Mechanical Performance Optimization And Key Construction Technology Of Cable Dome With Heavy Rigid Roof

The cable dome structure is a typical full-tension structure,and the prestress provides stiffness for the cable.During the forming process of the structure,the cable and the compression rod form a self-balance.As a rare 100-meter-span hybrid rigid roof cable dome structure in China,the Shunde Desheng Sports Center Gymnasium is composed of the external pressure ring,the ridge cable,the oblique cable,the ring cable,the brace rod and the inner pull ring.Among them,the cable-rod system of the inner two rings and the outermost ring adopts the Geiger type,and the second outer ring adopts the Levy type.The plane size of the oval cable-rod system is 105.5m×124.5m.In this paper,this structure of the project is used as the carrier to study the mechanical properties and key construction technology of the hybrid rigid roof cable dome structure,mainly including force-finding optimization of cable prestress,structural static analysis,natural vibration mode analysis,simulation of the whole construction process,construction error analysis,key node structure and construction technology.The specific research content and conclusions are as follows:First,this paper briefly introduces the research background,significance,classification and engineering cases of rigid and flexible roof cable dome structure.Then this paper expounds the current research status of domestic and foreign scholars on the mechanical properties of cable dome structures,the simulation of the whole construction process and construction errors analysis.Then the engineering carrier of this paper is introduced.Second,this paper proposes a step-by-step expansion method to find the force from the inside to the outside circle by circle.The iterative method and the small elastic mode method are used to determine the final prestress of the cable,so as to achieve the force-finding goal of the overall vertical displacement of the structure being close to 0 under the dead-load prestressed state.Then,the basic mechanical properties of the hybrid cable dome structure are studied from the three aspects:the prestress level,the ultimate limit state and the serviceability limit state.It is concluded that preventing cable relaxation is the key factor to control the prestress level of the project.It is also concluded that 1.0 times the cable prestress can avoid the relaxation of the cable and ensure that the overall prestress level is low.The structure meets the bearing capacity and stiffness requirements.Then,the natural vibration modal analysis is carried out by the dynamic response analysis method,and the first 20 mode shapes,periods and frequencies of the structure under the dead-load prestressing condition are obtained.The main mode shapes are horizontal torsional buckling and vertical bending buckling of the cable-rod system.Third,for the engineering carrier cable dome structure,the construction method of"inner ring vertical lifting+cable-rod system oblique traction lifting alternate"is adopted.Based on the principle of reducing the anchoring force of the ridge cable,the optimal time for anchoring the ridge cable is determined when the center elevation of the inner pull ring is close to the elevation of the anchoring ear plate of the ridge cable.The"nonlinear dynamic finite element form-finding method based on parabolic fitting"is used to carry out simulation of the whole construction process.The whole construction process is divided into 19 working conditions,and the key structural responses and changing laws such as configuration,cable force and stress under each working condition are obtained,which ensures the safety in the construction process.Fourth,this paper studies the influence of the sample size on the error analysis results,and determines that the subsequent error analysis is set to 500 samples.Then,the Monte Carlo method and the normal distribution model are used to conduct independent and coupled random error analysis on the cable length error,external node coordinate error and the tension error of the external oblique cable during the construction process,and the stress error response of the cable is obtained.The influence degree and sensitivity law of the error on the stress of the structural cable are summarized.The error control index of this project is put forward.The allowable value of the length error of the first and second ridge cables and oblique cables is±5mm,and the length errors of the remaining cables are set according to the specifications.The allowable value of the length error of the third and fourth ridge cables and oblique cables is±15mm.The allowable value of the length error of the first and third ring cables is±15mm.The allowable value of cable length error of the second ring cable is±L₀/5000.The allowable value of the coordinate error for the installation of external nodes is±30mm.The allowable value of the tension error of the outer oblique cable is±10%.Fifth,the structure and bearing capacity calculation method of the key nodes of cable ends and cable clips in the engineering carrier cable dome structure are introduced.Then,the key construction techniques at the construction site are introduced,mainly including:opening and laying of the cable,installation of the cable clamp,pulling and lifting of the cable-rod system,and tensioning of the cable.Finally,this paper systematically summarizes the research content and results of this paper,and points out the further work and research content of this structure.