Study On Seismic Isolation Technology Of High-Rise Building In A High Intensity Area

Earthquakes are natural disasters that humans cannot accurately predict.The destructive forces that occur when earthquakes occur are huge,often causing buildings to fall down,human casualties,and seriously affecting people's normal lives.China is located between the Pacific Rim earthquake belt and the Eurasian earthquake belt.It is an earthquake-prone country and its significance for disaster prevention and reduction is very important.With the rise of super high-rise buildings,the ever-increasing building height has brought more severe challenges to earthquake resistance.At the same time,the introduction of the new edition of the “China Seismic Parameters Zoning Map” and the partial revision of the “Code for the Seismic Design of Buildings” have caused high-rise buildings in many high-intensity areas to face over-limit problems when designing with traditional seismic methods,failing to meet regulatory requirements.The application of isolation technology can better solve this problem.Based on an engineering project in Langfang City,Hebei Province,this paper conducts seismic design and analysis of high-rise building in the high-intensity area of 8 degrees(0.3g),and uses the finite element software ETABS for seismic isolation design and analysis for building that is located with the same floor plan but exceeding the height limit under the same geological conditions.A comparative analysis of seismic design and isolation design is conducted from the aspects of isolation design concept,isolation design method and isolation design results.The main research content of the paper is as follows:(1)YJK software is used to perform seismic design of a high-rise building in the 8 degree(0.3g)area,and the calculation results are analyzed from the aspects of cycle ratio,displacement angle,stiffness ratio,rigid-weight ratio,shear-weight ratio,axial compression ratio,and shear bearing capacity ratio.Among them,the axial compression ratio of some frame columns and the displacement angle between structural layers exceed the limit.Increase the section size of some components and recalculate the structure.The layer displacement angle in the Y direction of the structure still does not meet the specification requirements.(2)YJK software is used to perform seismic isolation design of a high-rise building in the 8 degree(0.3g)area.The diameter of the bearings are calculated by standardizing the long-term surface pressure of the bearings not more than 15 MPa.A total of 62 rubber-insulated bearings which contains lead-core rubber isolation bearings and lead-free rubber isolation bearings and 20 viscous dampers are selected.The restoring force,wind resistance,and minimum eccentricity of the seismic isolation layer can all meet relevant regulatory requirements.(3)A time-history analysis of a high-intensity isolated and non-isolated high-rise building is conducted.Under the action of fortification earthquake,the ratio of interlaminar shear force and the ratio of interlaminar overturning moment between the seismic isolation structures and the non-isolated structures in the X and Y directions under the action of three seismic waves are calculated.The maximum value is the horizontal damping coefficient,which is 0.38.Therefore,it can be determined that the horizontal structure earthquake action and the seismic structure measures of the upper structure can be reduced by one degree.Under the action of rare earthquakes,the maximum compressive stress,tensile stress,and maximum horizontal displacement of the seismic isolation layer can meet the specification requirements.(4)From the design concept of isolation,design method of isolation,and design results of isolation,the seismic and seismic isolation design of a high-rise building in high-intensity areas is compared.The concept of flexible resistance of isolated structure can effectively reduce the seismic effect on the superstructure.The seismic isolation design method uses time-history analysis and the results are more accurate.Isolation design ensures the safety of personnel inside the structure and the normal use of non-structural components and equipment.The buildings studied in this article use seismic isolation design to save about 8% of the cost,and the indirect economic benefit after the earthquake is high.