Seismic Retrofitting, Base Isolation, Dynamical Testing and System Identification: A Case Study in Sicily

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ΑΡΙΣΤΟΤΕΛΕΙΟ ΠΑΝΕΠΙΣΤΗΜΙΟ ΘΕΣΣΑΛΟΝΙΚΗΣ ΤΜΉΜΑ ΠΟΛΙΤΙΚΏΝ ΜΗΧΑΝΙΚΏΝ -

Testing and : A Case Study in Sicily Giuseppe Oliveto, Department of Civil

BUILDINGS BEFORE SEISMIC REHABILITATION Characteristic compression strength

94 s longitudinal direction (too large for building type) T 2 =.

71 s transverse direction Available Seismic Resistance: 92% of required

1 ΑΡΙΣΤΟΤΕΛΕΙΟ ΠΑΝΕΠΙΣΤΗΜΙΟ ΘΕΣΣΑΛΟΝΙΚΗΣ ΤΜΉΜΑ ΠΟΛΙΤΙΚΏΝ ΜΗΧΑΝΙΚΏΝ - ΕΓΚΑΤΑΣΤΆΣΕΙΣ 19 ΜΆΙΟΣ 29 Seismic Retrofitting, Base Isolation, Dynamical Testing and : A Case Study in Sicily Giuseppe Oliveto, Department of Civil and Environmental Engineering University of Catania THE TWO SOLARINO BUILDINGS BEFORE SEISMIC REHABILITATION Characteristic compression strength of concrete 13 N/mm² (25 N/mm²) Periods of vibration: T 1 =.94 s longitudinal direction (too large for building type) T 2 =.86 s torsion T 3 =.71 s transverse direction Available Seismic Resistance: 92% of required resistance in the longitudinal direction 6% of required resistance in the transverse direction Maximum inter story drift: >> (Allowable value) Seismic Retrofitting 1

solution: Retrofitting by base isolation Two views of foundation system Seismic Retrofitting THE

2 FOUNDATION Foundation soil: limestone of the Climiti Mountain formation Inverted beam foundation with short columns supporting first storey Cutting of columns and building support relatively simple Ideal solution: Retrofitting by base isolation Two views of foundation system Seismic Retrofitting THE RETROFITTING DESIGN Strengthening of the superstructure First floor First storey Second and third storey Fourth storey 2

3 FOUNDATION ENLARGEMENT Seismic Retrofitting LAYOUT OF THE DUAL SEISMIC ISOLATION SYSTEM INCLUDING 12 HDRB AND 13 LFSB Laminated HDRB rubber bearing Low friction LFSB bearing Seismic Retrofitting Base Isolation 3

4 ISOLATION BEARINGS High Damping Rubber Bearing Low Friction Sliding Bearing Seismic Retrofitting Base Isolation ISOLATION BEARINGS High Damping Rubber Bearing Low Friction Sliding Bearing Seismic Retrofitting Base Isolation 4

5 TESTING APPARATUS Data acquisition system Electric connection cables Reaction wall Hydraulic jack Fuse Load cell Loading device Building Measurement equipment 15 acceleration transducers 12 displacement transducers SCHEMATIC VIEW OF LOADING DEVICE HYDRAULIC JACK SUDDEN RELEASE DEVICE LOAD CELL REACTION WALL 5

6 SUDDEN RELEASE DEVICE - BASIC IDEA F: APPLIED LOAD, N: TRACTION FORCE IN THE FUSE F N Hydraulic jack Fuse m Fuse F=mN N 1 Load cell F SUDDEN RELEASE DEVICE FUSE: CALIBRATED HS STEEL ROD PROTOTYPE 6

7 LOAD CELL AT THE HEAD OF LOADING DEVICE NOVATECH UK MODEL F25 CFRK LOCATION OF THE MEASURING STATIONS PENNY&GILES UK Linear Displacement Sensors MODEL SLS32 7

8 SCHEMATIC ACCELEROMETERS LAYOUT PCB Piezotronics Seismic Acceleration Transducer MODEL 393B31 Measuring stations and acquisition channels LOAD-DISPLACEMENT CURVE (L-D) 8

9 INITIAL PART OF LOAD-DISPLACEMENT CURVE DYNAMIC TEST N. 1 PERFORMED ON 9 JULY 24 9

10 DYNAMIC TEST N. 2 PERFORMED ON 9 JULY 24 DYNAMIC TEST N. 3 PERFORMED ON 9 JULY 24 1

11 PERIODS OF VIBRATION AND EQUIVALENT VISCOUS DAMPING RATIO TEST 1 TEST 2 TEST 3 LOAD-DISPLACEMENT CURVES FOR THE STATIC PHASES OF DYNAMIC TESTS TEST 1 TEST 2 TEST 3 11

12 LOW FREQUENCY COMPONENT OF PEAK ACCELERATION AND ESTIMATED BUILDING MASS TEST 1 TEST 2 TEST 3 FREE VIBRATION TESTS 12

13 SUDDEN RELEASE DEVICE SUDDEN RELEASE DEVICE 13

14 SUDDEN RELEASE DEVICE FREE VIBRATION TEST 14

15 FREE VIBRATION TEST FREE VIBRATION TEST 15

16 FREE VIBRATION TEST FREE VIBRATION TEST 16

17 FREE VIBRATION TEST FREE VIBRATION TEST 17

18 FREE VIBRATION TEST FREE VIBRATION TESTS 18

19 Wavelet Decomposition (8NCEE) Daubechies, I., Ten Lectures on Wavelets, Society for Applied Mathematics, Philadelphia, Pennsylvania. Morlet, J., Arens, G., Fourgeau, I., Giard, D., (1982). Wave propagation and sampling theory, Geophysics, 47, pp Newland, D., E., An Introduction to Random Vibration, Spectral & Wavelet Analysis, Longman, England. Walker, J., S., A Primer on Wavelets and their Scientific Applications, Chapman&Hall/CRC, London. Signal Treatment Wavelet Decomposition (8NCEE, Daub3, livello 6) Recorded Acceleration Fourier s Spectrum Signal Treatment 19

20 Wavelet Decomposition (8NCEE, Daub3, livello 6) Recorded Acceleration Fourier s Spectrum Signal Treatment Wavelet Decomposition (8NCEE, Daub3, livello 6) Recorded Acceleration Fourier s Spectrum Signal Treatment 2

21 Wavelet Decomposition (8NCEE, Daub3, livello 6) Recorded Acceleration Fourier s Spectrum Signal Treatment Wavelet Decomposition (8NCEE, Daub3, livello 6) Recorded Acceleration Fourier s Spectrum Signal Treatment 21

22 Wavelet Decomposition (8NCEE, Daub3, livello 6) Recorded Acceleration Fourier s Spectrum Signal Treatment Wavelet Decomposition (8NCEE, Daub3, livello 6) Recorded Acceleration Fourier s Spectrum Signal Treatment 22

23 Signal Treatment Signal Treatment Daub3 - level 11 Somma dei dettagli dal livello 7 al livello 11 Signal Treatment 23

24 Daub3 - level 11 Somma dei dettagli dal livello 7 al livello 11 Signal Treatment JSSI 24, 8NCEE 26 T [s] u [cm ] Fundamental Period versus Displacement Amplitude Elementary 24

25 PERIOD EVALUATION Displacement [cm] Time [s] Elementary EQUIVALENT DAMPING RATIOS (8NCEE 26) First mode damping ratios for base isolated building z [%] 25 z=z v +z f 2 z v 15 1 z f u [cm ] z, total equivalent damping ratio; z v, equivalent viscous damping ratio; z f, equivalent frictional damping ratio. Elementary 25

26 Frictional Damping uo Friction force f d uo f d Displacement c f 4 fd u 2 fdt f 3 2 mu 2 fdtd 2 ( 1 ) 3 2 mu Elementary ONE DEGREE OF FREEDOM SYSTEM Test N Treated floor accelerations Acceleration [ms 2 ] floor Same trend at all floors Differences on high frequency details Time [s] 26

27 ONE DEGREE OF FREEDOM SYSTEM ONE DEGREE OF FREEDOM SYSTEM 27

28 ONE DEGREE OF FREEDOM SYSTEM ONE DEGREE OF FREEDOM SYSTEM 28

29 MECHANICAL MODEL BS uo LD m f o FD Spring force Friction force k1 u uy k u Displacement mu cu f s u,u f signu u t u u t d uo f d f d uo Displacement SYSTEM PARAMETER VECTOR S,,u,u, 1 d y Spring force Friction force k1 u uy k u Displacement uo f d uo Displacement f d k m k 2 m u d f d k System (Hz) 1 (Hz) c 2m u d (m) u y (m) S S

30 IDENTIFICATION PROCEDURE 2 A e N A,B i1 ~ ~ A, A A t A, A A i B i ~ ~ t,t t t,t A S A S S ~ ~ ~ A S A State parameter vector Trial state parameter vector ~ A A j S ~ t t j S j ~ ~ ~ ~ A i,aj ti,t j Cij A,A t,t j ~ S ~ S ~ ~ ~ ~ ~ ~ A i,a A i,a ti,t ti,t Bi A,A t,t C ij X j Bi X j S j S j S S ~ X ~ IDENTIFICATION OF TEST FUNCTIONS System (Hz) 1 (Hz) u d (m) u y (m) S S Branches Error Identified parameters

31 DATA FROM SOLARINO TESTS Test N. 3 Untreated signal Treated signal (a) Original acceleration signal recorded on the 2 nd floor of the Solarino building; (b) Same signal after removal of high frequency components. DATA FROM SOLARINO TESTS Recorded and identified signals for test number 3 31

32 DATA FROM SOLARINO TESTS Identified system parameters, estimate of initial displacement and final quadratic error for model including viscous damping. Test Nominal u [m] Estimated u [m] ud [m] uy [m] [Hz] [Hz] e DATA FROM SOLARINO TESTS Identified system parameters, estimate of initial displacement and final quadratic error for model excluding viscous damping. Test Nominal u [m] Estimated u [m] ud [m] uy [m] [Hz] [Hz] e

33 IDENTIFIED PHYSICAL PARAMETERS Identified physical parameters for model including viscous damping; f as 1 kn Test f [kn] u [m] [rad/s] 1 [rad/s] m [kn s 2 /m] k [kn/m] k 1 [kn/m] u y [m] u d [m] f d [kn] mean st.dev c.o.v (%) IDENTIFIED PHYSICAL PARAMETERS Identified physical parameters for model including viscous damping; Test f [kn] u [m] [rad/s] 1 [rad/s] m [kn s 2 /m] k [kn/m] k 1 [kn/m] u y [m] u d [m] f d [kn] 3 127,4,118 3,2892 2, ,181, ,76,1169 3,2151 2, ,167, ,17,1228 3,316 2, ,179, ,48,927 3,2811 2, ,173, ,4,965 3,3942 2, ,118,25 32 mean 3,298 2, ,164,32 41 st.dev.,645, ,26,4 7 c.o.v (%)

34 IDENTIFIED PHYSICAL PARAMETERS Identified physical parameters for model excluding viscous damping; f as 1 kn Test f [kn] u [m] [rad/s] 1 [rad/s] m [kn s 2 /m] k [kn/m] k 1 [kn/m] u y [m] u d [m] f d [kn] mean st.dev c.o.v (%) IDENTIFIED PHYSICAL PARAMETERS Identified physical parameters for model excluding viscous damping; Test f [kn] u [m] [rad/s] 1 [rad/s] m [kn s 2 /m] k [kn/m] k 1 [kn/m] u y [m] u d [m] f d [kn] mean st.dev c.o.v (%)

35 STATIC AND DYNAMIC FRICTION COEFFICIENTS Test Identification of static and dynamic friction coefficients for LFSB Model including viscous damping Model excluding viscous damping f 1 kn f 12 kn f 1 kn f 12 kn as as s (%) d (%) s (%) d (%) s (%) d (%) s (%) d (%) mean st.dev c.o.v (%) as as RESULTS IN LITERATURE Oliveto, G., Caliò, I., Marletta, M., (24). Retrofitting of reinforced concrete buildings not designed to withstand seismic action: a case study using base isolation, 13 th WCEE, Paper No 954, Vancouver, Canada. Oliveto, G., Granata, M., Buda, G., and Sciacca, P., (24). Preliminary results from full scale free vibration tests on a four story reinforced concrete building after seismic rehabilitation by base isolation, JSSI 1 th Anniversary Symposium on Performance of Response Controlled Buildings, Yokohama, Japan. Oliveto, G., Marletta, M., (25). Seismic retrofitting of reinforced concrete buildings using traditional and innovative techniques, ISET Journal of Earthquake Technology, vol. 42 June September 25, pp , ISSN: Paper No 454. Oliveto, G., Scalia, G., (26). Free Vibration Tests Following Seismic Retrofitting by Base Isolation on the Solarino Buildings. 8th US National Conference on Earthquake Engineering (8NCEE). Oliveto, G., Scalia, G., (27). Wavelet analysis in dynamic identification of base isolated buildings: application to the Solarino buildings. ANIDIS XII Convegno Nazionale l Ingegneria Sismica in Italia Pisa. Oliveto, N., D., Scalia, G., Oliveto, G., (28). Dynamic identification of structural systems with viscous and friction damping. Journal of Sound and Vibration Oliveto, N., D., Scalia, G., Oliveto, G., (29). Time Domain Identification of Hybrid Base Isolation Systems using Free Vibration Tests. Earthquake Engineering and Structural Dynamics, to appear. 35

Seismic resistance of a reinforced concrete building before and after retrofitting Part II: The retrofitted building

Seismic resistance of a reinforced concrete building before and after retrofitting Part II: The retrofitted building M. Marletta, S. Vaccaro & I. Caliò Department of Civil and Environmental Engineering