Reinforced Polymer

<p>A number of attempts were made by different researchers in the last couple of decades to strengthen prestressed concrete (PC) I-girders in shear using externally bonded FRP (fibre reinforced polymer) reinforcement. The unanimous observation reported in the literature is the early debonding of FRP shear reinforcement around the internal angles of the I-section. Because of this undesirable phenomenon, the strength of the FRP is utilized inefficiently. This paper gives an overview of the techniques utilized in the past and their relative performance in order to develop a rational solution to the debonding problem, particularly for I-sections. The anchoring techniques used in the past includes different types of FRP anchors as well as mechanical anchors to protect FRP shear reinforcement from debonding on the I-section. It can be concluded that the definite solution to the debonding problem on I-sections has not been obtained yet. This is because of the complex failure modes of FRP shear reinforcement and PC I-girders.</p>

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