Decision‐making in a model‐based design process

Decisions early in the design process have a big impact on the life cycle performance of a building. The outcome of a construction project can be improved if different design options can rapidly be analysed to assist the client and design team in making informed decisions in the design process. A model‐based design approach can facilitate the decision‐making process if the design alternatives' performances can be evaluated and compared. A decision‐making framework using a performance‐based design process in the early design phase is proposed. It is developed to support decision‐makers to take informed decisions regarding the life cycle performance of a building. A scenario is developed in order to demonstrate the proposed framework of evaluating the different design alternatives' energy performance. The framework is applicable to decision‐making in a structured design process, where design alternatives consisting of both objective and subjective evaluation criteria can be evaluated.     

Risk‐minimizing approach to bid‐cutting limit determination

Intense price competition is quite common in the construction industry. In many markets, contractors have to cut their bids to compete, giving priority to winning enough contracts to sustain normal operation, and it is common to see a winning bid close to the expected project cost. While cutting bids not only gives up profits but also undoubtedly increases the risk of making a loss, the behaviour of contractors in intense competition is difficult to explain by existing academic bidding models. An approach to determining the lower limit of the bid for a project is proposed based on minimization of the overall loss risk defined by a probabilistic model. The approach can be used to prevent arbitrary over‐cuts in final bid decision where price competition is intense. Factors influencing the suggested bid‐cutting limit for a project are analysed. An illustrative example using real case data is provided.     

Non‐destructive investigation

So‐called ‘dynamic'or ‘counterflow'insulation systems have already been installed in buildings in France and Sweden for which significant improvements over ‘classic’ insulation methods have been reported. Here, the authors describe a French study, including full‐scale laboratory tests, into the actual efficiency of a ‘permeodynamic’ version. A theoretical model has been developed from which to derive thermal efficiency values, and is compared with the test results. The limits of such dynamic systems, and their most feasible applications, are then discussed. The main conclusion is that conventional insulation techniques remain competitive for houses, but permeodynamic systems offer greater possibilities for industrial buildings.     

Loan‐to‐value ratios in Sweden. The impact of financial deregulation

We ask how financial deregulation in Sweden during the 1980s affected housing finance by studying data on loan‐to‐value (LTV) ratios for home owners who moved recently. Accounting for the impact of demographic and economic determinants we find that LTV ratios were higher between 1985 and 1987 than in earlier and later years. This time pattern suggests that the deregulation of the mortgage institutions and the removal of the loan rate ceiling on banks in 1983 and 1984 were more important than abolishment of the bank loan ceiling in late 1985. They also indicate a decrease in loan demand and/or supply as early as 1988, i.e., well before the banking crisis.     

Finance‐based CPM/LOB scheduling of projects with repetitive non‐serial activities

Projects of repetitive non‐serial activities constitute a major category of construction projects which can be scheduled more conveniently using the line of balance (LOB) technique. Generally, scheduling activities such that the expenditures are always in balance with the available cash is a must to devise financially feasible schedules. The objective is to integrate a CPM/LOB model for a project of repetitive non‐serial activities with a cash flow model and utilize the integrated model to devise financially feasible schedules. The genetic algorithms (GAs) technique is employed to maximize the profit at the end of the project under the constraints of available cash. The optimization of the integrated models was demonstrated using an example project of 15 activities carried out at five units. The CPM/LOB model was validated against the results of a dynamic programming model in the literature and further by conducting a sensitivity analysis of the results of the integrated model. Finally, the model offers an effective financial planning tool for projects of repetitive non‐serial activities.     

Set‐point identification of a free‐fall triboelectrostatic separation process for plastic particles

Identification of the optimal operating conditions and evaluation of their sensibility to changes in certain critical factors are critical issues for the industrial application of electrostatic separation techniques. The aim of this paper is to validate an experimental procedure for optimising the selective sorting of non‐conductive constituents of granular industrial plastic wastes using a free‐fall triboelectrostatic separator.     

Payment and audit mechanisms for non private‐funded PPP‐based infrastructure maintenance projects

The introduction of a non private‐funded public–private partnerships (PPP) approach to the maintenance and operation of infrastructure facilities necessitates an equitable performance standard, a sensible penalty mechanism and a credible auditing system. Yet, with limited research on this type of scheme, it is not clear whether the payment and audit mechanisms can adequately gauge the performance of private partners and truly reflect the quality of service provided in their payment. The question is whether the reliability of the payment reduction and auditing mechanisms pertinent to the non‐private funded PPP infrastructure maintenance can be systematically verified. With reference to a case study in Hong Kong, field data have been collected and tested according to the sensitivity analysis and level of confidence. The results indicate that the level of payment reduction due to poor performance is fair and the audit frequency is adequate to reflect the overall performance of the service provider. The approaches adopted in this research should provide an objective basis for public and private partners to formulate a mutually acceptable and effective mechanism for non private‐funded PPP infrastructure maintenance contracts.     

Group‐level safety climate in the Australian construction industry: within‐group homogeneity and between‐group differences in road construction and maintenance

In modern organizations it is overly simplistic to assume that a uniform, organization‐wide climate for safety develops. Workgroup‐level safety climates are more likely to arise in decentralized organizations and their influence on occupational health and safety (OHS) behaviour is likely to be stronger when work is non‐routine, as in construction. The existence of workgroup‐level safety climates was examined in the Australian construction industry. A group‐level safety climate survey was conducted in a road maintenance and construction organization. The clear factorial structure produced in a larger sample of Australian defence logistics workers was not replicated and factors splintered, possibly due to the subject‐to‐item ratio in the construction study. However, the internal reliability consistency of the factors produced in the earlier pilot study was found to be acceptable for the construction industry data. Two requisite conditions for the existence of group‐level safety climates, i.e. (1) within‐group homogeneity; and (2) between‐group variation, were satisfied within the road construction and maintenance organization. The results indicate that distinct workgroup safety climates exist in construction, providing a theoretical explanation for why some workgroups perform better in OHS than others, despite having similar risk exposure.     

Mini‐blasting for repair work

High chloride content of the concrete had led to corrosion of reinforcement in the brackets supporting the access balconies of a block of flats in Copenhagen; also affected were parts of the balcony decks and some wall panels. Widespread replacement of the suspect components was chosen, including re‐casting of the support brackets in situ. How the old concrete of the brackets was removed by controlled local blasting is described by a member of Demex consulting engineers, who acted as explosive demolition consultants to this project.     

By‐products formation in catalytic combustion of aromatic compounds over a pt‐based catalyst

By‐products formation in the catalytic combustion of different aromatic compounds has been experimentally investigated. A commercial Pt‐based catalyst, in the shape of a short monolith, has been employed. Toluene, styrene, o‐xylene and cumene have been tested at low concentrations for conversions in the range 5–50%. The results confirm the formation of benzene in the combustion of toluene and styrene, as previously observed by other researchers, but in a very small amount; testing cumene, significant amounts of acetone have been found in the outlet flow. Some hypothesis about the reaction mechanism are put forward.     

The work‐life experiences of office and site‐based employees in the Australian construction industry

A survey was conducted among employees of a large Australian construction firm. Comparisons were made between employees who differed by gender and work location. Male employees in site‐based roles reported significantly higher levels of work to family conflict and emotional exhaustion than male employees who worked in the regional or head office. Site‐based male employees were also less satisfied with their pay than male respondents who worked in the regional of head office. Few significant differences were found between women who worked in different locations. Neither were significant differences between men and women who worked in the same location reported. The results are explained in terms of women's tendency to work in administrative, secretarial or support services roles, which typically demand fewer hours. The paper concludes that the experiences of site‐based construction employees, particularly men, warrant further attention to explore the sources of work‐life imbalance and burnout.     

Pesticide‐microbial interaction in the soil

Soils collected from the Gezira irrigation scheme in Sudan were incubated with five pesticides (pyrolan, α‐and β‐endosulphan, γ‐HCH and dieldrin), using three independent methods (incubation of microbial culture with soil and leachates, with carbon‐based growth media and with carbon‐free mineral salt agar). Endosulphan isomers were degraded by soil micro‐organisms to a much greater extent than pyrolan, dieldrin or γ‐HCH. When applied at low concentration (280 ppm), α‐endosulphan was broken down by both bacteria and fungi; whereas, β‐endosulphan was degraded mostly by bacteria and dieldrin was utilized by fungi. However, at high concentration (4000 ppm), γ‐HCH increased the growth of micro‐organisms (gram positive bacilli); but at this high concentration, the other pesticides inhibited all micro‐organisms in the Gezira soil.     

Audio‐visual interactions and soundscape preferences

The analysis of preferences for combinations of four sounds and eight visual landscapes revealed that the sound and not the visual component dominated the patterns of preference. This is attributed to the more varied nature of the sounds in comparison with the relatively homogenous quality of the visual scenes shown. The affective role of sound in combination with the visual setting deserves more attention and this traditional ingredient of landscaping deserves to be revived.     

Time‐dependent construction social costs model

Negative impacts of construction works on local traffic, environment and business have been pointed out by previous researchers. However, little work has been conductd on the quantification of such costs. A time‐dependent construction social costs (COSCO) model is developed for quantifying the negative impacts that result from construction operations during the field execution phase. The COSCO model is a simplified but practical model that calculates the construction social costs in a conservative way. A roadwork construction project is used to show the applicability of the COSCO model. It is found that the daily social cost was US$18?188–5.52 times the project construction cost. This is a striking illustration of management techniques for mediating the social costs of construction projects.     

Dispersion study for two‐dimensional modelling

Simulation of water quality variation in a particular river stretch or at a particular location with time requires mathematical modelling based on advection and dispersion phenomenon. In this context, estimation of an appropriate dispersion coefficient, which is a function of characteristics of a water body, is very essential and forms an important step in mathematical modelling. The tracer study conducted in this context on the river Ganga to estimate the dispersion coefficient is described in this paper with an analysis of data based on a stream‐tube approach. For the wide river Ganga, with a velocity in the range 0.3–0.5 m/s, the estimated transverse dispersion coefficient is 1.33 m²/s.     

Women's self‐perception: an inter‐sector comparison of construction,legal and nursing professionals

The issue of gender in the construction industry has received considerable attention. However, most of the research has been from a male perspective and has considered how male perceptions of females act as an impediment to women's career progression. An understanding of women's self‐perception is important because it helps to explain how women make sense of the barriers and challenges they face in a male dominated culture and how they seek to attain positive outcomes for themselves. A comparison of women in the construction industry with women in other male‐dominated (legal) and female‐dominated (nursing) industries reveals little variation in self perceptions. Indeed, women in the construction industry emerge relatively positively, with the highest overall level of self‐esteem. This is encouraging and surprising, given the considerable evidence of significant barriers to entry and career progression for women in the construction industry, compared to other industries. It indicates that the construction industry is not a special case and that support strategies used in other industries are directly transferable, although the culture of the construction industry may make them more difficult to implement.     

Web‐based integrated project control system

This paper presents a system that supports project time and cost control in an integrated manner. The system utilizes object‐oriented modelling to represent the process of project delivery. A set of control objects is designed to map the process of project control. Eighteen key indicators are considered to represent the resources utilized in each control object and serve as sensors to highlight problematic areas associated with unfavourable performance. A Three‐Tier Client/Sever computer system is designed to implement the developed system. Daily, weekly, monthly and/or yearly, period‐by‐period, and cumulative to‐date project performance reports are generated to provide the status at project, control object and resource levels. An example drawn from the literature is analysed to allow for comparison with the results obtained using the proposed methodology. The example also serves the purpose of demonstrating the use of the proposed system and illustrating its essential features.     

Fabric‐reinforced cement,folded plate

Vistarp Karbhari and Robert Nicholls, Professor of Civil Engineering at the University of Delaware, show that sandwich panels, having fabric‐reinforced cement mortar faces with triangularly folded cores, can be designed to maximize flexural stiffness per unit material cost. The authors suggest that a wide variety of loading conditions could be satisfied from stock sheet, folded to structural engineers’ individual designs.     

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