Optimal option selection for finishing works of high-rise building

Time-Cost Trade-Off Problem (TCTP), to determine optimal option among many options of construction work of high-rise building, is an issue that needs to be addressed to optimize construction duration with minimal cost. Despite the fact that the crashing process entailed in a network scheduling method is not suitable for the repetitive activities of a construction project, traditional time-cost trade-off focuses on the techniques for minimizing construction cost and time in a network-based scheduling method. In addition, time-cost relationships are usually presumed to be linear, not nonlinear. Since only integer durations (days) are considered in construction scheduling, linear approximation is not fully suitable to solve the TCTP. Thus, time-cost relationships need to be redefined at discrete points representing time-cost options. In addition, Tact scheduling is one of the most useful scheduling methods to reflect the repetitiveness usually demonstrated in a LOB (Line of Balance) form. However, Tact scheduling requires too much time and effort to determine Tact time, options (cost and time of activity), and the group of activities with the same option. Genetic Algorithms (GAs) are efficient in searching for optimal solutions among decision alternatives. Thus, the authors propose a time-cost trade-off method of Tact scheduling that uses GAs.