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Design, Manufacture, Transport and Integration on-site in Chile of ALMA Antennas

Design, Manufacture, Transport and Integration on-site in Chile of ALMA Antennas Antenna Seismic Verification PM#04- 17-18 May 2006 Dated November 18 h , 2005. Antenna Seismic Verification. References: Eurocode 8, Design provisions for earthquake resistance of structures

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Design, Manufacture, Transport and Integration on-site in Chile of ALMA Antennas

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  1. Design, Manufacture, Transport and Integration on-site in Chile of ALMA Antennas • Antenna Seismic Verification • PM#04- 17-18 May 2006 • Dated November 18h, 2005

  2. Antenna Seismic Verification References: • Eurocode 8, Design provisions for earthquake resistance of structures • ALMA Environmental Specification:ALMA-80.05.02.00-001-B-SPE • FEM Model: ANTD-33-000003-001-C-FEM

  3. The Antenna Seismic Verification has been performed by a FEM Spectrum Analysis • Steps in a Spectrum Analysis: • Obtain the natural frequencies and mode shapes of the structure by performing a Modal Analysis • 50 natural frequencies and modes up to 35 Hz have been considered

  4. Given the Response Spectrum, calculate the Modal Response of each mode • Single Point Response Spectrum Analysis • A unique Excitation has been applied to the Antenna foundations • Combination of the seismic action components according to Eurocode 8 • Calculate the Total Modal Response of the whole structure by combining the Modal Response of each mode • SRSS (Square Root of the Sum of the Squares) Method

  5. ALMA response spectrum from environmental specification According to Eurocode 8: • Combination of the horizontal component of the seismic action: • Ex “+” 0.30Ey • 0.30Ex “+” Ey • The vertical component of the seismic action has to be taken in account only in some cases (i.e. for cantilever elements) • it will be considered only for the platforms sub-assembly

  6. Natural frequencies and modes have been calculated up to 50th mode – 35 Hz ALMA - Spectrum Analysis.xls

  7. MODAL ANALYSIS 1st natural mode, cabin floor 2nd natural mode, global x

  8. MODAL ANALYSIS 4th natural mode, global y 35th natural mode, global z

  9. 9th natural mode, 2nd global torsional vibration MODAL ANALYSIS 8th natural mode, 1st global torsional vibration 10th natural mode

  10. MODAL ANALYSIS 8th natural mode, torsional vibration (with legs) 10th natural mode 3rd natural mode

  11. ANTENNA MODAL RESPONSE Total Response, displacement in x direction Total Response, displacement in y direction Total Response, displacement in z direction

  12. ANTENNA MODAL RESPONSE Total Response, displacement vector plot Total Response, resultant displacement contour plot

  13. ANTENNA MODAL RESPONSE σVM,max<10 MPa σVM,max=97.3 MPa Total Response, Von Mises stress contour plot Y=480/97.3=4.9 Elevation Membrane, Von Mises stress contour plot

  14. ANTENNA MODAL RESPONSE σVM,max=55 MPa Foundation interface block, Von Mises stress contour plot

  15. ANTENNA MODAL RESPONSE σVM,max=20 MPa Azimuth bearing, Von Mises stress contour plot σVM,max=41 MPa Saddle, Von Mises stress contour plot

  16. ANTENNA MODAL RESPONSE σVM,max=5 MPa BUS – Legs interface, Von Mises stress contour plot

  17. Design, Manufacture, Transport and Integration on-site in Chile of ALMA Antennas • Antenna Seismic Verification • PM#04- 17-18 May 2006 • Dated November 18h, 2005

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