Page 89 - Built Expressions - Online Construction Magazine - November 2014 Issue

Hulk Mechanised Building Crane Selection Main Process Selection Validation Requirements (General Contractors) (User) Crane Manager Report Experts Meeting Equipment integrated environment. The study Shape of the Reasoning feedback Rule of thumb Database included, general contractors, rental building Library of constructed -Industry heuristic & companies and engineering consultant buildings/(cases data) on -Construction Project requirement selected crane (s): types companies [1]. Type of Schedule structure (s) number; locations; & associated problems Structure Current Practice for Crane OUTPUT Design Team Selection Material Mobile Cost Tower Architectural Contractors generally aim at both Specifcations -Crane operator comparison –Design Professional Design Team proft and reputation when bidding -Site manager & fnancing Labour Relations for a job. To achieve reasonable Site Crane manager & Safety proft, contractors try to minimize the Constraints Cost Estimation cost of using equipment especially Project manager & Financing cranes on site. Normally they prefer OUTPUTS to use the smallest size crane capable of completing the task. However, Type of Number Position of Cost, Time, & Project Manager contractors rely on their in-house Crane (s) of Crane Crane (s) Productivity of Crane (s) and Crane Manger professional advice concerning the type of the crane to be used. Based on Fig. 1 Crane Selection Process Followed by General Contractor Companies this, contractors can be classifed into four groups: (a) General Contractors with in-house professionals and FACTORS AFFECTING CRANE SELECTION who own a number of cranes; (b) General Contractors with in-house Technical Factors Contractual Factors professionals who rely on rental • Site constraints • Method of operation • Site topography • Building structure and method of construction companies for the supply of cranes; • Access to the site • Construction schedule (c) General Contractors who owns • Terrain condition Economical Factors a number of cranes and depend on • Site layout and operational criteria • Size and number of cranes outside professional frm’s advice • Shape of the building • Cranes availability on the crane selection; and (d) • Weight and size of material • Running cost • Cranes capabilities General Contractors who use outside • Purchase vs rent professional frms for advice on crane • Dismantling method selection and on rental companies for Fig. 2 Factors Affecting Crane Selection cranes supply. This paper describes the process followed by the frst group, (i.e. between experts in different areas in most cases, is made between the General Contractors with in-house (i.e. design professionals, architects, crane manager, project manager, site professionals) who own a feet of fnance department representative). supervisor, and crane operator to cranes. Experts use solutions to similar The crane manager’s report may determine the type of a mobile crane, cases, involving crane selection they contain a recommendation for its attachments and location(s). faced in previous projects in addition selecting a particular crane together As is shown in Fig. (1), the fnal to heuristics and rules of thumb. with the factors considered during output consists of the number, type(s), Therefore analogical reasoning to the selection process. Based on this positions of cranes, and operational identify most common cases is required report, and additional information on costs. This output is further validated in order to establish a methodology the construction requirements which by studying the effect of the contractual for crane selection process for high- include: (shape of the building, type and the economical factors such as: rise building construction. Fig (1) of the structure, i.e. concrete or steel, the availability of the selected crane, illustrates the crane selection process construction program, site constraints, whether the selected crane can meet followed by this group. It is noted and the method of fnancing), and the construction program in terms that the crane selection is affected by alternatives of similar cases from the of capacity and production rates, the the building’s requirements that are company’s previous work, the experts effect of the selected crane on the included in the contract documents in their meeting would select the size structural and architectural design, and drawings. The process starts and type of a crane (i.e. tower or mobile and fnally the cost of the selected with a report prepared by the Crane crane). crane. Manager, regarding a meeting held For a mobile crane the decision In the case when changes to the Vol: 3 Issue: 11 November 2014 Built Expressions PG89