| Our country at present the traditional seismic strengthening has been studied,but the traditional seismic strengthening is by increasing the stiffness and strength of components "hard",while meet the requirements of the seismic performance,but with strengthening high cost,long construction period,wet homework more,serious environmental pollution and other shortcomings,compared with the traditional seismic strengthening,Isolation design reinforcement has the advantages of low cost,less wet operation time,simple construction and so on.At present,there are few cases of seismic isolation design reinforcement for irregular frame structures in China.Accordingly based on the actual project as an example to explore the different isolation reinforcement scheme for the structure design of the overall seismic performance,comparison of the single isolation bearings and compound isolation bearings,the seismic performance of vibration isolation design differences,for the seismic strengthening design of the structure of the flat irregular practice experience,further promote isolation reinforcement design method is applied to practical engineering.The main contents of this paper are as follows:(1)Based on the project of strengthening and transforming a factory building into a hospital in Yinchuan,Ningxia,the model selection,layout and simulation methods of different isolation bearings are studied.The model established by Winwin was compared with that established by SAP2000 software to verify the accuracy of its establishment and lay a foundation for the subsequent comparative analysis of seismic isolation structure design.(2)According to the mechanical properties of bearings,SAP2000 was used to establish the isolation structural model of pure LRB600 lead-bearing rubber bearings and the isolation structural model of LRB600,LRB700 and LRB800 lead-bearing rubber bearings.Then a parallel composite isolation structure consisting of LRB600 isolation bearing and friction sliding isolation bearing is adopted.At the same time,the surface pressure of rubber isolation bearings of various isolation schemes is calculated to verify whether the selection of bearings meets the requirements of specifications.(3)The method of base isolation is adopted in this paper.Since the deformation of isolation structure mainly occurs in the isolation layer,the deformation of isolation layer is checked for different isolation structures in rare earthquakes to meet the requirements of the code.(4)Conduct modal analysis on each isolation design scheme.The period of different isolation structures and the original structures are compared under the earthquake action and the influence degree of torsion effect on the whole structure.The response spectrum method of mode decomposition was used to analyze each scheme.The interstory displacement,acceleration and base shear of the structure are analyzed and compared.The isolation effect of single isolation bearing and compound isolation bearing on structure is compared.(5)For each isolation scheme,linear time history analysis under frequent earthquakes and nonlinear time history analysis under rare earthquakes are carried out.To structure displacement between layers,interlayer shear force and acceleration dynamic response index to compare three isolation scheme for shock absorption effect of the structure,as well as from different degree of energy dissipation structure and the structure provided by the additional damping ratio of the size of the Angle analysis of shock absorption effect of the structure,thus draws the optimal structure design.At the same time,the advantages and disadvantages of the isolation scheme are analyzed by combining the damping effect and economy.(6)Elastoplastic analysis is carried out on different isolation structures from the development of plastic hinge and the hysteretic energy dissipation of isolation bearings to study their damping performance in the whole seismic action process. |
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