Research Of Seismic Probabilistic Risk Assessment For Single-layer Reticulated Domes

With the idea of performance-based seismic design as foundation, the mechanicalanalysis and economic theory as a tools and reducing the total cost during the structure’slife cycle as the main goal, probabilistic seismic risk assessment, represents the maindevelopment direction of current anti-seismic applications. Great theoreticalachievements have been made in fields of high-rise buildings and large-span bridgesand are reflected in corresponding seismic design specification. However, theseachievements cannot be applied to large-span space structures directly, because theseismic behavior and damage mechanism of them is rather complex and with its owncharacteristics. As landmark buildings of a region or city, large-span space structures areof great social significance and economic value. It is particularly urgent to carry outtheoretical research on seismic risk assessment of them which could provide a basis fordecision making for accurate assessment of seismic risk and initial constructioninvestment. In this paper, seismic vulnerability and risk assessment is performed to atypical form of large-span space structures–single-layer reticulated domes in theKiewit system. The main research contents and results are as follows:(1) Parameter sensitivity analysis of single-layer reticulated domes under earthquakeDistribution models of parameters that associated with structure response of single-layerreticulated domes such as yield stress, elastic modulus and Poisson’s ratio of steel,diameter of member, thickness of tube, and roof weight. To reduce the number ofrandomness factors that needs to be considered in the seismic vulnerability analysis,sensitivity analysis is taken out to the above parameters. Influence of variation of eachparameter to structure response is obtained through evaluation of typical structureresponse such as the maximum displacement and plastic development depth of structure.Coefficient of variation of each structure response due to randomness of structuralparameters is calculated and compared with that of ground motion. Conclusions can bemade that, uncertainties of roof weight, yield stress and elastic modulus of steelconsidered as random variables and other parameters considered as deterministic factorsin the following seismic vulnerability analysis. The influence of initial geometric defectto the structure response is also analyzed in this paper. According to acceptanceprovision in―Technical specification for latticed shells‖,1/1500of span of reticulateddomes is taken as the initial geometric defect. And corresponding conclusion is madethat initial geometric defect considered as deterministic factor in seismic vulnerabilityanalysis.(2) Seismic vulnerability analysis of single-layer reticulated domesAt first, basic principles of seismic vulnerability analysis of structures is brieflydescribed. Index that represents the damage level of single-layer reticulated domes and grading standards of damage states for single-layer reticulated domes are studied. Withthis information, the method and basic steps of seismic vulnerability analysis for single-layer reticulated domes are obtained. Seismic vulnerability analysis is taken out to threesingle-layer reticulated domes of Kiewit system fully considering the uncertainties ofground motion and structural parameters, through Monte-Carlo simulation of structuralparameters as well as selection of ground motion records from the PEER database andCSMNC database. Through analysis of numerical simulation results, evaluation ofseismic vulnerability is made to the three structures.(3) Probabilistic seismic risk assessment of single-layer reticulated domesAt first, basic principles of seismic risk assessment of structures is briefly described.Seismic hazard analysis of construction sites, seismic vulnerability analysis,probabilistic damage analysis and analysis of economic losses and casualties are takenout to the three reticulated domes above. In the end, total cost during the structure’slife cycle (the sum of initial cost, maintenance cost and seismic loss) of several designschemes of a concert hall in the structure system of single-layer reticulated domes iscalculated. And the lowest total cost design scheme for each basic intensity is obtained.This example also reflects the significance of the seismic probabilistic risk assessmentof reticulated domes.