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Mechanics Based Modeling of the Dynamic Response of Wood Frame Building

UBC. 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.

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Mechanics Based Modeling of the Dynamic Response of Wood Frame Building

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  1. UBC 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

  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. UBCTEAM • 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. 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 Vertical Load Lateral Load Insulation Frame Wind Load Nails Double-side Panels

  6. Displacements & rotations Pure twist y,v y Rot-y z,w Mx z Mxy qdxdy dy Nx dy Rot-z dx dx x x,u Rot-x My Mxy Ny Structural Model • Element types • Panel - 4-node elastic orthotropic plate element • Frame - 3D elastic beam element • Nail - nonlinear spring element in x, y, z directions • Substructuring used in local-global transformations • Performed only in frame elements and connections to frame DOF in panel and frame elements

  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 • Pinched and asymmetric hysteresis loops • Stiffness and strength degradations • Possible issues • Solution Stability • Model Calibration • Material Properties

  9. Mechanics-Based Nail Model

  10. Monotonic and Cyclic Tests of 7.2 m Wall

  11. 40 40 0 80 -80 0 20 -40 40 60 40 80 100 Wall 5 Cyclic Test 20 30 Wall 3 0 20 MonotonicTest Wall 1 -20 10 -40 0 Monotonic and Cyclic Tests of 2.4 m Walls

  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 Inertia masses Support frame Distribution beam Shake table Shear wall specimen Longitudinal actuator Vertical actuators

  18. Model Verifications

  19. Model Verifications

  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

  26. Model Verification- Dynamic Case 3D Single Component Shaking

  27. Failed Shake Table Specimen

  28. Failed Shake Table Specimen

  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 1st pulse • Two Component Shaking (~0.26g pga) • Two side walls were severely damaged • Significant softening after 1st pulse

  30. Summary on Model Development • Modeling/analytical procedures • Program calibrations and verification (Dynamic case) • Study of structural parameters and performance • Experimental procedures • Verification of 3D finite element program • Static • Dynamic • Reliability based design procedures • 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 2nd floor

  33. Two Storey House Test

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