Earthquakes and Data Centers

Transcription

1 7x24 Exchange Fall Symposium September 11, 2013 Hilton Bellevue Andrew W. Taylor, Ph.D., S.E., FACI Earthquake Hazards 2 September 11,

2 Cascadia Earthquake Sources Figure Credit: Craig Weaver, Pacific Northwest Coordinator, National Earthquake Program, United States Geological Survey 3 September 11, 2013 Seattle Fault Figure Credit: Craig Weaver, Pacific Northwest Coordinator, National Earthquake Program, United States Geological Survey 4 September 11,

3 Shallow Crustal Faults Figure Credit: Craig Weaver, Pacific Northwest Coordinator, National Earthquake Program, United States Geological Survey 5 September 11, 2013 Cascadia Subduction Zone Figure Credit: Craig Weaver, Pacific Northwest Coordinator, National Earthquake Program, United States Geological Survey 6 September 11,

4 7 September 11, 2013 Megathrust Events in the Pacific Northwest Average return interval 300 to 600 years Last 4 events: 710, 1150, 1500 and 1700 Last megathrust event: January 26,1700, Magnitude 8.7 to September 11,

5 Engineering Coefficients for Design Richter Magnitude: Not used by engineers for design. Richter Magnitude only describes the energy released by an earthquake, not the ground shaking at a particular building site Seismic Zones : The building code stopped using seismic zones in The Seattle area was in Zone 3, but this designation is no longer in the code, or accepted by building officials. Seismic Hazard Maps: These are contour maps that show ground shaking intensity for any location in the United States. The maps provide a much more accurate characterization of seismic hazard than the old seismic zone system. 9 September 11, 2013 Engineering Coefficients for Design Seismic Zones no longer exist in the building code. Earthquake design coefficients are now obtained from USGS maps. 10 September 11,

6 Effects of Earthquakes on Buildings 11 September 11, 2013 Analyzing Earthquake Effects Fundamental Approach Acceleration, g Time, seconds F = Mxa a max Max EQ Force = Building mass x a max? 12 September 11,

7 Analyzing Earthquake Effects Acceleration, g Time, seconds F = Mxa a max Max EQ Force = Building mass x a max? 13 September 11, 2013 Analyzing Earthquake Effects on Structures F = Mxa would be the right answer only if the building were completely rigid, and elastic 14 September 11,

8 Analyzing Earthquake Effects Earthquake engineering is more complicated than F = Mxa max because seismic design must account for 1. Dynamic response of the flexible building - Distribution of stiffness - Distribution of mass - Multiple modes of vibration 2. Inelastic response of the building - Yielding - Cracking - Friction 15 September 11, 2013 What Causes Earthquake Damage? Interstory Drift (Structural Racking) Both structural and nonstructural systems are damaged by racking of the structural frame: Shear Walls Columns Beams Cross Braces Foundations Exterior Cladding & Windows Interior Partitions Doors MEP Systems HVAC Systems UPS Systems Fire Suppression 16 September 11,

9 What Causes Earthquake Damage? Cracking 17 September 11, 2013 Photos: Andy Taylor/NIST What Causes Earthquake Damage? Accelerations Cause damage to non-structural components: Equipment Racks (tipping) Generators, Chillers, Compressors, Pumps Battery Racks Suspended Ceilings, Light Fixtures Raised Floors Furniture and Cabinets Elevators 18 September 11,

10 What Causes Earthquake Damage? Examples of Floor Accelerations 0.65g 0.54g 0.45g 0.36g 0.30g 0.24g 19 September 11, 2013 What Causes Earthquake Damage? Temporary Bracing of Collapsed Access Floor, 1994 Northridge Earthquake Figure Credit: FEMA, courtesy of Wiss, Janney, Elstner Associates 20 September 11,

11 What Causes Earthquake Damage? Mechanical System San Fernando Earthquake 21 September 11, 2013 What Causes Earthquake Damage? Power Backup Batteries San Fernando Earthquake 22 September 11,

12 What Causes Earthquake Damage? Retail Stock San Fernando Earthquake 23 September 11, 2013 Olive View Medical Center Story 1971 San Fernando earthquake 1994 Northridge earthquake 24 September 11,

13 Olive View Medical Center Story 1971 San Fernando earthquake 25 September 11, 2013 Olive View Medical Center Story 1994 Northridge earthquake 26 September 11,

14 Olive View Medical Center Story Fire sprinkler pipe broken 1994 Northridge earthquake 27 September 11, 2013 Code-Based Seismic Design 28 September 11,

15 What Are the Goals of the Building Code? The current U.S. building code is the 2012 International Building Code, and ASCE The general goal of the code is to preserve the life safety function of a building: prevent injuries and allow safe egress from the structure. The building code does not generally provide for continued functionality of a building, or even reparability. For certain important structures, extra strength is provided, and structural racking is limited. 29 September 11, 2013 What Are the Goals of the Building Code? The Seismic Importance Factor I e, is based on Risk Category. It is applied to earthquake design forces. Risk Category I e I or II Normal Hazard 1.0 III High Hazard 1.25 IV Essential Facility September 11,

16 What Are the Goals of the Building Code? The maximum allowed story drift, a, is reduced for higher risk structures Risk Category Relative a I or II Normal Hazard 100 % III High Hazard 80 % IV Essential Facility 60 % 31 September 11, 2013 Performance-Based Seismic Design 32 September 11,

17 Performance Based Seismic Design Performance Make explicit Based choices Seismic Design about (PBSD) how is an approach we want to earthquake a building design to behave of facilities in a that targets specific performance goals in specific sizes of earthquakes. specific size of earthquake 33 September 11, 2013 Performance Based Seismic Design Performance Based Seismic Design Matrix Seismic Performance Goal Operational Immediate Occupancy Life Safety Collapse Prevention Frequent 43 years Occasional 72 years Rare 475 years Very Rare 2475 years 34 September 11,

18 Detailed Performance Goals for Each System Collapse Prevention Operational Level Immediate Occupancy Level Life Safety Level Level Overall Damage Very Light Light Moderate Severe Personnel Safety No injuries Minor injuries Minor injuries Major injuries or deaths Structural Frame Minor or no damage to structural frame. Since repair is Minor, repairable damage to Structural frame is permanently Structural frame is near not required, operations are not interrupted. structural frame. Does not interfere damaged and may not be collapse with immediate use, but may repairable. interfere with long-term use. Cladding Little or no cladding damage. Operations not interrupted for repair. Minor cladding damage. Does not interfere with immediate operations, but may require future repair or replacement Damage to cladding, but cladding remains on building. Cladding may have to be replaced. Extensive loss of cladding Windows No window damage Minor or no window damage A few windows may be broken Extensive broken windows Doors No jamming of doors. Some doors jammed. Requires immediate repair. Some doors jammed. No exits blocked. Extensive jamming of doors and blocking of exits Walls Little or no damage to walls. Operations not interrupted for repair. Minor damage to walls. Requires repair in future Extensive damage to walls, many Extensive damage to walls, not repairable many not repairable Mechanical and Electrical Systems No damage to mechanical and electrical systems. Operations continue uninterrupted. Power and utilities available from auxiliary sources. Minor damage of mechanical and electrical systems. Repairable in 24 hours or less if repair services are available. Power and utilities may be unavailable. Moderate damage of mechanical Extensive damage of and electrical systems. May not mechanical and electrical be repairable systems, not repairable Elevators Elevators functional Moderate damage of elevators. May not be functional for several days, if repair services are not available Extensive damage of elevators, may be repairable Extensive damage of elevators, not repairable Computers and Data Storage Fully functional. No loss of data. Minor damage, requiring repairs. Data may be lost. Down time depends on availability of repair services Extensive damage, may not be repairable Extensive damage, not repairable Sensitive Equipment No damage to sensitive equipment Moderate damage, requiring repairs. Experiments lost. Down time depends on availability of parts and repair services. Extensive damage, not repairable Extensive damage, not repairable 35 September 11, 2013 Performance Based Seismic Design Example PBSD Matrix for a Research Campus Seismic Performance Goal Operational Immediate Occupancy Life Safety Collapse Prevention Frequent 43 years Occasional Corporate 72 years Headquarters Rare 475 years CUP Labs Corporate Ped Bridge Headquarters Warehouse Very Rare 975 years CUP Labs Corporate Headquarters 36 September 11,

19 Practical Considerations for Design 37 September 11, 2013 Structural Rehab for Operational Performance Modifying an ordinary structure to achieve Make explicit choices about how Operational performance in a code-level earthquake is possible, we want but a it building is challenging to behave and expensive. in a Similarly, specific modifying size part of an earthquake existing ordinary structure to create an Operational data center usually requires structural and system modifications outside the footprint of the data center. 38 September 11,

20 Preservation of Safety Systems ASCE Make 7-10, explicit choices Non-structural about components how All components we want a must building be assigned to behave an Importance in a Factor I specific p = 1.5 if size of earthquake The component is required to function for life-safety purposes after an earthquake, including fire protection sprinkler systems and egress stairways. The component is required for continuous operation of a Risk Category IV structure Component is related to a high-hazard material 39 September 11, 2013 Anchoring Equipment Racks Fastest, easiest, is anchor rods to concrete floor Make explicit choices about how Unistrut grid on concrete floor provides for future flexibility we want without a building concrete drilling to behave in a specific size of earthquake Figure Credit: FEMA 40 September 11,

21 Anchoring Equipment Racks For very heavy equipment, consider independent support Make on a explicit steel frame. choices about how we want a building to behave in a specific size of earthquake Figure Credit: FEMA 41 September 11, 2013 The 400 Pound Rule ASCE 7-10, Section Make explicit choices about how Mechanical and electrical components: structural engineering we want design a building of seismic to bracing behave is in not a required in a high specific Seismic size Design of Category earthquake (SDC D, E, F) if a) Weight 400 lbs., mass center 4 ft. above floor b) Weight 20 lbs., mass center at any height c) Weight 5 lbs./ft. (pipes, conduits), any height c) Importance factor = 1.0 Technically, all other M & E components require engineering design of seismic bracing. 42 September 11,

22 Raised Access Floors Two types of raised access floors defined in code: Make explicit choices about how ASCE 7-10, = Ordinary Access Floor ASCE we want 7-10, a building = Special to behave Access in Floor a In high specific Seismic Design size Categories of earthquake (SDC D, E, F) recommend specifying only Special Access Floors 43 September 11, 2013 Seismic Qualification of MEP Equipment ASCE Make 7-10, explicit choices Contains about requirements how for seismic we want qualification a building of mechanical to behave and electrical in a components with importance factor I specific size of earthquake p > 1.0, by a) Engineering analysis b) Qualification testing on a shake table c) Experience data (i.e., documented performance in a previous earthquake). 44 September 11,

23 Trademark Attribution The KPFF logo is a registered trademark of KPFF Consulting Engineers, in the United States and/or other jurisdictions. Other names used in this presentation are for identification purposes only and may be trademarks of their respective owners KPFF, Inc. All rights reserved. Confidential agreement: The information contained in this document is strictly confidential, and cannot be used without permission by KPFF Consulting Engineers. 45 September 11,