Study On Seismic Performance Of Large-Scale Boiler Steel Frame Structures With Viscous Dampers

At present,Chinese power demand still has a large and sustained growth,and the situation that China mainly relies on thermal power installed power generation will still exist for a long time.Some large-scale boiler steel frame structures are often built in high-intensity areas,so the seismic performance of the structure needs to be improved.In order to facilitate the design,the boiler body is usually simplified to the mass load applied on the main frame,which is different from the analysis of the actual structure system with boiler body,so it is necessary to study the boiler’s influence on the seismic performance of the structure.In reality,the boiler body itself looks like a large-scale tuned mass damper,so appropriate shaking may be helpful to reduce the vibration of the structure.At present,the position of the boiler body is fixed by the anti-sway device.Although it can prevent the shaking of the boiler body from damaging the structure and equipment,it also limits the vibration absorption effect caused by the shaking of the boiler body.If the viscous dampers are placed between the frame and the boiler body to replace the anti-sway device,which can reduce the vibration of the boiler body by shaking within the allowable safety range.Also,the viscous damper can absorb energy to reduce the response of the structure At present,few studies have been done on the effect of viscous dampers in large boiler steel frames.The research work in this paper is mainly focused on the the effect of the boiler body in the seismic response of the structure system.Meanwhile,the influence of setting viscous dampers between the boiler body and the main frame on the seismic performance of the structure is studied.The main works of this paper are as follows:(1)By importing the STAAD model into ABAQUS using the command language,the finite element analysis model of large boiler system is developed.The formation and period of the structure was calculated by using the ABAQUS software,which are compared with the results based on STAAD software to validate the accuracy of the finite element model.Then the appropriate seismic records for time history analysis are selected according to the design conditions of the structure.The initial shape of boiler and the position of supporting boiler are determined.At last,the layout of viscous dampers is also determined.(2)The finite element models of structures with and without boiler body are developed.The finite element model is based on the Ningdong power plant with Seismic fortification intensity 7.The seismic responses of the structure along x direction under frequent and rare earthquake are analyzed.The influence of boiler body on the structure is analyzed.Also,the inter-story drift,the top displacement,the base shear,the internal stress state of main members and the torsion effect are studied.The results show that the simplified model of the boiler body changes the seismic response of the structure.Under frequent earthquake,the response of structure considering the boiler body is a little smaller than that without considering the boiler body,while the shaking of the boiler body can reduce the response of the structure under rare earthquake significantly.(3)The influence of different damping coefficients of dampers on the seismic performance of structures under rare earthquake is analyzed.The seismic response includes the inter-story drift,displacement time history,base shear time history,member stress level and the damping force.Compared with the structures without viscous dampers,the influence of the damper with different damping coefficient on the seismic response of the structure is obtained.It is found that when the damping coefficient is small,the seismic response changes greatly with the damping coefficient,and the seismic response changes slowly with the increase of damping coefficient.