A New Model for Solving Time Cost Quality Trade Off Problems in Construction
A poor quality affects project makespan and its total costs negatively, but it can be recovered by repair works during construction. We construct a new non linear programming model based on the classic multi mode resource constrained project scheduling problem considering repair works. In order to obtain satisfactory quality without a high increase of project cost, the objective is to minimize total quality cost which consists of the prevention cost and failure cost according to Quality Cost Analysis. A binary dependent normal distribution function is adopted to describe the activity quality; Cumulative quality is defined to determine whether to initiate repair works, according to the different relationships among activity qualities, namely, the coordinative and precedence relationship. Furthermore, a shuffled frog leaping algorithm is developed to solve this discrete trade off problem based on an adaptive serial schedule generation scheme and adjusted activity list. In the program of the algorithm, the frog leaping progress combines the crossover operator of genetic algorithm and a permutation based local search. Finally, an example of a construction project for a framed railway overpass is provided to examine the algorithm performance, and it assist in decision making to search for the appropriate makespan and quality threshold with minimal cost.
PloS one