RC T beams strengthened to shear with carbon fiber composites

Abstract

This paper presents the experimental data of the behavior of reinforced concrete beams strengthened to shear with carbon fiber composites. The tests were composed of eight T beams, b w =15 cm, h=40 cm, flange width 40 cm, flange height 8 cm, and length 300 cm, divided into two series with the same longitudinal steel reinforcement and a reference beam without strengthening in each series. The beams had two types of arrangement of internal steel stirrups. The test variables were the internal and external geometric ratio of the transverse reinforcement and the mechanical ratio of carbon fiber composites stirrups. All the beams were loaded at two points. The strengthened beams were submitted to a preloading and the strengthening was applied to the cracked beam. All the beams were designed in order to guarantee shear failure, and the ultimate load of the strengthened beams was 36% to 54% greater than the reference beams. The Cracking Sliding Model applied to the strengthened beams was evaluated and showed good agreement with the experimental results.Keywords: shear strengthening; reinforced concrete; external strengthening; carbon fiber composites.Este artigo apresenta os dados de ensaios de vigas de concreto armado reforçadas à força cortante com compósito de fibras de carbono. Os ensaios de oito vigas T, b w =15 cm, h=40 cm, largura da mesa igual a 40 cm, altura da mesa 8 cm, comprimento de 300 cm, divididos em duas séries com a mesma armadura longitudinal e uma viga de referência sem reforço externo para cada série. As vigas tinham dois tipos de arranjos de estribos internos de aço. As variáveis dos ensaios foram as taxas geométricas das armaduras transversais internas e externas, e a taxa mecânica da armadura em estribos de compósito de fibras de carbono. Todas as vigas foram carregadas em dois pontos. As vigas reforçadas foram submetidas a um carregamento prévio e reforçadas após a fissuração. Todas as vigas foram projetadas para garantir a ruptura por força cortante, e as forças últimas das vigas reforçadas foram de 36% a 54% superiores às das vigas de referência. O Modelo da Fissura Deslizante foi avaliado e mostrou boa concordância com os resultados experimentais.Palavras-chave: reforço à força cortante; concreto armado; reforço externo; compósito de fibras de carbono. RC T beams strengthened to shear with carbon

Behaviour of Concrete Elements under the Shear Forces and Strengthening with the Fibre Reinforcement Polymers

“…The different codes and different methods are used from the authors to analyze and to conclude the effects from shear force and also the calculations for strengthening of concrete beams. In this case, the authors used the: Eurocode (Table 1); ACI; CA/CSA-S806-02; JSCE (Japanese Society of Civil Engineers) and other manuals for design [1][2][3].…”

“…The reference beams in the experimental program failed by diagonal tension, and the strengthened beams failed by diagonal tension with simultaneous CFRP stirrups[1,[7][8][9].Failure of the beams occurred after the steel stirrup yielded and started to present an inclined shear crack that grew in the direction of the beam flange. Bending or anchorage failure did not occur (Fig.…”

Analytical model for assessing of strengthening the flexural beams with T and rectangular section

“…The technological innovation and the development of new materials have dominate this area showing an innumerous challenges and possibilities. Civil structures along the time suffer damages that implies, normally, in a reduction on it's structural capacity and the structural reinforcement might appear as a technical and economical solution (Spagnolo, et al [1]). A typical example of the reduction in carry capacity of structures happen due to reinforcement oxidation.…”

“…To project a reinforcement system implies on the adoption of suitable theoretical models, which allow simulating precisely the behavior of the reinforcement elements (Swamy,et al [15]; Bono, et al [16]; Gamino, et al [17]). Experimentally, was verified that reinforced concrete beams behavior, strengthened with compos-ites of carbon fiber, presents features whose observance has vital importance for the appropriate strengthening function (Beber [6]; Andreolli, et al [18]; Spagnolo, et al [1]). To simulate and comprehend this behavior, the applied methodology consisted to build moment-curvature diagram, generated by the data that were obtained through a numerical model, a similar methodology is observed in (El-Refaie, et al [19]; An, et al [3]; Al-Saidy, et al [20]), however the full model is not represented in these publications.…”