scholarly journals Experimental and analytical investigations of reinforced concrete beams strengthened by different CFRP sheet schemes.

2021 ◽  
Vol 15 (56) ◽  
pp. 123-136
Author(s):  
Mahmoud Madqour ◽  
khaled fawzy ◽  
Hilal Hassan
Keyword(s):  
Numerical Study ◽  
High Strength ◽  
Epoxy Adhesive ◽  
Ease Of Use ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Finite Element Program ◽  
Rc Structures ◽  
Bending Load

The use of bonded externally polymer reinforced fiber (FRP) Laminates has been introduced as an effective approach in rehabilitating (RC) structures due to their high strength, corrosion resistance, reduced weight, and ease of use. This paper discusses the experimental results of the flexural reinforcement of RC beams by CFRP sheets bonded by epoxy adhesive to the tensile surface of the beams. Using a four-point bending load system over an effective clear length of 1800 mm, a total of ten beams with an overall dimension of 150 * 200 * 2000 with different degrees of strengthening schemes were constructed and tested. A numerical study using ANSYS finite element program was conducted by modeling RC beams. The number of layers, strengthening scheme (side and U-shape bonding) and reinforcement ratio are the major parameters of the experimental study. the research indicate that the flexural strength of the beams was substantially improved as the layers of laminate increased between 31.80 and 71.50 % and using U shape in ends delaying or preventing debonding failure. The result obtained using ANSYS model showed acceptable agreement with the experimental results, with deviations varying no more than 10 % for all specimens. 

Repair of Severely Damaged Reinforced Concrete Beams with High-Strength Cementitious Grout

2020 ◽  
Vol 2674 (6) ◽  
pp. 372-384
Author(s):  
Antoine N. Gergess ◽  
Mahfoud Shaikh Al Shabab ◽  
Razane Massouh
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Cementitious Materials ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Rc Structures

High-strength cementitious materials such as high-performance concrete are extensively used for retrofit of reinforced concrete (RC) structures. The effectiveness of these materials is increased when mixed with steel fibers. A commonly used technique for strengthening and repair of RC beams consists of applying high-performance fiber-reinforced concrete jackets around the beam perimeter. This paper investigates the jacketing method for repairing severely damaged RC beams. Four 2 m (6 ft 63/4 in.) long rectangular RC beams, 200 × 300 mm (8 ×12 in.) were initially cast and loaded until failure based on three-point bending tests. The four beams were then repaired by thickening the sides of the damaged RC beams using a commercially available high-strength shrinkage grout with and without steel fibers. Strain and deformation were recorded in the damaged and repaired beams to compare structural performance. It is shown that the flexural strength of the repaired beams is increased and the crack pattern under loading is improved, proving that the proposed repair method can restore the resistance capacity of RC beams despite the degree of damage. A method for repair is proposed and an analytical investigation is also performed to understand the structural behavior of the repaired beams based on different thickening configurations.

scholarly journals DIAGONAL TENSION FAILURE OF RC BEAMS WITHOUT STIRRUPS / SKERSINE ARMATŪRA NEARMUOTŲ GELŽBETONINIŲ SIJŲ TEMPIAMASIS SUIRIMAS ĮSTRIŽAJAME PJŪVYJE

2012 ◽  
Vol 18 (2) ◽  
pp. 217-226 ◽  
Author(s):  
Guray Arslan
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Concrete Beams ◽  
High Strength ◽  
Theory Of Elasticity ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Codes Of Practice ◽  
Slender Beams

The shear failure of reinforced concrete beams is one of the fundamental problems in civil engineering; however, the diagonal tension strength of reinforced concrete (RC) beams without stirrups is still in question. This paper focuses on the prediction of diagonal cracking strength of RC slender beams without stirrups. In slender beams, flexural cracks develop in the tension zone prior to a diagonal cracking. Using the basic principles of mechanics, but cracking included, and theory of elasticity, a diagonal cracking strength equation is proposed for both normal and high strength concrete beams. The proposed equation, the requirements of six codes of practice and seven equations proposed by different researchers are compared to the experimental results of 282 beams available in the literature. It is found that the predictions from the proposed equation are in good agreement with the experimental results. Santrauka Gelžbetoninių sijų suirimas įstrižajame pjūvyje – viena pagrindinių problemų statybos inžinerijoje. Tačiau skersine armatūra nearmuotų gelžbetoninių sijų įstrižasis tempiamasis stipris nėra visiškai ištirtas. Šiame straipsnyje nagrinėjamas siaurų, be skersinės armatūros gelžbetoninių sijų įstrižojo pjūvio pleišėjimas. Siaurose sijose plyšiai tempiamojoje zonoje atsiranda anksčiau negu įstrižajame pjūvyje. Taikant klasikinius mechanikos principus ir tamprumo teoriją, pasiūlyta normalaus stiprio arba stipriojo betono sijų istrižojo pjūvio atsparumo pleišėjimui apskaičiavimo lygtis. Siūloma lygtis, pagrįsta šešių projektavimo normų reikalavimais ir septyniomis kitų autorių lygtimis bei palyginta su literatūroje pateiktais 282 sijų eksperimentinių tyrimų rezultatais. Nustatyta, kad pagal siūlomą lygtį atlikti skaičiavimai gerai sutampa su eksperimentiniais rezultatais.

scholarly journals Experimental and Analytical Study on Reinforced Concrete Beams in Bending Strengthened with FRP

2014 ◽  
Vol 8 (1) ◽  
pp. 153-163 ◽  
Author(s):  
C. C. Spyrakos ◽  
I. G. Raftoyiannis ◽  
L. Credali ◽  
J. Ussia
Keyword(s):  
Reinforced Concrete ◽  
Analytical Investigation ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Laboratory Research ◽  
Rc Beams ◽  
Rc Structures ◽  
Factors Affecting ◽  
Frp Composites ◽  
Anchoring System

The performance of the interface between fiber reinforced polymer (FRP) composites and concrete is one of the key factors affecting the behavior of strengthened reinforced concrete (RC) structures. Existing laboratory research has shown that RC beams strengthened with FRP sheets usually fail because of either debonding of the impregnated fabric from the concrete substrate or fracture of the FRP. This work presents an experimental and analytical investigation of the effectiveness of FRP strengthening sheets on RC beams aiming at increasing their flexural strength and stiffness. Experimental results obtained from beam specimens tested under four-point bending are examined with main parameters being the resin type and the anchoring system. In addition, the procedure suggested by the EC8 - Greek Assessment & Retrofitting Code (EC8-GARC) provisions is applied and compared with the experimental results.

scholarly journals TEXTILE REINFORCED MORTAR BASED FLEXURAL STRENGTHENING OF REINFORCED CONCRETE BEAMS

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Muhammad Imran Rafiq ◽  
Ameer Baiee
Keyword(s):  
Reinforced Concrete ◽  
Basalt Fiber ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Rc Beams ◽  
Rc Structures ◽  
Flexural Strengthening ◽  
Strengthening Technique ◽  
Textile Reinforced Mortar

Strengthening of reinforced concrete (RC) structures is often necessary due to the change of using or to enhance the strength of deteriorated existing RC structures attributed to aging and environmental effects. Interfacial bond between the existing RC member and the strengthening layer is known to be the main factor for any successful strengthening technique. This study investigates the efficiency of utilizing high strength cementitious connectors in preventing the debonding of textile reinforced mortar (TRM) strengthening layer from substrate concrete of RC beams. An experimental program is developed to investigate the effect of strength of mortars and the distribution of cementitious connectors on the behavior of the strengthened beams. TRM comprising eight and sixteen textile basalt fiber layers were utilized in these experiments. The results demonstrate the effectiveness of cementitious connectors on the failure mode of strengthened beams by means of controlling the debonding of TRM. The increase in cracking and ultimate loads is demonstrated due to the strengthening of RC beams using TRM.

scholarly journals The Effectiveness of the DIC as a Measurement System in SRG Shear Strengthened Reinforced Concrete Beams

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 265
Author(s):  
Marco Francesco Funari ◽  
Salatore Verre
Keyword(s):  
Reinforced Concrete ◽  
Measurement System ◽  
Shear Crack ◽  
Weight Ratio ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Image Correlation ◽  
Rc Beams ◽  
Rc Structures ◽  
Number Of Layers

Steel Reinforced Grout (SRG) materials are generating considerable interest as strengthening system of reinforced concrete (RC) structures. They are finding increasing use in several civil engineering applications mainly due to the advantages they offer over traditional material such as high strength to weight ratio, ease of application, durability and low price. This paper describes the results of an experimental investigation carried out on SRG shear strengthened RC beams and gives evidence of the Digital Image Correlation (DIC) effectiveness as a measurement system. The tests performed had two main objectives: (i) assess the effectiveness of continuous and discontinuous U-wrapped jackets comprising a different number of layers and strips; (ii) assess the shear crack distribution during the tests by means of the DIC measurements. The results confirmed that reinforcing RC beams with SRG jackets can increase the load-bearing capacity; when the beam was reinforced with a continuous two-layered SRG strip, an increase of 84% was observed (compared to the unreinforced beam). The Linear Variable Differential Transformers (LVDT) measurements validated the results obtained by means of the DIC.

scholarly journals Torsional Strengthening of Low-Strength RC Beams with Post-Tensioned Metal Straps: An Experimental Investigation

2020 ◽  
Vol 17 (12) ◽  
pp. 1399-1411
Author(s):  
Monthian SETKIT ◽  
Thanongsak IMJAI ◽  
Udomvit CHAISAKULKIET ◽  
Reyes GARCIA ◽  
Komsan DANGYEM ◽  
...  
Keyword(s):  
Failure Modes ◽  
Beam Current ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Control Beam ◽  
Torque Capacity ◽  
Low Strength ◽  
Conservative Values ◽  
Post Tensioned

This article investigates the behaviour of low-strength reinforced concrete beams under pure torsion with and without strengthening. Four beams were cast and tested in torsion: i) a control beam without vertical reinforcement, ii) two beams with internal stirrups designed for shear and torsion demands using different stirrup spacing (50 and 100 mm), and iii) a beam having steel stirrups with a spacing of 100 mm strengthened using high ductile post-tensioned metal straps (PTMS). The main objective of the PTMS strengthening solution was to investigate the enhancement of torsional strength confined along the beam. The failure modes, torsional capacities, rotation, and strengthening performance in torsion are discussed in in this study. The experimental results indicate that the PTMS improved the cracking torque capacity by up to 15 % compared to the control beam. Moreover, the PTMS also increased the ultimate torque by up to 19 % compared to the unstrengthened beam. Current code equations to predict the torsional capacity of RC beams are also compared with the experimental results. It is found that the predictions obtained by current ACI equation gives a good agreement and yield in general conservative values compared to the experimental ones.

Predicting the effect of stirrups on shear strength of reinforced normal-strength concrete (NSC) and high-strength concrete (HSC) slender beams using artificial intelligence

2006 ◽  
Vol 33 (8) ◽  
pp. 933-944 ◽  
Author(s):  
H El Chabib ◽  
M Nehdi ◽  
A Saïd
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
High Strength ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Design Parameters ◽  
Rc Beams ◽  
Shear Reinforcement ◽  
Strength Concrete ◽  
Shear Design

The exact effect that each of the basic shear design parameters exerts on the shear capacity of reinforced concrete (RC) beams without shear reinforcement (Vc) is still unclear. Previous research on this subject often yielded contradictory results, especially for reinforced high-strength concrete (HSC) beams. Furthermore, by simply adding Vc and the contribution of stirrups Vs to calculate the ultimate shear capacity Vu, current shear design practice assumes that the addition of stirrups does not alter the effect of shear design parameters on Vc. This paper investigates the validity of such a practice. Data on 656 reinforced concrete beams were used to train an artificial neural network model to predict the shear capacity of reinforced concrete beams and evaluate the performance of several existing shear strength calculation procedures. A parametric study revealed that the effect of shear reinforcement on the shear strength of RC beams decreases at a higher reinforcement ratio. It was also observed that the concrete contribution to shear resistance, Vc, in RC beams with shear reinforcement is noticeably larger than that in beams without shear reinforcement, and therefore most current shear design procedures provide conservative predictions for the shear strength of RC beams with shear reinforcement.Key words: analysis, artificial intelligence, beam depth, compressive strength, modeling, shear span, shear strength.

Implication of Unbondedness in Reinforced Concrete Beams

2012 ◽  
Vol 587 ◽  
pp. 36-41 ◽  
Author(s):  
S.F.A. Rafeeqi ◽  
S.U. Khan ◽  
N.S. Zafar ◽  
T. Ayub
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Failure Mode ◽  
Shear Failure ◽  
Concrete Beams ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Flexural Capacity ◽  
Flexural Reinforcement

In this paper, behaviour of nine (09) RC beams (including two control beams) after unbonding and exposing flexural reinforcement has been studied which were intentionally designed and detailed to observe flexural and shear failure. Beams have been divided into three groups based on failure mode and unbounded and exposed reinforcement. Beams have been tested under two-point loading up to failure. Experimental results are compared in terms of beam behaviour with respect to flexural capacity and failure mode which revealed that the exposed reinforcement does not altered flexural capacity significantly and unbondedness positively influences shear strength; however, serviceability performance of beams with unbonded and exposed reinforcement is less.

Nonlinear Analysis of Steel Reinforced High Strength and High Performance Concrete Eccentric Columns

2010 ◽  
Vol 450 ◽  
pp. 223-226 ◽  
Author(s):  
Shan Suo Zheng ◽  
Wei Wang ◽  
Bin Wang ◽  
Lei Li ◽  
Yi Hu
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Numerical Models ◽  
Constitutive Models ◽  
High Strength ◽  
Failure Criteria ◽  
Experimental Results ◽  
Finite Element Program ◽  
Calculation Results ◽  
Element Program

According to experiment of four steel reinforced high strength and high performance concrete(SRHSHPC) columns with different eccentricity, this paper establishes four equally parameter numerical models by finite element program ANSYS. The failure mechanism, failure mode and mechanical behaviors of the SRHSHPC columns with large and small eccentricity can be revealed by comparing the numerical simulation results with the corresponding experimental results. And the approximate plane-section assumption in SRHSHPC eccentric columns is verified by the study of the relationship between load and strain. It is shown that when constitutive models and failure criteria of SRHSHPC and steel are in precise case, the calculation results agree well with the corresponding experimental results.

Experimental and numerical study of the dynamic response of an adhesively bonded automotive structure

2020 ◽  
Vol 234 (14) ◽  
pp. 3385-3397
Author(s):  
NDD Silva ◽  
JJM Machado ◽  
EAS Marques ◽  
PMGP Moreira ◽  
LFM da Silva
Keyword(s):  
Adhesive Bonding ◽  
Numerical Study ◽  
Low Cost ◽  
High Strength ◽  
Epoxy Adhesive ◽  
Lap Joints ◽  
Impact Response ◽  
Vehicle Body ◽  
Component Level ◽  
The Impact

Based on economic and environmental factors related to energy efficiency, the automotive industry is being increasingly encouraged to design lighter structures, making use of adhesive bonding in vehicle body frames. To meet the standards of the automotive sector, adhesive joints must provide high strength and stiffness, low cost and good energy absorption at a component level, thereby ensuring good impact strength and passenger safety. This work aims to study, at room temperature (24°C), the impact response of a real scale automotive structure bonded with a crash-resistant epoxy, allowing to access the suitability of adhesives for automotive structural purposes. The epoxy adhesive was found to successfully transfer the loads to the aluminium substrates and not to compromise the integrity of the structure, as its failure was dominated by the behaviour of aluminium. Results obtained with a numerical model of the component were found to be in close agreement with the experimental failure load, demonstrating that numerical analysis can be a viable tool to predict the structure’s behaviour. In addition, a polyurethane was used as an alternative to the epoxy system to bond the structure, proving that the joint behaves better in the presence of a more flexible adhesive, as no failure was found for this case. Aluminium single-lap joints with two adhesive thicknesses were tested as a complement to understand the influence of this parameter on the impact response of a joint, showing a 21% decrease in strength when the highest thickness was used.

Sign in / Sign up

Export Citation Format

Share Document