Composites In Civil Engineering Research Articles

10th International Conference on FRP Composites in Civil Engineering

10th International Conference on FRP Composites in Civil Engineering

Effect of Fiber Wrapping on Bending Behavior of Reinforced Concrete Filled Pultruded GFRP Composite Hybrid Beams.

The application of pultruded fiber reinforced polymer (FRP) composites in civil engineering is increasing as a high-performance structural element or reinforcing material for rehabilitation purposes. The advantageous aspects of the pultrusion production technique and the weaknesses arising from the 0° fiber orientation in the drawing direction should be considered. In this direction, it is thought that the structural performance of the profiles produced by the pultrusion technique can be increased with 90° windings by using different fiber types. This paper presents experimental studies on the effect of FRP composite wrapping on the flexure performance of reinforced concrete (RC) filled pultruded glass-FRP (GFRP) profile hybrid beams with damage analysis. The hybrid beams are wrapped fully and partially with Glass fiber reinforced polymer (GFRP) and carbon fiber reinforced polymer (CFRP) composites. Hybrid beam specimens with 0° to 90° fiber orientations were tested under three- and four-point bending loads. Based on the experimental load–displacement relationship results, initial stiffness, ductility, and energy dissipation capacity were compared. The experimental findings revealed that the maximum load-carrying capacities of beams produced with pultrude profiles increased by 24% with glass wrapping and 64.4% with carbon wrapping due to the change in the damages. A detailed damage analysis is provided. Similarly, significant increases were observed in structural performance ratios such as initial stiffness and ductility ratio.

Effect of simulated hygrothermal environment on the flexural and interlaminar shear strength of particulate-filled epoxy-coated GFRP composites

The application of glass fiber-reinforced polymer (GFRP) composites in civil engineering and construction has gained significant interest in the last decade. Such applications require information on the long-term performance and durability of fiber composite materials because these materials are directly exposed to aggressive environments. This comparative study evaluated the effect of a simulated hygrothermal environment on the durability of GFRP composite laminates with and without a particulate-filled epoxy coating. The three-point bending test was conducted to characterize the degradation of interlaminar shear strength and flexural properties of GFRP composites before and after conditioning at combined high moisture and temperature for 0, 1000, 2000, or 3000 h. Dynamic mechanical analysis was also conducted to characterize the changes in the thermomechanical properties of the composite laminates. The results show that hygrothermal conditioning had a negative impact on the flexural and interlaminar shear strength of uncoated GFRP laminates, but this could be efficiently minimized with the use of a particulate-filled polymer-epoxy coating.

Artificial Weathering Resistance Test Methods for Building Performance Assessment of Profiles Made of Natural Fibre-Reinforced Polymer Composites.

A growing popularity of profiles made of natural fibre-reinforced polymer composites in civil engineering encourages determining test methods relevant for building performance assessment. Weathering resistance is among the key aspects that condition the durability of building structures. The paper includes a comparative analysis of two artificial weathering resistance test methods. Polyvinyl chloride and wood flour composite profiles were tested. They were subjected to UV and spraying (X-exposure) and UV, spraying and wetting by condensation (F-exposure), both at different exposure times. The influence of the applied weathering procedures on the composite’s microstructure and its mechanical characteristics were analysed. No changes in the microstructure of brittle fractures were observed. However, surface morphology changes were revealed, noticeably greater following X-exposure than F-exposure. F-exposure exerted significant influence on the mechanical properties of brushed profile, including, but not limited to, flexural modulus. Whereas X-exposure exerted more influence on the mechanical properties of non-brushed profile.

Geopolymers and Fiber-Reinforced Concrete Composites in Civil Engineering.

This paper discusses the influence of fiber reinforcement on the properties of geopolymer concrete composites, based on fly ash, ground granulated blast furnace slag and metakaolin. Traditional concrete composites are brittle in nature due to low tensile strength. The inclusion of fibrous material alters brittle behavior of concrete along with a significant improvement in mechanical properties i.e., toughness, strain and flexural strength. Ordinary Portland cement (OPC) is mainly used as a binding agent in concrete composites. However, current environmental awareness promotes the use of alternative binders i.e., geopolymers, to replace OPC because in OPC production, significant quantity of CO2 is released that creates environmental pollution. Geopolymer concrete composites have been characterized using a wide range of analytical tools including scanning electron microscopy (SEM) and elemental detection X-ray spectroscopy (EDX). Insight into the physicochemical behavior of geopolymers, their constituents and reinforcement with natural polymeric fibers for the making of concrete composites has been gained. Focus has been given to the use of sisal, jute, basalt and glass fibers.

In-situ experiment on long-term behaviour of GFRP pipes under permanent bending

The present study aims at studying the long-term behaviour of composites (GFRP) subjected to permanent bending. The specificity of this study largely rests on the original conditions of in situ ageing of the specimens within an experimental structure of elastic gridshell, built in 2006 and disassembled in 2014. This prototype was made of rectilinear tubes which were elastically deformed into a 3D stable shape. The structural members constituted hence a unique set of relaxation tests in ambient conditions where a wide variety of curvatures were imposed by the 3D shape. After dismounting, the tubes were sorted according to their permanent curvature in the structure. They were then subjected to three kinds of tests: recovery, longitudinal bending and transverse bending tests. The results were then compared with those obtained during the construction of the prototype, before ageing, and with members aged under the same conditions but not mechanically loaded. The experimental results confirm the usual recommendations for using composites in civil engineering, which suggest limiting the flexural stresses to 30% of the tensile strength to avoid damage or creep problems. At the same time, they confirm the safety and long-term robustness of the concept of double curvature structures obtained by elastic deformation of a composite plane grid.

Modal properties identification of a novel sandwich footbridge – Comparison of measured dynamic response and FEA

Abstract A modern sandwich composite footbridge made of high-tech materials, being an example of practical application of laminated composites in civil engineering, is presented. The in situ non-destructive testing of the footbridge, aiming to identify modal properties and pedestrian comfort, is described. The measured eigenmodes and eigenfrequencies are compared with numerically estimated values. Finite element analyses of the footbridge are performed with aid of pure equivalent single layer shell and shell-solid models using Abaqus 6.14 environment. Application of the models is assessed basing on the obtained results in the field of footbridge dynamic response description capabilities.

A novel sandwich footbridge - Practical application of laminated composites in bridge design and in situ measurements of static response

A novel sandwich composite footbridge is presented in the paper, as an example of practical application of laminated composites in civil engineering. The in situ static load tests of the footbridge before its acceptation for exploitation are shown and discussed. The results are compared with the corresponding ones from a numerical equivalent single layer model of the sandwich structure created within the framework of finite element method. The numerical solutions, are slightly higher than the measured in situ ones. Hence, it is concluded that the chosen method of structural analysis is efficient enough to recreate static behavior of the bridge and thus it is accepted for application in civil engineering.

Hybrid wood-polymer composites in civil engineering

Hybrid wood-polymer composites in civil engineering

A review of recent research on the use of cellulosic fibres, their fibre fabric reinforced cementitious, geo-polymer and polymer composites in civil engineering

Abstract Environmentally-friendly monofilament cellulosic fibres have been widely used as alternatives for conventional steel reinforcement within concrete. Recently, the use of cellulosic fibre fabrics and their fabric reinforced polymer composites as reinforcement materials within and/or outside of construction materials (e.g. concrete) has gained popularity due to their inexpensive cost and favourable specific mechanical properties compared with synthetic fibre fabrics (e.g. E-glass). This review presents a summary of recent development on cellulosic fibre Fabric Reinforced Cementitious (FRC) and Fabric Reinforced Geopolymer (FRG) composites, as well as their cellulosic Fabric Reinforced Polymer (FRP) composites as reinforcements of concrete, masonry and timber structures for civil engineering applications. This review covers: (1) properties (i.e. chemical composition, microstructure, mechanical properties and cost) of monofilament cellulosic fibres and their comparison with synthetic fibres, the relationship between fibre chemical composition and fibre mechanical properties, parameters affect fibre properties; (2) properties (e.g. fabrication of monofilament fibres to fabrics and structures) of cellulosic fibre fabrics, properties of polymer matrices, and properties (i.e. flexural, tensile, impact, insulation and fire properties) of cellulosic fabric FRP composites; and (3) properties (compressive, flexural and tensile and impact properties) of cellulosic FRC and FRG composites, and the properties of cellulosic FRP composites reinforced concrete, masonry and timber structures. In addition, the degradation mechanisms of cellulosic FRC and FRP are discussed. Furthermore, the durability of FRC, FRG and FRP composites are reviewed and the methods to improve the durability of FRC, FRG and FRP composites from the aspects of fibre modification and matrix modification are reviewed and summarized.

Special Issue on the 10th Anniversary of IIFC

Special Issue on the 10th Anniversary of IIFC

Effets de l’irradiation aux UV sur les propriétés mécaniques des matériaux composites polymères

The use of polymer matrix composites in civil engineering and construction (including offshore) is becoming increasingly attractive. Therefore, the mechanical performance as a function of outdoor environment, particulary after high intensity UV- exposures, is becoming a real issue. In this work, samples made out of monolithic vinylester as well as vinylester/glass-fiber composite we re exposed to UV-radiation. The mechanical behaviour of these samples was characterized mainly using nanoindentation. Laser Scanning Confocal Microscopy (LSCM) was used to quantify the topography of the samples that were roughened following UV-exposure. A method is he rein developed and is based on a cross-cut of samples and a polish of the transverse face providing a mirror finish needed for nanoindentation while avoiding the elimination of the exposed surface. This method is enabling the estimate of the local Young?s modulus and hardness as a function of exposure time, while specifying the thickness of the material affected by UV.

Concrete columns confined with CFRP wraps

Today, there is an increasing use of fiber reinforced polymer (FRP) composites in civil engineering as reinforcement of existing structures. In particular, FRP composites offer higher strength and Young’s modulus than traditional steel devices, also easy handling and installation, excellent resistance to corrosion and they can be plastered after application. When FRP wraps are used to confine compressed pillars, the effective contribution of the composite cannot be accurately evaluated because it begins to work as the stress state of the member grows. In the present paper, some theoretical relationships available in literature and in current international design guidelines, regarding the evaluation of confinement effect on wrapped concrete columns, are analyzed and compared with experimental test results. Based on these considerations, we propose a new formula that is in good agreement with the experimental test results that were produced for the purpose and reported both in the present paper and in a previously published research study. Although empiric, the proposed formula is able to reproduce the structural response of wrapped specimens and the failure mode as observed in the experimental tests.

Compressive Behavior of Concrete Confined by Mechanism-Based Fiber Composite Bistable Structure

The application of fiber-reinforced polymer (FRP) composites in civil engineering has advanced drastically in recent years, especially in the retrofit of concrete bridge columns. However, composite’s typical nonductile behavior and low-energy absorption are some of the concerns that have yet to be fully addressed. The objective of this research is to investigate a new mechanism-based bistable composite structure as the wrapping system for concrete columns to improve the energy absorption and damage tolerance. The bistable structure consists of energy-absorbing main links (primary load carrier) and waiting links (secondary load carrier to be activated after main link fails). A series of uniaxial compression tests on cylindrical concrete members wrapped with hybrid carbon-glass FRP bistable structure were conducted to demonstrate the concept and study the effect caused by link geometry. The results showed that a controlled failure with signs of failure (warning) was achieved in the system and both the ducti...

Numerical Simulation Procedure of RC Beam Reinforcement with FRP

The use of fiber reinforced polymers (FRP) to reinforce reinforced concrete(RC) structure has become one of the main applications of composites in civil engineering. FRP composite is analyzed using the serial/parallel mixing theory, which deduces the composite behavior from the constitutive equations of its components. Numerical procedure of RC beam reinforceed with FRP is studied based on the finite element method. The numerical results accord with the test results. The validity of the proposed procedure is proved comparing numerical and experimental results.

Polymer composites in construction: a brief history

This paper discusses the development of advanced polymer composite material applications in civil and structural engineering over the past three decades. It illustrates the rapid growth in its utilisation in comparison with other construction materials, and the reasons for this. The material has extraordinary mechanical and important in-service properties, which when combined with other materials are utilised to improve stiffness, strength and durability and lower the whole-life cost and environmental impact. The paper demonstrates the types of structure that have been developed from the material, and the most advantageous way to employ composites in civil engineering. There is, however, generally a 20-year period from the fundamental innovation stage to the final use of the product by industry: this seems a very slow process. The paper concludes by summarising key successes of advanced polymer composites in construction.

A numerical procedure simulating RC structures reinforced with FRP using the serial/parallel mixing theory

The use of fiber reinforced polymers (FRP) to reinforce and retrofit reinforced concrete (RC) structures has become one of the main applications of composites in civil engineering. This paper describes a procedure, based on a finite element formulation, that can be used to perform numerical simulations of RC structures reinforced with FRP. Composites are treated using the serial/parallel mixing theory, which deduces the composite behavior from the constitutive equations of its components. A new construction-stages algorithm is developed for simulating retrofitted structures. The performance of the proposed formulation is proved comparing numerical and experimental results. Finally, the developed code is used to obtain the optimum FRP reinforcement configuration for a RC frame structure.

Properties 0–3 PZT–Portland cement composites

Smart structural composites are multifunctional structural materials which can perform functions such as sensing strain, vibration reduction and are essential because of their relevance to mitigation and structural vibration control. Cement-based piezoelectric composites have been developed as smart structural composites. The goal of this work is to produce cement-based piezoelectric composites using lead zirconate titanate (PZT) and Portland cement (PC) with xPZT–(1 − x)PC (where x = 0.3, 0.6 and 0.9). The composites were pressed together and cured in 100% RH curing chamber for 3 days before measurements. Dielectric constant ( ɛ r) at room temperature and piezoelectric coefficient ( d 33) of the 0–3 piezoelectric PZT–Portland cement composites with different PZT content were investigated. The results show these composites have ɛ r and d 33 values of up to 536 and 87 pC/N, respectively, and there is a good potential for the application of these cement-based piezoelectric composites in civil engineering.

Composites realized by hand lay-up process in a civil engineering environment: initial properties and durability

The repair, the reinforcement as well as the setting in safety of buildings and existing reinforced and/or pre-stressed concrete structure is a real technological stake and a socio-economic problem for the near future. The introduction of composites in civil engineering is an interesting answer to these goals, but they brought an important amount of new problems that have to be solved for safe structural applications under combined mechanical and environmental loadings. In fact during the past five years, we have witnessed exponential growth in research or field demonstrations of fiber-reinforced composites in civil engineering. Manufacturers and designers have now access to a wide range of composite materials. However, they face great problems with forecasting the reliability of composite materials. Their introduction in civil engineering applications is a difficult operation due to working environment and weathering conditions. The objective of this paper is to study the effect of these conditions and their consequences on the mechanical properties of the final composite. An analysis of the rheological (viscoelastic) properties was carried out in order to observe the glass transition temperature evolution according to reactive mixture stoichiometry and weathering conditions.

解析的平均化手法に界面剥離を組み込んだ複合材料要素

Application of composites in civil engineering, such as repair of bridges and piers by graphite-epoxy composites, is growing rapidly. One of the problems in strength of composite materials is interfacial debonding between the fiber and matrix. We here employ an analytical model considering partial debonding along fiber's interface, and construct a finite element, in which an approximate scheme to calculate the stress re-distribution due to partial debonding is included. Several numerical examples and comparisons with experimental data show the characteristics and feasibility of this model.