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Analytical Results for Shake Table Test Program: Modeling Info

NEESR Project Inertial Force-Limiting Floor Anchorage Systems for Seismic Resistant Building Structures. Analytical Results for Shake Table Test Program: Modeling Info. Zhi Zhang Dr. Robert Fleischman Dr. Dichuan Zhang The University of Arizona. 11/18/2013. Test Sequence for Phase I and II.

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Analytical Results for Shake Table Test Program: Modeling Info

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  1. NEESR Project Inertial Force-Limiting Floor Anchorage Systems for Seismic Resistant Building Structures Analytical Results for Shake Table Test Program: Modeling Info Zhi Zhang Dr. Robert Fleischman Dr. Dichuan Zhang The University of Arizona 11/18/2013

  2. Test Sequence for Phase I and II The following test sequence is proposed: Notes: • Phase I: Inertial Force Limiting Anchorage System (IFAS); Phase II: PSA; Phase III: HS Rebar SW • Intensity of service level earthquake = 2/3 of DBE • 5 seconds free vibration will be added between two different runs • For Tests 7,14,21: The scale factor of MCE BE05 is estimated nominally at 1.15 and will be adjusted depending on the response of the structure to the BE05 DBE and MCE tests. • The polarity of tests 7,14,21 will be reversed to prevent ratcheting of the structure.

  3. SKT Specimen Analytical Model

  4. Analytical Model of Test Structure • 3D nonlinear model using ANSYS • Large deflection: for P-Delta effect • Floors and walls: 3D shell elements with smeared mass • Columns: 3D elastic beam • PT bar: link elements with initial strain; pads modeled as elastic spring • Wall base: fiber model of base of wall (ignoring steel armor for now) • Column end condition: fiber model for interface joint • Friction dampers and BRBs: nonlinear link elements • Rubber bearings: uncoupled uniaxial elastic springs in translation; uniaxial elastic spring stiff in compression, flexible in tension • Energy dissipator: nonlinear spring • PSA: 3D elastic beam

  5. Shear Wall Base Fiber Model 8” 84” EW Shear wall base section (above armor) PT bar ED device Confined Concrete Confined Concrete Unconfined Concrete 1” 3” 3” Shear wall 1” NS wall also use 8.1ksi unconfined concrete strength and mander model for confined concrete. 19” 46” 19” EW wall Confined Concrete Unconfined Concrete Ultimate strain: 0.02 Note: armor ignored Mander model (8.1ksi) Test results f’c=8.1ksi from testing EW wall strength: 7.781ksi NS wall strength: 8.460 ksi NS wall strength: 9.270 ksi Modified-Kent-Park (8.1ksi) Modified-Kent-Park (7ksi, currently used)

  6. ED Device Property Energy dissipator hysteresis Force incensement is assigned very slow after deformation exceeds this point. Analytical model calibration based on test 1 ED Hysteresis used in SKT model (Two single ED) Energy dissipator is modeled using nonlinear spring with kinematic strain hardening behavior. 1: Luis Alberto Toranzo-Dianderas. The using of rocking walls in confined masonry structures: a performance-based approach. Ph.D. Thesis, The University of Canterbury, 2002.

  7. PT Bar Property PT bar stress-strain Elastic modulus: 29700 ksi Initial stress: 90 ksi Yield stress: 121 ksi Ultimate stress: 150 ksi NS wall EW wall

  8. PT Bar Rubber Pad Same node Rubber Pad PT bar Pad Hysteresis Nodes on PT Bar Nodes on Wall K=250 kip/in PT Bar Constrain the translational degrees of freedom for every pair PT bar rubber pad only used in EW wall, one pad for each bar, and 250 kip/in per pad. The thickness of pad is used as 5”. Pad is modeled with uniaxial elastic spring. EW Wall

  9. Column Fiber Model at Interface-Two layer of unconfined concrete fiber #7 Gr100 rebar 8” 0.75” 0.75” 1.625”x4=6.5” Slab Fiber model at column base 0.75” 8” Rigid Shell Only 1 #7 rebar go through the cross section 1.625”x4=6.5” 8” Half assigned to outside fibers 0.75” 8” 8” Fibers Column Half assigned to inside fibers 8” Rigid Shell 8” 8” concrete fiber Test results 8” Confined concrete fibers Column strength: 5.583 ksi Column strength: 7.781 ksi #7 Gr100 rebar1 Unconfined concrete fibers, located at the edge of unconfined concrete 73” 75” Mander model Increase column A and I by 89/75 to make it as real fc’=6ksi 1: Jian Zhao and Sri Sritharan. Modeling of strain penetration effects in fiber-based analysis of reinforced concrete structures. ACI Structural Journal, Vol.104, Issue 2, 2007 8” concrete fiber

  10. Gr 100 Rebar Property 1 ASTM A 1035 Gr100 Reinforcing Steel Property Used in analysis1 Normalized bar stress Normalized bar slip From MMFX2 Ductility coefficient Syyield slip SuUltimate slip Recommended: 30Sy~ 40Sy Steel slippage at one end b stiffness reduction factor: Recommended: 0.3 ~ 0.5 Su= 35Sy , b = 0.4 1: Michael Briggs, Shelby Miller, David Darwin and JoAnn Browning. Bond behavior of grade 100 ASTM A 1035 reinforcing steel in beam-splice specimens. Structural Engineering and Engineering Materials SL Report 07-1.

  11. Modeling of Dampers: Friction Damper and BRB Core plate FD schematic drawing Yield Strength: 8 kips Initial stiffness: 240 kip/in Force @ 1”: 13 kips (8% strain) BRB hysteresis FD hysteresis 1” 1” 13 kips Slip load: 19 kips Initial stiffness: 10690 kip/in 13 kips FD schematic drawing and hysteresis BE05 MCE BRB schematic drawing and hysteresis

  12. Parameters for Rubber Bearing EW RB shear response EW RB axial response

  13. Parameters for Rubber Bearing EW RB out of plane rotation response EW RB compression response EW RB bending + axial Rigid plate Shear spring Rigid plate Because the coupling RB model didn’t generate big difference in structural behavior, simple RB model was selected. Coupled axial and bending spring

  14. Modeling of Bumpers Half-size bumper hysteresis Bumper test set up Test unloading ANSYS model Test loading From test, loading and unloading stiffness is different from each other, but they are very stable in cyclic test. In ANSYS, use a uniaxial elastic spring to model the bumper (energy dissipation capacity is ignored)

  15. Modeling of PSA Y Rigid shell to model the thickness of shear wall Shear wall X PSA Z PSA Rigid shell on shear wall Rigid shell to model the half thickness of slab Slab 4.5” Two nodes are at the same location, couple UX, UZ, RotY together Use rigid shell to model the true thickness of slab and shear wall separately. Thickness of rigid shell on wall is half of the story height (3.5’) in top floor and story height (7’) in other floors. Thickness of rigid shell on slab is using the slab length in the direction of arranging PSAs divided by number of PSAs in the same direction. Constrain the two translational DOFs and one rotational DOF between PSA and shear wall

  16. Modeling of Slab Slab Concrete Test results 1st level: 6.670 ksi 1st level: 7.205 ksi 1st level: 6.619 ksi 1st level: 6.485 ksi 2nd level: 6.279 ksi 2nd level: 6.109 ksi 2nd level: 6.336 ksi Slab is modeled with cracked elastic concrete property (0.25E0), fc’= 6.1 ksi

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