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 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 CFRP Laminates Reinforcing Performance of Short-Span Wedge-Blocks Segmental Beams

Fibers ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 6 ◽  
Author(s):  
Ali A. Abdulhameed ◽  
AbdulMuttalib I. Said
Keyword(s):  
American Concrete Institute ◽  
Fiber Reinforced Polymers ◽  
Carbon Fiber Reinforced Polymers ◽  
Construction Technique ◽  
Reinforced Polymers ◽  
Cfrp Laminates ◽  
Rapid Construction ◽  
Short Span ◽  
A New Technique ◽  
Ultimate Loading

Two of the main advantages of segmental construction are economics, as well as the rapid construction technique. One of the forms of segmental construction, for structural elements, is the segmental beams that built-in short sections, which referred to segments. This research aims to exhibit a new technique for the fabrication of short-span segmental beams from wedge-shaped concrete segments and carbon fiber reinforced polymers (CFRP) in laminate form. The experimental campaign included eight short-span segmental beams. In this study, two selected parameters were considered. These parameters are; the number of layers of CFRP laminates and the adhesive material that used to bond segments to each other, forming short-span segmental beams. The test results showed that for segmental beams reinforced by 2-layer of CFRP laminates, undergoes less deflection and sustained considerable ultimate loading value of 38.4%–104% than beams reinforced by 1-layer. Moreover, the test of segmental beams fabricated by adhering to the concrete segments with epoxy resin exhibited an increase in ultimate loading by 16%–65% than beams constructed using cementitious adhesive for bonding the wedge-shaped segments. Theoretically, segmental beams were analyzed by the American Concrete Institute (ACI) 440.2R-17 procedure with slight modifications. The analysis gave an overestimation of flexural strength for segmental beams when compared with experimental outcomes.

scholarly journals Compósitos cimentícios de alto desempenho para aplicação como substrato de transição em vigas

2016 ◽  
Vol 6 (1) ◽  
pp. 52-63
Author(s):  
V. J. Ferrari ◽  
A. P. Arquez ◽  
J. B. De Hanai
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
High Performance ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymers ◽  
Short Fibers ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Material Tests

Compuestos cementíceos de alto desempeño para su aplicación como sustrato de transición en vigasRESUMENEste estudio muestra el desarrollo y análisis del comportamiento de los materiales compuestos de cemento reforzado con fibras de alto rendimiento. El material descrito se desarrolló específicamente para su aplicación como sustrato de transición, o capa de reparación de la formación de la brida tensada vigas de hormigón reforzado con polímeros de flexión reforzado con fibras de carbono (PRFC). Diecinueve compuestos diferentes fueron producidos por el proceso de hibridación. Se varió la cantidad de fibras cortas y microfibras de acero. Para analizar el comportamiento de los ensayos de flexión en tres puntos materiales prismas se realizaron Jagged. La respuesta del material se analizó teniendo en cuenta parámetros de tenacidad a la flexión y (fractura). Materiales compuestos de alto rendimiento evidencia a través de un comportamiento pseudo- endurecimiento.Palabras clave: compuestos cementíceos; vigas de concreto; sustrato de transición. High performance cementitious compounds and their application as transition substrate for beamsABSTRACTThis study presents the development and analysis of the behavior of high performance cementitious compounds reinforced with fibers. The material described was specifically developed for its application as a transition substrate, meaning, a repair layer that forms the tensed span of the flexion reinforced concrete beams with carbon fiber reinforced polymers (CFRP). Nineteen different compounds were produced by the hybridization process. The volume of the short fibers and of the steel microfibers varied. To analyze the behavior of the flexural material, tests were done in three points in tests tubes with their notches. The response of the material was analyzed considering the tenacity parameters (to flexion and fracture). The high performance of the compounds through the behavior of pseudo-hardening was confirmed.Keywords: cementitious compounds; concrete beams; transition substrate. Compósitos cimentícios de alto desempenho para aplicação como substrato de transição em vigasRESUMONeste estudo apresenta-se o desenvolvimento e a análise do comportamiento de compuestos cementíceos de elevado desempeño reforzados com fibras. O material descrito foi especificamente desarrollado para aplicación como um sustrato de transición, ou seja, camada de reparo que forma o banzo traccionado de vigas de concreto reforçadas à flexão com polímeros reforzados com fibras de carbono (PRFC). Dezenove diferentes compuestos foram produzidos pelo processo de hibridização. Variou-se o volume de fibras curtas e de microfibras de aço. Para analisar o comportamiento do material à flexão, ensaios em três pontos em prismas entalhados foram realizados. A resposta do material foi analisada considerando-se parâmetros de tenacidade (flexional e ao fraturamento). Ficou evidenciado o elevado desempeño dos compuestos através de comportamiento de pseudo-encruamento.Palavras-chave: compuestos cementíceos; vigas de concreto; sustrato de transición.

Strengthening and repair of one-way and two-way self-compacted concrete slabs using near-surface-mounted carbon-fiber-reinforced polymers

2019 ◽  
Vol 22 (11) ◽  
pp. 2435-2448 ◽  
Author(s):  
Ahmed M Ashteyat ◽  
Yousef S Al Rjoub ◽  
Ala’ T. Obaidat ◽  
Huthaifah Dagamseh
Keyword(s):  
Carbon Fiber ◽  
Ultimate Strength ◽  
Fiber Reinforced Polymers ◽  
Concrete Slabs ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Near Surface ◽  
Near Surface Mounted ◽  
Carbon Fiber Reinforced

The effectiveness of near-surface-mounted carbon-fiber-reinforced polymers on strengthening and repair of self-compacted concrete slabs was investigated experimentally and numerically. Twenty slabs were cast (10 one-way and 10 two-way) and tested under four-point load. Strengthening and repair effectiveness was investigated on slabs using near-surface-mounted carbon-fiber-reinforced polymer strips with straight and inclined orientation. Repair was performed on eight slabs using near-surface-mounted carbon-fiber-reinforced polymer strips with an orientation based on the best cost/capacity ratio, with two preloading levels: 35% and 50% of the ultimate load of the control slab. The results showed that using near-surface-mounted carbon-fiber-reinforced polymers increases the ultimate strength of one-way strengthened self-compacted concrete slabs (45%–163%) for both strip orientation, with the straight orientation performing better. Also, the cracking load and stiffness increased, while deflection decreased. The increase in ultimate strength for strengthened two-way slabs was 15% to 17%. The ultimate deflection and toughness of the two-way strengthened slabs increased 43% and 34%, respectively. Using near-surface-mounted carbon-fiber-reinforced polymers restored the load capacity of repaired one-way and two-way slabs but was more effective for one-way slabs. The repaired one-way slabs regained up to 223% of the control slabs’ ultimate strength, with a significant increase in stiffness (296%). The repaired two-way slabs regained up to 116% of the control slabs’ ultimate strength. The strength was higher in the case of the 50% preload compared to 35% preload. The finite element model shows somehow a reasonable capability of predicting the experimental behavior with a gap in terms of the stiffness and the maximum load.

scholarly journals Evaluation of Wedge-Block Concrete Beams Reinforced with EBR-CFRP Laminates by Modified ACI 440.2R-2017 Guide

2019 ◽  
Author(s):  
Ali Abdulhameed ◽  
AbdulMuttalib Said
Keyword(s):  
Concrete Beams ◽  
American Concrete Institute ◽  
Cementitious Materials ◽  
Fiber Reinforced Polymers ◽  
Small Scale ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Cfrp Laminates ◽  
A New Technique ◽  
Two Parameters

Concrete beams built from individual segments connected to each other by special mechanism referred as segmental beam. The aim of this research is to exhibit a new technique for fabrication of small scale segmental beams from wedge shape unreinforced concrete segments and pultruded carbon fiber reinforced polymers (CFRP) in laminate form. Eight segmental beams including two parameters are tested experimentally. The first parameter is the area of CFRP and second is the adhesive material used to bond segments of the beams. The test shows that segmental beams have a higher ratio of CFRP area undergoes less deflection and sustain higher ultimate loading value of 38.4%. Moreover, the test of beams with concrete segments adhered by epoxy resin sustain a higher load than segments adhered by cementitious materials about 11.87%. Theoretically, segmental beams were analyzed by modified American Concrete Institute ACI 440.2R-17 report with slight modifications. The analysis results in an overestimation of flexural strength of segmental beams when compared with experimental outcomes.

scholarly journals Ductility of the Tensile Zone in Bent Wooden Beams Strengthened with CFRP Materials

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5451 ◽  
Author(s):  
Agnieszka Wdowiak-Postulak ◽  
Janusz Brol
Keyword(s):  
Cross Sections ◽  
Experimental Tests ◽  
Maximum Load ◽  
Fiber Reinforced Polymers ◽  
Tension Zone ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Reinforced Beams ◽  
Scale Models ◽  
Strength And Stiffness

This article presents experimental results from the bending of technical-scale models of beams reinforced in the tension zone with CFRP (Carbon Fiber Reinforced Polymers) materials, with a focus on the benefits resulting from the increased ductility in the tension zone of these beams. In experimental tests, the mechanical properties of reinforced beams were compared with unreinforced beams in terms of the maximum load, deflection, images of damage, stiffness, and distribution of deformation. The results showed that the proposed reinforcement solution was advantageous due to its strength and stiffness, and the safety of the structure. Based on this analysis, it was concluded that the reinforcement of wood with CFRP materials has a positive effect on the behavior and safety of structures. Also, a method of analytical checking of strengthened beams with small cross-sections was presented in the article.

scholarly journals Carbon Fiber Reinforced Polymers

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5545
Author(s):  
Francesca Lionetto
Keyword(s):  
Carbon Fiber ◽  
Carbon Fibers ◽  
High Performance ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Production Methods ◽  
Carbon Fiber Reinforced ◽  
Out Of Autoclave

The current demand for lightweight and high-performance structures leads to increasing applications of carbon fiber reinforced polymers, which is also made possible by novel production methods, automation with repeatable quality, the reduced cost of carbon fibers, out of autoclave processes such as resin transfer molding and resin infusion technologies, the re-use of waste fibers, development in preform technology, high-performance, fast-curing resins, etc [...]

Processing of Carbon Nanotubes and Carbon Nanofibers towards High Performance Carbon Fiber Reinforced Polymers

2017 ◽  
Vol 742 ◽  
pp. 31-37 ◽  
Author(s):  
Gerald Singer ◽  
Harald Rennhofer ◽  
Gerhard Sinn ◽  
Miriam M. Unterlass ◽  
Josef Wendrinsky ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Fiber ◽  
Carbon Nanofibers ◽  
High Performance ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Cfrp Composite ◽  
Carbon Fiber Reinforced

Carbon fiber reinforced polymers (CFRPs) are promising composite materials for high-performance and lightweight applications, gaining increasing interest in aerospace and automotive industries. Epoxy thermosets are frequently used as polymer matrices of CFRPs, which are usually responsible for failure of the composite. In this work different types of carbon nanotubes (CNTs) and carbon nanofibers (CNF) are added to the epoxy resin to improve mechanical properties of the whole CFRP composite. The dispersion of the fillers on a three-roll mill (TRM) is shown comparing their dispersion behavior in the resin. Results of increased modulus and strength of the hierarchical composite in four-point bending tests are presented.

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