Research On Robust Scheduling Of Prefabricated Building Under Uncertainty

Under the current situation of transition and upgrading of construction industry,prefabricated building becomes the important direction of reform of Chinese construction industry due to its significant advantages.For prefabricated building with the integral management of assembly working area,component production working area and logistics working area is more complex than traditional building,there exists a major bottleneck problem affecting its promotion caused by lack of a suitable scheduling management system.There are few researches on the scheduling of prefabricated building under uncertainty.Some uncertainties occurring in the construction of prefabricated building,such as severe weather,default in mechanical equipment and unskilled workers,can lead to delay of the schedule,deviation between baseline schedule and real schedule,even unworkable schedule and cascade effect of prefabricated building with multidimensional working areas,which has serious effects on construction time and cost.Therefore,research on robust scheduling of prefabricated building under uncertainty has important application background and research meanings.Firstly,the key and difficult points in scheduling of prefabricated building are concluded combined with its characteristics from the view of general contractor.Secondly,the conceptual model is used to simulate the whole scheduling process,and a representative scheduling unit reflecting parallel scheduling process of the working areas is selected as a research object.Furthermore,the technique of simultaneous transformation in scheduling areas based on time is applied,and the technique of coordination scheduling led by assembly working area and the technique of robust design of the whole scheduling process are put forward to study the problems of nonsynchronous scheduling of distributed resources,mutual restraint due to different working areas and robust design.On the basis of the techniques applied,proactivereactive scheduling model is established considering the interference of time uncertainty.The proactive scheduling of the model generates a baseline schedule with the comprehensive optimum of total resource cost and robustness,taking into account weighted activity slack used to measure robustness and the idea of optimum allocation of resources.And the reactive scheduling of the model deals with unexpected interference in the execution phase and then generates a feasible schedule by reactive scheduling inside the working units and coordination scheduling between the working units in consideration of quality robustness and solution robustness.Besides,heuristic algorithm based on priority rules is proposed to solve the model with different objectives.Finally,the core scheduling techniques,the proactive-reactive scheduling model and its solving algorithm are proved practical and effective through an empirical study of the typical floor of prefabricated building.The results show that the method of proactive-reactive scheduling presented in this paper is feasible and effective to obtain the objectives.And the method gives the methodological support for schedule planning and adjusting dynamically of prefabricated building as well as providing a new idea for the method of similar robust project scheduling.