| Prefabricated construction is a new production method of the construction industry with many advantages such as high production efficiency,low environmental pollution,and energy-saving as well as high product quality.At present,China's traditional construction industry mode must be advanced to industrialization,intelligence,and prefabrication due to increasing labor and environmental cost as well as the development stage of the country.Therefore,the national and local governments are vigorously promoting and supporting the development of prefabricated construction.Although many prefabricated residential building projects were carried out and completed,the mainstream construction process is yet done in the traditional way where the construction drawing precedes the component disassembly and splitting,manufacturing,and construction organization.The traditional construction results in disordered component disassembly and splitting,too many component types,complicated construction procedures,slow construction speed,low efficiency,poor construction quality,and high construction cost.These challenges greatly restrict the promotion of prefabricated houses.This research aims to formulate improved methods of residential spatial design as well as optimization of construction assembly and vertical transportation appliances for the overall improved construction efficiency.Based on the main objective,the study has three main research questions: 1)How to improve construction efficiency from the aspect of spatial configuration? 2)How to improve the efficiency of intelligent component assembly?3)How to improve the efficiency of transporting components on the construction site?The study reviewed that the existing spatial design for residential building is guided by the basic need of functional space and re-organizing the spatial arrangement is done through a partial transformation during the operation stage.In addition,the assembly sequence of components and the layout of vertical transportation appliances depend on previous experience instead of simulation calculation by scientific evaluation standard.Based on the review,this study addresses the challenges through presenting and testing the alternative configuration type for spatial arrangement and optimizing the number of components arranged in the combined large space.In addition,it selects independent and simple components for easy disassembly and assembly processes.Further,it uses the intelligent optimization algorithm to solve the assembly sequence optimization of components and positioning optimization of lifting appliances.The study in this dissertation is organized into 7 chapters.Chapter 1 reviews the frontier researches on the development of prefabricated construction and intelligent construction in recent years.Based on the purpose of the study,a special focus is given to the construction system of reinforced concrete residential building structures.Chapter 2 summarizes the problem of existing living spatial configuration and clarifies the importance of component combinations for spatial configuration.It proposes to make big components by a cast-in-place method and hierarchical assembly technologies to combine them into large and regular spaces as well as to limit the type and quantity of components.Chapter 3 proposes a method to improve construction efficiency based on spatial optimization.It describes the specific cast-in-place and hierarchical assembly technologies for making big components in detail.It also demonstrates the improvement of construction efficiency through a significant reduction of the construction cost based on the reduction of the type and quantity of components(reduction of concrete volume by 20.5% by reduction of components by 11 types).Chapter 4 makes a comparative analysis of the cast-in-place industrialization and off-site precast concrete.It starts from the four critical success factors that affect the construction of reinforced concrete structures(i.e.,concrete,formwork,rebar,and scaffolding).It also presents the application of the AHP method to quantitatively analyze the advantages of building large-space dwellings using cast-in-place and hierarchical assembly technologies in comparison with the off-site precast concrete.Chapter 5 proposes component optimization through the use of independent,simple,direct component geometry,and parallel assembly sequence,as well as high-durability components.Chapter 6 establishes the evaluation indexes for component weight and quantity,as well as installation difficulty and working hours in the assembly process.It also discusses the upgraded optimization algorithms to find the best assembly sequence in a short time.In addition,it presents the BIM simulation method to control on-site construction.Chapter 7 presents the firefly algorithm in order to determine the best tower-crane layout planning.The analysis establishes a multi-objective optimization model based on the BIM model in order to obtain the coordinate information of component material supply points,component initial positions,and optional tower crane positions.The main innovations of the dissertation are: Firstly,it proposes and presents the method of restricting the type and quantity of structural components using regular large space optimization from the perspective of spatial configuration.Fewer types and quantity of components are more favorable for manufacturing,transferring,and assembling components.Secondly,it establishes an evaluation index reflecting the assembly characteristics of building components based on the optimization method of the assembly sequence of mechanical products.It also introduces the simulated annealing program module based on the traditional genetic algorithm.The findings showed the rapid and efficient assembly sequence of components can be achieved through the application of an innovative intelligent optimization algorithm in order to create a clear simulation video of the assembly process and also to control the overall procedure of the on-site construction.Thirdly,it reforms the key technology of obtaining the world coordinates of components by combining the BIM model and CAD topographic map as the BIM software can only obtain the relative coordinates of components.It forms the tower crane positioning optimization model by clarifying the transfer relationship between the component material supply point,the component initial positions,the optional tower crane positions,and the cooperative relationship between each position as well as the tower crane operation.It also solves the problem of lifting appliances layout optimization in actual projects by using the firefly algorithm.Words approximately 101,000 with 135 tables and figures. |
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