Description:
Purpose - The purpose of this paper is to describe an innovative information and decision support tool (ToolSHeD™) developed to help construction designers to integrate the management of OHS risk into the design process. The underlying structure of the prototype web-based system and the process of knowledge acquisition and modelling are described. Design/methodology/approach - The ToolSHeD™ research and development project involved the capture of expert reasoning regarding design impacts upon occupational health and safety (OHS) risk. This knowledge was structured using an innovative method well-suited to modelling knowledge in the context of uncertainty and discretionary decision-making. Example "argument trees" are presented, representing the reasoning used by a panel of experts to assess the risk of falling from height during roof maintenance work, The advantage of using this method for modelling OHS knowledge, compared to the use of simplistic rules, is discussed Findings - The ToolSHeD™ prototype'development and testing reveals that argument trees can represent design safety risk knowledge effectively. Practical implications - The translation of argument trees into a web-based decision support tool is described and the potential impact of this tool in providing construction designers (architects and engineers) with easy and inexpensive access to expert OHS knowledge is discussed. Originality/value - The paper describes a new computer application, currently undergoing testing in the Australian building and construction industry. Its originality lies in the fact that ToolSHeD™ deploys argument trees to represent expert OHS reasoning, overcoming inherent limitations in rule-based expert systems.
Description:
There are many improvements to operation that can be made to a water distribution system once it has been constructed and placed in ground. Pipes and associated storages and pumps are typically designed to meet average peak daily demands, offer some capacity for growth, and also allow for some deterioration of performance over time. However, the 'as constructed' performance of the pipeline is invariably different to what was designed on paper, and this is particularly so for anything other than design flows, such as during times of water restrictions when there are significantly reduced flows. Because of this, there remain significant benefits to owners and operators for the adaptive and global optimisation of such systems. The present paper uses the Ouyen subsystem of the Northern Mallee Pipeline, in Victoria, as a case study for the development of an optimisation model. This has been done with the intent of using this model to reduce costs and provide better service to customers on this system. The Ouyen subsystem consists of 1600 km of trunk and distribution pipeline servicing an area of 456,000 Ha. The system includes 2 fixed speed pumps diverting water from the Murray River at Liparoo into two 150 ML balancing storages at Ouyen, 4 variable speed pumps feeding water from the balancing storages into the pipeline system, 2 variable speed pressure booster pumps and 5 town balancing storages. When considering all these components of the system, power consumption becomes an important part of the overall operation. The present paper considers a global optimisation model to minimise power consumption while maintaining reasonable performance of the system. The main components of the model are described including the network structure and the costs functions associated with the system. The final model presents the cost functions associated with the pump scheduling, including the penalties descriptions associated with maintaining appropriate storages levels and pressure bounds within the water distribution network.
Description:
Discussion of Natalya N. Warner, Philippe E. Tissot, Storm flooding sensitivity to sea level rise for Galveston Bay, Texas, Ocean Engineering 44 (2012), 23-32
Description:
Wastewaters are increasingly being reused in public spaces to supplant the use of potable water. In this study we investigated possible trace organic contaminants in wastewater from a dairy factory applied to a recreation reserve. Samples were taken of recycled dairy factory wastewater used to irrigate the reserve and from the subsurface drainage system after irrigation and after rainfall. Using gas chromatography–mass spectrometry, it was found that irrigation drainage mostly contained different compounds to those in rainfall drainage. This drainage water was found to contain residues of three agrochemicals (dicamba, 0.4 ± 0.07
Description:
Assessment of the stability of embankment and cut slopes over the life of a project are critical issues for railway and motorway infrastructure projects. Experience has shown that many slope failures occur during or shortly after rainfall. Analyses show that failure is initiated by the reduction in near surface suction over some critical depth in the slope. A simple method is proposed in this paper to estimate the time needed for a wetting front to develop. The method which is a modification of the traditional Green–Ampt infiltration model assumes that ponding of water cannot occur on soil slopes and as a consequence soil in the wetted zone remains partially saturated at the point of slope failure. It differentiates between cases where the initial suction in the slope is high and the rate of infiltration is controlled by the rainfall intensity (supply controlled) and, situations where the suction is low, and the rate of infiltration is controlled by the infiltration capacity of the soil (demand controlled). When applied to a case history where field measurements of infiltration into a slope were available the new method provided a reasonable approximation of the measured infiltration time.
Description:
This paper describes the development of a model to analyse the rate of infiltration and run-off experienced by a partly saturated soil slope during rainfall. The paper first reviews some of the most popular infiltration models used in geotechnical analysis, and highlights some of the problems associated with their application. One particular model, the Horton Equation is extended to include rainfall intensity directly in its formulation. The new model is shown to predict infiltration responses, which agree with field measurements. In the final section the influence of the rainfall intensity and pattern of rainfall (variation of rainfall intensity) on the infiltration response of a soil is investigated using the new model.
Description:
In this paper, ways of improving planning, execution and management of projects using Numerical Design Structure Matrix (NDSM) method are presented to address interdependency of feedback and iteration, which is common in engineering projects management. The NDSM is an alternative approach to traditional project management tools such as Program Evaluation and Review Technique (PERT), Critical Path Method (CPM), and Gantt chart that can only allow the modelling of sequential and parallel processes in projects. As a case study, the model is tested on a set of tasks in a complex petroleum oil field development project, where task sensitivity and information variability attributes are derived. By applying the NDSM method, project duration is optimized and hence total cost of the project is reduced significantly.
Description:
In this paper, researchers investigate the social impact of water restrictions on households in the Ballarat and District Water Supply System. They present a general framework for evaluating the social impact of water restrictions which centres on perceptions of economic circumstances, health and well-being and community character and cohesion. Using qualitative and quantitative research methods, researchers confirm that existing water restrictions are indeed having an impact, although the extent of that impact varies along key dimensions. Researchers also identify underlying drivers of attitudes towards water restrictions, namely the direct impact of water restrictions on the household, and beliefs regarding the equitable application of restrictions across the community. The research findings are significant at a number of levels. At the local level, they provide water resource practitioners and policy makers with systematic data on which to base future water resource decisions and the communication messages and support strategies that accompany such decisions. More broadly, the findings shed light on an issue of critical national importance and they contribute to our theoretical knowledge of its impacts and complexities, and strategies for measurement.
Description:
Free spans or suspended spans normally occur in subsea pipelines due to the irregularity of seabed and/or the scouring action of sea water. A problem of significance to the free spans of subsea pipeline is that currents or waves flowing across pipelines can shed vortices and induce vibration which may cause fatigue damage to the pipelines. Natural frequencies of free spans are required when solving vibration amplitude and cyclic stresses in the free span. The natural frequency is usually calculated with simplified equations, where factors such as boundary conditions and axial forces are not accurately taken into account. In this study, the influence of boundary conditions, mass of hydrocarbon products, axial force, and multiple spans on the natural frequencies of pipeline are investigated and corresponding suggestions are provided for frequency calculation.
Description:
Cracked thin-walled rectangular hollow section (RHS)-to-RHS cross-beam connections are repaired with carbon fibre reinforced polymer (CFRP) composites and constant amplitude fatigue experiments are conducted on them. A pilot test is first conducted on a square hollow section (SHS)-to-SHS T-connection to explore an effective method of applying CFRP. Due to the “peel off” effect at the corner region of the SHS-to-SHS specimen, early debonding appears in the pilot test which only results in a small increase in fatigue life. Circumferential or transverse restraining CFRP patches are added in the RHS-to-RHS cross-beam specimens which prevent early debonding successfully and lead to significant increase in fatigue life.
Description:
This paper describes a set of experimental tests of subsea pipeline steel connections under combined forces: one set of force is fatigue load, which is the simulation of the variation caused by currents or waves flowing across pipelines; another set of force is hoop force, which is constant tension force introduced by internal and external pressures. The steel connections are made of two steel plates joined together by single-sided girth welds. One central notch is machined on the weld toe. The specimens under combined forces are compared with those subjected to fatigue loads alone. It is found that the hoop force could affect the fatigue life of subset pipeline steel connections and also reduce the initiation angle of the crack propagation.
Description:
In this study, a novel and enhanced soil-structure model is developed adopting the direct analysis method using FLAC 2D software to simulate the complex dynamic soil-structure interaction and treat the behaviour of both soil and structure with equal rigour simultaneously. To have a better judgment on the inelastic structural response, three types of mid-rise moment resisting building frames, including 5, 10, and 15 storey buildings are selected in conjunction with three soil types with the shear wave velocities less than 600m/s, representing soil classes Ce, De and Ee, according to Australian Standards. The above mentioned frames have been analysed under two different boundary conditions: (i) fixed-base (no soil-structure interaction) and (ii) flexible-base (considering soil-structure interaction). The results of the analyses in terms of structural displacements and drifts for the above mentioned boundary conditions have been compared and discussed. It is concluded that considering dynamic soil-structure interaction effects in seismic design of moment resisting building frames resting on soil classes De and Ee is essential.