Optimal Design Method Of Loop-free Single-layer Hyperbolic Cable Net Structure

The loop-free single-layer hyperbolic cable net structure studied in this paper is a new type of cable network structure,which has the advantages of uniform cable force distribution,large structural rigidity,strong resistance to continuous collapse and low cost.However,due to its special and complex shape,it is necessary to carry out new form-finding analysis methods to determine its plane geometry shape and cable design scheme according to architectural requirements.The determination of cable section also needs a more simple and effective method.The cable intersection angle is variable and the internal nodes are dense,so it is necessary to innovate the node structure and optimize the cable clamp removal.Based on this,this paper takes the roof size of a stadium as an example to study the optimization design method of single-layer cable network structure without inner ring on saddle surface.By proposing a new plane geometry shape design method and a new cable section determination method,a loop-free single-layer hyperbolic cable net structure that meets the shape requirements is obtained.The optimization analysis of cable clamp removal is carried out.By studying the influence of cable clamp disassembly on the static and dynamic characteristics of the structure,the importance of cable clamping in different positions is clarified.The final optimization scheme for cable clamp removal was finalized.In this paper,a new shape design method-moving support node method is proposed.The influence of the boundary shape control equation of the inner and outer rings of the structure,the number of bearing supports and the difference in the number of bearing nodes at both ends of each cable on the plane geometry of loop-free single-layer hyperbolic cable net structure is explored.The method takes the plane geometry control parameters and the plane coordinates of the support nodes as the decision variables,and obtains the plane geometry closest to the inner and outer boundaries of the target through optimization analysis.Taking a stadium roof structure as an example,the feasibility of the plane geometry design method of loop-free single-layer hyperbolic cable net structure on saddle surface based on the moving support node method is verified.A new method for determining the cable section of loop-free single-layer hyperbolic cable net structure is proposed,which is the control prestress method.The method finds the form of the structure by giving a preliminary cable section,and determines the internal force distribution coefficient at each position of the cable net structure.Under the premise of controlling the structural deflection limit,the cable strain and cross-sectional area are adjusted under the condition of fixed stress ratio,and the optimal cable cross-sectional area design scheme is obtained by comparing the steel consumption of the cable.The cable clamp optimization of loop-free single-layer hyperbolic cable net structure includes structural innovation and layout optimization.This paper proposes a new cable clamp monomer structure which can realize the design of double cable body,splicing any free angle and air fine tuning.By comparing the differences between the 31 cable clamp removal schemes and the initial analysis model in terms of the maximum vertical displacement of the structure,the cable force and the natural vibration period of the structure determine the importance of different parts of the cable clamp to the structure.Finally,it is determined that the loop-free single-layer hyperbolic cable net structure after removing the two-ring cable clamp near the innermost ring boundary is the optimal scheme.By comparing the optimized loop-free single-layer hyperbolic cable net structure without inner ring and the spoke-type single-layer cable net structure,the economic indicators,static performance and dynamic characteristics of the two schemes are compared.The results show that the loop-free single-layer hyperbolic cable net structure is significantly less than the spoke scheme in terms of cable amount,cable end anchorage amount and large cable clamp amount,and the economic index is better.The scheme of single-layer cable net structure without inner ring has larger stiffness,better integrity,smaller cable force and more uniform cable force distribution.The loop-free single-layer hyperbolic cable net structure still maintains stable shape after cable breakage and the cable force loss is not obvious,and the progressive collapse resistance is better.