http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:11534 The monolithic structural action of various types of walls of flanged cross section and walls with engaged stiffeners or returns (nonrectangular sections) is critically dependent on the shear capacity of the interface between the components making up the section. An assessment of the shear capacity of the interface may also be required as part of the elastic or inelastic analysis of structural elements. Observation of past earthquake events has confirmed that effectively connected flanges also directly influence the seismic performance of nonrectangular sections by providing a more robust and seismically resistant structural element. To analyze the significance of the parameters that influence the vertical shear resistance of interfaces of flanged sections of masonry obtained using different types of bonding and bonding patterns (header units, shear connectors, and wire ties), a series of specimens with “H-shaped” cross sections was tested. The vertical shear capacity of the interface at the flange-web intersection was assessed in each case and compared to predicted code capacities. Considerable strength reserves and shear ductility were observed in almost all cases. Following the experimental study, a numerical investigation was carried out using a simplified micromodeling finite element approach. It showed that both the size of the specimen as well as the boundary and applied loading conditions on the flanges can significantly influence the observed vertical shear resistance of the interfaces of specimens with the same bonding pattern. Using the results of the numerical investigation, the critical parameters for a test to determine the vertical shear capacity of brick masonry nonrectangular cross sections are assessed and the governing parameters for a suitable shear test suggested. 2012-09-17T00:35:37.303Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:10570 Cyclic load tests were performed on two series of unreinforced masonry wallettes with a damp-proof course placed either between the first two masonry courses or between the concrete base and the wallette. Two types of failure were observed, namely sliding and compression (toe crushing) failure. Wallettes that failed in compression exhibited limited energy dissipation. Wallettes which failed through sliding displayed considerable energy dissipation and behaved in a quasi ductile manner. Greater ductility was observed in the wallettes with the DPC in the bed joint rather than at the wallette–slab interface, indicating that the former detail would be more desirable for enhanced seismic performance. Simple analytical models for predictions of failure shear load are proposed and discussed. 2012-03-30T00:55:49.035Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:5944 This paper describes the utilisation of a predictive model for studying the thermal performance of masonry housing based on a neuro-fuzzy approach using a set of training data collected from four test house modules. The room temperatures for the four modules have been predicted from a collection of interior surface temperatures using the ANFIS platform. It has been shown that for the test modules the ANFIS Sugeno-type modelling approach offers an accurate and reliable prediction tool by which given input-output patterns could be achieved with a satisfactory level of accuracy. 2012-03-12T06:42:20.353Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:8210 This paper summarises the results of a combined numerical, statistical and experimental study concerned with the use of dissimilar walling systems on the external parts of a given building envelope. The rational behind this “hybrid wall” concept, as opposed to conventional approaches where identical walls are used in a building envelope, is to achieve a more effective distribution of thermal mass across the envelope and, hence, improve the overall thermal performance of the building. The effectiveness of the “hybrid wall” concept was investigated using a series of hypothetical building modules of common Australian residential constructions, namely Light Weight (LW), Brick Veneer (BV), Reverse Brick Veneer (RBV) and Cavity Brick (CB). These designs were examined numerically using a commercial energy rating tool known as “AccuRate”, statistically using JMP software and experimentally using a novel benchscale setup developed as part of this study. The performance of each design was evaluated by its energy consumption. The numerical predictions and experimental data highlighted that the east and west walls have the most impact on the energy consumption under Australian climatic conditions. It was found that considerable reductions in the energy consumption could be achieved in cases where the hybrid wall concept was implemented through the use of high thermal mass insulated walls on the east and west sides of the building envelope. 2011-07-11T05:00:09.012Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:8139 Loadbearing masonry construction is a building system composed of masonry walls and concrete slabs, with the masonry walls supporting the slabs and acting as the main structural element resisting the lateral loads from wind and earthquake. In Australian practice, these buildings usually incorporate slip joints, which are placed between the unreinforced masonry walls and concrete slabs, to allow for long term differential movements between the walls and the slabs. In some areas they also serve as a membrane type damp-proof-course. Loadbearing masonry buildings are often composed of reinforced concrete slabs and supporting masonry walls arranged in a cellular pattern. In Australia, these buildings usually incorporate slip joints in the interfaces between walls and slabs, to allow for long term relative displacements caused by brick growth, concrete shrinkage, and thermal expansion and contraction. A common application of this technique is for ''walk up" apartment buildings up to five storeys [Page (2002)]. In this system of building, wind and earthquake actions are resisted by the floor slab acting as horizontal diaphragm in conjunction with the loadbearing walls. The load path therefore includes the slip joints at the wall-floor interface. The distribution of those actions among the walls of that building initially depends on the elastic stiffness and arrangement of the walls. However, once either softening of masonry or slip in the joints occurs, a redistribution of shear loads will result. The redistribution of shear is a complex process and is influenced by many factors, such as the nonlinear behaviour of masonry and slip joints, the compressive stress level in the walls, and the walls arrangement [Sing-Sang et al. (2006)].In asymmetrical buildings, the centre of mass does not coincide with the centre of wall stiffness. Hence, the lateral loading action tends to twist the building, and causes an increase of shear in the walls located at one side of the centre of stiffness, and a reduction of shear in the other walls. The building twisting also induces shear loading in the walls perpendicular to the lateral load direction. This behaviour may accelerate or delay the masonry softening and the slip in the joints. When either softening of masonry or slip in the joints occurs, the centre of wall stiffness will also change its position. Thus, during the loading process the effects of building torsion may change the shear distribution making the prediction of wall forces a very complex process. 2011-07-06T23:00:03.650Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:8138 The differential movements are caused by brick growth, concrete shrinkage, and thermal expansion/contraction. In Australia, loadbearing unreinforced masonry is a common system of construction for "walk up" apartment buildingsup to five storeys. Although unreinforced masonry structuresgenerally perform poorly in seismically active areas,they are frequently used in Australia because Australia is located in a region with low to moderate seismic risk [Page (2002)]. This form of construction creates a challenge for seismic design, as clear load paths need to be established for seismic forces despite the limited shear capacity of the slip joints whose design has been governed by serviceability requirements. For low to moderate earthquake loading (as for Australia), this can be achieved by the appropriate choice of slip joint material. 2011-07-06T23:00:03.639Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:7166 The Masonry Research Group at The University of Newcastle, Australia has embarked on an extensive research program to study the thermal performance of common walling systems in Australian residential buildings by studying the thermal behaviour of four representative purpose-built thermal test buildings (referred to as ‘test modules’ or simply ‘modules’ hereafter). The modules are situated on the university campus and are constructed from brick veneer (BV), cavity brick (CB) and lightweight (LW) constructions. The program of study has both experimental and analytical strands, including the use of a neuro–fuzzy approach to predict the thermal behaviour. The latter approach employs an experimental adaptive neuro–fuzzy inference system (ANFIS) which is used in this study to predict the room (indoor) temperatures of the modules under a range of climatic conditions pertinent to Newcastle (NSW, Australia). The study shows that this neuro–fuzzy model is capable of accurately predicting the room temperature of such buildings; thus providing a potential computationally efficient and inexpensive predictive tool for the more effective thermal design of housing. 2011-02-03T00:10:02.737Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:6840 The decline in engineering degree enrolments in many western nations poses a range of challenges that are easy to identify but difficult to address. There have been at least 30 major reports on the issue of engineering enrolments in universities and a great many more on an allied issue, enrolments and achievement in science and maths areas at a secondary school level. Typically such reports are funded through government or private agencies at local, regional and national level, and their authors obtain access to significant numbers of respondents, and secondary data sources; however, because of their size and scope the reports are rarely synthesised. Indeed, their lack of influence is often noted and deplored. This study undertakes the task of drawing together reports directed specifically at engineering enrolments to identify the main influences that result in enrolments or work against enrolments. The influences identified fall into four strands and can be seen to form the basis of a complex structure; understanding of the structure has the potential to enhance future research in this critically important area. 2010-12-03T01:00:03.704Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2755 Masonry is cost competitive on a life cycle basis with other forms of construction, and should therefore be considered as a structural material more frequently by both architects and engineers. Post-tensioned geometric sections of masonry are structurally efficient wall systems. Post-tensioning with carbon fibre reinforced polymer (CFRP) is an attractive solution to potential corrosion problems with unbonded tendons. Tests on CFRP post-tensioned diaphragm walls have revealed that shear strength in prestressed masonry is an area deserving more study and improvement. The tests also showed that the bonding pattern of the masonry at the web-flange junction can have a substantial effect on the resulting strength of that connection. A test series to evaluate the effects of prestress force and bed reinforcement on shear strength has been carried out and a summary of the results is presented here. Tests to determine the effect of bonding pattern on the strength of the web-flange connection have also been conducted. 2010-09-14T02:20:01.857Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:173 This paper investigates the behaviour of masonry load-bearing walls subjected to differential vertical load. A new approach for evaluating the interaction of intersecting walls is used, focusing on the mechanism of load transfer and the resulting shear stresses. The study is carried out using finite element modelling. Previous full-scale tests are used to verify the features of the numerical model. Once confirmed, the model is then used to study the phenomenon, varying parameters such as the number of floors and the dimensions of the walls. It is shown that the distance down the wall at which homogenization of the applied loads occurs can be predicted by application of the Saint Venant's Principle. The distribution of shear stresses along the interface can be simulated by a simple parabolic distribution. A simple design procedure is proposed, allowing more realistic, cost-effective designs of load-bearing masonry structures. © 2005 NRC Canada. 2010-09-14T01:58:45.199Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:5899 The paper describes a new experimental testing procedure for characterising the shear behaviour of mortar joints under combined shear and compression loading. The test apparatus subjects a single joint specimen of annular circular cross section to normal compressive force combined with torsion. The choice of annular cross section results in predictable distributions of normal and shear stresses across the mortar joint, allowing shear behaviour at a material point to be characterised. The latter has been a widely reported shortcoming of existing mortar joint shear tests which all result, to varying degrees, in complex, non-uniform distributions of shear and normal stresses across the mortar joint. The paper describes the test methodology and details the results of a preliminary series of tests conducted using the apparatus. 2010-09-14T01:58:13.095Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2754 The effect of age on bond strength and mortar microstructure was investigated as part of an ongoing masonry bond strength research program at The University of Newcastle. Previous work has shown that both strength losses and strength gains occur with age. The potential loss of bond strength with time has structural implications as the design of masonry using the Australian masonry standard AS 3700–2001 is based on the 7 d bond strength. In this investigation, a single mortar-and-unit combination (dry pressed clay and 1:1:6 mortar) cured under ambient laboratory conditions was studied. Bond strength was determined at ages ranging from 3 to 365 d using a small-scale uniaxial tension test. Maximum bond strength was observed to occur at 180 d with strength minima occurring at 90 and 365 d. Scanning electron microscopy and X-ray diffraction techniques were used to further identify the mortar constituents and hydration levels. Changes in the density of the paste microstructure were observed up to 28 d, which correlated with the initial increase in bond strength. No other microstructural change to account for the strength variations between 28 and 365 d could be observed using these techniques. 2010-09-14T01:57:17.939Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:955 Despite the common use of walls as bracing systems in masonry buildings, limited research has been carried out on the behaviour of masonry panels with openings, especially for unreinforced walls. This paper deals with such walls subjected to vertical and in-plane horizontal loadings, focusing on the coupling effect of the material over the openings. The study starts with a brief discussion of the system structural behaviour and the alternatives for its numerical simulation. A series of tests is described, starting with a single panel without openings and then two panels with openings with the piers each side of the opening having the same dimensions as the single panel. The paper discusses the performance of the panels in relation to the observed strength as well as the failure modes. Experimental and theoretical results are compared, showing the accuracy of the numerical models used in the study. 2010-04-27T06:40:27.065Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1740 This paper investigates the behaviour of masonry load-bearing walls subjected to differential vertical load. A new approach for evaluating the interaction of intersecting walls is used, focusing on the mechanism of load transfer and the resulting shear stresses. The study is carried out using finite element modelling. Previous full-scale tests are used to verify the features of the numerical model. Once confirmed, the model is then used to study the phenomenon, varying parameters such as the number of floors and the dimensions of the walls. It is shown that the distance down the wall at which homogenization of the applied loads occurs can be predicted by application of the Saint Venant's Principle. The distribution of shear stresses along the interface can be simulated by a simple parabolic distribution. A simple design procedure is proposed, allowing more realistic, cost-effective designs of load-bearing masonry structures. 2010-04-27T06:09:35.935Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:5457 The impact of thermal mass on the thermal performance of several types of Australian residential construction, namely: cavity brick (CB), brick veneer (BV), reverse brick veneer (RBV), and light weight (LW) constructions, was examined numerically using the commercial AccuRate energy rating tool developed by the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO). The performance of each construction type was evaluated using four different hypothetical building envelopes, referred to here as building modules. It was found that the thermal mass had a dramatic impact on the thermal behaviour of the modules studied, particularly in those where the thermal mass was within a protective envelope of insulation. The RBV and CB constructions were found to be the most effective walling systems in this regard. 2010-04-27T04:48:15.973Z ]]>