Research on Mechanical Properties of Truss String Structure with Spring Rods

Ordinary truss string structures have been widely used in many practical projects and achieved good economic benefits because of its advantages known as reasonable distribution of stresses, light weight and convenient construction. However, the wind uplift damage often occurs in strong wind areas due to the light self-weight of the structure. To avoid this kind of phenomenon, reduce the loss of economic property, give full play to the characteristics of truss string structure, and improve its safety and applicability, a spring rod device suitable for truss string structure system is designed. The device can realize the use of resisting strong wind and bearing normal load, and meet the requirements of truss string structure in strong wind area.
In order to deeply study the influence of the device on the structural performance improvement and further explore the influence law of the spring bar on the mechanical characteristics of structure, a truss string structure with a span of 150 m, a height of 45 m and a length of 160 m was taken as the research object, the influence of stiffness, arrangement position and arrangement angle of the spring rod device on the mechanical performance of the structure was analyzed by using commercial finite element software MIDAS/Gen. Firstly, the design concept and structure of spring rod device were introduced, its components and working principle were described in detail, and the method of simulating the device in finite element software was also described. Then, the spring stiffness of 20,50, 100, 300 kN/mm were taken respectively, and the spring bars with each stiffness were arranged under the first, second and third secondary truss of the string truss in turn, and the maximum displacement, maximum stress and maximum cable force of the structure under the specific load combination were calculated. Finally, the angle between the spring rod and the ground was set as 30°, 45°, 60° and 90° respectively, the maximum displacement of the structure under the load combination controlled by wind load was calculated, and the influence of the spring rod arrangement on the dynamic performance of the structure was analyzed.
The results show that:1) Under the "1. 3 dead+1. 5 live" load combination, the spring bar device stiffness is 100 kN/mm and is arranged under the second truss, the maximum displacement, maximum stress and maximum cable force of the structure decrease by 60. 12%, 34. 68% and 32. 13%, respectively, indicating that the device has obvious effect on the structure against the dead load and live load. The stress and cable force of the structure are greatly reduced, and the burden of the structure system can be reduced; but when the spring stiffness is greater than 50 kN/mm, the device has no obvious effect on the structural performance. 2) Under the load combination of "1. 3dead + 1. 05live + 1. 5wind", the maximum displacement of the structure is reduced by 54. 77% when the angle between the spring rod device and the ground is 30°, which indicates that the spring rod can effectively reduce the impact of wind load on the structure. 3) From the view of the natural frequency of the structure, except for the first period, the vibration period of the truss structure with spring rods is smaller than that of the ordinary one, so the device can increase the stiffness of the structure.