Fast Calculation Method For The Seismic Failure Peak Ground Acceleration Of Single-layer Reticulated Domes

As a large-span space structure commonly used in engineering,the reticulated shell structure has been widely used in our country’s infrastructure construction.Despite its good seismic performance,the reticulated shell structures had been damaged to varying degree,or even collapsed by earthquakes over the years.Therefore,the dynamic failure analysis of the single-layer reticulated dome and the calculation of its seismic failure peak ground acceleration with the guarantee rate to some extent can provide a basis for the design of the single-layer reticulated dome,which has theoretical and engineering significance.The current method for calculating the seismic failure peak ground acceleration of the single-layer reticulated dome is mainly the finite element method（FEM）nonlinear time-history response analysis,which is extremely time-consuming and needs to complete a complicated data processing.Moreover,the calculation results of the FEM nonlinear time-history response analysis are only for the seismic waves involved in the analysis,which are not statistically significant.Having taken references from the the seismic failure peak ground acceleration calculation method of the single-layer reticulated dome based on the elasto-plastic buckling theory,proposed by Japanese scholars,this thesis proposed a fast calculation method for the seismic failure peak ground acceleration of the single-layer reticulated dome which is applicable to China’s relevant structural design regulations and has the statistical significance to some extent.And a fast calculation program is compiled,the calculation results of it are the statistical values with relatively high guarantee rate.The main research contents of this thesis are as follows:（1）The calculation method of the seismic failure peak ground acceleration of the single-layer reticulated dome based on the elasto-plastic buckling theory proposed by Japanese scholars is studied.28 examples of single-layer reticulated dome according to China’s relevant structural design regulations are designed and the correctness of the finite element model of the examples are verified.The surface peak acceleration A_max0and the structural design spectral acceleration S_ad0 in the method proposed by Japanese scholars are corrected,and the fast calculation method for the seismic failure peak ground acceleration of the single-layer reticulated dome which is suitable for the relevant structural design regulations in China and has the statistical significance to some extent is preliminarily constructed.（2）The plasticity index in the fast calculation method is studied.The finite element elastoplastic static analyses of 28 single-layer reticulated domes are conducted,and the corresponding plasticity index is obtained.Based on the above analyses,the relationships between the plasticity index and the span,roof weight,rise-span ratio,member section thickness,member section outer diameter of the dome are analyzed.A fitting formula to directly calculating the plasticity index according to the above parameters is given,thereby the finite element elastoplastic static analysis process is eliminated.（3）The dynamic ductility coefficient in the fast calculation method is studied.The FEM nonlinear time-history response analyses of 28 single-layer reticulated domes are conducted,and the corresponding dynamic ductility coefficient is obtained.Based on the above studies,a statistical analysis was carried out,and the statistical values of the dynamic ductility coefficients of all the single-layer reticulated domes under the action of frequent earthquakes and rare earthquakes,which would be built in the Dujiangyan area and with structural parameters within a certain range,are respectively given.Thereby the FEM nonlinear time-history response analysis process is eliminated.（4）The correctness,efficiency and statistical significance of the fast calculation method proposed in this thesis are verified.Through the above three works,a fast calculation method for the seismic failure peak ground acceleration of the single-layer reticulated dome has been formally established,which is suitable for China’s relevant structural design regulations and has the statistical significance to some extent,and a fast calculation program has been compiled based on this.Nine verification examples of single-layer reticulated domes with static stability coefficients around 2.0 are designed,and the calculation results and time of the seismic failure peak ground acceleration of the above-mentioned nine domes by the fast calculation program and the FEM nonlinear time-history response analysis are compared and analyzed,which can verify the correctness,efficiency and statistical significance of the fast calculation method proposed in this thesis.The conclusions of this thesis are as follows:a fast calculation method for the seismic failure peak ground acceleration of the single-layer reticulated dome is proposed which is suitable for China’s relevant structural design regulations and has the statistical significance to some extent.First,it determines the design structural parameters and seismic design parameters of the single-layer reticulated dome.Then,it calculates the dead load and seismic action,elastic buckling load and plastic load,and elasto-plastic buckling load of the dome’s calculation node defined in this method.Finally,the seismic failure peak ground acceleration with relatively high guarantee rate is calculated based on the elasto-plastic buckling load of the single-layer reticulated dome.The calculation formula of the plasticity index in the method is fitted.The results show that the plasticity index is a quadratic function of the rise-span ratio of the dome and linear functions of other structural parameters.The statistical value of the dynamic ductility coefficient in the method is obtained.The results are as follows:The statistical value with a 95%guarantee rate of the dynamic ductility coefficient of the single-layer reticulated dome with a certain range of structural parameters（the span is between 40 m and 100 m,the roof weight is between 60 kg/m~2 and 360 kg/m~2,the rise-span ratio is between 1/7 and 1/2,the member section thickness is between 6.0 mm and 8.5 mm and the member section outside diameter is between148 mm and 168 mm）under frequent earthquakes in Dujiangyan area is 1.234,and the statistical value with a 95%guarantee rate of the dynamic ductility under rare earthquakes in Dujiangyan area is 1.533.The correctness,efficiency and statistical significance of the fast calculation method in this thesis are verified.The details are as follows:the seismic failure peak ground acceleration calculated by the fast calculation method proposed in this thesis is smaller than the FEM nonlinear time-history response analysis results of seven different seismic waves,which shows that the method is correct and safe,and that the calculation results of the method in this thesis are the statistical values with relatively high guarantee rate.At the same time,the calculation time of the method in this paper is 198 times shorter than that of the time-history response analysis method（only one seismic wave is calculated and the calculation time is the average calculation time of all amplitude modulation peaks）.