The Applicability And Shaking Table Test Of Sliding Bearing Of Large-span Roof Structure

In recent years,the large-span spatial structures have been widely used in cities.In order to ensure that the structural system is more reasonable and reliable,corresponding seismic measures should be taken in this kind of large-span structure project.Considering the influence of uneven temperature,dynamic load and construction convenience and other factors,sliding bearing is often used to achieve the effect of vibration reduction.Based on the successful application of unidirectional sliding bearing in the structure named ‘FAST’ which is the world’s largest single aperture radio telescope.Whether this kind of sliding bearing is applicable to large-span roof structure and can effectively limit the deformation of the structure to achieve the damping effect needs to be further explored.A large-span space hybrid structure with upper large-span steel roof + lower frame-shear wall is the researching object.To link the steel structure and the concrete structure with the supporting bent steel column.One-way sliding bearings are set on the top of steel column to connect steel roof truss members.This paper mainly introduces the influence of sliding bearing on the serviceability and mechanical properties of roof structure,and the radial restraint of roof and bent joint bearing is changed(fixed bearing is added to compare with the original one).The shaking table test of the two connection modes of 1/50 scale model earthquake simulation was carried out in proper sequence.The dynamic response of the structures connected by the two bearings is compared under the condition of 6 degree seismic frequent and basic intensity.In order to discuss whether the design of the sliding bearing is reasonable or whether it can play a role in seismic reduction.As well as the reliability of the structure with unidirectional sliding bearing is verified by the input of different seismic waves in the 6 degree rare intensity and 7 degree rare earthquake test stages.The main research work of this paper is as follows:(1)The prototype structure is simplified equivalently.Due to the plane size of the structure is too large,the scale should not be too small and the size and bearing capacity of the vibration table are limited,therefore,the lower four plane irregular frame shear-wall structure is simplified as a regular structure with similar dynamic characteristics to its floor model.Additionally,the steel roof is simplified on the premise that the shape,mass distribution and natural mode deformation of the steel roof are approximate.Furthermore,the YJK model of concrete structure and the Midas model of steel structure for small earthquake elastic response spectrum analysis were established to verify the correctness of the simplified model.(2)Shaking table test design.The simplified structure is based on the similarity relation theory and the main anti lateral force component similarity principle.A 1:50shaking table test model is designed and manufactured.Counterweight calculation,layout of measuring points and completion of loading system plan and other test preparations are finished in this paper.Moreover,the seismic input of 6 degree frequent occurrence and fortification intensity is carried out for the structure with one-way sliding bearing and fixed bearing.Then,the structural model with unidirectional sliding bearing is tested by seismic intensity from degree 6 to 7.(3)Comparative study on shaking table test results of seismic performance of structures.The results has shown that the small limited plane stiffness of the large-span roof and the rotation of the upper vertical member of the support is designed to be 0.03 rad,the one-way sliding bearings produce displacement component and shares the force of the weak layer,which has obvious effect on enhancing the horizontal seismic performance of the upper roof and effectively controls its dynamic response.(4)Analysis of dynamic response results of structure under large earthquake.The dynamic characteristics,acceleration and displacement response under the input of different seismic waves are measured.The damage characteristics of the model structure are observed and recorded.More than that,the weak nodes and positions of the structure are determined.The seismic response of the prototype structure is derived from the model seismic response according to the dynamic similarity relationship.In accordance with the test results,the seismic performance of the prototype structure and the rationality of the structural scheme design are evaluated.In this paper,the dynamic characteristics,acceleration time history and displacement response of the structural model with two kinds of steel structure connected supports are compared.On conclusion,the deformation of the upper structure with sliding bearing has stronger resistance to structural deformation under the same seismic input.It shows better seismic performance in dynamic characteristics and horizontal dynamic response.Because the stiffness in plane of large-span roof is usually not large,for the convenience of fabrication and installation,this kind of sliding bearing is suitable for large-span space structure,which not only improves the stiffness of the X-direction and Y-direction and has a positive effect on horizontal seismic performance of the structure,but also helps to balance the forces of the bearing connecting members and improve the overall seismic performance of the structure.Besides,the paper also verifies that the seismic performance of the structure with sliding bearing meets the requirements of the established objectives,and the overall structure design is safe and reasonable.It is of great significance to provide important experimental verification and application value for the follow-up scientific research and engineering application.