Study On Floor Acceleration Response Spectra Of Typical RC Structures

Seismic disasters occur frequently in China.In recent years,studies have found that the loss caused by non-structural components in earthquakes is much greater than the loss caused by structural damage.Although the "Code for Seismic Design of Buildings "(GB50011-2010)has introduced non-structural components Part,but there are no detailed measures for seismic design of non-structural components in the code.It is only clear that the non-structural seismic fortification objectives should be coordinated with the threelevel fortification objectives of the main structure,while the seismic design of nonstructural components of the building is closely related to the response spectrum of the floor,so it is significant to study the amplification law of the floor response spectrum.In China's building structure,reinforced concrete structure accounts for the vast majority in cities and non-structural components in the structure do not distinguish structural types for seismic design.It is possible to overestimate or underestimate the amplification effect of floors.In order to study the distribution law of the floor response spectrum of the reinforced concrete structure along the height of the structure,this paper uses the method of finite element numerical simulation analysis to study.The main research contents are as follows:1.Introduced the basic concept of floor response spectrum at home and abroad and the development history of non-structural component seismic resistance.It was found that most of the floor response spectrum was obtained by direct spectrum to spectrum method and then explored,and the accuracy was not effectively guaranteed,and The domestic floor response spectrum research is mainly focused on nuclear power plant equipment,and there is very little research on ordinary commercial residences or residential buildings.2.A total of 1100 sets of ground motions are selected from the PKPM ground motion database and the PEER ground motion database.According to the site category and design earthquake grouping in China,the corresponding site characteristic periods are 0.2s,0.25 s,and 0.3s,0.35 s,0.4s,0.45 s,0.55 s,0.65 s,0.75 s and 0.9s,select the ground motion according to the design spectrum of the corresponding site period in the specification.Under the principle that the typical structure is unknown,select each type of site The corresponding 104 ground motions are used for elastic time history analysis and 3 ground motions are selected for elasto-plastic time history analysis;by considering the main period and height of various types of reinforced concrete structures in China in different fortification intensity zones,a total of 31 models of three types of reinforced concrete structures were established,including frame structure,frame shear wall structure and shear wall structure,all structures are designed according to GB50011-2010.3.For the selected ground motion and various typical structures of reinforced concrete,based on the characteristic period corresponding to the site where the structure is located,use the corresponding ground motion to perform elastic time history analysis and elasto-plastic time history analysis respectively to obtain the selected floors of each structure The absolute acceleration time-history data of each floor can be obtained by excitation interpolation method.4.Through calculation and analysis,the similarities and differences of the three types of reinforced concrete structures on the amplification of earthquakes are compared and the various types of amplification factors(PFA/PGA,PSA/PFA,PSA/PGA)along the structure height are given.By comparing the results of PFA/PGA with the simplified formulas given by NEHRP2015,IBC2015 and GB50011-2010,the advantages and disadvantages of each simplified formula are discussed,according to the obtained results,a simplified formula suitable for various structures and various amplification factors is given.Among them,for non-high-rise structures of frame structures,frame shear walls and shear wall structures,the distribution of PFA/PGA along the structural height(z/h)can be simplified to 1+3z/h,shear wall and frame shear high-rise structures,PFA/PGA does not distribute nearly linearly along the height of the structure,and different structures have different enlargement laws.This paper gives the corresponding fitting formulas;PSA/PFA has obvious distribution along the structure height,and the value of PSA/PFA is 5 on each floor;PSA/ PGA and PFA/PGA have almost the same magnification law along the height of the structure.The formulas given in this paper are given under the calculation of small earthquakes.The overall amplification trend of nonlinear PFA/PGA along the height of the structure is similar to that of elasticity,but the maximum difference is 3-4 times.