CFRP strengthening system to increase fatigue resistance of bridges

Stress Concentrations ◽

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>

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

ISRN Civil Engineering ◽

10.5402/2012/202171 ◽

2012 ◽

Vol 2012 ◽

pp. 1-14 ◽

Author(s):

Kh. M. Heiza ◽

N. N. Meleka ◽

N. Y. Elwkad

Keyword(s):

Load Capacity ◽

New Technique ◽

Deep Beams ◽

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.

2nd International RILEM Symposium on Advances in Concrete through Science and Engineering ◽

Flexural behavior of reinforced concrete beams strengthened with externally-bonded carbon fiber reinforced polymers

10.1617/2351580028.091 ◽

2006 ◽

Author(s):

M. Reza Esfahani

Keyword(s):

Reinforced Concrete ◽

Carbon Fiber ◽

Concrete Beams ◽

Reinforced Concrete Beams ◽

Flexural Behavior ◽

Fiber Reinforced ◽

Reinforced Polymers ◽

Externally Bonded

Bond between Concrete and Multi-Directional CFRP Laminates

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.133-134.917 ◽

2010 ◽

Vol 133-134 ◽

pp. 917-922 ◽

Author(s):

José Sena-Cruz ◽

Joaquim Barros ◽

Mário Coelho

Keyword(s):

Carbon Fiber ◽

Civil Engineering ◽

Structural Elements ◽

Engineering Applications ◽

Reinforced Polymers ◽

Cfrp Laminate ◽

Cfrp Laminates ◽

Pullout Tests

Recently, laminates of multi-directional carbon fiber reinforced polymers (MDL-CFRP) have been developed for Civil Engineering applications. A MDL-CFRP laminate has fibers in distinct directions that can be arranged in order to optimize stiffness and/or strength requisites. These laminates can be conceived in order to be fixed to structural elements with anchors, resulting high effective strengthening systems. To evaluate the strengthening potentialities of this type of laminates, pullout tests were carried out. The influence of the number of anchors, their geometric location and the applied pre-stress are analyzed. The present work describes the carried-out tests and presents and analyzes the most significant obtained results.

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

Journal of Engineering ◽

10.31026/j.eng.2019.08.05 ◽

2019 ◽

Vol 25 (8) ◽

pp. 62-79 ◽

Cited By ~ 1

Author(s):

Ali Adel Abdulhameed ◽

AbdulMuttalib Issa Said

Keyword(s):

Carbon Fiber ◽

Design Procedure ◽

Interface Condition ◽

Fiber Reinforced ◽

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

Fibers ◽

10.3390/fib8010006 ◽

2020 ◽

Vol 8 (1) ◽

pp. 6 ◽

Cited By ~ 3

Author(s):

Ali A. Abdulhameed ◽

AbdulMuttalib I. Said

Keyword(s):

American Concrete Institute ◽

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.

Parametric Study on Seismic Rehabilitation of Masonry Buildings Using FRP Based upon 3D Non-Linear Dynamic Analysis

Buildings ◽

10.3390/buildings8090124 ◽

2018 ◽

Vol 8 (9) ◽

pp. 124 ◽

Author(s):

Eissa Fathalla ◽

Hamed Salem

Keyword(s):

Dynamic Analysis ◽

Nonlinear Dynamic Analysis ◽

Seismic Zone ◽

Lateral Loads ◽

Load Bearing ◽

Cfrp Laminates ◽

Seismic Rehabilitation ◽

Applied Element Method

Unreinforced load-bearing masonry (URM) buildings represent a significant portion of the non-engineered old buildings in many developing countries aiming to reduce the construction cost. The walls of those buildings are developed to resist gravity loads. Lateral loads induced by earthquakes or wind may cause severe their damage. In the current study, a numerical investigation is carried out for a seismic assessment of a typical four-story, load-bearing building in Giza, Egypt. The full 3D nonlinear dynamic analysis is carried out using the Applied Element Method (AEM), which proved to be efficient in such case where partial or total collapse is expected. The study includes two earthquake zones in Egypt called zone (3) and zone (5B), which are the actual studied building seismic zone and the highest seismic activity zone in Egypt, respectively. Carbon fiber reinforced polymers (CFRP) laminates with different thicknesses and different configurations are used in strengthening unreinforced masonry walls to study the efficiency of the proposed rehabilitation technique on a realistic structure.

A new approach of stiffness degradation modeling for carbon fiber-reinforced polymers under cyclic fully reversed bending

Journal of Composite Materials ◽

10.1177/0021998317690239 ◽

2017 ◽

Vol 51 (20) ◽

pp. 2889-2897 ◽

Author(s):

Ali Amiri ◽

Matthew N Cavalli ◽

Chad A Ulven

Keyword(s):

Fatigue Life ◽

Carbon Fiber ◽

Fatigue Behavior ◽

Flexural Modulus ◽

Fiber Reinforced ◽

Reinforced Polymers ◽

Structural Applications ◽

Carbon Fiber Reinforced

Carbon fiber-reinforced polymers are being used in advanced structural applications such as aerospace, automotive, and naval industries. Therefore, there is a rising need for predicting their fatigue life and improving their fatigue behavior. In this study, the fatigue behavior and changes in flexural modulus of bidirectional carbon fiber-reinforced polymers due to cyclic fully reversed bending are investigated. A unique fixture is designed and manufactured to perform fully reversed four-point bending fatigue tests on (0 °/90 °)15 carbon/polyester specimens with a stress ratio of R = −1 and frequency of 5 Hz. The expected downward trend in fatigue life with increasing maximum applied stress was observed in the S–N curves of samples. Based on the decay in the flexural modulus of the specimens, a modified exponential model is proposed to predict the life of carbon fiber-reinforced polymers under fully reversed bending. The empirical constants in the model are calculated based on the results of experiments. The model is applied to predict the fatigue life of the samples that did not fail during the tests and cycle-to-failure of the specimens are found.

Innovative experimental and finite element assessments of the performance of CFRP-retrofitted RC beams under fatigue loading

Science and Engineering of Composite Materials ◽

10.1515/secm-2016-0101 ◽

2018 ◽

Vol 25 (4) ◽

pp. 661-678

Author(s):

Ata Hojatkashani ◽

Mohammad Zaman Kabir

Keyword(s):

Finite Element ◽

Fatigue Testing ◽

Fatigue Behavior ◽

Experimental Studies ◽

Fatigue Loading ◽

Element Model ◽

Rc Beams ◽

Fiber Reinforced ◽

Carbon Fiber Reinforced Polymers

Abstract Numerous experimental studies have proven the efficiency of externally bonded fiber-reinforced polymer (FRP) systems on structural concrete elements, such as reinforced concrete (RC) beams. The current paper presents an analytical formulation of mechanical constants based on the results of experimental data, which were acquired from fatigue testing of intact and CFRP-retrofitted RC beams. A total of six scaled RC beams were prepared for the test, three of which were strengthened with carbon fiber-reinforced polymers (CFRPs). A specific finite element model coupled with experimental results from the proposed RC beams made it possible to compare the theoretical and experimental fatigue behavior of RC beams with and without composite reinforcement. The developed numerical model was then extended to evaluate a higher number of fatigue load cycles, as recommended by bridge codes. This was carried out to monitor the performance of CFRP-retrofitted RC beams in terms of flexural stiffness deterioration and damage propagation. The relationships presented in this paper were calibrated to the tested specimens. Moreover, they were useful for the design of RC and CFRP-retrofitted RC beams and for predicting fatigue performance, including the damage behavior of constituent materials.

Investigation of the Electro-Discharge Open-Hole Machining on the Structural Behavior of Carbon Fiber Reinforced Polymers

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.657.321 ◽

2014 ◽

Vol 657 ◽

pp. 321-325 ◽

Author(s):

Apostolos Korlos ◽

Dimitrios Tzetzis ◽

Gabriel Mansour

Keyword(s):

Finite Element ◽

Factor Model ◽

Operational Parameters ◽

Stress Concentrations ◽

X Ray ◽

Stress Criterion ◽

Open Hole ◽

Hole Machining

The current work investigates the electro-discharge machining (EDM) of plain woven carbon reinforced polymer composites with pulse durations of 100 μs, 200 μs, 300 μs, currents 1 A, 3 A and 5 A, and a voltage of 100 V. An x-ray computed tomography (CT) is employed to examine the delaminations, while a delamination factor model utilizing the equivalent delamination diameter provides the measuring quantity for assessment. Finite element simulations compute the stress concentrations around the holes by taking into account the delamination equivalent diameters of the open-holes, as monitored from the x-ray CT. The Whitney-Nuismer point stress criterion is utilised in order to predict the failure strength of the machined open-hole laminates and it is compared with the experimentally derived mechanical strength values. The results reveal that EDM is a feasible method for open-hole machining of composites, however proper selection of the operational parameters is needed. By accurately measuring the peripheral delamination areas of the machined holes, it is shown that the analysis of the mechanical behaviour of the plain woven laminates by the means of finite element method and the Whitney-Nuismer criterion can accurately predict the response of such composites when subjected to tensile loads.

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

Sustainability ◽

10.3390/su11051374 ◽

2019 ◽

Vol 11 (5) ◽

pp. 1374 ◽

Cited By ~ 1

Author(s):

Vicente Alcaraz Carrillo de Albornoz ◽

Eva García del Toro ◽

M. Isabel Más-López ◽

Alfredo Luizaga Patiño

Keyword(s):

High Performance ◽

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.