Use Of Glass Fiber Reinforced Polymer Research Articles

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.

GFRP Bridge Deck Panel

The aim of the research is design and analysis of new bridge deck panel made of glass fiber reinforced polymer (GFRP). Use of GFRP in construction is rapidly growing in last few years. The reason for use GFRP is its low self weight in compare of strength and high resistance against weather influenced degradation resulting in long life. Using GFRP for the construction of the bridge deck leads to lightweight construction that can pass the required wheel load. Lightweight design is appreciated for temporary bridge which is expected to be transported and assembled often on places of current need. Long durability and resistance against weather degradation also reduces maintenance costs of bridge deck. Design of deck panel will be done on the base of loading experiments and FEM analysis. The main use of GFRP bridge deck panel is for temporary bridge but it is possible to extend its use on permanent or movable bridges.

Glass Fibre Reinforced Polymer Pultruded Flexural Members: Assessment of Existing Design Methods

Glass fibre reinforced polymer (GFRP) pultruded profiles are being increasingly used in bridge and building construction as an alternative to traditional materials because of their several favourable properties that include high strength, low self-weight, short installation times, low maintenance requirements and improved durability. In spite of these advantageous characteristics, there are some factors delaying the widespread use of GFRP pultruded profiles in civil infrastructure, one of which is the lack of widely accepted design codes. This paper presents the results of analytical, experimental and numerical investigations on the structural behaviour of GFRP pultruded profiles, the objective of which was to evaluate the relative accuracy of existing design methods. A survey of analytical formulae available for the design of GFRP pultruded flexural members at both service and ultimate limit states is first presented. Subsequently, results of a test programme carried out at Instituto Superior Técnico (IST) are briefly discussed—the experiments included material characterization tests and full-scale flexural tests on I-section simply supported beams and cantilevers. These tests allowed for the evaluation of the service behaviour of GFRP flexural members and some of their most relevant failure mechanisms and respective ultimate loads. Results from experimental tests are compared with those obtained from analytical formulae and numerical models in order to evaluate the relative accuracy of existing design methods.

Fatigue and Strength Evaluation of Two Glass Fiber-Reinforced Polymer Bridge Decks

The use of glass fiber-reinforced polymer (GFRP) bridge decks is appealing for applications where minimizing dead load is critical. This paper describes fatigue and strength testing of two types of GFRP decks being considered for use in the retrofit of an aging steel arch bridge in Snohomish County, Washington, where a roadway expansion is necessary and it is desirable to minimize the improvements to the arch superstructure. Each test used a setup designed to be as close as practicable to what will be the in situ conditions for the deck, which included a 2% cross slope for drainage. The fatigue testing consisted of a single 116 kN (26 kip) load applied for 2 million cycles, which corresponds to an AASHTO HS-25 truck with a 30% impact factor, and the strength testing consisted of multiple runs of a monotonically applied minimum load of 347 kN (78 kips). Results from the fatigue testing indicated a degradation of the stiffness of both deck types; however, the degradation was limited to less than 12% over the duration of loading. Further, the results showed both deck types accumulated permanent deck displacement during fatigue loading and one deck type used a detail with poor fatigue performance. That detail detrimentally impacted the overall deck performance and caused large permanent deck deformations. It was also found that degradation of composite behavior between the deck and girders occurs during fatigue loading and should be included in design.

Light Vaults With Frescoes or Stuccoes Strengthened by Glass Fiber-Reinforced Polymer (GFRP) — the Role of the Reinforcement on Intrados Strains: First Experimental Data

In many historical buildings built between the 16th and 19th centuries, light vaults are present made by wooden structures and mats of reeds and plaster carrying frescoes or stuccoes of architectural and historical value on the lower surface. Some of these structures today are in a precarious state of conservation, and a wide program of rehabilitation has started, especially with the use of glass fiber-reinforced polymer (GFRP) bandages on the upper surface. This article experimentally evaluates the effect that GFRP extrados bandages may have on the mechanical behavior of this system. In particular, the main issue is to evaluate how GFRP extrados reinforcement affects the intrados surface strains of the fresco or stucco plaster. Results show that GFRP reinforcement changes the mechanical behavior of the original system. In particular, under a particular load condition, intrados plaster surface — and thus frescoes or stuccoes — may deform more in the reinforced case than in the original case. Thus, looking forward to have more experimental results, GFRP strengthening should be carefully applied to this historic system to avoid frescoes and stuccoes on the intrados surface that could more easily crack for loads that were carried with no fissures before GFRP strengthening.

Field study of glass-fibre-reinforced polymer durability in concrete

The Canadian Highway Bridge Design Code (CHBDC) does not permit the use of glass-fibre-reinforced polymer (GFRP) for primary reinforcement or prestressing tendons in concrete components. The restriction on the use of GFRP in concrete was based on published laboratory studies indicating that GFRP is not stable in the alkaline environment of concrete. In 2004, ISIS Canada sponsored an extensive study of the durability of GFRP in concrete by removing cores from GFRP-reinforced concrete components of five 5- to 8-year-old structures from across Canada. Three teams working independently at several Canadian universities used a variety of analytical methods to (i) investigate whether the GFRP in concrete field structures had been attacked by alkalis and (ii) compare the composition of GFRP removed from in-service structures with the composition of control specimens that were saved from the projects and not exposed to the concrete environment. The analytical results have confirmed that the GFRP in concrete did not suffer any damage during the 5–8 years of exposure. As a result of this study, the CHBDC in its forthcoming (second) edition has permitted the use of GFRP for both primary reinforcement and prestressing tendons in concrete components, provided the maximum stress level in GFRP at the serviceability limit state is kept at or below 25% of its ultimate strength. It was also found that, contrary to some claims, concrete over GFRP bars does not crack even if the depth of cover is as thin as 28 mm.Key words: alkali attack, barrier wall, crack, deck slab, depth of cover, fibre-reinforced polymer (FRP), glass-fibre-reinforced polymer (GFRP).