Technical gazette, Vol. 23 No. 1, 2016.
Original scientific paper
https://doi.org/10.17559/TV-20140108112928
Mixed-integer nonlinear programming based optimal time scheduling of construction projects under nonconvex costs
Rok Cajzek
; Gic gradnje d.o.o., Sv. Florijan 120, SI-3250 Rogaška Slatina, Slovenia
Uroš Klanšek
orcid.org/0000-0002-7341-8761
; University of Maribor, Faculty of Civil Engineering, Transportation Engineering and Architecture, Smetanova ulica 17, SI-2000 Maribor, Slovenia
Abstract
Optimal project scheduling under nonconvex time-cost relations represents a challenging problem in construction management. The nonconvex time-cost relations may appear in a construction project when several different duration options are available for its activities due to alternative technological processes enabled for their realization or wide accessibility of production resources. The source of nonconvexity of the project scheduling optimization problem can also be the project penalty- or bonus-duration relations arranged within the construction contract. The aim of this paper is to present the mixed-integer nonlinear programming (MINLP) based optimal time scheduling of construction projects under nonconvex costs. For this purpose, the MINLP model was developed and applied. A numerical example from literature and an example of construction project time-cost trade-off analysis under practical nonconvex penalty function are given in the paper to demonstrate advantages of MINLP optimization. The example from literature first presented the capability of the MINLP approach to obtain the optimal solution for difficult, highly combinatorial nonconvex discrete project scheduling problem. Thereupon, the following example revealed that the optimal project time-cost curve may take very nonuniform shape on account of discrete nature of activity direct cost options and nonconvex relation between project duration and total cost. In this way, the presented study intends to provide practitioners with new information from the field of optimization techniques for project scheduling as well as an alternative view on performance of total cost when project duration is changed.
Keywords
construction management; discrete optimization; mixed-integer nonlinear programming; nonconvex costs; time scheduling
Hrčak ID:
153150
URI
Publication date:
19.2.2016.
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