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

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 ◽  
Fiber Reinforced Polymers ◽  
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.

scholarly journals A Robust Numerical Methodology for Fatigue Damage Evolution Simulation in Composites

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3348
Author(s):  
Angela Russo ◽  
Andrea Sellitto ◽  
Prisco Curatolo ◽  
Valerio Acanfora ◽  
Salvatore Saputo ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Carbon Fiber ◽  
Fatigue Behavior ◽  
Fatigue Loading ◽  
Fiber Reinforced Polymers ◽  
Loading Conditions ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Damage Propagation

Composite materials, like metals, are subject to fatigue effects, representing one of the main causes for component collapse in carbon fiber-reinforced polymers. Indeed, when subject to low stress cyclic loading, carbon fiber-reinforced polymers exhibit gradual degradation of the mechanical properties. The numerical simulation of this phenomenon, which can strongly reduce time and costs to market, can be extremely expensive in terms of computational effort since a very high number of static analyses need to be run to take into account the real damage propagation due the fatigue effects. In this paper, a novel cycle jump strategy, named Smart Cycle strategy, is introduced in the numerical model to avoid the simulation of every single cycle and save computational resources. This cycle jump strategy can be seen as an enhancement of the empirical model proposed by Shokrieh and Lessard for the evaluation of the fatigue-induced strength and stiffness degradation. Indeed, the Smart Cycle allows quickly obtaining a preliminary assessment of the fatigue behavior of composite structures. It is based on the hypothesis that the stress redistribution, due to the fatigue-induced gradual degradation of the material properties, can be neglected until sudden fiber and/or matrix damage is verified at element/lamina level. The numerical procedure has been implemented in the commercial finite element code ANSYS MECHANICAL, by means of Ansys Parametric Design Languages (APDL). Briefly, the Smart Cycle routine is able to predict cycles where fatigue failure criteria are likely to be satisfied and to limit the numerical simulation to these cycles where a consistent damage propagation in terms of fiber and matrix breakage is expected. The proposed numerical strategy was preliminarily validated, in the frame of this research study, on 30° fiber-oriented unidirectional coupons subjected to tensile–tensile fatigue loading conditions. The numerical results were compared with literature experimental data in terms of number of cycles at failure for different percentage of the static strength. Lastly, in order to assess its potential in terms of computational time saving on more complex structures and different loading conditions, the proposed numerical approach was used to investigate the fatigue behavior of a cross-ply open-hole composite panel under tension–tension fatigue loading conditions.

Pre-Failure Deflection and Residual Load Capacity of Reinforced Lightweight Aggregate Concrete Beams under High-Cycle Fatigue

2010 ◽  
Vol 146-147 ◽  
pp. 926-936 ◽  
Author(s):  
How Ji Chen ◽  
Te Hung Liu ◽  
Chao Wei Tang
Keyword(s):  
Fatigue Testing ◽  
Load Capacity ◽  
Fatigue Behavior ◽  
Lightweight Aggregate ◽  
Fatigue Loading ◽  
Normal Weight ◽  
Lightweight Aggregate Concrete ◽  
Rc Beams ◽  
Aggregate Concrete ◽  
Normal Weight Concrete

The present study experimentally investigated the pre-failure and post-fatigue behavior of reinforced concrete (RC) beams constructed with lightweight aggregate concrete (LWAC) in comparison with that constructed of normal weight concrete (NWC) of the same compressive strength (40 MPa). A total of twelve RC beams were tested under different fatigue loadings. Based on the experimental observations, the midspan total deflection measured in the fatigue testing consisted of the elastic and plastic components. The mechanismof the two deflection components developed with load cycles was different. The experimental results showed that the fatigue resistance of LWAC beams was better than that of NWC beams for the same fatigue loading levels. It was reflected in both the lower evolution of fatigue damage and the smaller growth of midspan residual deflection. After 2 million cycles, an average increase in residual load capacity of about 8% was found in the NWC beams, while that in the LWA beams remained virtually unchanged.

scholarly journals Seismic Analysis of Reinforced Concrete Pier Strengthened by Carbon Fiber Reinforced Polymers

2020 ◽  
Vol 23 (3) ◽  
pp. 313-318
Author(s):  
Sarah Fadhil Abass ◽  
Bassman R. Muhammad ◽  
Qais A. Hasan ◽  
Qais A. Hasan
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Seismic Analysis ◽  
Bridge Pier ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Carbon Fiber Reinforced

In this vast world after an earthquake lessons are learned; many strategies have been considered in order to achieve a proper seismic strength capacity.The aim of this paper is studying the seismic behavior of a typical reinforced concrete bridge pier in Iraq and implementing a proper technique of strengthening in order to fix any damage that had happened.Structure of a full scale three-dimensional finite element model was used in order to simulate a reinforced concrete pier via the computer software ABAQUS/CAE 2017 using concrete plasticity damage model (CDP).Under the action of Halabja earthquake, which was recorded at city of Halabja in Iraq on 12 November 2017, the behavior of model was traced, analyzed and the resulted damages were managed.The finite element analysis results indicated that the proposed configuration of carbon fiber reinforced polymers laminates substantially increases the lateral load strength and deformation capacity of the bridge pier

NONLINEAR FINITE ELEMENT ANALYSIS OF FRP STRENGTHENED RC BEAMS

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Prabin Pathak ◽  
Y. X. Zhang
Keyword(s):  
Finite Element ◽  
Plastic Material ◽  
Experimental Studies ◽  
Material Model ◽  
Element Model ◽  
Steel Reinforcement ◽  
Elastic Model ◽  
Fe Model ◽  
Rc Beams ◽  
Element Analysis

A simple, accurate and efficient finite element model is developed in ANSYS for numerical modelling of the nonlinear structural behavior of FRP strengthened RC beams under static loading in this paper. Geometric nonlinearity and material non-linear properties of concrete and steel rebar are accounted for this model. Concrete and steel reinforcement are modelled using Solid 65 element and Link 180 element, and FRP and adhesive are modelled using Shell 181element and Solid 45 element. Concrete is modelled using Nitereka and Neal’s model for compression, and isotropic and linear elastic model before cracking with strength gradually reducing to zero after cracking for tension. For steel reinforcement, the elastic perfectly plastic material model is used. FRPs are assumed to be linearly elastic until rupture and epoxy is assumed to be linearly elastic. The new FE model is validated by comparing the computed results with those obtained from experimental studies.

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

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 Polymers ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Polymers ◽  
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.

Non-Traditional Shape Variations on Bistable Carbon Fiber Reinforced Polymer Laminates

2020 ◽  
Author(s):  
Christopher M. Nelon ◽  
Jonathan Figueroa ◽  
Oliver J. Myers ◽  
Aaron Shepard
Keyword(s):  
Finite Element ◽  
Carbon Fiber ◽  
Large Scale ◽  
Fiber Reinforced Polymers ◽  
Small Scale ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Carbon Fiber Reinforced ◽  
Polymer Laminates

Abstract The ability of a material to display two equilibrium states, called bistability, has been previously observed in carbon fiber reinforced polymers (CFRPs). For bistability to occur, the laminate must consist of an unsymmetric layup about its midplane which generates internal residual stress from thermal contraction. Prior studies have observed bistability in CFRPs with small-scale rectangular geometries where all sides were less than 250 mm. The aim of this paper is to demonstrate the existence of bistability in large-scale CFRPs with rectangular and non-rectangular geometries. Experiments and finite element analyses were conducted to determine the viability of bistability in large-scale CFRPs where at least one length aspect of the specimen was greater than or equal to 304.8 mm. Specimens whose shapes included rectangles, deltoids, triangles, and circles, were fabricated and tested to determine the presence of bistability and the associated curvature for each cured equilibrium state. Rectangular specimens had a side length of 914.4 mm and widths that varied from 177.8 to 457.2 mm. For the deltoids, triangles, and circles, one length aspect (i.e. the height, hypotenuse, and diameter, respectively) equaled 304.8 mm. Finite element models were created to compare the equilibrium shapes’ curvatures and displacements with the experimental laminates; the existence of bistability was also examined using a nondimensionalized bifurcation plot. Experimentally, bistability was found to occur for the fabricated laminates up to six plies. As the studied laminates could be considered thin, they displayed cylindrical cured shapes. The non-traditional shaped CFRPs followed bistability trends found for traditional, small-scale, rectangular laminates. An inverse relationship between the ply count and curvature was exhibited for the large-scale, rectangular laminates; curvature decreased as the number of plies in the laminate increased.

scholarly journals Experimental Investigation of Reinforced Concrete Beam with Openings Strengthened Using FRP Sheets under Cyclic Load

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3127
Author(s):  
Rania Salih ◽  
Fangyuan Zhou ◽  
Nadeem Abbas ◽  
Aamir Khan Mastoi
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Cyclic Load ◽  
Reinforced Concrete Beam ◽  
Fiber Reinforced Polymers ◽  
Cyclic Behavior ◽  
Rc Beams ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced

In this study, the cyclic behavior of reinforced concrete (RC) beam with openings strengthened using carbon fiber-reinforced polymers (FRPs) was experimentally investigated. Seven rectangular RC beams were cast and strengthened through external bonding of carbon fiber-reinforced polymer (CFRP) sheets around the beam web opening with different orientations to evaluate the maximum resistance, secant stiffness, strength degradation, ductility, energy dissipation capacity and behavior of the specimens’ failure mode under cyclic load. One solid beam without an opening (i.e., control specimen) and six beams constructed with circular web openings typically located in the middle of the beam and adjacent to the supports were used in the experiments. Among the six specimens with opening configuration, two beams were unstrengthened, and the remaining four specimens were strengthened with two layers of FRP sheets with vertical and inclined scheme orientation. Numerical studies were performed on ABAQUS software, and finite element modelling analysis results were verified through experiments. Results demonstrated that the use of FRP sheets has a significant effect on the cyclic behavior of RC beams, thereby improving the maximum strength and ultimate displacement to approximately 66.67% and 77.14%, respectively. The validated finite element models serve as a numerical platform to apply beneficial parametric studies, where the effects of opening size and bond length are investigated.

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