Resource Optimization And Robust Scheduling Of Repetitive Projects Based On The Characteristic Of Controlling Activities

Repetitive projects represent a special class of construction projects that are constructed repetitively among various units and activities.Examples of typical repetitive projects include highways,pipelines,tunnels,bridges,and high-rise buildings,which represent a large portion of the construction industry.Repetitive projects have a significant impact on social and economic development with large investment scale,high resource consumption and long construction period.Therefore,an effective schedule plays a key role in the successful implementation of repetitive projects.In addition,there are more and more uncertainty in the construction of repetitive projects,because of the.These uncertainties will affect the implementation of the schedule,resulting in project delays and economic losses.Therefore,this paper focuses on the resource allocation and robust scheduling of repetitive projects,in order to provide support for managers' decision-making.Based on the Line of balance method which is a repetitive project scheduling tool,this paper analyzes the related properties and rules of controlling path and controlling activities in repetitive projects.Based on the mathematical description of LOB scheduling tool,a method of determining LOB controlling path is proposed based on the concept of controlling point.According to the position of controlling point,LOB controlling activity types are divided into four types:the forward controlling activity,the backward controlling activity,the beginning controlling activity and the end controlling activity.The identification criteria and production rate change interval are presented in this paper.Based on the classification of controlling activities,this paper gives the decision formula of LOB project total project duration.Finally,combined with the characteristics of controlling activities and the formula of the total project duration,four propositions about the relationship between the controlling activity and the total duration are proposed,which provides theoretical basis for further optimization of repetitive projects.Based on the theory of controlling activities characteristics,this paper analyzes the structural characteristics of resource allocation problem,studies the relationship between the resource allocation of the controlling activity and the total project duration,and obtains the conditions that an optimal schedule need to satisfy.Furthermore,this paper designs pruning function and integrates the resource allocation problem properties into the process of algorithm,and proposes a branch and bound algorithm.The results of case study show that compared with other algorithms proposed in the existing literature,the algorithm proposed in this paper can find the exact optimal solution of the problem quickly,and the calculation effect and efficiency have been significantly improved.The simulation results show that the pruning strategy designed by the backward controlling activity and the end controlling activity can significantly improve the efficiency of the proposed algorithm.Based on the study of resource allocation problem,this paper further studies the robust scheduling optimization problem of repetitive projects under uncertain environment.The concept of robustness is introduced to repetitive project scheduling for the first time to measure the anti-interference capability of a schedule.Because of the inapplicability of the existing float theory,a new concept of float is proposed in this paper,and a robust measurement index is designed based on it.Considering two optimization objectives of the minimization of project resource requirements and the maximization of robustness,this paper establishes a two-objective repetitive robust scheduling optimization model,and develops a multi-objective optimization decision framework by combining the ?-constraint method and TOPSIS.Examples and simulation results show that the proposed theoretical and method can obtain a schedule with low resource demand and strong anti-interference ability,which provides an effective tool for project managers to make decisions in uncertain environment.