1,721,386 research outputs found
Evaluation of mechanical properties of carpet fibre reinforced concrete
No full textIncorporating suitable material in concrete to improve its performance is an important consideration in the construction industry. Using short fibres as an additive to improve its mechanical properties has been of great attention. Different types of fibres can be used as intrinsic reinforcement to enhance concrete performance. Some of the fibres used in concrete are recycled waste materials such as carpet fibres. This paper aims to investigate the static properties of fibre reinforced concrete (FRC) utilising short carpet fibres shredded and prepared from the carpet industry waste. Thereafter, the economic considerations regarding use of carpet fibres in concrete are discussed. There have not been any comprehensive studies on the effectiveness of carpet fibres in concrete, whereas there is a more comprehensive literature available for other types of fibres such as steel fibres. The effect of adding recycled carpet fibres on the strength development of FRC have been studied and the results are compared to control concrete. Fresh properties i.e. slump, air content and wet density and hardened properties i.e. compressive strength and modulus of rupture after 7 and 28 days of ageing are reported. © 2013 Taylor & Francis Group
Seismic performance improvement of stone masonry buildings in mud mortar
No full textIn this paper, a new reinforcement method suitable for stone masonry houses built with mud mortar is presented. The effectiveness of such reinforcement system has been observed by bending strength test of rubble wall specimens prepared in the laboratory. Flexural strength test results with this intervention have shown that the wall can have large deformation without significant loss of strength. Such property is highly desired in buildings for resisting seismic loads. With due consideration to applicability and affordability of potential users, this technique seems as one of the best options for improving the seismic performance of the type of buildings under consideration. © 2013 Taylor & Francis Group
Effects of temperature, relative humidity and outdoor environment on FRP-concrete bond
No full textThis paper presents the results of an experimental study undertaken to investigate the effects of temperature, relative humidity and exposure to outdoor environment on externally bonded FRP-concrete connection performance.Two types of FRP, namely, carbon and glass, were externally bonded to concrete prisms of 300mm length, 200mm width and 150mm height with two part epoxy impregnation resin and the specimens were exposed to three different environmental conditions for extended durations. The bond strengths of control (unexposed) and exposed specimens were investigated by single-lap-joint shear test (pull-out test). Results of exposed specimens were compared to those of control specimens in terms of bond strengths, strain profiles and failure modes. Based on the results to date, the most significant degradation of bond strength was observed in specimens exposed to outdoor environment. Distinct change in behaviour of FRP-concrete bond has been observed from strain profiles plotted at different levels of applied loads after being exposed to three different environmental conditions. © 2013 Taylor & Francis Group
Multi-objective design optimisation of GFRP sandwich beams\ud
No full textA novel Glass Fibre Reinforced Polymer (GFRP) sandwich panel was developed by an Australian manufacturer for civil engineering applications. This research is motivated by the new applications of GFRP sandwich structures in civil engineering such as slab, beam, girder and sleeper. An optimisation methodology is developed in this work to enhance the design of GFRP sandwich beams. The design of single and glue laminated GFRP sandwich beam were conducted by using numerical optimisation. The numerical multi-objective optimisation considered a design two objectives simultaneously. These objectives are cost and mass. The numerical optimisation uses the Adaptive Range Multi-objective Genetic Algorithm (ARMOGA) and Finite Element (FE) method. Trade-offs between objectives was found during the optimisation process. Multi-objective optimisation shows a core to skin mass ratio equal to 3.68 for the single sandwich beam cross section optimisation and it showed that the optimum core to skin thickness ratio is 11.0
Smart structures embedded with MR dampers using non-Affine Fuzzy Control
No full textA five-storey building model is equipped with a pair of MR (magneto-rheological) dampers installed at the last floor. This smart structure is imposed to scaled earthquake records (in this case, El-Centro earthquake). Actuators are installed on the fourth storey where a Fuzzy Logic Controller is used to deal with the non-Affine nonlinear dynamics encountered. The aim of this work is to mitigate the structure's vibration due to external excitations via the Fuzzy Logic Controller and the MR damper installed. In the end, the controlled case (structure equipped with MR dampers and Fuzzy Logic Controller) is compared with the uncontrolled case. Simulation results show considerable reductions of the seismic vibration of the structure while the damper current applied is within its working range. © 2013 Taylor & Francis Group
Numerical and experimental investigations of stress wave propagation in utility poles under soil influence
No full textOver the past decades, different types of non-destructive testing (NDT) methods have been developed for the condition assessment of timber structures. Stress wave methods, which are based on stress wave propagation theory, are considered to be simple and cost-effective tools for identifying damage as well as embedment length of timber poles/piles. However, due to the lack of understanding on wave propagation in such structures, especially under the influence of surroundings such as soil, these methods encounter difficulties in producing reliable results. In this paper, an investigation was carried out on the wave propagation behaviour in utility timber poles with consideration of soil effects. The commercial finite element (FE) analysis software ANSYS was used to simulate stress wave propagation in a timber utility pole under the influence of soil. In order to verify the numerical findings, laboratory testing was also conducted in conjuction with the numerical modelling. © 2013 Taylor & Francis Group
Application of flexible façade systems in reducing the lateral displacement of concrete frames subjected to seismic loads
No full textFaçade systems, as an integral part of multi-storey buildings, and as non-structural systems are susceptible to potential failurewhen subjected to severe environmental forces such as earthquakes, if not designed properly. In this paper an alternative method using movable façade systems as an energy absorbing device is proposed in order to decrease the amount of energy imparted to the main structure during seismic activities. Analytical investigation concerning inter-storey drift limits of main structures and seismic drift assessment methods of glazed façades will be conducted. SAP2000 program is used for the numerical analyses. A series of inelastic time history analyses are carried out to determine the behaviour and response of the proposed system in a typical concrete frame structure under two earthquake records. Application of flexible connections in façade systems can, if properly designed, reduce the inelastic deformation of the structural models in comparison to the case without flexible connections. © 2013 Taylor & Francis Group
Dynamic behaviour of flexible facade systems in tall buildings subjected to wind loads
No full textIn recent years many new devices, as energy absorber systems, have been introduced in tall building. But most of them have some disadvantages such as complexity of design and large spaces needed for their installation. Façade systems, as an integral part of high-rise buildings, and as non-structural systems are susceptible to potential failure when subjected to wind, if not designed properly. In this paper an alternative method using multi-skin façade systems as an energy absorbing device is proposed in order to decrease the amount of energy imparted to the main structure during high speed winds and cyclones. A series of elastic and inelastic time history analyses using SAP2000 have been carried out to assess the structural dynamic response of a proposed 45 storey building with reinforced concrete frame structure under a simulated harmonic wind load, which derived from three second gusts according to provisions of Australian wind code (AS/NZ 1170.2). The preliminary results indicate that it is possible to make use of the double skin façade system in tall buildings to work as a damper device, if the connections are properly designed, to minimise the wind induced vibrations of the primary structure as well as reducing inter storey drift. © 2013 Taylor & Francis Group
Assessment of key response quantities for design of a cable-stayed bridge subjected to sudden loss of cable(s)
No full textStays of cable-stayed bridges have potential to lose their support instantly by extreme loadings such as earthquake, thunder strike, vehicle impact, wind and malicious attacks. The sudden loss of cable(s) provides unpredictable stress redistribution on the deck and towers, as well as the large deflections of the entire bridge. This phenomenon is the cause of one of the most critical situations for the cable-stayed bridges, termed "zipper-type collapse" (i.e. the mechanism of the progressive collapse by the redistribution of stresses). Considering such a sudden loss of cable in the design of a cable-stayed bridge is essential. Although cable loss scenarios are associated with material as well as geometrical nonlinearities, in design of cable-stayed bridges, such an extreme loading scenario is analysed typically by using linear elastic models. In this paper, a linear elastic 2D and a fully nonlinear 3D finite element model of an idealised steel cable-stayed bridge are developed and analysed to determine the effect of sudden loss of cable on the progressive collapse of the bridge at global and local stress levels.A parametric dynamic analysis for the bridge model with different cable loss scenarios under symmetrical or unsymmetrical load cases is investigated. The bridge model studied in this paper showed that the 2D model can adequately capture global behaviour of the bridge. The 3D model showed the most significant stress concentration occurring under the symmetrical case are limited to small areas and are negligible. © 2013 Taylor & Francis Group
Inelastic lateral seismic response of building frames under influence of bedrock depth variations incorporating soil-structure interaction
No full textIn this study, a fifteen storey moment resisting building frame is selected in conjunction with a soft clayey soil, representing soil class Ee, according to Australian Standards. Different bedrock depths including 10 m, 20 m, and 30m are employed in the numerical modelling using finite difference software FLAC 2D. The above mentioned frame has been analysed under two different boundary conditions: (i) fixed-base (no soilstructure interaction), and (ii) flexible-base (considering soil-structure interaction). Inelastic dynamic analyses under influence of different earthquake records for three mentioned bedrock depths are conducted, and the results in terms of inelastic lateral deflections and inter-storey drifts for the above mentioned boundary conditions are compared and discussed. The results indicate that the bedrock depth variations play a significant role in inelastic lateral seismic response of the building frame under the influence of soil-structure interaction. As the bedrock depth increases, lateral deflections and inter-storey drifts of the structures increase. The mentioned effects can change the performance level of the structures from life safe to near collapse or total collapse. © 2013 Taylor & Francis Group
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