Research And Application Of The Installation Technology For The Integral Lifting In Stages Of Large-span Space Grid Structures

There are many advantages in large-span space grid structure,such as large span,light weight,beautiful spatial shape,good elastoplastic performance,and high fire resistance.It has been widely used in public buildings such as hangars,exhibition halls,railway stations,stadiums,etc.However,the structure of the large-span space grid structure is complex,and there are many influencing factors in construction.The detailed design of construction drawings varies with the different construction schemes,and hence structural analysis is difficult.The optimization of the construction plan,the analysis of the structural assembly technology,and the research on the structural installation technology and control methods are key tasks for the quality and safety in construction,and have received great attention.This research takes the installation of the grid structure of the roof of the No.101 maintenance hangar of Chengdu Tianfu Airport as the background,and studies key technologies of the roof during the installation process,mainly including the following contents:(1)By consulting relevant researches,the advantages and disadvantages of various installation methods,the scope of application and the characteristics of construction technology are analyzed basing on the main installation methods of large-span space grid structure;The most suitable "Staged overall improvement method" is selected by the expert opinion consultation method.(2)Study the welding sequence in the process of assembling the grid,and put forward the welding sequence "From center to the surrounding" and the principle of"Single pole double welding,double pole single welding";Construction technology of the high-altitude mending poles of the grid frame is analyzed and the grid hall part adopts the principle of “Small internal force first,large internal force later”is determined.Truss part of the gate adopts the principle of “Partition first,then section”and “Main first,then secondary " high-altitude refill technology.(3)By analyzing the factors influencing the arrangement of the lifting points,the working principle of the lifting equipment and the characteristics of the lifting structure during the lifting process.Layout principles of the number of lifting points and the location of the lifting points are determined to achieve the effect of balancing the forces on each lifting point;Method of determining the equipment configuration by comprehensively considering factors such as meeting the lifting force demand,the highest comprehensive efficiency of each hydraulic pump station,the system safety and reliability is proposed;The use of laser rangefinder to optimize the accuracy of the displacement sensor is also proposed,with selecting the frequency converter to control the speed of the synchronous lifting control technology,to achieve the purpose of synchronous lifting of the overall grid.(4)The stepped tension construction technology at one end is adopted to determine the tension parameters,construction process and construction methods with analysis of the structure and construction conditions of the lower chord beam of the gate truss.The grouting and anchorage closure are analyzed,and the corresponding construction methods are put forward in the meantime.(5)SAP2000 is used to establish the finite element model of the roof grid structure and temporary support.Stress and displacement of the roof grid structure and temporary lifting support in each lifting stage are analyzed,and the results are compared with the corresponding design specifications.A comparison is taken to verify the rationality and applicability of adopting the "Integrated promotion method in stages";Aiming at the problem of the lifting displacement difference caused by the unsynchronized lifting point during the lifting process,the internal force of the net frame under the two cases of single lifting point asynchronous displacement difference and double lifting point unsynchronized combined displacement difference is analyzed,and the existence of the net frame is obtained.The most unfavorable working condition is the asynchronous lifting with different displacement.Measures to reduce the asynchronous lifting displacement difference of the grid suspension point are proposed;The reinforcement and crack width of the pressure-bearing column of the concrete structure are also checked.The result of the check shows that the designed pressure-bearing column of the concrete structure can meet the requirements of lifting installation.