Genetic Algorithm–Based Method for the Deadline Problem in Repetitive Construction Projects Considering Soft Logic

Abstract

The discrete time-cost trade-off problem (DTCTP) is a multiobjective problem usually encountered in practical projects. Current optimization methods for this problem in repetitive construction projects often assume that there is only one work sequence between units. In practice, however, the work sequence is not necessarily unchangeable. Scheduling with variable work sequences is known as the soft logic method. This study develops a mathematical model considering soft logic to address the DTCTP in repetitive construction projects. The objective is to select a set of activity modes, start times, and work sequences between units such that the total cost is minimized while meeting a given deadline. A targeted genetic algorithm is also presented, in which only the activity modes and work sequences between units are encoded, and suitable start times of all subactivities are then determined using a linear programming approach. Two example projects are analyzed, and their computation results support that applying soft logic provides more flexibility in scheduling for reducing project duration and cost.