Model Test And Numerical Simulation On Semi-Active Control Of Seismic Responses Of Tall Building Using MRF-04K Damper

Structural vibration control as a new technology is a valid method to reduce theseismic disaster. The semi-active control based on the smart materials provides anew approach to theory developing and engineering application of the structuralvibration control. Magnetorheological (MR) damper is a kind of semi-activecontrol device based on the smart MR liquid with the properties of lower powerrequirement, high speed response and great damping force, and has extensiveapplication prospects in the vibration control for civil structures.In this thesis, a kind of MR damper designed and manufactured recently,named as MRF-04K damper, and three control algorithms, includingInstantaneous Optimal Control (IOC), Classical Optimal Control (COC) andLinear Quadratic Gauss Control (LQG), are introduced. The semi-active controlsystem based on MRF-04K damper is designed, and the semi-active control lawand control effect are defined.The shaking-table test on a one-third scaled steel frame model installed anMRF-04K damper is carried out under three different seismic inputs. The testedresults show that, whichever in the passive control or the semi-active control,the peak values of relative displacements of the model structure are reduced by45% and their root-mean-square values are decreased by 70%, and the peakvalues of the accelerations are reduced by 30% and their root-mean-squarevalues are decreased by 75%. This demonstrates that the MRF-04K damper is anideal control device for engineering application of structural control and canachieve better control effectiveness with less control force.The numerical simulation on a Benchmark model of 20-storey steelstructure installed 30 MRF-04K dampers on each floor is performed under threedifferent seismic inputs. The simulated results show that, whichever in thepassive control or the semi-active control, the peak values of relativedisplacements of the Benchmark model structure are reduced by 20% and theirroot-mean-square values are decreased by 28%, and the peak values of theaccelerations are reduced by 13% and their root-mean-square values aredecreased by 17%. This demonstrates that the control system based on theMRF-04K damper has perfect control effect.Through investigating the respective characteristics of the three controlalgorithms, it is found that the semi-active control based on the LQG algorithmonly needs the feedback of acceleration responses of the model structure andpresents more economic and is easier to be realized than the semi-active controlbased on the COC and IOC algorithms. Therefore, LQG algorithm is an optimumcontrol algorithm for implementation of semi-active control using the MRdamper.