Abstract This paper reports on the results of an experimental study on glass fibre reinforced pol... more Abstract This paper reports on the results of an experimental study on glass fibre reinforced polymer (GFRP) pultruded profiles subjected to low-velocity impact loading. The effects of impactor mass on the impact response of pultruded composites were investigated. Composite specimens were tested under two series of loading conditions using a drop-weight impact facility. The first set of tests was conducted with different impactor masses (i.e. 5.5, 10.5, 15.5 and 20.5 kg) under the same impact energy of 67 J. The specimens in the second set were subjected to varying impactor masses of 6, 12, 24 and 36 kg at the same initial velocity of 4.4 m/s, resulting in different impact energies. The internal and external damage of pultruded composites was analysed to compare the failure mechanisms, including matrix cracking, delamination, and fibre breakage, as functions of the initial impact energy. The results showed that the extent of impact-induced damage increased with ascending impact energies (ascending impactor masses) up to the point at which the specimen was perforated. The initial impact energy was the dominant parameter that controlled the damage tolerance characteristics of pultruded composites. Furthermore, it was found that a significant longitudinal crack was a precursor to ultimate failure.
Abstract A small-scale fire test was performed on a wood-cement panel intended as a permanent for... more Abstract A small-scale fire test was performed on a wood-cement panel intended as a permanent formwork. The tested panel was subjected on one side to a uniform heat flux of about 6 kW/m2. Measurements of the temperature profiles were recorded with thermocouples embedded in the sample. The density and its variation with temperature were obtained by taking weight measurements. The thermal conductivity of the wood-cement composite at room temperature was determined using the hot plate method. Its variation with temperature and that of the specific heat were determined using analytical and numerical approaches. Using the obtained data, a pyrolysis model, implemented in Abaqus, was developed to simulate the effect of heat in the panel. The validation of the model is carried out by simulating charring tests. The model provided reasonable predictions for the thickness of the charred layer and the temperatures profiles across the depth of the panel. The model can supplement the testing of small laboratory samples to characterise the fire performance of these panels, and hence help establish their certification for use in sustainable construction.
Advanced Fibre-Reinforced Polymer (FRP) Composites for Structural Applications, 2013
Abstract: Despite considerable potential and many advantages over conventional materials, composi... more Abstract: Despite considerable potential and many advantages over conventional materials, composites are making limited progress in the field of infrastructure applications, where the only niche market for composites is in FRP deck construction over steel girders and externally bonded FRP repair. The reasons, of course, are to be found in their high initial cost compared with conventional materials. This can only be addressed through the use of large-volume automated processes such as pultrusion and filament winding, which have the potential to lower the cost of raw materials and technologies for all applications. This chapter summarises the current level of applications of filament winding in the infrastructure industry.
This work deals with the virtual simulation of the sheet metal stamping process. The main objecti... more This work deals with the virtual simulation of the sheet metal stamping process. The main objective is to predict when and where the cracks can appear in the workpiece during the forming operation. A local approach based on the strong coupling between anisotropic elastoplasticity with mixed nonlinear work hardening (isotropic and kinematic) and an isotropic ductile damage is proposed. The
Bond behavior is an important issue in the design and performance of reinforced concrete structur... more Bond behavior is an important issue in the design and performance of reinforced concrete structures. In this research the bond property between glass fibre reinforced polymer (GFRP) bars, a corrosion resistant substitute to steel bars, and fly-ash based Geopolymer Cement (GPC) concrete, a more environmental friendly alternative to Ordinary Portland Cement (OPC) concrete, is investigated. When compared to OPC concrete, fly-ash based GPC concrete has a different micro structures and hydration process, which may affect its bond performance. A total of 18 pull-out specimens containing 16 mm GFRP rebar embedded in GPC and OPC concrete cylinders with 100 mm diameter and 170 mm height were prepared. Embedment lengths of three, six, and nine times the rebar diameter were taken as the main test variables. For each specimen, the test results include the bond failure mode, the average bond strength, the slip at the loaded and free end and the bond–slip relationship curves. With these test resu...
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 1992
In the past, the theory of thermoplasticity has been confined to metal type materials exhibiting ... more In the past, the theory of thermoplasticity has been confined to metal type materials exhibiting an elastic-perfectly-plastic behaviour. This paper describes the application of this theory to modelling the response of a nonlinear hardening material (concrete in the present case) under transient temperature and stress. The difficulties arising from the application of the theory of thermoelastoplasticity to modelling the behaviour of concrete at elevated temperatures are discussed, together with the inadequacy of the existing algorithms that were proposed for perfectly plastic materials, to cope with a nonlinear hardening case. An integration scheme derived from the Euler backward scheme is used to integrate the rate equations. The resulting model is used to analyse existing biaxial data and investigate the effect of a sustained load on the deformational response of concrete under biaxial loading and elevated temperature.
ABSTRACT As a result of tightening of environmental legislation, there is a renewed interest in t... more ABSTRACT As a result of tightening of environmental legislation, there is a renewed interest in the technology of alkali activated concrete also known as geopolymer concrete (GPC). Yet, for GPC to assume its own niche in the construction market, it must display equal or better properties at elevated temperatures than Ordinary Portland Cement (OPC) concrete. Currently there is sufficient evidence that GPC has a better resistance to fire; however not all of its behavioural aspects at high temperatures have been investigated. The aim of this research therefore is to investigate its deformational behaviour, in particular the existence or lack of transient creep, which OPC is known to undergo under first time heating when subject to compressive stresses. It was found that not only GPC undergoes transient creep, but also exhibits both expansive and contractive volume changes during heating. It was also found that GPC maintains its structural integrity at 1000 °C.
When concrete is subjected to elevated temperatures under a state of compressive stresses, it exp... more When concrete is subjected to elevated temperatures under a state of compressive stresses, it experiences transient creep. Although it is particularly relevant to the behavior of columns that most of the time are under a state of compression, its effects on the behavior of beams has hardly attracted any interest. Yet, in a real fire situation, it is possible for a beam to be subject to intensive heat on the compressive face. Using a previously developed finite element code, which is capable of considering transient creep either explicitly as an additional strain rate component or implicitly through the deformation properties of concrete, a systematic study on its effects on the behavior of beams is presented. It was found that transient creep does not have an effect on simply supported beams heated on the tensile face. On the other hand, when both the load and the heating are applied on the compressive face, transient creep has a major effect on the deformational behavior of the beam.
Using the analytical approaches developed, the cross section of the new fibre composite beam desc... more Using the analytical approaches developed, the cross section of the new fibre composite beam described in the prequels to this paper is designed in order to avert secondary failure modes. A series of specimens have been built and put through a thorough testing regime to establish the performance of the beam. To gain confidence in the analytical models and achieve further understanding of the beam behaviour, a rigorous nonlinear finite element analysis is also presented. It was found that the analytical model agreed relatively well with the experiment and the FE analysis, thus validating the underlying assumptions.
Abstract This paper reports on the results of an experimental study on glass fibre reinforced pol... more Abstract This paper reports on the results of an experimental study on glass fibre reinforced polymer (GFRP) pultruded profiles subjected to low-velocity impact loading. The effects of impactor mass on the impact response of pultruded composites were investigated. Composite specimens were tested under two series of loading conditions using a drop-weight impact facility. The first set of tests was conducted with different impactor masses (i.e. 5.5, 10.5, 15.5 and 20.5 kg) under the same impact energy of 67 J. The specimens in the second set were subjected to varying impactor masses of 6, 12, 24 and 36 kg at the same initial velocity of 4.4 m/s, resulting in different impact energies. The internal and external damage of pultruded composites was analysed to compare the failure mechanisms, including matrix cracking, delamination, and fibre breakage, as functions of the initial impact energy. The results showed that the extent of impact-induced damage increased with ascending impact energies (ascending impactor masses) up to the point at which the specimen was perforated. The initial impact energy was the dominant parameter that controlled the damage tolerance characteristics of pultruded composites. Furthermore, it was found that a significant longitudinal crack was a precursor to ultimate failure.
Abstract A small-scale fire test was performed on a wood-cement panel intended as a permanent for... more Abstract A small-scale fire test was performed on a wood-cement panel intended as a permanent formwork. The tested panel was subjected on one side to a uniform heat flux of about 6 kW/m2. Measurements of the temperature profiles were recorded with thermocouples embedded in the sample. The density and its variation with temperature were obtained by taking weight measurements. The thermal conductivity of the wood-cement composite at room temperature was determined using the hot plate method. Its variation with temperature and that of the specific heat were determined using analytical and numerical approaches. Using the obtained data, a pyrolysis model, implemented in Abaqus, was developed to simulate the effect of heat in the panel. The validation of the model is carried out by simulating charring tests. The model provided reasonable predictions for the thickness of the charred layer and the temperatures profiles across the depth of the panel. The model can supplement the testing of small laboratory samples to characterise the fire performance of these panels, and hence help establish their certification for use in sustainable construction.
Advanced Fibre-Reinforced Polymer (FRP) Composites for Structural Applications, 2013
Abstract: Despite considerable potential and many advantages over conventional materials, composi... more Abstract: Despite considerable potential and many advantages over conventional materials, composites are making limited progress in the field of infrastructure applications, where the only niche market for composites is in FRP deck construction over steel girders and externally bonded FRP repair. The reasons, of course, are to be found in their high initial cost compared with conventional materials. This can only be addressed through the use of large-volume automated processes such as pultrusion and filament winding, which have the potential to lower the cost of raw materials and technologies for all applications. This chapter summarises the current level of applications of filament winding in the infrastructure industry.
This work deals with the virtual simulation of the sheet metal stamping process. The main objecti... more This work deals with the virtual simulation of the sheet metal stamping process. The main objective is to predict when and where the cracks can appear in the workpiece during the forming operation. A local approach based on the strong coupling between anisotropic elastoplasticity with mixed nonlinear work hardening (isotropic and kinematic) and an isotropic ductile damage is proposed. The
Bond behavior is an important issue in the design and performance of reinforced concrete structur... more Bond behavior is an important issue in the design and performance of reinforced concrete structures. In this research the bond property between glass fibre reinforced polymer (GFRP) bars, a corrosion resistant substitute to steel bars, and fly-ash based Geopolymer Cement (GPC) concrete, a more environmental friendly alternative to Ordinary Portland Cement (OPC) concrete, is investigated. When compared to OPC concrete, fly-ash based GPC concrete has a different micro structures and hydration process, which may affect its bond performance. A total of 18 pull-out specimens containing 16 mm GFRP rebar embedded in GPC and OPC concrete cylinders with 100 mm diameter and 170 mm height were prepared. Embedment lengths of three, six, and nine times the rebar diameter were taken as the main test variables. For each specimen, the test results include the bond failure mode, the average bond strength, the slip at the loaded and free end and the bond–slip relationship curves. With these test resu...
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 1992
In the past, the theory of thermoplasticity has been confined to metal type materials exhibiting ... more In the past, the theory of thermoplasticity has been confined to metal type materials exhibiting an elastic-perfectly-plastic behaviour. This paper describes the application of this theory to modelling the response of a nonlinear hardening material (concrete in the present case) under transient temperature and stress. The difficulties arising from the application of the theory of thermoelastoplasticity to modelling the behaviour of concrete at elevated temperatures are discussed, together with the inadequacy of the existing algorithms that were proposed for perfectly plastic materials, to cope with a nonlinear hardening case. An integration scheme derived from the Euler backward scheme is used to integrate the rate equations. The resulting model is used to analyse existing biaxial data and investigate the effect of a sustained load on the deformational response of concrete under biaxial loading and elevated temperature.
ABSTRACT As a result of tightening of environmental legislation, there is a renewed interest in t... more ABSTRACT As a result of tightening of environmental legislation, there is a renewed interest in the technology of alkali activated concrete also known as geopolymer concrete (GPC). Yet, for GPC to assume its own niche in the construction market, it must display equal or better properties at elevated temperatures than Ordinary Portland Cement (OPC) concrete. Currently there is sufficient evidence that GPC has a better resistance to fire; however not all of its behavioural aspects at high temperatures have been investigated. The aim of this research therefore is to investigate its deformational behaviour, in particular the existence or lack of transient creep, which OPC is known to undergo under first time heating when subject to compressive stresses. It was found that not only GPC undergoes transient creep, but also exhibits both expansive and contractive volume changes during heating. It was also found that GPC maintains its structural integrity at 1000 °C.
When concrete is subjected to elevated temperatures under a state of compressive stresses, it exp... more When concrete is subjected to elevated temperatures under a state of compressive stresses, it experiences transient creep. Although it is particularly relevant to the behavior of columns that most of the time are under a state of compression, its effects on the behavior of beams has hardly attracted any interest. Yet, in a real fire situation, it is possible for a beam to be subject to intensive heat on the compressive face. Using a previously developed finite element code, which is capable of considering transient creep either explicitly as an additional strain rate component or implicitly through the deformation properties of concrete, a systematic study on its effects on the behavior of beams is presented. It was found that transient creep does not have an effect on simply supported beams heated on the tensile face. On the other hand, when both the load and the heating are applied on the compressive face, transient creep has a major effect on the deformational behavior of the beam.
Using the analytical approaches developed, the cross section of the new fibre composite beam desc... more Using the analytical approaches developed, the cross section of the new fibre composite beam described in the prequels to this paper is designed in order to avert secondary failure modes. A series of specimens have been built and put through a thorough testing regime to establish the performance of the beam. To gain confidence in the analytical models and achieve further understanding of the beam behaviour, a rigorous nonlinear finite element analysis is also presented. It was found that the analytical model agreed relatively well with the experiment and the FE analysis, thus validating the underlying assumptions.
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