Seismic Analysis for a Turbine Building with Spring Supported Turbine / Generator Deck

2. Seismic Analysis for a Turbine Building with Spring Supported Turbine / Generator Deck Feifei Lu, PE Shaw Power Group, Charlotte, NC June 23, 2011

3. Topic Outline • Overall Introduction • Turbine building • Spring and damper device • Method Discussion • Results Comparison • Conclusion • MathCad Application

4. Background Introduction • steel framing structure • EBF & SCBF eccentrically braced frame (EBF) below the Turbine operating deck and special concentric braced frame (SCBF) above the operating deck

5. Background Introduction • Turbine Building: structural steel frame • First-Bay: concrete structure • Foundation: 6 feet deep reinforced concrete foundation mat

6. Spring & Damper Device

7. Spring Pedestal Design Basis • Benefits of spring pedestal: • Seismic Isolation of TG • Vibration isolation of TG • Generic site design

8. Spring Devices • Stiffness matrix is used to model each spring device. (Ref. GT STRUDL Vol.1 Section 2.1.9.2.4) Horizontal spring matrix and Vertical spring matrix GT STRUDL Input:

9. Damper Devices • Viscous Damper Element is used to model the damper devices. (Ref. GT STRUDL Vol.3 Section 2.4.3.7) GT STRUDL Input:

10. Method discussion • Method 1: Weighted Average Composite Modal Damping • Method 2: Viscous Damper Element with Rayleigh Proportional damping (Ref. GTStrudl Damping Models for Dynamic Analysis by Dr. Swanger)

11. Method discussion (Method 1) • Method 1: Weighted Average Composite Modal Damping (Ref. NRC REGULATORY GUIDE 1.61 : DAMPING VALUES FOR SEISMIC DESIGN OF NUCLEAR POWER PLANTS)

12. Method discussion (Method 1) • Based on viscously damped free vibration (Ref. Dynamics of Structures Theory and applications to Earthquake Engineering, Second Edition, By Anil K. Chopra) Therefore, ζ =

13. Method discussion (Method 1) • Sample calculation:

14. Method discussion (Method 1) GT STRUDL Input: CONSTANT MODAL DAMPING PROPORTIONAL TO STIFFNESS 0.04 MEMBERS… $ ( All Steel member) MODAL DAMPING PROPORTIONAL TO STIFFNESS 0.07 MEMBERS… $ ( All Concrete member) $ SPRING DAMPER MODAL DAMPING PROPORTIONAL TO STIFFNESS 0.488 MEMBERS … $ (Horizontal springs) MODAL DAMPING PROPORTIONAL TO STIFFNESS 0.226 MEMBERS … $ (Vertical springs) …… …… …… …… COMPUTE MODAL DAMPING RATIOS AVERAGE BY ELEMENT ……

15. Method discussion (Method 2) • Rayleigh damping value for the rest of the structure is calculated based on the classic Rayleigh damping method. (Ref. GTStrudl Damping Models for Dynamic Analysis by Dr. Swanger)

16. Method discussion (Method 2) GT STRUDL Input: CONSTANT DAMPING PROPORTIONAL TO STIFFNESS 3.36E-3 MASS 0.421 …… ....... …… COMPUTE MODAL DAMPING RATIOS PROPORTIONAL BY ELEMENT

17. UBC 1997 Typical Design Response Spectrum - 5% of Critical Damping Response Spectrum Ref. "Fundamentals of Earthquake Engineering", Elnashai, Amr, and Di Sarno, Luigi-Wiley 2008, pp. 242.

18. Response Spectrum

19. Results (Mode Shape)

20. Results (Mode Shape)

21. Results (Mode Shape)

22. Results (Model Damping)

23. Results (Displacement) Method 1 Method 2 ****SUMMARY OF MAXIMUM GLOBAL DISPLACEMENTS**** INDEPENDENT IN EACH COORDINATE ============================================= * RESULT * MAXIMUM LOAD JOINT * *========*==================================* * X-DISP * 0.702437E+00 801 JCON685 * * Y-DISP * 0.122054E+01 802 J2180072 * * Z-DISP * 0.103463E+00 802 J2180128 * ============================================= ****SUMMARY OF MAXIMUM GLOBAL DISPLACEMENTS**** SRSS VECTOR LENGTHS =============================================== * RESULT * MAXIMUM LOAD JOINT * *==========*==================================* * XYZ-DISP * 0.122351E+01 802 J2180072 * * XY-DISP * 0.122350E+01 802 J2180072 * * XZ-DISP * 0.702589E+00 801 JCON685 * * YZ-DISP * 0.122055E+01 802 J2180072 * =============================================== ****SUMMARY OF MAXIMUM GLOBAL DISPLACEMENTS**** INDEPENDENT IN EACH COORDINATE ============================================= * RESULT * MAXIMUM LOAD JOINT * *========*==================================* * X-DISP * 0.713116E+00 801 JCON685 * * Y-DISP * 0.124141E+01 802 J2180072 * * Z-DISP * 0.105379E+00 802 J2180128 * ============================================= ****SUMMARY OF MAXIMUM GLOBAL DISPLACEMENTS**** SRSS VECTOR LENGTHS =============================================== * RESULT * MAXIMUM LOAD JOINT * *==========*==================================* * XYZ-DISP * 0.124452E+01 802 J2180072 * * XY-DISP * 0.124451E+01 802 J2180072 * * XZ-DISP * 0.713273E+00 801 JCON685 * * YZ-DISP * 0.124141E+01 802 J2180072 * ===============================================

24. Results (Force in Spring Device) X-dir RS analysis results

25. Results (Force in Spring Device) Y-dir RS analysis results

26. Results (Force in Damper Device) Damper element force Calculation Each mode Vi = Via-Vib By ABS method V = | | Force: F = c * V

27. Results (Force in Damper Device) Damper element force Calculation

28. Conclusion • Spring device and damper device can be successfully modeled in GT STRUDL. • Both methods give results consistent with each other. • To achieve more accurate results, time history analysis needs to be performed.

29. MathCad Application • Benefits: Efficiency and Automation • Generate load combination input file from Excel file. • Transform structural coordinates to move and rotate structure geometry. • Offset mass distribution to create 5% torsional seismic effect for response spectrum analysis.

30. Load Combination • Example: Input file (Excel file)

31. Load Combination • Example: MathCad file

32. Load Combination • Example: Output file (txt file)

33. Transform Structure • Modular Stair Tower.pps • Coordinate Transformation Function.html • Original purpose of using MathCAD to transform structure is to simulate the process of rigging and installing stair tower module. Same as the “MOVE OBJECT” command. (Why not use “MOVE OBJECT” ? ) • Later on, it is found this little program is very useful to transform any structure and combine structures in different orientation and origins together.

34. Transform Structure 75 degree • 90 degree

35. Transform Structure • 60 degree • 45 degree

36. Transform Structure • 30 degree • 15 degree

37. Transform Structure • Combine with TB • Stairs Module

38. Torsional seismic effect • The objective is to redistribute the structure's mass such that the requirements for accidental torsion are met. • At each level of the structure where it is desired to include accidental torsion, the mass will be re-distributed such that the new center of mass has been offset from its original position the required distance (normally 5% of the structures maximum dimension perpendicular to the direction of motion as code requirement).

39. Torsional seismic effect • SEISMIC LOAD.html • Input: JC2.xls MASS DEAD2.xls • Output: UBC-X-TOR.xls UBC-Y-TOR.xls

40. Torsional seismic effect

41. Acknowledgements • The GT STRUDL analytical model used in this presentation is based on the Turbine Building for the Westinghouse AP1000 Advanced Passive Light Water Reactor Electric Power Generating Plant. Westinghouse Electric Company is the owner of the design. The original GT STRUDL analytical model was created by Toshiba Corporation/Obayashi Corporation in Japan. The design activity is being completed by Shaw under contract to Westinghouse. • Dr. Michael Swanger Computer Aided Structural Engineering Center (GTSTRUDL)Structural Engineering, Mechanics, and MaterialsGeorgia Institute of Technology

42. References • GT STRUDL User Reference Manual • NRC REGULATORY GUIDE 1.61 • Dynamics of Structures Theory and applications to Earthquake Engineering, Second Edition, Anil K. Chopra • GTStrudl Damping Models for Dynamic Analysis, Michael H. Swanger, PhD • Fundamentals of Earthquake Engineering, Elnashai, Amr, and Di Sarno, Luigi-Wiley 2008 • UBC-1997

43. Question ?