SERIES Workshop Role of Research Infrastructures in Performance-based Earthquake Engineering September 2, 2010, Ohrid

Transcription

1 SERIES Workshop Role of Research Infrastructures in Performance-based Earthquake Engineering September 2, 21, Ohrid Experimental evaluation of the seismic performance of steel buildings with passive using real-time hybrid simulation Theodore L. Karavasilis University of Oxford James M. Ricles, Richard Sause Lehigh University Cheng Chen San Francisco State University

2 Vision Design of steel MRFs with passive to be more economical and perform better than conventional steel MRFs Economical & Higher performance More safety Decreased construction cost (less steel weight) Less damage repair cost Decreased downtime and economic losses Steel MRF with 4.57m 3.96m 9.15m = 36.6m

3 Vision Objectives 1. New cost-effective passive structural are needed 2. Practical performance-based seismic design procedures for buildings with should be developed 3. New damper designs and practical design procedures should be experimentally validated

4 Compressed elastomer damper Fabrication (Corry Rubber Company) cost-effective 1. Bonding of elastomer onto a steel bar 2. Elastomer pre-compressed into a steel tube 3. Weld together three tubes 4. Damper attached to the structure

5 Compressed elastomer damper Innovation Elastomer is compressed in tube. Interface between elastomer and tube is not bonded, allowing elastomer to slip relative to tube 1. Elastomeric damping output under small deformation amplitudes 2. Friction damping output under large deformation amplitudes 3. Controlled peak damper force Force Elastomeric damping output Controlled peak damper force Friction damping output Deformation

6 Characterization tests of the damper NEES RTMD facility in ATLSS Center Damper in test setup Loading protocol xp Deformation amplitude Variables Loading condition parameters Elastic Range Time (sec) With Slip Deformation Amplitude Frequency 3, 6, 9, 12 and 15 mm 21, 27, 33, 39 and 45 mm.5, 1.,1.5, 2., 3. and 4. Hz.5, 1.,1.5, 2. and 3. Hz Temperature Typical Ambient Temperature: ~14-16 C Typical Ambient Temperature: ~14-16 C

7 Before Slip Damper hysteresis After Slip Force (KN) K eq (KN/mm) f=2 Hz Deformation (mm) f=.5 Hz f=1. Hz f=1.5 Hz f=2. Hz f=3. Hz Deformation (mm) Force (KN) f=2 Hz Deformation (mm) Damper mechanical properties Equiv. Stiffness Loss factor Loss factor f=.5 Hz f=1. Hz f=1.5 Hz f=2. Hz f=3. Hz Deformation (mm)

8 Vision Objectives 1. New cost-effective passive structural are needed 2. Practical performance-based seismic design procedures for buildings with should be developed 3. New damper designs and practical design procedures should be experimentally validated

9 Performance-based design of buildings with Control story drifts, residual drifts, plastic deformations and total floor accelerations! Competing objectives: Drifts vs. Total Accelerations ( c+ c ) u& + f Strength of yielding d R = a structure t m Added damping This work: Reduce strength of steel MRF + add to decrease drifts without increasing total accelerations

10 Simplified performance-based design procedure Simplified design procedure (SDP) proposed by Lee et al. (25) Period Damping Ratio α = (Kb/K) β = (Kd/K) Design Spectrum Damping Reduction Factor K d K b Equivalent Static Lateral Forces K

11 Prototype steel office building Elevation 4.57m m 3.96m m 4@9.15 m 9.15m = 36.6m Plan Moment resisting frame 6@9.15=54.9 m Moment resisting frame Moment resisting frame Moment resisting frame

12 Perimeter seismic resistant frames of the prototype building The frames are designed as: 1. Conventional steel SMRF using the equivalent lateral force procedure of seismic code OR 2. Steel MRF with compressed elastomer to: 9.15m 5 = 36.6m 4@ m 5 = 36.6m achieve performance higher than that of the conventional steel SMRF 4.57m 3.96m 4.57m 3.96m AND reduce steel weight (insert and supporting braces in steel MRF with less strength than that of the conventional SMRF)

13 1. Design as a conventional steel SMRF (UD1V) Satisfies the member strength criteria and the 2% story drift limit of IBC 26 MRF Column Section Beam sections Steel weight (KN) T 1 (sec) V /W Story stiffness s (KN/m) θ max (%) µ UD1V W14x211 1 st story: W24x84 2 nd story: W21x st 2 nd st story: nd story: Design as a steel MRF with less strength/weight (UD5V) Design base shear.5v (V: design base shear of UD1V)-no drift criteria. Dampers added to control drifts MRF UD5V Column Section W14x12 Beam sections 1 st story: W24x55 2 nd story: W18x4 Steel weight (KN) T 1 (sec) V /W Story stiffness s (KN/m) 1 st 2 nd st story: 367 nd story: θ max (%) µ

14 Design of compressed elastomer for UD5V FRAME a β n ξ t (%) θ max (%) u d /u d.slip u d /u d.dam Dampers 1 st Story UD5V nd 13 compressed elastomer to achieve: Higher performance UD5V with : θmax max = 1.6% Conventional steel SMRF (UD1V): θmax max = 2.4% 3% reduction of steel weight UD5V: 124 kn kn (Braces) =141.2 kn Conventional steel SMRF (UD1V) =2 kn

15 Vision Objectives 1. New cost-effective passive structural are needed 2. Practical performance-based seismic design procedures for buildings with should be developed 3. New damper designs and practical design procedures should be experimentally validated

16 Experimental Validation Studies Real-Time Hybrid Simulation Use of Real-time Integrated Control System for Real-Time Hybrid Simulation Ground motions: Scaled natural ground motions. Building Design Cases: UD5V (with ) RTMD Integrated Control System

17 HybridFEM (Karavasilis et al. 29) Runs under matlab and simulink/compatible with xpc Target to allow real-time execution Advanced modeling (extended element library) Fiber Beam-column element Analytical brace hysteresis fiber σ ε section resultant shear forcedeformation elastic section fiber section Experimental brace hysteresis

18 CR Integration Algorithm New real-time CR integration algorithm (Chen and Ricles 28) k= to (n-1) () i+ 1 x i x = k=k+1 e ( k+ 1) force F i+1, structural Response x x& 2 i + 1= xi + 1+ t x& i +α2 t x ( k ) x & experimental substructure = x& + t α i+ 1 i 1 xi + 1 = xi + ( xi + 1 xi )/ n ( k+ 1) impose x i + 1 e( k+ 1) measureri+ 1 e( n 1) i+ 1 ri+ 1= r + keq ( xi+ 1 x i i & x i & x analytical substructure impose x i+ 1 measure ( n 1) i+ 1 ) i a ri + 1 && x i=i+1 1 i+ 1 = m i+ 1 i+ 1 i+ for k=(n-1) ( F c x& r 1) e a ri+ 1 = ri+ 1+ ri+ 1 CR algorithm: - Explicit - Unconditionally stable - Enables continuous actuator motion Μ x&& & + Cx + R a i i+ 1+ R e i+ 1= P i i+ 1 x 1 & α & x x 2 i+ = xi+ t xi+ 2 t & i 1= x& i+ α & 1 x + t i i CR Algorithm Implementation for Real-time α Hybrid Simulation 1 and α 2 : integration parameters determined using discrete control theory to attain unconditional stability,. 2 α1 = α2 = 4(4 M+ 2 t C + t K ) 1 M

19 Test setup 2nd story 3.96m 4.57m Closeup of Damper 9.15m = 36.6m 5 1st story

20 Analytical and experimental substructures Total structural system: frame with Lean-on column Analytical substructure: frame without Experimental substructures: 2 nd story damper + 1 st story damper 122 dofs and 72 beam-column elements

21 Repeatable tests Hybrid Simulations A total of 1 real-time hybrid simulations are conducted (5 accelerograms scaled to the DBE and MCE intensity levels) Statistical experimental response results incorporating the ground motion variability are obtained Earthquake Station Component Magnitude (M w ) Distance (km) Scale factor Loma Prieta 1989 Hollister - S & P HSP Manjil 199 Abbar ABBAR--T Northridge 1994 N Hollywood - Cw CWC ChiChi 1999 TCU15 TCU15-E DBE MCE ChiChi 1999 TCU49 TCU49-E

22 Experimental results Actuator Control: Synchronization Subspace Plots 4 2 RMS=3.7e-4 (a) Second floor (DBE) 4 2 RMS=1.3e-4 (c) Second floor (MCE) d c (mm) (b) First floor (DBE) 4 (d) First floor (MCE) 2 RMS=3.6e-4 2 RMS=2.5e-5 d c (mm) d m (mm) d m (mm) Adaptive Inverse Compensation (Chen and Ricles 29) Actuator command displacement accurately achieved RMS c m ( d d ) c (d ) = 2 2

23 Experimental results (damper hysteresis) Dampers designed to re-center (no slip) under the DBE! 1 (a) Second story damper (DBE) 1 (c) Second story damper (MCE) Force (kn) Force (kn) (b) First story damper (DBE) Deformation (mm) (d) First story damper (MCE) Deformation (mm) 4

24 Experimental results (floor displacement Displacement (m) (a) Second floor (DBE) time histories) UD5V with UD1V (c) Second floor (MCE) Displacement (m) (b) First floor (DBE) No residual drifts under the DBE!!! Time (sec) (d) First floor (MCE) Modest (easy to repair) residual drifts under the MCE!!! Time (sec) 6

25 Experimental results (median values of response parameters) Median peak story drift of the MRF with : 1.4% => slightly lower than the 1.6% design drift => validation of the practical performance-based design procedure

26 Experimental results (median 2 nd floor response spectra) 4 3 UD1V (DBE) UD5V with (DBE) UD1V (MCE) UD5V with (MCE) Sa (g) 2 1 T 2 T Period (sec)

27 Summary and conclusions Real-time hybrid simulation was successfully utilized to experimentally evaluate the seismic performance of steel MRFs with. Ensemble of ground motions applied resulting in various damage levels to analytical substructure No need to repair test specimen (damage occurs in analytical substructure) Response statistics obtained MRFs with compressed elastomer can be designed using the SDP to perform better than conventional SMRFs, even when the MRF with is significantly lighter in weight than the SMRF. Compressed elastomer become more effective for lighter steel MRFs

28 Acknowledgements National Science Foundation Award No. CMS NEES Consortium Operation Pennsylvania Infrastructure Technology Alliance Corry Rubber Company

29 Thank you!