Systematic Optimization Of Concrete Formwork Reuse Under The Background Of Intelligent Construction

With the rapid development of the domestic architecture,engineering,and construction(AEC)industry,the requirements of concrete structures as well as concrete formwork are increasing frequently.Concrete formwork referring to a kind of temporary construction materials is reused to support and shape fresh concrete into different concrete components in construction tasks.However,the reuse planning and management of concrete formwork have been overlooked for decades since common construction materials,such as rebar,cement,aggregates,etc.,attract more attention in the AEC industry.The lack of the reuse planning and management of concrete formwork leads to not only higher construction costs and lower management performance,but also wasting natural resources and increasing construction waste,which is against the needs of the development of green construction.On the other hand,conducting intelligent construction via intelligent technologies or intelligent technology-based management modes can improve the performance of on-site planning and management.Therefore,this dissertation focuses on the systematic optimization of concrete formwork reuse under the background of intelligent construction using intelligent technologies,such as building information modeling(BIM),agent-based modeling and simulation(ABMS),and intelligent decision-making methods.A construction site is inherently a complex system in which various planning and management activities are conducted.Of them,the planning and management of concrete formwork involves purchase,processing,storage,and reuse processes,and is always conducted by manual efforts.When construction schemes are designed,optimizing the quantities of concrete formwork in the mentioned processes with intelligent technologies is an effective approach to improving the efficiency and accuracy of planning,lowering the on-site total cost,saving the consumption of raw materials,and reducing the generation of construction waste.Based on the subsystem optimization,considering the concrete formwork reuse system consisting of various construction sites in a certain district,the inter-project synchronization optimization of concrete formwork and the optimal cooperation mode for construction sites can trigger further effectiveness and efficiency improvement for both construction sites and the AEC industry.In addition,the global synchronization optimization can provide a solid foundation to promote the development of green construction.Accordingly,the major research efforts and contributions are listed as follows.(1)To solve the inefficient and high-cost problems in the purchase and processing planning of on-site concrete formwork,a BIM-based framework for concrete formwork reuse planning at a single construction site is proposed.First,BIM technology is applied to extract the geometric and semantic information of cast-in-place concrete structures.The rule-based algorithm is then developed to calculate the demands of concrete formwork according to trades’ know-how.Finally,a two-dimensional cutting stock optimization model is developed and solved by a designed genetic algorithm,which are employed to optimize the purchase quantities and processing plans.Results show that the proposed BIM-based framework enables the accurate and automatic calculation of the demands of concrete formwork reuse and realizes the 28% cost-savings of concrete formwork in the case study.(2)Based on construction site layout planning(CSLP)problems,the study on dynamic CSLP and three-dimensional visualization problems for the storage and processing facilities of concrete formwork at a single site is conducted considering onsite formwork storage and transportation.First,depending on the construction schedule and the information of concrete components in BIM models,the dimensions of on-site temporary facilities and the transportation frequencies between them are calculated.Then,a dynamic CSLP model is formulated using the A-star algorithm to calculate the transportation distances between temporary facilities,and a heuristic algorithm is developed to solve the optimization model.Finally,the parametric modeling method is employed to visualize the optimized layout planning in the BIM model.Results show that conducting dynamic CSLP with the temporary facilities of concrete formwork plays an important role in cost-savings and providing the references for making decisions on formwork reuse among construction sites.(3)To solve the idle and underutilization problems of on-site concrete formwork,dynamic supply chains for formwork reuse among construction sites are developed to study the optimal actions and strategies of each site.First,the decisions and strategies of construction sites are analyzed by formulating the concrete formwork reuse mathematical model for a single site in terms of minimizing the total cost.Second,agent-based modeling and simulation(ABMS)is employed to establish the dynamic supply chain for concrete formwork reuse and the individual actions and interactions are then analyzed.Finally,a case study of Chongqing consisting of six construction sites under construction is used and three simulation scenarios are designed to illustrate and demonstrate the proposed dynamic supply chains and the developed simulation model.Simulation results indicate that the proposed simulation model is accessible to mimic the dynamic changes in the formwork reuse supply chain and analyze the optimal strategies of distinct construction sites.On the other hand,the proposed dynamic formwork reuse supply chain further enables the cost-savings of concrete formwork and the lower consumption of the standard pieces of concrete formwork.(4)To solve the problems involving cooperation alliance development,profit allocation,and compensation distribution for a breach of contract,a cooperation optimization method for construction sites in dynamic supply chains or networks is investigated based on the previous studies on formwork reuse.First,a bi-objective optimization model aiming to minimize the total cost and the total quantity of the standard pieces of concrete formwork is formulated and solved via the improved non-dominated sorting algorithm-Ⅱ to develop cooperation alliances for concrete formwork reuse in a certain district.Second,the Shapley model is employed to allocate the cost savings fairly to supply chain participants,construction sites.Accordingly,the actual cost of each construction site can be obtained.Finally,when the breach of contract occurs within the cooperation alliance,the Shapley model is applied to calculate the defaulting compensation.Results show that the proposed method can facilitate the cooperation between construction sites in a certain district to reuse concrete formwork.On the other hand,when a breach of contract occurs,it also guarantees the deserved revenues of nondefaulting construction sites and figures out the liability of defaulting construction sites that break the contract.In general,the mentioned research efforts contribute to providing the references for on-site managers to conduct accurate concrete formwork planning and enrich the body of knowledge for concrete formwork planning.In addition,the appropriate cooperation mode integrating BIM,ABMS,intelligent algorithms,etc.for the inter-project synchronization optimization of concrete formwork can further improve the level of onsite intelligent management,and the green and intelligent construction can be promoted.