| In recent years,with the acceleration of urbanization and the overall development of building industrialization,in order to obtain more living space and reduce building pollution,prefabricated buildings have been vigorously promoted by the government.Hoisting operation is the main and important process of prefabricated concrete construction,which largely controls the pace of construction flow and affects the construction progress.With the increase of building height and the requirement of prefabrication rate,the single task and total task of vertical transportation of tower crane increase,which puts forward higher requirements for the lifting capacity of tower crane.And the mechanical cost of the tower crane is high.The proper layout of the tower crane can improve the construction efficiency and reduce the construction cost.However,in the actual decision-making process,the construction layout of the tower crane depends on the experience of the construction manager,taking the maximum component quality to meet the whole site scheduling as the minimum requirement,often resulting in the selected tower crane model is too large,the use efficiency is low,idling and other phenomena.Therefore,it is more and more urgent to carry out the research of tower crane layout optimization in order to obtain more scientific methods to determine the optimal selection and positioning of tower crane.The main research contents and achievements are as follows:(1)Based on the above background,this paper focuses on the research status of tower crane layout optimization.First of all,through literature review,on-site investigation and expert interview,identify the main influencing factors of the preliminary selection of tower crane(such as building height,prefabricated component quality,construction project scope of work,etc.)and the main influencing factors of the preliminary positioning of tower crane(such as building foundation,geological conditions,surrounding environment,high-voltage line,etc.),and clarify the above influencing factors The influence mechanism provides a theoretical basis for the follow-up model;(2)Based on the influencing factors such as building height and the quality of the largest prefabricated components in the construction project,the model of the tower crane is preliminarily selected;secondly,combined with the mutual constraints of the location of the tower crane,the installation and stacking position of the prefabricated components,the installation position of the tower crane or the stacking position of the prefabricated components is preliminarily selected,and the mathematical model of the applicable scope of the tower crane is constructed The mathematical model of the application scope of model and prefabricated component yard is developed on the Matlab platform,and the model is verified by an example.It is found that when other conditions are certain,the larger the model of tower crane,the larger the installation scope of its own or corresponding prefabricated component yard;(3)Based on the optimization objectives of the shortest hoisting time,the minimum hoisting cost and the maximum value engineering coefficient of the construction project,combined with the hoisting process of the tower crane,the mathematical models of the optimization of the single facility layout of the tower crane,the optimization of the deformation layout of the single facility of the tower crane and the optimization of the layout of the single facility of the prefabricated component yard are established,and solved by enumeration method in the Matlab platform has completed the programming development,and verified the model with examples,and found the rule that the hoisting time of tower crane changes with its position under different mathematical models.(4)Based on the optimization objectives such as the shortest time,the minimum hoisting cost and the maximum value engineering coefficient of the construction project,combined with the hoisting process of the tower crane,the multi facility layout mathematical model of the tower crane and the prefabricated component yard is established,and the enumeration method is used to solve it,and the programming development is completed on the Matlab platform;after that,the genetic algorithm is used to improve the solving speed,and a calculation example is carried out It is found that the results of the multi facility layout optimization model combined with genetic algorithm meet the accuracy requirements,and it has passed the verification;(5)Based on an engineering case,the influence of prefabrication rate on the layout optimization of tower crane is explored.It is found from the solution results that if the change of hoisting time of prefabricated components,hoisting time of cast-in-place parts,total hoisting time of construction project and maximum value engineering coefficient is continuous with the increase of prefabrication rate,hoisting time of prefabricated components will increase by 58.543 min,hoisting time of cast-in-place parts will decrease by 21.44 min,and hoisting time of construction project will increase by 1% in this project case The total hoisting time increased by 37.10 min,and the value engineering coefficient increased by 0.009 when C6018 was selected. |
