Isolation Design And Economic Analysis Of Construction Projects In High Intensity Areas

China has a vast territory,complex geological conditions and active underground plate,and frequent geological activities have resulted in a large number of earthquakes.According to statistics,nearly half of the land area is located in areas with high seismic intensity above VII degrees,involving 23 provincial capital cities.The traditional design idea of "constructing a rigid structure" not only makes the upper structure of the building bulky and expensive,but also cannot effectively reduce the seismic response of the structure in high intensity areas.To solve this common problem,two methods of response spectrum analysis and time history analysis were adopted to study the seismic isolation design of buildings in high seismic intensity areas,so as to further improve and strengthen the seismic theory and seismic design method to ensure the "three characteristics" of building structure in high seismic intensity areas.The main contents of this paper include:(1)PKPM and ETABS were used to model a four-story frame structure in high seismic intensity area.When the input structural parameters were the same,the results indicated that there were some differences in the shear force between floors output by aforementioned two methods.In contrast,the results of time-history analysis were more conservative than those of response spectrum analysis.(2)Based on the frame structure in high seismic intensity zone,the performance and economic analysis of the structure with isolation bearing were carried out.The specific examples were to compare the performance and economy of the isolated and non-isolated models of different frames(2-story frame,4-story frame and 6-story frame)at different intensities(7 degrees,8 degrees,and 9 degrees).The results showed that when the low-rise buildings in high intensity areas adopted the seismic isolation design,it would reduce the cost of the superstructure.However,because the cost of the isolation layer is almost the same as that of the superstructure,the economic advantages and disadvantages of the two structures cannot be clearly reflected.In addition,when the floors were higher,adding a seismic isolation layer would significantly reduce the cost of the superstructure,while the additional cost of the seismic isolation layer was not high,and the overall economic efficiency of the building was greatly improved.The study showed that for the same area,the higher the floor,the better economic efficiency of the buildings with the seismic isolation.(3)Taking the structure of the Science and Technology Building of the Second Middle School in Longxi County,Gansu Province as an example,the project adopted new isolation technology,arranging it above the foundation roof,and installing the isolation bearing on the bottom of the isolation layer column.The PKPM software was used to design the superstructure,and the ETABS2016 was used to analyze the time history of the isolated structure.By comparing the differences of interlayer shear force before and after isolation under the input of five simulated waves and two artificial waves,the horizontal damping coefficient of the structure was obtained,and the interlayer drift angle and the wind resistance checking of the isolated structure model under rare earthquakes were carried out.Then combined with the economic analysis of Chapter 3 to compare the direct construction cost of the non-isolated structure and isolated structure,the economics of the isolated structure was analyzed briefly.The results showed that the isolation design of the traditional seismic structure in high seismic intensity area can greatly improve the safety of the structure itself,and the design method can be more flexible after the size of the superstructure is reduced.In the aspect of economy,the isolated structure can reduce the strength and quantity of concrete,meet the level goal of "small earthquake is not bad,large earthquake can be repaired",and reduce the project cost to a certain extent.Compared with the cost of this project,the cost can be saved by about 5% after isolation,and the indirect economic benefits of this structure project can also be improved.