Journal of Construction Engineering and Management

Accurate assessment of hoisting times is crucial for planning construction activities. The objective of this paper is to develop reasonably accurate prediction models to assess hoisting times of tower cranes. Twenty variables considered attributable to the hoisting time are evaluated. In modeling the hoisting movements, the upward hoisting and downward hoisting of a hoisting cycle are classified as the supply hoisting and the return hoisting. Multiple regression techniques are used for analyzing and building up the models. The hoisting of precast concrete facades and concrete skips are studied. The significance of the variables are discussed and compared. Finally, the paper presents an example of applying the models.

Recently, the top-down construction method has been applied to building construction to secure excavation safety by providing rigid diaphragm walls. Usually, proper and economical formwork systems need to be selected for successful top-down construction. This paper proposes a nonshored top-down formwork system (referred to as NSTD) as a modified formwork system for top-down construction. The NSTD method provides sufficient workspace for excavating under the suspended forms. Upon completion of concrete placement and curing on the ground level slab, the formwork system is lowered to the next floor, and the process is repeated down to the lowest underground floor. The advantages of the NSTD method include a reduction in the excavation duration and an improvement in the quality of the underground concrete work by the hanging-type formwork. A case study was performed to verify the validity of the NSTD by comparing its schedule and cost effectiveness with those of traditional top-down methods.

Efficiently using site space to accommodate resources throughout the duration of a construction project is a critical problem. It is termed the “dynamic layout planning” problem. Solving it involves creating a sequence of layouts that span the entire project duration, given resources, the timing of their presence on site, their changing demand for space over time, constraints on their location, and costs for their relocation. A dynamic layout construction procedure is presented here. Construction resources, represented as rectangles, are subjected to two-dimensional geometric constraints on relative locations. The objective is to allow site space to all resources so that no spatial conflicts arise, while keeping distance-based adjacency and relocation costs minimal. The solution is constructed stepwise for consecutive time frames. For each resource, selected heuristically one at a time, constraint satisfaction is used to compute sets of feasible positions. Subsequently, a linear program is solved to find the optimal position for each resource so as to minimize all costs. The resulting sequence of layouts is suboptimal in terms of the stated global objective, but the algorithm helps the layout planner explore better alternative solutions.

It is common for a construction project to encounter delays. There are several reasons that can contribute to delaying a project. Analyzing the various causes that contribute to a project's delay is an important task to resolving it. Determining, in a scientific manner, the impact, timing, and the contributing effect of each of those causes to the overall delay should assist in helping the parties settle the delay without litigation. Project participants are becoming more aware of the high costs and risks associated with delay claims and their litigation. Thus, the construction industry needs to develop methodologies and techniques to prevent and more efficiently resolve delay claims. While many practitioners have been following some kind of a methodology for analyzing delay claims, a written exposition of such a methodology is not widely available in the literature. Thus, this paper presents a written exposition of a generic methodology for analyzing delay claims. This methodology has been developed and successfully used, by the writer, in various projects to resolve delay claims. The developed methodology will be illustrated through its application in those projects. Moreover, this methodology shows that while there are several techniques for analyzing delay claims, very few of these can be considered adequate. The use of such an adequate technique is a key in obtaining a fair allocation of the delay responsibility. This paper's methodology utilizes one of these few adequate techniques for analyzing delay claims.

Resources for construction activities are limited in the real construction world. To avoid the waste and shortage of resources on a construction jobsite, scheduling must include resource allocation. A multicriteria computational optimal scheduling model, which integrates the time/cost trade-off model, resource-limited model, and resource leveling model, is proposed. A searching technique using genetic algorithms (GAs) is adopted in the model. Furthermore, the nondominated solutions are found by the multiple attribute decision-making method, technique for order preference by similarity to ideal solution. The model can effectively provide the optimal combination of construction durations, resource amounts, minimum direct project costs, and minimum project duration under the constraint of limited resources.

Performance bonds and guarantees have been the subject of considerable litigation in recent years in not only the United Kingdom but also some other common law jurisdictions. The aim of the research reported in this paper is to identify the issues most commonly in dispute and the legal principles governing their resolution. Possession of knowledge of the issues and principle should alert the construction and engineering industries and their legal advisers to the matters that need serious attention in the drafting and negotiation of these instruments. Clarity in the legal principles should also contribute to a reduction in litigation. The issues identified include: (1) Whether an instrument is a conditional or an on-demand bond; (2) the effect of failure on the part of the beneficiary to give notices; (3) availability of an injunction to restrain the surety from paying after a call has been made by the beneficiary; (4) availability of an injunction to restrain a beneficiary from receiving payment after a demand has been made; (5) availability of an injunction to restrain a beneficiary from making claim; (6) availability of a Mareva injunction to freeze the fruits of a call; (7) meanings of certain phrases used in the instruments; and (8) a duty to account for proceeds of a call. The principles governing their resolution were also identified. Particular attention must be paid to (1) any ambiguity whether a surety is liable is always construed in the surety's favor; and (2) prejudicial conduct by the beneficiary releases the surety unless the instrument provides expressly to the contrary.

Construction is a process-based industry. In such an industry it is important to have a clear understanding of the process. One way to achieve this is by the use of a process model. In a European Community funded research project the business process of a small U.K. construction company was modeled and analyzed. Both visual modeling and enactable modeling techniques were used in this exercise. This paper aims to show how process understanding can be better achieved by a combination of visual models and enactable models. This is supported by examples from the construction company process studied. The tools and techniques used in this exercise are those developed by the collaborators of the project. The visual modeling is done using ProcessWise WorkBench and Role Activity Diagrams. The view of the business process given by the ProcessWise WorkBench models is predominantly process based, whereas Role Activity Diagrams provide a role based view of the process. The enactable modeling is done using RolEnact, a modeling tool that enacts formal specifications of processes.

The Building for Environmental and Economic Sustainability (BEES) tool implements a rational, systematic technique for selecting cost-effective green building products. The technique is based on consensus standards and designed to be practical, flexible, and transparent. The Windows-based decision support software, aimed at designers, builders, and product manufacturers, includes actual environmental and economic performance data for 24 building products across a range of functional applications. BEES measures the environmental performance of building products using the environmental life-cycle assessment approach specified in the latest versions of ISO 14000 draft standards. The approach is based on the belief that all stages in the life of a product generate environmental impacts and must be analyzed. The stages include raw material acquisition, manufacture, transportation, installation, use, and waste management. Economic performance is measured using the ASTM standard life-cycle cost method. The technique includes the costs over a given study period of initial investment, replacement, operation, maintenance and repair, and disposal. Environmental and economic performance are combined into an overall performance measure using the ASTM standard for multiattribute decision analysis.