scholarly journals Thermomechanical Characterization of CFRPs under Elevated Temperatures for Strengthening Existing Structures

Fibers ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 80
Author(s):  
Christina Papadimitriou ◽  
Lazaros Melidis ◽  
Lambros Kotoulas ◽  
Nikolaos Makris ◽  
Konstantinos Katakalos
Keyword(s):  
Thermal Loading ◽  
Elevated Temperatures ◽  
Tensile Load ◽  
Concrete Columns ◽  
Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Existing Structures ◽  
Structural Reinforcement ◽  
Constant Tensile Load

Fiber-reinforced polymers (FRP) are rapidly gaining acceptance from the construction sector due to their large effectiveness. They are mainly used as confining reinforcement for concrete columns and as tensile reinforcement for concrete beams, columns and slabs. FRPs are already used to a large extent for applications such as bridges and parking lots, where elevated temperatures are not the main risk. Their increasing use as structural reinforcement is hampered by the concern related to their behavior at elevated temperatures as the relevant research is deficient. Thanks to the significant advantage of FRPs’ mechanical properties, further investigation into the influence of heating on their mechanical behavior may solve many doubts. The present study examines the influence of temperatures, ranging among 50, 100 and 250 °C, on the tensile strength of FRP laminates with carbon fibers (CFRP). In addition, the resistance of CFRP specimens to low-cycle thermal loading at the temperatures of 50, 100 and 250 °C under constant tensile load was investigated. The experiments were carried out in the laboratory of Experimental Strength of Materials and Structures of Aristotle University of Thessaloniki.

scholarly journals Behavior of Columns Confined With FRP Fabrics under Repeated Lateral Loads

2019 ◽  
pp. 1-19
Author(s):  
Hesham A. Haggag ◽  
Nagy F. Hanna ◽  
Ghada G. Ahmed
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Axial Load ◽  
Axial Loading ◽  
Concrete Columns ◽  
Fiber Reinforced Polymers ◽  
Lateral Loads ◽  
Reinforced Concrete Columns ◽  
Reinforced Polymers ◽  
Axial Capacity

The axial strength of reinforced concrete columns is enhanced by wrapping them with Fiber Reinforced Polymers, FRP, fabrics.  The efficiency of such enhancement is investigated for columns when they are subjected to repeated lateral loads accompanied with their axial loading.  The current research presents that investigation for Glass and Carbon Fiber Reinforced Polymers (GFRP and CFRP) strengthening as well.  The reduction of axial loading capacity due to repeated loads is evaluated. The number of applied FRP plies with different types (GFRP or CFRP) are considered as parameters in our study. The study is evaluated experimentally and numerically.  The numerical investigation is done using ANSYS software. The experimental testing are done on five half scale reinforced concrete columns.  The loads are applied into three stages. Axial load are applied on specimen in stage 1 with a value of 30% of the ultimate column capacity. In stage 2, the lateral loads are applied in repeated manner in the existence of the vertical loads.  In the last stage the axial load is continued till the failure of the columns. The final axial capacities after applying the lateral action, mode of failure, crack patterns and lateral displacements are recorded.   Analytical comparisons for the analyzed specimens with the experimental findings are done.  It is found that the repeated lateral loads decrease the axial capacity of the columns with a ratio of about (38%-50%).  The carbon fiber achieved less reduction in the column axial capacity than the glass fiber.  The column confinement increases the ductility of the columns under the lateral loads.

scholarly journals Aplicação da análise hierárquica como ferramenta de tomada de decisão para escolha do compósito de reforço com polímeros reforçados com fibras

2013 ◽  
Vol 3 (3) ◽  
pp. 161-176
Author(s):  
D. H. Perelles ◽  
M. F. Medeiros ◽  
M. R. Garcez
Keyword(s):  
Decision Making ◽  
Glass Fibers ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Analytic Hierarchy ◽  
Reinforced Polymers ◽  
Structural Reinforcement ◽  
De Se ◽  
Hierarchy Process ◽  
Decision Making Tool

RESUMOO reforço de estruturas com Polímeros Reforçados com Fibras (PRF) é uma alternativa que tem sido muito utilizada em intervenções executadas em elementos de concreto armado. A fibra de carbono é a mais empregada na formação dos compósitos de reforço utilizados em obras civis. Existe, no entanto, a possibilidade de se ampliar as opções de fibras formadoras do compósito utilizando as fibras de aramida e de vidro. Como uma ferramenta alternativa de tomada de decisão, o Método de Análise Hierárquica, baseado em critérios analisados de forma qualitativa e quantitativa, será utilizado neste trabalho para a avaliação das fibras de carbono, aramida e vidro, de forma a se obter qual material seria o mais apropriado para a execução de um reforço estrutural considerando como principais parâmetros de análise os custos dos materiais e as tensões e as deformações que os elementos poderão apresentar. A aplicação desta técnica de interpretação de resultados se mostrou muito útil, podendo ser considerada adequada para estudos que exijam uma tomada de decisão entre diferentes sistemas de reforço com PRF.Palabras clave: Reforço estrutural; polímeros reforçados com fibras; carbono; aramida; vidro; método da análise hierárquica.ABSTRACTStrengthening structures with Fiber Reinforced Polymers (FRP) is an alternative that has been used in interventions performed on reinforced concrete elements. Carbon fibers are the most used in the formation of composite reinforcement used in civil works. There is, however, possible to expand the options of forming fibers using the composite fibers of aramid and glass. As an alternative decision-making tool, the Analytic Hierarchy Process, based on criteria analyzed qualitatively and quantitatively, will be used in this work for the evaluation of carbon, aramid and glass fibers in order to obtain what material would be more suitable for the implementation of a structural reinforcement considering how key parameters of analysis material costs and the tensions and strains that may exhibit elements. This decision-making tool showed useful and can be considered suitable to select different FRP systems.Keywords: Structural strengthening; fiber-reinforced polymers; carbon; aramid; glass; hierarchical analysis method.

scholarly journals Characterization of fiber matrix interface of continuous‐discontinuous fiber reinforced polymers on the microscale

PAMM ◽  
2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Benedikt Rohrmüller ◽  
Michael Schober ◽  
Kerstin Dittmann ◽  
Peter Gumbsch ◽  
Jörg Hohe
Keyword(s):  
Fiber Reinforced Polymers ◽  
Matrix Interface ◽  
Fiber Reinforced ◽  
Reinforced Polymers ◽  
Discontinuous Fiber ◽  
Fiber Matrix Interface ◽  
Fiber Matrix

Experimental Characterization of the Fiber Angles of Multiple Curved Laminate Segments Using Prepreg-Based Carbon Fiber Reinforced Polymers as a Structure for a Non-Engaging Bellows Coupling

2019 ◽  
Vol 809 ◽  
pp. 555-562
Author(s):  
Christian Oblinger ◽  
André Baeten ◽  
Klaus Drechsler
Keyword(s):  
Carbon Fiber ◽  
Rotation Axis ◽  
Fiber Reinforced Polymers ◽  
Main Task ◽  
Experimental Characterization ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Carbon Fiber Reinforced

This paper deals with the experimental characterization of the fiber angles of multiple curved laminate segments using prepreg-based carbon fiber reinforced polymers as a structure for a non-engaging bellows coupling. The main task of this generic shaft coupling is the torsionally stiff torque transmission and the compensation of axial displacement as well as the angular misalignment of metallic shafts. The multiple curved structure can be manually draped by several cut segments using epoxy-based fabric prepreg. Moreover, the intended initial fiber orientation of the laminate is ±45° with respect to the rotation axis of the structure. For the experimental determination of the local fiber angles various CFRP cut segments were defined as CFRP specimens with varying number of layers and constant width. All investigations were based on cured CFRP specimens. The measurements were performed with a robot-assisted optical surface sensor and an optical digital microscope. The influence of the manual draping process according to the z-method could be quantitatively determined by the fiber angle measurements.

scholarly journals Concrete columns confined with different composite materials

2018 ◽  
Vol 199 ◽  
pp. 09012 ◽  
Author(s):  
Jacopo Donnini ◽  
Valeria Corinaldesi
Keyword(s):  
Composite Materials ◽  
High Performance ◽  
Optimal Solution ◽  
Concrete Columns ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced Polymers ◽  
Vapor Permeability ◽  
Fiber Reinforced ◽  
Existing Structures ◽  
Low Performance

In the last decades, the need for upgrading, strengthening and retrofitting of existing concrete structures is rapidly growing. Composite materials showed to be an optimal solution to face this problem, combining high efficacy with low invasiveness. The use of Fiber Reinforced Polymers (FRP) to wrap concrete columns has been widely investigated and became a very successful method to improve their structural performances. However, it has been recognized that FRPs, due to the presence of an organic resin, have a few drawbacks, such as poor mechanical behavior at high temperatures, lack of vapor permeability and impossibility to be installed on wet surfaces. This experimental work aims to propose a comparison between three different innovative methods as possible strengthening solutions for existing concrete columns. The structural behavior of 20 reduced scale concrete columns, realized by using a low performance concrete, in order to reproduce the poor mechanical properties of existing structures, was investigated. Two unreinforced column were tested in compression as reference. Six of them where reinforced by applying an external layer of FRP, with different types of fabric reinforcement (made of carbon or PBO fibers). Six columns were reinforced by using the same fabrics coupled with an inorganic matrix (FRCM) instead of epoxy. Six other columns were reinforced by using a layer of High Performance Fiber Reinforced Concrete (HPFRC) of 3 cm thick. Experimental results have been analyzed and performance of the three reinforcement systems have been compared.

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