Semi-active Control of Civil Structures Based on the Prediction of the Structural Response: Integrated Design Approach 15 Fig. 5. Optimal control design parameters Fig. 6. BCJL2 wave (PGA=4.0 [m/s 2 ]) 165 Semi-Active Control of Civil Structures Based on the Prediction of the Structural Response: Integrated Design Approach 16 Will-be-set-by-IN-TECH Fig. 7. Time histories of r 15 and a 15 for BCJL2 wave (Optimized structure, PGA=4.0 [m/s 2 ]) ×× × × Fig. 8. Time histories of the variable damping coefficients of VCDs for BCJL2 wave (Optimized structure PGA=4.0 [m/s 2 ]) 166 Vibration Analysis and Control – New Trends and Developments Semi-active Control of Civil Structures Based on the Prediction of the Structural Response: Integrated Design Approach 17 Fig. 9. RMS values of the relative displacement RMS(r k ), k = 1, ,15(BCJL2wave) 167 Semi-Active Control of Civil Structures Based on the Prediction of the Structural Response: Integrated Design Approach 18 Will-be-set-by-IN-TECH Fig. 10. RMS values of the absolute acceleration RMS(a k ) , k = 1, . . . , 15 (BCJL2 wave) 168 Vibration Analysis and Control – New Trends and Developments Semi-active Control of Civil Structures Based on the Prediction of the Structural Response: Integrated Design Approach 19 Fig. 11. Peak values of the relative displacement max | r k | , k = 1, . . . , 15 (BCJL2 wave) 169 Semi-Active Control of Civil Structures Based on the Prediction of the Structural Response: Integrated Design Approach 20 Will-be-set-by-IN-TECH Fig. 12. Peak values of the absolute acceleration max | a k | , k = 1, ,15(BCJL2wave) 170 Vibration Analysis and Control – New Trends and Developments Semi-active Control of Civil Structures Based on the Prediction of the Structural Response: Integrated Design Approach 21 6. Conclusion In this chapter the integrated design of civil structural systems and the semi-active control law is considered. The vibration control device (VCD) that is under development by the authors is adopted for the semi-active control. The VCD is the mechanism consists of the ball-screw and the flywheel that is for the inertial resistance force and the electric motor and the electric circuit for the damping resistance force with the variable damping coefficient. The semi-active control based on the one-step ahead prediction of the structural response is proposed. With the predictive semi-active control the stiffness property of the building, the parameters of VCDs and the weighting matrix used in the semi-active control are simultaneously optimized so that the control performance on vibration suppression for various recorded and artificial earthquake disturbances is optimized. The Genetic Algorithm is adopted for the optimization. The simulation study is conducted for the fifteen story building. The performance on vibration suppression of the semi-active control system obtained by the integrated design method is verified with the earthquake wave that is not employed in the GA-based optimization. The result of the simulation study shows the effectiveness of the proposed design methodology and the importance of the integrated design approach for control system design including semi-active control. The future research subjects are summarized as follows: • Integrated design of the semi-active control system including the optimization of the location of the VCDs • Semi-active control for a simplified model of the real structural system • Experimental study using a full-scale building with VCDs 7. References Casciati, F., Magonette, G., & Marazzi, F. (2006). Technology of Semiactive Devices and Application in Vibration Mitigation, Wiley, New York. Dyke, S.J., Spencer, Jr., B.F., Sain M.K. & Carlson J.D. (1996). Modeling and control of magnetorheological dampers for seismic response reduction, Smart Materials and Structures, Vol. 5: 565-575. Gavin H.P. (2001). Control of seismically excited vibration using electrorheological materials and Lyapunov methods, IEEE Transactions on Control Systems Technology, Vol. 9: 27-36. Grigoriadis, K.M., Zhu, G. & Skelton, R.E. (1996). Optimal Redesign of Linear Systems, Transactions of the ASME, Journal of Dynamics, Systems, Measurement and Control, Vol. 118: 598-605. Hiramoto, K., Doki, H. & Obinata, G. (2000). Optimal Sensor/Actuator Placement for Active Vibration Control Using Explicit Solutions of Algebraic Riccati Equation, Journal of Sound and Vibration, Vol. 299: 1057-1075. Hiramoto, K. & Grigoriadis, K.M. (2006). Integrated Design of Structural and Control Systems with a Homotopy Like Iterative Method, International Journal of Control, Vol. 79: 1062-1073. Karnopp, D., Crosby, M.J., & Harwood, R.A. (1974). Vibration control using semi-active force generator, Transactions of the ASME, Journal of Engineering for Industry, Vol. 96: 619-626. Kurata, N., Kobori, T., Takahashi M., Niwa N. & Midorikawa H. (1999). Actual seismic response controlled building with semi-active damper system, Earthquake Engineering & Structural Dynamics, Vol. 28: 1427-1447. 171 Semi-Active Control of Civil Structures Based on the Prediction of the Structural Response: Integrated Design Approach 22 Will-be-set-by-IN-TECH Ohtake T., Sunakoda K. & Matsuoka, T. (2006). Study on vibration control device using power generator, Proceedings of ASME PVP 2006, Vancouver, #PVP2006-ICPVT-11-93534. Iwata, N., Hama, T. & Soda, S. (1999). Seismic control of the soft-first-story building by sifting method in sliding mode control, Journal of Structural and Construction Engineering, (No. 816): 83-90. Onoda, J. & Hattka R.T. (1987). An Approach to Structure/Control Simultaneous Optimization for Large Flexible Spacecraft, AIAA Journal, Vol. 25: 1133-1138. Sodeyama, H., Suzuki, K. & Sunakoda, K. (2004). Development of large capacity semi-active seismic damper using magneto-rheological fluid, Transactions of the ASME, Journal of Pressure Vessel Technology, Vol. 126: 105-109. Spencer, B.F., Dyke, S.J. & Deoskar, H.S. (1998). Benchmark problems in structural control: Part I - Active mass driver system, Earthquake Engineering & Structural Dynamics, Vo l. 27: 1127-1139. 172 Vibration Analysis and Control – New Trends and Developments 9 Seismic Response Control Using Smart Materials Sreekala R, Muthumani K, Nagesh R Iyer CSIR/Structural Engineering Research Centre India 1. Introduction Earthquakes are highly destructive natural phenomena resulting in the massive deterioration of civil infrastructure, which becomes highly significant wih increasing urban population. Performance of structural systems needs to be improved recalling the huge loss of life and destruction to constructed facilities caused by various earthquakes. Protection of lifelines and infrastructural facilities are of utmost importance during a seismic event. There have been considerable research efforts in seismic vibration control for the past several decades. Developments of new techniques and new materials, which are not traditionally used in civil engineering structures, offer significant promise in reducing the seismic risk. Smart materials may be described as materials that can sense an external stimulus (e.g:- stress, pressure, temperature change, magnetic field, etc.) and initiate a response. They may belong to one of the four classes namely metals or alloys, polymers, ceramics or composites. Metals and alloys of different metals are considered as classical materials with lot of research activities around the globe . Shape Memory Alloys (SMA) belongs to the class of smart materials which are well known for its peculiar characteristics, which can be stress or temperature, induced. The research area which deals with structural applications of this variety of smart materials are promising (Sreekala& Muthumani, 2009) for structural health monitoring and vibration control. Nickel Titanium (NiTi) Alloys are well known for its super elastic and shape memory properties and they belong to the class of Shape Memory Alloys (SMA). Presently SMA’s are mainly applied in medical sciences, electrical, aerospace and mechanical engineering and also can open new applications in civil engineering specifically in seismic protection of buildings. Super elastic nitinol is found to be very effective for passive vibration control, as it can sustain large amounts of inelastic deformation and recover that deformation at the end of the process with good energy dissipation compared to regular metallic materials. Various tests are conducted on NiTi wires in CSIR-SERC to evaluate the possibility of using SMA as an energy dissipating material with re-centering capabilities. Ability to sustain and recover large amounts of inelastic deformation during reversed cyclic loading with extra ordinary fatigue resistance make super elastic NiTi suitable candidate for seismic risk reduction. Quasi static and dynamic tests conducted with various parameters like pre strain, amplitudes and frequency for a number of cycles establishes the behavior which is suitable for seismic applications. It is interesting to find that from the quasi-static behavior of the material an optimum value of pre strain, which is material dependent, can be selected and [...]... stiffness and energy loss per cycle The equivalent viscous damping expresses the 188 Vibration Analysis and Control – New Trends and Developments effectiveness of the material in vibration damping It is calculated based on the average energy dissipated per cycle It is calculated as eq = WD/(2 KS2) (1) 1200 1000 Stress in w elastic deformation of Martensite starts hich Stress,MPa 80 0 684 MPa 600... stress 83 0MPa)- frequency of loading 0.5 Hz Cycles (strain range 9%, max stress 83 0MPa) The various parameters and the testing scheme are selected in a way to understand the behavior of the material during earthquakes Initially a sinusoidal cyclic test on SMA wires was performed for constant amplitude of 5 mm [ Fig.7(a)- 7(d)] Usually earthquake 180 Vibration Analysis and Control – New Trends and Developments. .. the 182 Vibration Analysis and Control – New Trends and Developments transition from linearly elastic to super-elastic occurs at a stress of approximately 597 MPa The yield stress of 597 Mpa and ultimate stress of 1100 Mpa is comparable with the idealized behavior of SMA (Dolce, 1994) (a) 16 14 12 Load (kg) 10 8 6 Pre-Strain- 7% 1mm @0.5Hz 2mm @0.5Hz 3mm @0.5Hz 5mm @0.5Hz 7mm @0.5Hz 4 2 0 0 2 4 6 8 10... Deformation(mm) (a) (b) 2Hz-1450 -th cycle 8 Load(kg) 6 4 2 0 0 2 4 6 Deformation(mm) (c) Fig 10 (a) to (c) Changes in the shape of the curve during varying frequencies 6 186 Vibration Analysis and Control – New Trends and Developments Fig 11 Effect of pre-strain on the energy dissipation (1.2 mm diameter wires)- frequency of loading 0.5 Hz 1200 1000 Stress(MPa) 80 0 600 Quasi-Static 7%-3mm 7%-7mm 6%-7mm... is found from the experiment that the hysteresis loops narrow and translate upwards when there is an increase in strain amplitude, while the branches of the curve relevant to the 184 Vibration Analysis and Control – New Trends and Developments phase transformations harden, thus yielding an increase in the stress levels (Sreekala et al,20 08) This trend is observed in the case of cycling around 7% pre-strain,... in a position controlled test set up at constant rate of loading 0.025mm/sec Fig.4 shows the stress strain curve for quasi-static loading It is compared with the behavior of the 1mm diameter steel wire which is used for binding purposes in construction A sinusoidal cyclic test on SMA wires was performed for maximum amplitude of 5 mm 1 78 Vibration Analysis and Control – New Trends and Developments Fig...174 Vibration Analysis and Control – New Trends and Developments adopted in vibration control applications Mathematical models were developed to predict the maximum energy dissipation capability of the material under study The tests verify the potential... energy dissipation per unit mass of material Comparing the well known rubber isolators and steel hysteretic dampers which belong to the class of quasi-elastic devices and elastoplastic devices respectively, re-centering devices gain the best mechanical characteristics of 176 Vibration Analysis and Control – New Trends and Developments both The shortcomings of the traditional restrainers can potentially... wires were NiTi alloy with 55 % Ni and balance titanium spooled NiTi The wire selection is made in such a way that Ni-Ti alloy wire with equi-atomic composition possesses better dissipation property and higher resistance to corrosion and fatigue The material is straight annealed super elastic NiTi wires and has its latent heat and specific gravity 14500 J/kg and 6479 .85 kg/m3 (0.234 lbs/in3) respectively... are meant for repeated cycling Various types of vibration control devices can be made with the material used The technologies using smart materials are useful for both new and existing constructions The chapter highlights various structural applications of this class of smart materials available in addition to the suitability of this material for vibration control applications Protection of structures . strain, which is material dependent, can be selected and Vibration Analysis and Control – New Trends and Developments 174 adopted in vibration control applications. Mathematical models were. acceleration RMS(a k ) , k = 1, . . . , 15 (BCJL2 wave) 1 68 Vibration Analysis and Control – New Trends and Developments Semi-active Control of Civil Structures Based on the Prediction of the. Vibration Analysis and Control – New Trends and Developments 1 78 Fig. 3. The photograph of the super elastic SMA wire samples (Available in spool form) -0.02 0.00 0.02 0.04 0.06 0.08