Kang-Min Choi, Kang-Min Choi, Graduate Student, KAIST, Korea Hyung-Jo Jung Hyung-Jo Jung, Professor, Sejong National University, Korea In-Won Lee In-Won Lee, Professor, KAIST, Korea The 17 th Engineering Mechanics Conference of ASCE University of Delaware, Newark, DE June , 2004 Fuzzy Control Strategy for Seismic Response Reduction of Smart Base Isolated Benchmark Building

Structural Dynamics & Vibration Control Lab., KAIST, Korea 2 CONTENTS I NTRODUCTION H YBRID C ONTROL S YSTEM D ESIGN U SING F UZZY A LGORITHM C ONTROL R ESULTS C ONCLUSIONS

Structural Dynamics & Vibration Control Lab., KAIST, Korea 3 I NTRODUCTION Fuzzy theory has been recently proposed for the active structural control of civil engineering systems. The uncertainties of input data from the external loads and structural responses are treated in a much easier way by the fuzzy controller than by classical control theory. If offers a simple and robust structure for the specification of nonlinear control laws.

Structural Dynamics & Vibration Control Lab., KAIST, Korea 4 investigate the effectiveness of the hybrid control system using fuzzy control strategy for seismic protection of smart base-isolated building Objective of this study:  Hybrid control system : Passive control device + active or semiactive control device

Structural Dynamics & Vibration Control Lab., KAIST, Korea 5 H YBRID C ONTROL S YSTEM D ESIGN U SING F UZZY A LGORITHM Structural Model Benchmark structure - is a base-isolated eight-story, steel-braced framed building, 82.4-m and 54.3-m wide, similar to existing buildings in Los Angeles, California Superstructure - is modeled as a three dimensional linear elastic system Superstructure and base - are modeled using 3 master DOF per floor at the center of mass

Structural Dynamics & Vibration Control Lab., KAIST, Korea 6 Passive Base Isolation Systems Such as sliding and elastomeric bearing systems, reduce the super-structure response But with increased base displacements in near-fault motions Current practice is to provide non-linear passive dampers to limit the bearing displacements However, this increase the forces in the superstructure and also at the isolation level Active and semiactive devices present alternatives to passive non-linear devices

Structural Dynamics & Vibration Control Lab., KAIST, Korea 7 In this study, - Linear elastomeric isolation system consisted of 92 low damping elastomeric bearings - Nonlinear isolation system consisted of 61 friction pendulum bearings and 31 linear elastomeric bearings - for a total of 92 bearings are used for benchmark building problem. Active and semiactive control devices - 16 active or semiactive control devices, 8 in X and 8 in Y direction, are placed at the isolation level

Structural Dynamics & Vibration Control Lab., KAIST, Korea 8 Active Control System Design Base Isolated Building Structure Active Fuzzy Controller Fig. 1. Control diagram of the active control system of base isolated building

Structural Dynamics & Vibration Control Lab., KAIST, Korea 9 Design of fuzzy controller - Fuzzy input : base displacement and base velocity ( ) - Fuzzy output : desired control force ( ) - Membership functions NLNSZEPSPL -YY0 NEZEPO X0 -X Input membership functionOutput membership function - A reasonable range of input values must be selected for the input membership functions since, if the range is too large or too small, the outermost membership functions will rarely or essentially be used, respectively, and thus limit the variability of the control system.

Structural Dynamics & Vibration Control Lab., KAIST, Korea 10 - Fuzzy rule NEZEPO NEPLPSZE PSZENS POZENSNL NE ZE PO  ====== Negative Zero Positive NL NS ZE PS PL  ========== Negative Large Negative Small Zero Positive Small Positive Large

Structural Dynamics & Vibration Control Lab., KAIST, Korea 11 Semiactive Control System Design Fig. 2. Control diagram of the semiactive control system of base isolated building Base Isolated Building Structure Fuzzy Controller MR Damper

Structural Dynamics & Vibration Control Lab., KAIST, Korea 12 MR damper model - The damper is modeled using a spring, a dash pot and hysteretic element in parallel MR damper model Force displacement relationship of MR damper

Structural Dynamics & Vibration Control Lab., KAIST, Korea 13 Design of fuzzy controller - Fuzzy input : base displacement and base velocity ( ) - Fuzzy output : desired command voltage ( ) - Membership functions NLNSZEPSPL -YY0 NEZEPO X0 -X Input membership functionOutput membership function  The absolute value in output command voltage is used

Structural Dynamics & Vibration Control Lab., KAIST, Korea 14 C ONTROL R ESULTS Active and semiactive control – linear elastomeric isolation system Elastomeric Bearings

Structural Dynamics & Vibration Control Lab., KAIST, Korea 15 Time history responses (for active control) Fig. 3. Time history responses in the NS direction for El Centro earthquake FN and FP components acting on the benchmark building: Base displacement and top floor acceleration responses for active control, linear elastomeric system

Structural Dynamics & Vibration Control Lab., KAIST, Korea 16 Evaluation criteria (for active control) J1J1 J2J2 J3J3 J4J4 J5J5 J6J6 J7J7 J8J8 J9J9 Newhall Slymar El Centro Rinaldi Kobe Jiji Erzinkan

Structural Dynamics & Vibration Control Lab., KAIST, Korea 17 - Actuators are used apply the active control forces to the base of the structure - Most of the responses quantities are reduced substantially from the uncontrolled cases - The results which indicate peak and RMS base displacements show the benefit of active control strategy and fit in with purpose on benchmark problem

Structural Dynamics & Vibration Control Lab., KAIST, Korea 18 Fig. 4. Time history responses in the NS direction for El Centro earthquake FN and FP components acting on the benchmark building: Base displacement and top floor acceleration responses for semiactive control, linear elastomeric system Time history responses (for semiactive control)

Structural Dynamics & Vibration Control Lab., KAIST, Korea 19 Evaluation criteria (for semiactive control) J1J1 J2J2 J3J3 J4J4 J5J5 J6J6 J7J7 J8J8 J9J9 Newhall Slymar El Centro Rinaldi Kobe Jiji Erzinkan The overall performance of the semiactive control system is superior to that of active control system

Structural Dynamics & Vibration Control Lab., KAIST, Korea 20 Maximum evaluation criteria for all seven earthquakes Sample controller (LQG) Active fuzzySemiactive fuzzy J1J J2J J3J J4J J5J J6J J7J J8J J9J J1J1 J2J2 J3J3 J4J4 J5J5 J6J6 J7J7 J8J8 J9J9 - The overall performance of active control system is comparable to that of sample controller - However, the overall performance of semiactive control system is slightly better those of other controllers

Structural Dynamics & Vibration Control Lab., KAIST, Korea 21 Results for corner drifts (normalized by uncontrolled values) Active LQRClipped optimalActive fuzzySemiactive fuzzy Newhall Sylmar El Centro Rinaldi Kobe Jiji Erzinkan

Structural Dynamics & Vibration Control Lab., KAIST, Korea 22 Active and semiactive control – Nonlinear frictional isolation system Frictional Type Elastomeric Bearings

Structural Dynamics & Vibration Control Lab., KAIST, Korea 23 Evaluation criteria (for active control) J1J1 J2J2 J3J3 J4J4 J5J5 J6J6 J7J7 J8J8 J9J9 Newhall Slymar El Centro Rinaldi Kobe Jiji Erzinkan Most of the responses quantities are not good compared to uncontrolled cases - Active control system reduces peak and RMS base displacements but increase the inter-story drift of structure and floor accelerations

Structural Dynamics & Vibration Control Lab., KAIST, Korea 24 Evaluation criteria (for semiactive control) J1J1 J2J2 J3J3 J4J4 J5J5 J6J6 J7J7 J8J8 J9J9 Newhall Slymar El Centro Rinaldi Kobe Jiji Erzinkan Results of semiactive control system are similar to those of active cases

Structural Dynamics & Vibration Control Lab., KAIST, Korea 25 Maximum evaluation criteria for seven earthquakes Sample controller (Passive-on) Sample controller (Skyhook) Active fuzzySemiactive fuzzy J1J J2J J3J J4J J5J J6J J7J J8J J9J J1J1 J2J2 J3J3 J4J4 J5J5 J6J6 J7J7 J8J8 J9J9 - The overall performances of the active and semiactive fuzzy control systems are better than those of sample controllers except base displacement

Structural Dynamics & Vibration Control Lab., KAIST, Korea 26 Results for corner drifts (normalized by uncontrolled values) SkyhookActive fuzzySemiactive fuzzy Newhall Sylmar El Centro Rinaldi Kobe Jiji Erzinkan

Structural Dynamics & Vibration Control Lab., KAIST, Korea 27 CONCLUSIONS Active and semiactive fuzzy controller are investigated for benchmark problem with linear elastomeric and nonlinear frictional isolation systems When

Structural Dynamics & Vibration Control Lab., KAIST, Korea 28 Thank you for your attention!