Glass Fiber Reinforced Polymer Plates Research Articles

Flexural behaviour of pultruded glass fibre reinforced polymer composite beams with bolted splice joints

Pultruded glass fibre reinforced polymer (GFRP) composite wide flange (WF) beams were fabricated with mid-span splice joints. The joints comprised: two or six GFRP plates bolted to the flanges. The bolts were torqued to 3, 20 and 30Nm. The 2.9m span simply supported spliced beams were tested in symmetric three-point flexure. Each beam was subjected to three load – unload cycles and loads, mid-span deflections, support rotations and splice plate surface strains were shown to be linear and repeatable. Spliced beam transverse stiffnesses were quantified as functions of bolt torque for both splice plate configurations and were shown to increase linearly as the bolt torque increased. Transverse stiffnesses of unspliced and six-plate bolted/bonded splice jointed beams were compared and the stiffness of the splice bonded beam was shown to be about 47% stiffer than the splice bolted beam with a bolt torque of 3Nm.

Finite-Element Formulations for the Spatial Static Response of Steel Beams Bonded to a GFRP Plate

This study develops four finite elements (FEs) for the analysis of wide-flange steel beams reinforced with a glass fiber–reinforced polymer (GFRP) plate bonded together via an adhesive layer. The formulations treat each of the steel beams and GFRP plates as Vlasov-Gjelsvik thin-walled beams. Two elements are based on shear-deformable kinematics, whereas the other two are based on non-shear-deformable kinematics. The formulations capture the longitudinal-flexural and lateral-torsional responses of the system. Results are then compared with three-dimensional FE analysis solutions based on a current computer program, and the importance of incorporating shear-deformation effects is illustrated, particularly when predicting predominantly torsional responses. The formulation is used to investigate the interaction effect of the shear modulus of the adhesive layer and the length of the GFRP plate.

Effects of corrosive environments on properties of pultruded GFRP plates

Glass Fiber Reinforced Polymer (GFRP) composites have low permeability and high corrosion resistance. In recent years, as the use of GFRP in applications requiring high corrosion resistance has gradually expanded, its long-term performance in highly corrosive environments has caught public attention worldwide. Nevertheless, there is only limited theoretical research and accumulated test data on the corrosion resistance of GFRP. This paper analyses the long-term performance of GFRP in highly corrosive environments. Samples cut from pultruded GFRP profiles were exposed to alkaline, saline, and acidic solutions of different concentrations at 60°C. Additionally, the effects of acidic solutions at high temperature (90°C) were investigated. Flexural properties, changes in the flexural fracture mechanism, hardness, the rate of weight gain, changes in appearance, and scanning electron microscopy (SEM) images of fracture sections were analyzed over periods of 7, 15, 30 and 90days. Results indicate that flexural strength decreases with increased exposure time to both acidic and alkaline solutions. Under conditions of high concentration acidity and high temperature acidity, respectively, flexural strength decreases even more drastically. Additionally, it was found that saturated NaCl solution has little effect on GFRP.

Comparison of Shear Strength Equation for Flat Plates with GFRP Plate

In this study, shear test performed to investigate the shear behavior of flat plate that reinforced by embedded GFRP(glass fiber reinforced polymer) plate with openings. Shape of the GFRP shear reinforcement is a plate with several openings to ensure perfect integration with concrete. The test parameters include the distance between the column face and the first line of GFRP plate and number of GFRP plate vertical strip. The result of test showed that when number of GFRP plate vertical strip was increased, shear strength improved. The shear strength for flat plate reinforced GFRP plate in various codes including ACI 318, BS 8110, EUROCODE 2, and KCI were compared to provide more rational approach for reinforced concrete flat plates with GFRP plate.

Evaluation of Shear Strength for Reinforced Flat Plates Embedded with GFRP Plates

Abstract In this study, The purpose of this study is to experimentally investigate the shear behavior of reinforced flat plate embedded with GFRP(glass fiber reinforced polymer) plate with openings. The GFRP shear reinforcement is manufactured into a plate shape with several openings to ensure perfect integration with concrete. The test was performed on 7 specimens. the parameters include the type of reinforcement and amount of the shear reinforcement., From the test, we analysed the crack, failure mode, Strain, load-displacement graph. a calculation of the shear strength of reinforced flat plate with GFRP plate based on the ACI 318-11 was compared with the test results. The results of the experiment indicate that GFRP plate is successfully applied as a shear reinforcement in the flat plate under punching shear. Keywords :shear reinforcement, flat plate, glass fiber reinforced polymer(GFRP), shear strength. † Corresponding author: Tel: +82-31-201-2542; E-mail: kimhc@khu.ac.krReceived March 13 2014; Revised March 27 2014;Accepted March 28 2014Ⓒ2014 by Computational Structural Engineering Institute of KoreaThis is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License(http://creativecommons. org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

A numerical investigation of overstrength and ductility factors of moment resisting steel frames retrofitted with GFRP plates

This paper reports the results of an investigation conducted to assess the effectiveness of using glass fiber reinforced polymer (GFRP) plates to enhance the overstrength and ductility factors of moment resisting steel frames. The GFRP plates are bonded to the flanges of steel beams of the frame with an aim to enhance their local buckling capacities and consequently their ductility. The flexural behaviour of GFRP retrofitted beams is first determined using a nonlinear finite element model developed in-house. In this numerical model, consistent shell elements are used to simulate the flanges and web of the steel beam as well as the GFRP plate. The interface between the steel and the GFRP plate is simulated using a set of continuous linear spring system representing both the shear and peeling stiffness of the adhesive based on values obtained from a previous experimental study. The moment–rotation characteristics of the retrofitted beams are then implemented into the frame model to carry out nonlinear static (pushover) analyses. The seismic performance level of the retrofitted frames in terms of overstrength and ductility factors is then compared with that of the bare frame. The results show a significant enhancement in strength and ductility capacities of the retrofitted frames, especially when the beams of the frame are slender.

Rehabilitation and Restoration of Old Steel Railway Bridges: Laboratory Experiment and Field Test

Preventive maintenance on aged steel railway structures is all important due to their long service time after completion. This paper introduced a strengthening method for old steel railway bridges by using rubber-latex mortar, glass fiber reinforced polymer (GFRP) plates, lightweight rapid hardening concrete, and reinforcing bars. Both laboratory tests and field tests were performed to confirm the effects of the present strengthening method. In total, two old railway bridges were employed in this study. One of them has been in service for around 100 years. The static loading test was performed in the laboratory. Experimental results, including load-deflection response, strain distribution on the structural steel, GFRP plates as well as concrete, were given and compared between the original steel railway bridge and the strengthened bridge. Theoretical results were also provided to make a comparison with the experimental results. Both the experimental and theoretical results indicated that the present renovation method could greatly enhance the rigidity and reduce the stress levels of old steel members, resulting in the extension of the residual service life of the old steel railway bridge. In addition, field tests were performed on the other old railway bridge, which has been used for 86 years, and stress variation on the railway bridge under the running train was measured and the effects of the present strengthening method in the real service condition were also confirmed.

Screw connectors for thin topping, timber–concrete composites

Thin concrete toppings can be applied to existing timber floors to form a composite, thereby improving the floor’s serviceability performance. Critical to the success of the upgrade is the effectiveness of the shear connectors which transfer forces between the timber floor and topping. This paper presents the results of pushout testing of a novel glass fibre reinforced polymer plate connector which demonstrate that the connectors have greater strength and stiffness compared to self-tapping screws.

Multi-Physics Blast Analysis for Steel-Plated and GFRP-Plated Concrete Panels

The blast damage behaviors of steel-plated and glass fiber reinforced polymer (GFRP)-plated concrete panels exposed to explosive are investigated. In order to improve efficiency and accuracy of numerical analysis, the multi-physics method of coupled Eulerian-Lagrangian discretization is used. To enhance the reliability of the simulation results, the equation of state, strength, and failure model of materials are implemented in an explicit program, AUTODYN. In particular, the implemented formulation includes the strain rate-dependent plasticity for concrete and a transversely isotropic elastic constitutive model for GFRP. The retrofitted concrete panels are compared to non-retrofitted concrete panels, and the deflection and deflection ratio are reduced by steel and GFRP plates. To validate the implemented material models and analysis method, a comparison is made with the reported experimental results. The maximum deflection of the panel from the numerical analysis agrees closely with the results of the experiments. Finally, a discussion of the numerical results with respect to code criteria and energy absorption capacity is presented.

Retrofitting tubular steel T-joints subjected to axial compression in chord and brace members using bonded FRP plates or through-wall steel bolts

T-joints of Hollow Steel Sections (HSSs) are vulnerable to local instabilities of the web under the orthogonal compression in both members. Unlike W-sections stiffeners cannot be installed inside the closed sections. Therefore, alternative strengthening methods are needed. This experimental study explored the effectiveness of two retrofitting methods by controlling the web buckling of the longitudinally compressed 203×76×3.09mm chord, which is also subjected to transverse axial compression loading through the brace member. The web height-to-wall thickness (h/t) ratio of the chord is 65. In the first method, 8mm diameter through-wall steel bolts were used to brace the webs of the chord at the vicinity of the brace. In the second method, 76×185×9.5mm glass fiber reinforced polymer (GFRP) plates were adhesively bonded to the two webs of the chord at the brace location. Two levels of sustained axial compression load were induced in the chord, representing 45% and 80% of its full axial capacity, in addition to control specimens without axial loads. The transverse brace load was then gradually increased to failure. The through-wall steel bolts increased the joint capacity by 13–25%, depending on the chord’s axial load level, while the bonded GFRP plate increased the capacity by 38–46%.

매립형 유공 GFRP 판으로 보강된 RC보의 전단거동에 관한 실험적 연구

이 연구의 목적은 매립형 유공 GFRP(glass fiber reinforced polymer) 판으로 보강된 철근콘크리트 보의 전단 거동에 관하여 실험적으로 연구하였다. 보강재의 형상, 보강면적, 보강재 두께 및 폭의 영향을 변수로 선정하였다. 전단경간비가 2.8인 일반보 총 9개의 시험체에 대한 전단실험을 수행하였다. GFRP 판이 철근 스터럽으로 보강한 경우보다 단위보강면적당 전단강도가 3.6배 향상되었다. 보강면적에 따른 전단성능을 평가한 결과 전단보강면적이 증가함에 따라 전단강도도 증가하였다. 보강재의 형상에 따라 전단성능의 영향을 평가한 결과 평행사변형 GFRP 판이 기본격자형 GFRP판보다 전단강도가 우수한 것으로 나타났다. 일정한 보강면적에서 보강재의 폭 및 두께를 변수로 두었을 때 폭이 증가할수록 전단성능이 향상되는 것을 확인할 수 있었다. 결과적으로, GFRP 판으로 전단 보강된 철근콘크리트 보의 ACI 318M-08 기준식에 의한 최대전단강도와 실험에 의한 최대전단강도를 비교하였다. 또한, ACI 318M-08, CSA-04, EC2-02기준식의 최대전단보강면적과 시험체의 최대전단보강면적을 비교하였다.

Improvement of local buckling behaviour of steel beams through bonding GFRP plates

Glass fiber reinforced polymer (GFRP) composites are used extensively to strengthen and/or to rehabilitate infrastructures. The current study focuses on the use of GFRP for enhancing local buckling behaviour of wide flange steel beams. The study is conducted numerically using a nonlinear finite element model developed in-house. In the numerical model, consistent shell elements are used to simulate the flanges and web of the steel beams as well as the GFRP plates. The interface between the steel and GFRP plates is simulated using a set of continuous linear spring systems representing both the shear and peel stiffness of the adhesive based on values obtained from a previous experimental study. The numerical model is validated using test results and numerical predictions available in literature. Various failure modes, including GFRP rupture, adhesive shear failure, and local buckling of the flanges of beams are included in the model. The effect of geometric imperfection and residual stresses are also included. The model is then used to conduct a parametric study to assess the effect of bonding GFRP plates on enhancing the local buckling behaviour of wide flange steel beams. The results reveal that the effectiveness of this approach especially for the case of slender beams.

Enhancement of buckling capacity of steel plates strengthened with GFRP plates

The current study assesses the enhancement in the buckling capacity of steel plates through bonding glass fibre reinforced polymer (GFRP) plates. Despite their low modulus of elasticity, GFRP plates are relatively thick and, therefore, can be efficient in magnifying the buckling capacity of the retrofitted steel plates. In this application, a heavy duty adhesive system that was tested in a previous experimental programme is employed to bond the steel and the GFRP plates. The current study is conducted numerically using a nonlinear shell element model to simulate the steel and GFRP plates and a special contact element to simulate the flexibility of the adhesive medium. The failure modes in the adhesive and the GFRP plates, based on real strength values, as well as the instability of the entire system are considered. A buckling magnification factor relating the capacity of the retrofitted system to the capacity of the corresponding bare steel plate is evaluated. The study considers two types of boundary conditions as well as two types of in-plane compatibility between the steel and GFRP plates. The effect of geometric imperfection is also studied. Both elastic and inelastic stability analyses are considered in this investigation.

Structural GFRP Permanent Forms with T-Shape Ribs for Bridge Decks Supported by Precast Concrete Girders

A new concrete bridge deck cast onto glass fiber–reinforced polymer (GFRP) stay-in-place (SIP) structural forms is studied. The forms, which replace the bottom layer of conventional rebar, are essentially flat plates with T-up ribs. They span between support girders spaced at 1,772 mm and are lap-spliced using adhesive and mechanical fasteners. Special attention was given to the detailing of monolithic connections between the deck and girders to simulate continuity. The flange of the supporting concrete girders had a rough surface finish and protruded steel stirrups and mimicked AASHTO Type III girders. Five full-scale decks were tested to (1) compare the novel system with a conventional RC deck, (2) examine the effect of eliminating a top layer of orthogonal GFRP rebar, (3) assess a practice commonly used in bridge deck tests of using simple spans resting on neoprene pads, neglecting connection to girders, and (4) examine a commercially available all-GFRP deck, using the same GFRP panels but with a top GFRP plate fastened to the T-up ribs. Four auxiliary flexural specimens were tested to examine the lap-splice. The concrete deck with GFRP SIP form showed 33% higher strength than the conventional RC deck. It also achieved a peak load 7.8 times higher than the service load plus impact. Deflection under the service load was less than span/1,600. Remarkable deformability and pseudoductility was achieved at ultimate load, beyond punching shear, because of the progressive failure of the lap-splice. The simply supported deck failed at a slightly lower strength than the monolithically cast one but had a much lower stiffness.

Bond Strength Between Cast-in-Place Ultra-High-Performance- Concrete and Glass Fibre Reinforced Polymer Plates Using Epoxy Bonded Coarse Silica Sand

Abstract A significant amount of attention has been directed toward the use of fibre reinforced polymer (FRP) materials in structural applications, particularly as main components in hybrid structural members. As a result, the need for an effective connection mechanism that can maintain full composite action at the interface between adjacent dissimilar materials is critical in order to achieve optimum performance of the hybrid structural members. The objective of this experimental program was to investigate the bond performance between glass fibre reinforced polymer (GFRP) plates and cast-in-place Ultra-High-Performance- Concrete (UHPC) using epoxy bonded coarse silica sand aggregates at the bond interface. Both shear and tension tests were conducted using three different types of epoxy adhesives. The general effectiveness of the connection mechanism at the bond interface as well as the relative performance of each epoxy adhesive used were investigated. Analysis showed that, of the three epoxy adhesives tested, the specimens bonded at the interface between the UHPC and GFRP plates using the moisture tolerant epoxy adhesive intended for bonding of hardened concrete and steel performed the best.

Long‐term hygrothermal response of perforated GFRP plates with/without application of constant external loading

AbstractThe use of glass fiber‐reinforced polymer (GFRP) composites is increasingly being considered in various applications where the composite is subjected to harsh hot and humid conditions. Although information on the performance of GFRP under hot and humid conditions is available, the characteristics and the response of perforated GFRP under such conditions have not been fully explored. In this article, the response of perforated GFRP plates subject to hot and humid environment is examined. The applicability and accuracy of Fick's model for establishing the amount of moisture absorption by such composites is examined, and an improved model is proposed. The article also demonstrates the influence of constant external loading on such perforated GFRP while undergoing conditioning in a hot and humid environment. Moreover, since the strength and stiffness of composites can be significantly affected by harsh environments, the degradation in the strength and stiffness of the perforated GFRP as a function of time is established. A new model is proposed wherein degradation of the strength of such perforated composites may be established as a function of time and geometric entities. The model can also account for the influence of the applied loading. POLYM. COMPOS. 2012. © 2012 Society of Plastics Engineers

New Bridge Deck Cast onto Corrugated GFRP Stay-in-Place Structural Forms with Interlocking Connections

AbstractIn this study, pultruded glass fiber reinforced polymer (GFRP) corrugated plates, connected together through pin-and-eye connections, were investigated as stay-in-place (SIP) forms for concrete decks. The SIP form completely replaced the bottom layer of reinforcement, whereas a top GFRP mesh was provided. Special attention was given in simulating the details of deck connection to supporting girders. Full-scale deck specimens, including a control deck with conventional steel reinforcement, were cast on concrete supports simulating a girder spacing of 1,780 mm. The 410-mm-wide supports had a rough surface finish along with protruding steel stirrups to simulate the flange of an AASHTO type III girder. An additional cantilevered specimen was tested to examine the feasibility of using SIP forms in deck overhangs at exterior girders. The study also investigated the effects of GFRP plate thickness and bond with concrete on performance. All specimens, except the cantilevered one that failed in flexure, ha...

Modeling of Buckling and Wrinkling Behavior in GFRP Plate and Sandwiches Subjected to Biaxial Compression–Tension Loading

A model for predicting the buckling and wrinkling behavior of glass-fiber-reinforced polymer (GFRP) plates and sandwich panels subjected to in-plane biaxial compression–tension loading is presented in this paper. In-plane biaxial compression–tension loading occurs in the webs of plate girders or cell-core sandwiches. The model is able to simulate two counteracting effects of increasing transverse tension load on buckling and wrinkling loads as observed in experiments. A stabilizing effect tends to push the plate back to the median plane and thereby delays the onset of buckling/wrinkling instability. In contrast, lateral contraction accelerates the bending of the plate, which leads to a significant decrease in buckling/wrinkling loads. In composite plates, the first effect predominates and increases the buckling loads, while in sandwich panels the second effect is dominant and decreases the wrinkling loads. The theoretical predictions are in good agreement with the corresponding experimental results.

Experimental evaluation of bolt pull-through in pultruded glass-fibre-reinforced polymer plate

An experimental investigation of the bolt pull-through stiffness and strength of pultruded glass-fibre-reinforced polymer (GFRP) plate is described. Details of an adjustable bolt pull-through test rig are presented. The rig was used to carry out 80 low and ultimate load tests on single bolts loaded in tension at the centres of square pultruded GFRP plates. In the tests, one plate thickness, two bolt diameters, four plate side lengths, two sets of plate edge conditions and two orientations of the principal orthotropic axes with respect to one of the edge conditions were investigated. Transverse stiffnesses as well as damage and ultimate tensile loads of the bolt–plate specimens were quantified from the test data. The latter are presented graphically to illustrate the effects of bolt diameter, plate slenderness, plate edge conditions, etc. on stiffnesses and damage/ultimate loads. Failure modes are also described and illustrated.

Numerical analysis of pultruded GFRP box girders supporting adhesively-bonded concrete deck in flexure

This paper presents the modeling of pultruded glass fiber reinforced polymer (GFRP) box girders consisting of built-up hat-shape sections and flat plates. The study addresses the effect of a thin concrete deck adhesively bonded to the top GFRP plate on flexural performance, as well as the behavior under positive and negative bending that simulates continuous girders. A three-dimensional finite element (FE) approach is proposed to predict the behavior of the GFRP system, including experimental validation. The efficacy of the girders is compared with other metallic box girders: carbon steel and corrosion-resistant metals, namely, stainless steel and aluminum. Failure is generally due to debonding of the concrete deck, and as such, the ultimate strength is not affected much by the girder material used. The study examines the single girder behavior as well as girder-group systems, to assess load distribution. It is shown that the AASHTO LRFD approach for load distribution can reasonably be used for the proposed girder systems. Design recommendations as to material selection are addressed to better use the girder system.