Analysis Of Mechanical Performance And Research On Key Construction Technology Of Spoke-type Single And Double-layer Hybrid Cable Nets

The spoke-type single and double-layer hybrid cable net structure is a new structural form that combines the spoke-type single and double-layer cable net structure,it has novel appearance and good spatial expression.As the first spoke-type single and double-layer hybrid cable net structure in the world,the canopy of Leshan Olympic Sports Center Stadium is composed of outer pressure ring beams,single-layer radial cables,double-layer radial cables,struts,single-layer ring cables and double-layer ring cable.The size of the canopy structure is 244×235m and the cantilever length is 44 m.Based on the Leshan Olympic Sports Center Stadium project,this paper conducts research on the mechanical properties and key construction techniques of the spoke-type single and double-layer hybrid cable net.The content includes the analysis of structural performance,construction method comparison,the analysis of the whole construction process,the test of the anti-slip performance of the cable clamp,the design of key joints and the construction technology.Specific research content and conclusions are as follows:The basic concepts,structural characteristics and typical engineering applications of single and doublespoke cable net structures are summarized,and the research status of domestic and foreign research on the structural performance,construction forming technology,the whole construction process and cable clamp anti-sliding performance of spoke-type cable nets is expounded.The overview of the background project of this article is introduced,including structural characteristics,cable materials and specifications,main joint forms,etc.The mechanical properties of the spoke-type single and double-layer hybrid cable net structure are studied,including static performance and natural vibration characteristics.The static performance analysis includes three parts: the effect of prestress levels,reliability analysis on serviceability limit state and ultimate limit state.The load conditions are composed of dead load,live load,wind load and temperature effect.In the analysis of natural vibration characteristics,the load case with the dead load is selected to obtain the various modes of the structure.The structural characteristics that affect the construction sequence of the cable net of this project are introduced in detail,including special cable joints,cable force distribution,etc.Through comparative analysis,the construction method of overall traction and lifting,tensioning and anchoring in batches is proposed,in which the lower radial cables of the double-layer cable net should be anchored at last.During the lifting process,the distance between the upper and lower loop cables is not enough to install the struts.For this reason,through the comparison and analysis of two schemes,the construction method of the crane assisted lifting the upper loop to install the struts is determined.5 steps of cable net construction are proposed and refined into 18 construction conditions for simulation analysis,and the ANSYS finite element models for analysis of the whole construction process are established.The analysis method of the nonlinear dynamic finite named NDFEM are introduced,and the whole construction analysis is conducted based on this method.A series of key construction parameters are obtained which are used to guide the on-side construction.The necessity of the cable clamp anti-slip performance test for this project is explained,and the test object,test system and test method are introduced.The cable clamp anti-sliding performance experiment is carried out.The torque coefficient and average reduction of high-strength bolt tightening force,cable clamp anti-sliding bearing capacity and comprehensive friction coefficient are determined,all of which meet the designing requirements and have enough safety coefficient.The key joint of the cable net structure of Leshan Olympic Sports Center Stadium is mainly introduced,including the radial cable joints and the loop cable joints.The cable-net construction technology is introduced,including the selection of construction equipment,cable-net assembly,cable clamp pre-tightening,strut installation and cable traction,lifting and tensioning,etc.,which will have reference significance for the construction of similar projects in the futureFinally,a systematic summary of the main research contents and results is presented,and the unsolved problems and further research directions are pointed out.