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Mechanics Based Modeling of the Dynamic Response of Wood Frame Building By Ricardo Foschi, Frank Lam,Helmut Prion, Carlos Ventura Henry He and Felix Yao.

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Presentation on theme: "Mechanics Based Modeling of the Dynamic Response of Wood Frame Building By Ricardo Foschi, Frank Lam,Helmut Prion, Carlos Ventura Henry He and Felix Yao."— Presentation transcript:

1 Mechanics Based Modeling of the Dynamic Response of Wood Frame Building By Ricardo Foschi, Frank Lam,Helmut Prion, Carlos Ventura Henry He and Felix Yao University of B.C. CUREe-Caltech Woodframe Project Element 1 - Researchers Meeting University of California, San Diego January 2001 UBC

2 UBC Research Project: Reliability and Design of Innovative Wood Structures under Earthquake and Extreme Wind Conditions Combined analytical and experimental studies to evaluate the performance of wood frame structures Reliability procedures to consider the randomness of loading and system response Funded by Forest Renewal BC Collaborations with CUREe-Caltech Woodframe Project

3 UBC TEAM Principal researchers: R.O. Foschi, F. Lam, H. Prion, & C. Ventura F. Yao, H. Li, Y.T. Wang – Structural Analysis, Reliability H. He - Modeling and testing of simple 3D structures M. Popovski - Glulam frames D. Moses, N. Allotey, A. Schreyer - Nail & bolted connections R. Mastschuch, B. Sjoberg - Reinforced bolted connections N. Richard, P. Welzel - Openings M. Stefanescu, G. Finckenstein - Japanese Post & Beam Frames Full scale shake table testing of 2 storey buildings

4 3-D Model of Wall Systems Develop and verify 3D structural analysis model with mechanics based nail hysteresis subroutine – Model Development – Input Data – Full Scale Test Data Completed verification of static, cyclic and dynamic behaviour (2D) Completed verification of static behaviour (3D) – (PI: ROF, FL – HH)

5 Wind Load Lateral Load Vertical Load Double-side Panels Frame Nails Insulation Structural Model Light-frame building structure Sandwich diaphragm type components with optional insulation layer Wide range of material properties Multiple load inputs Load/displacement control

6 Structural Model Element types o Panel - 4-node elastic orthotropic plate element o Frame - 3D elastic beam element o Nail - nonlinear spring element in x, y, z directions Substructuring used in local-global transformations o Performed only in frame elements and connections to frame DOF in panel and frame elements NxNx NyNy MxMx MyMy dx dy x,u y,v z,w Rot-x Rot-y Rot-z M xy dx dy x y z Pure twistDisplacements & rotations qdxdy

7 Mechanics Based Nail Hysteresis Beam elements (nail) on nonlinear foundations (panel and frame) Basic material properties – Non-linear Stress Strain Behaviour of the steel – Non-linear Embedment Properties of the Wood Hysteresis behaviour

8 Cyclic Behaviour Mechanics based nail model was implemented into 3D program Single nail case compared to test results o Pinched and asymmetric hysteresis loops o Stiffness and strength degradations Possible issues o Solution Stability o Model Calibration o Material Properties

9 Mechanics-Based Nail Model

10 Monotonic and Cyclic Tests of 7.2 m Wall

11 Monotonic and Cyclic Tests of 2.4 m Walls Wall 5 Wall 3 Wall Monotonic Test Cyclic Test

12 Model Verification - Monotonic Case 1

13 Model Verification - Monotonic Case 2

14 Model Verification - Cyclic Case 1

15 Model Verification - Cyclic Case 2

16 Model Predictions - Cyclic Case

17 Shake Table Test set up of 2.4 wall Support frame Shake table Longitudinal actuator Vertical actuators Shear wall specimen Distribution beam Inertia masses

18 Model Verifications Shear Wall Fundamental Frequency Experimental Results (Hz) Model Predictions (Hz) Jtest 10a – 2.4x2.4 Jumbo Panel Jtest 11 – 1.2x2.4 Regular Panels

19 Model Verifications Jtest11 Regular Panel Jtest10a Jumbo Panel TestModel Test Model Displ. (mm) Accel. (g)

20 Model Verification - Dynamic Case 2D

21 Model Predictions - 3-D Static Response

22 Model of an Eccentric Structure

23 Specimen Details

24 Model Verification - Static Case 3D

25 3D Model Verification Vibration Frequencies Vibration ModeExperimental Results (Hz) Model Predictions (Hz) No.1 (Sway Motion E-W) No.2 (Sway Motion N-S) No.3 (Torsion)8.8

26 Model Verification - Dynamic Case 3D Single Component Shaking

27 Failed Shake Table Specimen

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29 3D Simplified Model Test Observations Significant torsional response Single Component Shaking (~0.4g pga) – Damage initiated in the narrow wall – Adjacent long wall was also severely damaged – Significant softening after 1 st pulse Two Component Shaking (~0.26g pga) – Two side walls were severely damaged – Significant softening after 1 st pulse

30 Summary on Model Development Modeling/analytical procedures Program calibrations and verification (Dynamic case) o Study of structural parameters and performance Experimental procedures  Verification of 3D finite element program Static  Dynamic Reliability based design procedures o Response Surfaces Approaches

31 UBC’s Large Shake Table 20 ft by 25 ft rigid frame Low friction roller bearings 67 kip, 36 inch actuator

32 Subsystem testing Simulated weight of 2 nd floor

33 Two Storey House Test

34


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