• Steel and Composite Structures
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• v.21 no.4
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• pp.921-947
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• 2016

Concrete Filled Fibre Reinforced Polymer Tube (CFFT) for new columns construction has attracted significant research attention in recent years. The CFFT acts as a formwork for new columns and a barrier to corrosion accelerating agents. It significantly increases both the strength capacity (Strength enhancement ratio) and the ductility (Strain enhancement ratio) of reinforced concrete columns. In this study, based on predefined selection criteria, experimental investigation results of 134 circular CFFT columns under axial compression have been compiled and analysed from 599 CFFT specimens available in the literature. It has been observed that actual confinement ratio (expressed as a function of material properties of fibres, diameter of CFFT and compressive strength of concrete) has significant influence on the strength and ductility of circular CFFT columns. Design oriented models have been proposed to compute the strength and strain enhancement ratios of circular CFFT columns. The proposed strength and strain enhancement ratio models have significantly reduced Average Absolute Error (AAE), Mean Square Error (MSE), Relative Standard Error of Estimate (RSEE) and Standard Deviation (SD) as compared to other available strength and strain enhancement ratios of circular CFFT column models. The predictions of the proposed strength and strain enhancement ratio models match well with the experimental strength and strain enhancement ratios investigation results in the compiled database.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.922-927
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• 2006

There is a concern with worldwide deterioration of highway bridges, particularly reinforced concrete. The advantages of fibre reinforced plastic(FRP) composites over conventional materials motivate their use in highway bridges for replacement of structures. Recently, an FRP deck has been installed on a state highway, located in New York State, as an experimental project. In this paper, a systematic approach for analysis of this FRP deck bridge is presented. Multi-step linear numerical analyses have been performed using the finite element method to study the structural behavior and the possible failure mechanism of the FRP deck-superstructure system Deck's self-weight and ply orientations at the interface between steel girders and FRP deck are considered in this study. From this research, the results of the numerical analyses were corroborated with field test results. Analytical results reveal several potential failure mechanism for the FRP deck and truss bridge system The results presented in this study may be used to propose engineering design guideline for new and replacement FRP bridge deck structure.

• Computers and Concrete
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• v.20 no.5
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• pp.583-593
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• 2017

Applications of fibre-reinforced polymer (FRP) composites for retrofitting, strengthening and repairing concrete structures have been expanded dramatically in the last decade. FRPs have high specific strength and stiffness compared to conventional construction materials, e.g., steel. Ease of preparation and installation, resistance to corrosion, versatile fabrication and adjustable mechanical properties are other advantages of the FRPs. However, there are major concerns about long-term performance, serviceability and durability of FRP applications in concrete structures. Therefore, structural health monitoring (SHM) and damage detection in FRP-retrofitted concrete structures need to be implemented. This paper presents a study on investigating the application of Rayleigh wave for detecting debonding defect in FRP-retrofitted concrete structures. A time-of-flight (ToF) method is proposed to determine the location of a debonding between the FRP and concrete using Rayleigh wave. A series of numerical case studies are carried out to demonstrate the capability of the proposed debonding detection method. In the numerical case studies, a three-dimensional (3D) finite element (FE) model is developed to simulate the Rayleigh wave propagation and scattering at the debonding in the FRP-retrofitted concrete structure. Absorbing layers are employed in the 3D FE model to reduce computational cost in simulating the practical size of the FRP-retrofitted structure. Different debonding sizes and locations are considered in the case studies. The results show that the proposed ToF method is able to accurately determine the location of the debonding in the FRP-retrofitted concrete structure.

• Structural Engineering and Mechanics
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• v.40 no.1
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• pp.105-120
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• 2011

The strengthening and rehabilitation of reinforced concrete structures with externally bonded carbon fibre reinforced polymer (FRP) laminates has shown excellent performance and, as a result, this technology is rapidly replacing steel plate bonding techniques. This paper addresses this issue, and presents results deals with the influence of external bonded CFRP-reinforcement on the time-dependent behavior of reinforced concrete beams. A total of eight reinforced concrete beams with cracked and un-cracked section, with and without externally bonded CFRP laminates, were investigated for their creep and shrinkage behavior. All the beams considered in this paper were simply supported and subjected to a uniform sustained loading for the period of six months. The main parameters of this study are two types of sustained load and different degrees of strengthening scheme for both cracked and un-cracked sections of beams. Both analytical and experimental work has been carried out on strengthened beams to investigate the cracking and deflection performance. The applied sustained load was 56% and 38% of the ultimate static capacities of the un-strengthened beams for cracked and un-cracked section respectively. The analytical values based on effective modulus method (EMM) are compared to the experimental results and it is found that the analytical values are in general give conservative estimates of the experimental results. It was concluded that the attachment of CFRP composite laminates has a positive influence on the long term performance of strengthened beams.

• Steel and Composite Structures
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• v.33 no.5
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• pp.663-679
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• 2019

In this work, a simple four-variable trigonometric shear deformation model with undetermined integral terms to consider the influences of transverse shear deformation is applied for the dynamic analysis of anti-symmetric laminated composite and soft core sandwich plates. Unlike the existing higher order theories, the current one contains only four unknowns. The equations of motion are obtained using the principle of virtual work. The analytical solution is determined by solving the eigenvalue problem. The influences of geometric ratio, modular ratio and fibre angle are critically evaluated for different problems of laminated composite and sandwich plates. The eigenfrequencies obtained using the current theory are verified by comparing the results with those of other theories and with the exact elasticity solution, if any.

• Advances in materials Research
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• v.8 no.1
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• pp.25-36
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• 2019

The utilization of fibre in concrete production not only solves the problem of disposing this solid waste but helps conserve natural resources. This study investigated the effect of waste aluminum shavings on bond strength of laterized concrete. Laterized concrete spliced beams of $150{\times}250{\times}2150mm$ and $175{\times}275{\times}2300mm$ were prepared. Fifteen specimens with 16 mm and 20 mm were cast with the addition of aluminium shavings at varying percentages of 1vol%, 1.5vol% and 2vol%; another ten specimens with 16 mm and 20 mm diameter bars at 0% of aluminium shavings were cast as control. Concrete cubes of number were prepared, three taken for each set of various percentages of aluminium shavings were used to determine the concrete strength. It was observed from the analysis that the compressive strength decreased as the percentage of aluminium shavings increased, while the aluminium shavings increased the bond between concrete and steel. However, for normal concrete there was an increase in bond resistance with increase in aluminium shavings. The bond resistance of 16 mm was found to be higher than that of 20 mm in all the specimens tested.

• Steel and Composite Structures
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• v.35 no.5
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• pp.627-634
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• 2020

The past years were marked by an increase in the use of wood waste in civil and mechanical constructions. Date palm waste remains also one of the most solicited renewable and recyclable natural resources in the composition of composite materials. In Algeria, a great amount of this type of plant wastes accumulates every year. In order to make use of this waste, a new wood-epoxy composite material based on date palm petiole particleboard is developed. It makes use of date palm petiole particleboard as reinforcement and epoxy resin as matrix. The size of the particles reinforcement are between 1~3 mm and proportion of reinforcement used is 37%. In this work, experimental and numerical studies are conducted in order to characterize the wood fibre-epoxy plates. Firstly, experimental modal analysis test was carried out to determine Young's modulus of the elaborated material. Then, in order to validate the results, compression test was conducted. Furthermore, additional information about the shear modulus of this material is obtained by performing an experimental modal analysis to extract the first torsional mode. Moreover, a finite element model is developed using ANSYS software to simulate the vibration behaviour of the plates. The results show a good agreement with the experimental modal analysis, which confirms the values of Young's modulus and shear modulus.

• Structural Engineering and Mechanics
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• v.38 no.6
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• pp.697-714
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• 2011

Assessing the ductility of reinforced concrete sections and members has been a complex and intractable problem for many years. Given the complexity in estimating ductility, members are often designed specifically for strength whilst ductility is provided implicitly through the use of ductile steel reinforcing bars and by ensuring that concrete crushing provides the ultimate limit state. As such, the empirical hinge length and neutral axis depth approaches have been sufficient to estimate ductility and moment redistribution within the bounds of the test regimes from which they were derived. However, being empirical, these methods do not have a sound structural mechanics background and consequently have severe limitations when brittle materials are used and when concrete crushing may not occur. Structural mechanics based approaches to estimating rotational capacities and rotation requirements for given amounts of moment redistribution have shown that FRP plated reinforced concrete (RC) sections can have significant moment redistribution capacities. In this paper, the concept of moment redistribution in beams is explained and it is shown specifically how an existing RC member can be retrofitted with FRP plates for both strength and ductility requirements. Furthermore, it is also shown how ductility through moment redistribution can be used to maximise the increase in strength of a member. The concept of primary and secondary hinges is also introduced and it is shown how the response of the non-hinge region influences the redistribution capacity of the primary hinges, and that for maximum moment redistribution to occur the non-hinge region needs to remain elastic.

• Composites Research
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• v.32 no.4
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• pp.171-176
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• 2019

In this paper, the strength of the composite securement device was characterised by FE analysis. Preliminary frontal crash analysis for the vehicle, equipped with the conventional steel securement device, was carried out according to the ISO 10542 for special transportation to obtain loading data, which were applied to securement device during crash. The securement device consists of block, guide and rail and the weight fraction of rail was the highest among them, therefore, it is desirable to reduce weight of rail by applying carbon/epoxy composite. Also, it was found that 27% of lightweight effect was obtained by hybrid rail that bottom part was replaced by a composite compared to the conventional rail, i.e., made of SAPH 440, without sacrificing the structural strength.

• Steel and Composite Structures
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• v.43 no.1
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• pp.19-30
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• 2022

The static strength and fatigue crack resistance of the aircraft skin structures depend on the materials used and joint type. Most of the commercial aircraft's skin panel structures are made from aluminium alloy and carbon fibre reinforced epoxy. In this study, the fatigue resistance of four joint configurations (metal/metal, metal/composite, composite/composite and composite/metal) with riveted, adhesive bonded, and hybrid joining techniques are investigated with experiments and finite element analysis. The fatigue tests were tension-tension because of the typical nature of the loads on aircraft skin panels susceptible of experimenting fatigue. Experiment results suggest that the fatigue life of hybrid joints is superior to adhesive bonded joints, and these in turn much better than conventional riveted joints. Thanks to the fact that, for hybrid joints, the adhesive bond provides better load distribution and ensures load-carrying capacity in the event of premature adhesive failure while rivets induce compressive residual stresses in the joint. Results from FE tool ABAQUS analysis for adhesive bonded and hybrid joints agrees with the experiments. From the analysis, the energy release rate for adhesive bonded joints is higher than that of hybrid joints in both opening (mode I) and shear direction (mode II). Most joints show higher energy release rate in mode II. This indicates that the joints experience fatigue crack in the shear direction, which is responsible for crack opening.