Fraunhofer WKI and 1b University of Braunschweig, Germany, formerly Penn State University, University Park, PA, USA 2

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1 1 High-performance composite-reinforced earthquake resistant buildings with self-aligning capabilities: Shake table tests of laminated timber frames with threedimensional moment connections B. Kasal, 1ab,2 Team: A. Heiduschke 2, S. Pospisil 3, S. Urushadze 3, Z. Zembaty 4, N. Rüther 1a, P. Bobra 4, A. Marynowicz 4, M. Dietz 5, L. Dihoru 5 1a Fraunhofer WKI and 1b University of Braunschweig, Germany, formerly Penn State University, University Park, PA, USA 2 HESS TIMBER GmbH & Co. KG, Kleinheubach, Germany 3 ITAM, Czech Academy of Sciences, Prague, Czech Republic 4 University of Technology, Opole Poland 5 University of Bristol, UK

2 Why timber frames in seismic applications? high strength/mass ratio low mass density Why moment connections? no need for lateral bracing high design flexibility drift limitation 8-story timber frame. Minneapolis, MN, 1920 s.

3 Methodology Preliminary shake table tests Epoxy-concrete 2-D BCC tests Steel Mockup single-story full scale frame shake table test Self-tapping screws Cross-laminated decks 3-D connection tests Frictional connections 1:3 scale 3-story frame shake table test

4 Preliminary shake table tests proof of concept development of 3-D moment connections self-correcting mechanism drift control

5 Piston Displacement (mm) Experiment mockup frame connections Time (s)

6 Testing of 2D moment connections interface reinforcement - contact stiffness in joints with large rotations strain gauges LVDT load image analysis LVDT

7 Self-tapping screw design

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9 Moment (knm) Dissipated Energy (knm/rad) Results 0,4 0,3 0,2 Energy dissipation 30 0, Time (s) Hysteresis plot ,003-0,002-0,001 0,000 0,001 0,002 Rotation (rad) Load and displacement amplitudes

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11 Single story full scale test - design and instrumentation accelerometers strain gauges

12 strain gauges CLT deck 4 x 1000 kg mass 3D moment connections deck installation h=2100 mm a= 2600x2600 mm deck=4100x4100 mm Instrumentation: u, u, u 45, ε column instrumentation 3D shaking table

13 Instrumentation

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15 increasing intensity Test sequence (general) impact snap white noise seismic impact white nose sine sweep seismic... natural frequencies synthetic EQ

16 Fourier Amplitude Spectrum (mm/sec²) The tests Frequency (Hz)

17 The drift Drift of the frame during the seismic test h/50 Rotation of the connection versus drift of the building

18 3 story frame.. Instrumentation: u, u, u 45, ε

19 Analysis estimate of the response and design forces

20 The model

21 Testing of 3D moment connections - Test and instrumentation

22 What is expected: zero Hypothesis H 01 : Unreinforced and reinforced joints will have about equal stiffness but H 02 : unreinforced joint will fail in brittle mode while H 03 : reinforced joint will exhibit higher ductility compared to unreinforced joint

23 Axial load rollers hydraulic actuators and load cells cyclic static loading

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25 Moment (knm) Moment (knm) Testing of 3D moment connections GF Epoxy Fabric E 2 1 F( ) d unreinforced tension perpendicular to fibers Rotation (rad) Rotation (rad)

26 Dissipated Energy (knm-rad) Amplitude (mm) Energy dissipation in the joints Time (s) 1 0 Unrenforced Reinforced Time (s)

27 Difference in dissipated energy (%) Rotation of the joint (rad) Energy dissipation is a key parameter E 2 1 F( ) d Time (s) Difference in energy dissipation for joints yielding in material interface (unreinforced) and joints with significant friction (reinforced).

28 Natural frequencies

29 Test sequence No. Excitation type TIR file Ref. (TA3_1110_) Excitation level PGA/RMS/amplitude Direction excitation of X Impact test Y 3 L1R1 No dead load - Static load test 4 L2R1 150 kg on 1 st floor (column 1) - 5 Snapback-pullover test P1R N Y 6 White noise N1R1 ~0.1g (RMS) X 7 N2R1 ~0.1g (RMS) Y 8 White noise N3R1 ~0.1g (RMS) X+Y 9 S1R1 ~0.1g (amplitude) X 10 Sweep sine S2R1 ~0.03g (amplitude) X 11 S3R1 ~0.03g (amplitude) Y 12 First seismic test T1R1 ~0.1g / 0.02g* (PGA) X+Y+Z 13 White noise N4R1 ~0.1g (RMS) X+Y 14 Second seismic test T2R1 ~0.3g / 0.06g* (PGA) X+Y+Z 15 White noise N5R1 ~0.1g (RMS) X+Y 16 Third seismic test T3R1 ~0.5g / 0.1g* (PGA) X+Y+Z 17 White noise N6R1 ~0.1g (RMS) X+Y 18 Fourth seismic test T4R1 ~1.0g / 0.2g* (PGA) X+Y+Z 19 White noise N7R1 ~0.1g (RMS) X+Y 20 Fifth seismic test T5R1 ~2.0g (PGA) X+Y * vertical excitation (Z)

30 Loading

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32 Column shear failure after 2g seismic test

33 Results-example Prior to seismic test After the 1 st seismic test

34 Frequency (Hz) Frequency (Hz) Natural frequency f1 f2 f3 8 1 st data point removed Natural frequency f1 f2 f PGA (g) PGA (g)

35 Conclusions drifts are difficult to control even if the BTC are relatively stiff the natural frequency of the system with frictional BTC drops after the 1 st seismic event and then the stiffness of the system degrades with load magnitudes only slightly 3-D BTC are possible and can be designed to dissipate energy both systems ( rigid BTC and frictional BTC) can be designed as selfcorrecting the composite reinforcement can be used to balance the stiffness of members and connections the 3-D BTC weaken the columns significantly. The shear failure could not be mitigated by reinforcement (however, the load magnitude was far beyond expected values)

36 Acknowledgment The help of Kyle Karchner (Penn State)Pablo Guindos (WKI), Toby Polocoser (TU Braunschweig) and technitians and staff of the University of Bristol and WKI Braunschweig is gratefully acknowledged. The research leading to these results has received funding from the European Community's Seventh Framework Program [FP7/ ] for access to the dynamic testing facility of the University of Bristol, UK, under grant agreement No Significant financial support was provided by Fraunhofer WKI.