Optimal Analysis For High-rise Buildings With Outrigger Systems Subject To Multiple Hazards

An outrigger system,a huge frame commonly consisting of a core/frame,outriggers,and perimeter columns,can significantly enhance the vibration-resistant performance of high-rise buildings.The lateral bending of the core due to external excitations triggers the outrigger’s rotation.The outrigger’s rotational deformation then causes axial extension or compression in the perimeter columns.The axial deformations of the perimeter columns then produce a restraining moment acting on the core that is reverse to the motion of the core and reduces the core’s lateral deformation.While,it provides sufficient lateral stiffness for high-rise buildings,it can result in a large internal force in the core at the outrigger floor.Such internal force increases the vulnerability of high-rise buildings subject to strong hazard intensities.More recently,damped outriggers have been shown that they help improve the vibration-resistant performance of high-rise buildings intensely,compared with conventional outriggers.The major works of this thesis are summarized as follows:1.This thesis proposes spectrum analysis-based simplified models of different single outrigger systems under seismic loads.After calibrated by ANSYS finite element models,the simplified models are used to perform single parameter analyses and dimensionless parameter analyses.The single parameter analyses help observe variations of optimal outrigger locations with different structural factors,and hence help construct corresponding dimensionless parameters.Based on results from dimensionless parameter analyses,this thesis finally develops probabilistic models of optimal outrigger locations as functions of the dimensionless parameters.2.Considering interactions among different outriggers along the height,this thesis proposes spectrum analysis-based simplified models for multi-outrigger systems under seismic loads.The models for the damped multi-outrigger systems are developed using the complex mode superposition response spectrum method to obtain peak seismic responses.Based on single parameter analyses,we define dimensionless parameters to characterize each of the multi-outrigger systems.Probabilistic models are developed to define the optimal locations of multiple outriggers as functions of such dimensionless parameters.Combining the simplified models and the probabilistic models of optimal outrigger locations,this thesis finally estimates fragilities for 5 types of multi-outrigger systems using a traditional method.3.Considering seismic loads and wind loads,the study domain of this thesis is transferred from the time domain to the frequency domain.Some performances of outrigger systems in frequency domain are first investigated using the minimized frequency response function method.This thesis then proposes pseudo excitation method-based simplified models of different single-outrigger systems subject to seismic and wind loads.Using these new simplified models and parameter analyses,this thesis develops probabilistic models of optimal outrigger locations and optimal damping parameters for single outrigger systems and multioutrigger systems under seismic and wind loads.4.With the sufficient input information from structural models and excitation models,this thesis establishes and runs finite element models for high-rise buildings with outrigger systems using ANSYS to obtain structural responses(i.e.,output information).Thanks to numerous non-linear time-history analyses,a database with the input-output information is constructed to formulate probabilistic demand models and Kriging metamodels.Both predictive models capture the relevant uncertainties and provide unbiased estimates,however,the probabilistic demand models have higher accuracy than the Kriging metamodels.They are finally used for fragility estimates of an example high-rise building with three types of outrigger systems under three types of hazards.