Seismic Response Semi-active Control Of Space Truss Structure Based On The Piezoelectric Friction Damper

In this article, based on the stress and deformation characteristics of space truss structureunder the action of the earthquake, two kinds of piezoelectric semi-active friction damperwere designed by using converse piezoelectric effect of the piezoelectric materials, Based onthis, the corresponding control theory and engineering application methods of space trussstructure were put forward, and the corresponding earthquake simulating shaking-table testwas conducted and analyzed. The specific work and research content are as follows:(1) According to the physical and mechanical performances of the domestic specialpiezoelectric pile, two kinds of semi-active piezoelectric friction damper were designed. Itsworking principle is that the damper can change the voltage of piezoelectric actuator based onthe structural seismic response to change the positive pressure of frictional contact surface inreal-time, and adjust the friction force of the damper to realize the structure semi-activecontrol of seismic response. The structure of the damper was designed by reasonableconstruction measures that fully ensured the piezoelectric pile can normally drive and givefull play to the semi-active damper control function. By using the self-assembly test device,the voltage-mechanical property tests of the semi-active piezoelectric friction dampers werecarried out under a variety of working conditions, the relationship between voltage anddriving force was gotten and the mechanics model of piezoelectric friction damper wasestablished considering the affections of the initial preload pressure and the damper shellstiffness.(2) Based on the modern structure control theory and the dynamics motion equations ofspace truss structure under earthquake excitation, the corresponding state space model of thestructure was established. At the same time, the mass matrix and stiffness matrix buildingmethods of the space truss structure were analyzed based on the basic theory of finite element method, the integration formula of the control position matrix and relative state transitionmatrix for the piezoelectric friction damper were deduced. According to the results of theabove theoretical analysis and derivation, the structure semi-active control simulation for thepiezoelectric friction damper under earthquake excitation was realized based on MATLABfuzzy logic toolbox and combining with SIMULINK visual modeling function, which providethe basis for further theoretical and experimental study.(3) In which the controllable degree based on modal analysis was made as performanceindex, the fitness function required by the optimized configuration standards was compiled,and the analysis program using MATLAB genetic algorithm toolbox was designed andcompiled, the self-compiling program was used to analyze and research the damperconfiguration optimizations of an practical space truss structure and a model structure. Theanalysis results showed that the increasement of the dampers made great influence on theincreasement of the control effect when the damper quantity is small, and when the dampernumber reaches a certain amount, damper quantity didn’t influence on the control effectobviously more and more. At the same time, the two kinds of fuzzy semi-active controlsimulation analysis of configuration50piezoelectric friction dampers of optimized conditionand random condition of the practical structure were analyzed, the analysis results showedthat the control effect of optimized configuration was better than that of random configuration,and usually its control effect can be increased by20%, which verified the necessity of theresearch on structure optimization control.(4) Based on the fuzzy semi-active control algorithm, using the self-organizing andself-learning ability of neural network, a fuzzy neural network semi-active control method ofthe space truss structure was designed, which realized fuzzy neural network semi-activecontrol of the space truss structure. And two El-Centro seismic inputting simulations of aspace truss structure and a reticulated shell structure were analyzed by the above method. Theresults showed that the node displacements and velocities of the model structure had beenobviously controlled, and its control effect in general can amount to25%. The fuzzy neuralnetwork control rule extracted from LQR active control of the space truss structure wasapplied to all controllers of the reticulated shell structure, the simulation analysis resultshowed that this rule also can have obvious inhibition effect of seismic response, the overallcontrol effects of both structure were similar, which explained the certain universality of the control rules based on fuzzy neural network algorithm.(5) According to the main deformation and mechanical characteristics of powertransmission tower structures of power system, a test model of transmission tower was madeby simplifying the bars, and the earthquake shaking table test of the model structure wasconducted and researched on3d and4.1mX4.1m vibration bench which has six freedomdegrees. When test, the main frequencies and vibration modes of the structure were first testedby using white noise frequency sweep, and then the EL-centro earthquake shaking table testsof the structure under control or non-control was carried out and analyzed under a variety ofworking conditions, the semi-control methods had two damper optimal arrangement schemesand two damper random arrangement ones respectively arranged on the supports and cables.The experiment showed that in addition to that the control effect of the random cablecondition was not obvious, other conditions both in the overall acceleration and peakacceleration were well controlled, and the biggest control effect can reach42%, whichverified the effectiveness of the piezoelectric friction damper for the space truss structure’ssemi-active control. Among them, for the support conditions, the control effects of theoptimized condition appeared not much different from the random condition ones under theaction of different amplitude seismic waves. For the cable ones, the control effects of theoptimized condition appeared much better than the random condition ones under the action ofdifferent amplitude seismic waves.