Construction Molding Mechanics Performance Study Of Spoke-like Cable Truss Structure

The spoke-like cable-truss structure is a kind of large-span prestressed space structure system,which is evolved from the force principle of bicycle wheels.Its structural features: There is a rigid outer ring beam under pressure,which is connected to the inner tensioned inner ring through a radial radial cable truss.Due to the pre-extension tension between the cable and the pressure balance of the outer ring beam,the entire structure belongs to the self-balanced force system.Its characteristics such as light weight,high efficiency,large span,light weight,and low steel consumption make it widely used in large-scale public buildings such as stadiums at home and abroad.In this paper,the structure of a circular Spoke-like cable truss roof structure is studied.The structural static performance,dynamic performance,pre-construction pre-construction technology,construction forming method and structural impact resistance are systematically studied and combined with model tests.The theoretical analysis was verified.Draw the following conclusions:(1)A digital simulation pre-assembly research is performed on the cable head and ear plate of ring beam with a 1:10 scaled model of a cable-truss structure.Firstly,based on the BIM technology,the structural design is established,and the three-dimensional theoretical model is established.The three-dimensional laser scanning technology is used to scan the natural state cable to obtain the measured model of the cable;the flexible cable has a high degree of geometric nonlinearity and the characteristics of prestressing,a method of correcting the digital model of the flexible cable is proposed.The feature fitting point of the component is selected and the digital simulation is pre-assembled through the coordinate transformation.The result of the misaligned edge is complemented with the finite element correction,and the force variation is within 5%.Finally,the actual tension forming test is carried out on a 1:10 scale model of a Spoke-like cable-truss structure.The results of the digital simulation pre-assembly and the results of the test are compared to verify the reliability of the results of the digital simulation pre-assembly.(2)In order to research the modal analysis and experiment of a round Spoke-like cable-truss structure,a 1:10 scale structure model was designed.With the finite element model of the structure,the first 6 orders of frequencies and modes were obtained,the influence of three parameters: pretension,span-to-rise ratio,ring cable diameter on the natural vibration characteristics were analyzed.With sinusoidal excitation method,the first four natural frequencies and modes were obtained.Finally,comparing the analysis of the experimental results and theory,the results provide reference value for structural dynamic performance evaluation and seismic design.It is shown that the frequency deviation is within 10%,and the experimental vibration mode and theoretical mode are basically consistent.At the same time,the first and second modes are the anti-symmetric vibration,the third is the torsional vibration of the inner ring,and the fourth is the relative torsional vibration of the inner ring.(3)Based on the idea of step by step to enhance the overall tension,three tensioning methods are proposed,which include radial cable tensioning scheme,ring cable tensioning scheme and inner strut elevation scheme.In order to study mechanical characteristics and development of the tensioning process,the tensioning experiment and simulation analysis of three kinds of tensioning schemes were carried out.The experiment is based on the structural model with a diameter of 6 meters,using radial cable tensioning scheme,ring cable tensioning scheme and inner strut elevation scheme to test the model.The results of comparative analysis show that the cable-tensioning process of the three schemes has the same characteristics.The radial cable tensioning scheme required has the largest tonnage of tensioning tools,but the operation is simple.The inner strut elevation scheme has longest duration.The ring cable tensioning scheme has the smallest tonnage of tensioning tools,but ring cables have to install special structure.Finally,comparing the results of tension test with the simulation results,radial cable tensioning scheme is suitable for this Spoke-like cable-truss structure.The conclusions have practical significance for the construction of such prestressed structures.(4)In order to study the impact resistance of prestressed steel structures,drop hammer impact tests were performed on the Spoke-like cable truss model to study the mechanical properties of the structure under different impact loads.Using dynamic data acquisition instrument and cable force sensor,the time history curve of each radial cable force,circumferential cable force,and node displacement time history curve during the drop hammer impact were obtained.Numerical simulations were performed using Ls-Dyna software to investigate the impact responses of structures at different impact points.The preliminary results show that,unlike the rigid structure,the reaction time of the structure is about 80 ms longer and the impact response time of the structure is about 1000ms;the impact of the impact on the lower cable system is greater;the loss of cable force after the drop hammer impact Less than 1%,vertical displacement of about 7mm,is a slight damage to the elasticity.