COSTCO, SAN FRANCISCO A PRESCRIPTIVE AND PERFORMANCE BASED ANALYSIS OF FIRE PROTECTION SYSTEMS AND DESIGN

Transcription

1 COSTCO, SAN FRANCISCO A PRESCRIPTIVE AND PERFORMANCE BASED ANALYSIS OF FIRE PROTECTION SYSTEMS AND DESIGN Presented by Ian Levine June, 2016 Photo courtesy of Google Maps

2 PRESENTATION OVERVIEW BUILDING DESCRIPTION STRUCTURAL DESIGN ALARM AND DETECTION EGRESS SPRINKLER SYSTEM ANALYSIS PERFORMANCE BASED ANALYSIS Photo credit to FrenchiesGigiandLola via youtube

3 BUILDING OVERVIEW Area: 122,000 sq.ft. Ceiling Height: 30 ft. Open floor plan Mixed Occupancy Construction Mercantile High Piled Storage Restaurant Kitchen, Bakery Office Concrete slab Exposed, noncombustible 3 PLAN NORTH TRUE NORTH Satellite Image courtesy of Google Maps Photo courtesy of Google Maps

4 A LOOK INSIDE Ventilation Steel deck Steel open web truss 4 Draft curtains Steel wide flange beam Rack storage Presented by Ian Levine Winter 2016 Wide flange steel column Concrete floor Wide aisles Photo courtesy of Google Maps Details shown typical of all Costco stores

5 STRUCTURAL DESIGN: What type of construction is allowed for this 122,000 sq.ft. structure? 5 Building Area: 122,000 sq.ft. Factor of increase based on frontage and automatic fire protection: 3.48 Maximum floor area per IBC 2012 Table 503: 35,000 sq.ft. Allowable construction type: I-A, I-B Presented by Ian Levine Winter 2016 California Building Code 2012 Photo courtesy of Google Maps

6 FIRE RESISTANCE RATINGS SUMMARY 6 IBC 2012 Tables 601 & 602; code & 716.5

7 WHAT IF?

8 DETECTION AND ALARM - OVERVIEW 7 Combination heat/ smoke detector Horn Strobe Notification Appliance Emergency Response Automatic fire sprinkler system Fire alarm control panel Backup power source Central monitoring station

9 ALARM AND DETECTION SYSTEM LAYOUT 8 PLAN NORTH TRUE NORTH

10 DETECTION RESPONSE ANALYSIS HEAT RELEASE RATES OF POTENTIAL FUEL LOADS 9 SOURCES: SFPE Handbook, 4 th ed; AIAA

11 HEAT DETECTOR RESPONSE DETACT Input Parameters 10 DETACT Results Response Time = 53s HRR = 1250 kw Note: Sprinkler response time = 95s Manual pull stations are required Is this layout cost effective?

12 NOTIFICATION 12 Required NA sound level: 40 db + 15 db = 55 db (15 dba above ambient) Requirement met using 99 dba alarm (6 dba Rule) Required strobe candela intensity per NFPA 72, Table (b) Note: EVACS is not recommended for this building

13 EGRESS CAPACITY 13 EGRESS CAPACITY > TOTAL OCCUPANT LOAD = OK!

14 EXIT PLAN 14 DEAD END: 98 ft PLAN NORTH Maximum travel distance: 225 ft (250 ft limit)

15 DECISION MAKING DURING EGRESS Recognition: Become aware of some danger. (smoke, alarm, seeing fire) 2. Validation: Gather more information (talk to others, look for smoke/fire) 3. Definition: Assess the threat, understand its seriousness 4. Evaluation: Decide how to respond (behaviors of others? Exit locations?) 5. Commitment: Take action 6. Reassessment: If necessary, take additional action. Stress levels rise. NFPA Fire Protection Handbook, ed. 20

16 EXPECTED EVACUATION TIME 16 Actual 1 story department store data

17 OCCUPANCY MAP 17

18 SYSTEM AREA MAP 18

19 SPRINKLER RESPONSE DETACT 11 TYCO ELO-231 Standard Spray Upright 11.2 k-factor ¾ orifice Response Time = 95s HRR = 4500 kw

20 PRESCRIPTIVE APPROACH SUMMARY STRUCTURAL: Fire resistance ratings requirements are satisfied Foams sprays, protective membranes, concrete wraps if additional protection is required A&D: Heat/Smoke detectors not required Manual pull stations o Occupancy > 500 Horn-strobes spaced to 68 ft o 6 db rule Heat detection by sprinklers o 53s vs. 95s response time EGRESS: Occupant load = 3,208 Egress capacity = 4,340 Total exit time = 4 min SPRINKLERS: 4 systems Extremely high demand Large orifice sprinklers System redesign to lower pressure and flow required from the source Pump with secondary water source if necessary

21 PERFORMANCE BASED DESIGN (PBD) Past vs. Future Specific to building, location, occupancy, and use NFPA 101 Life Safety Code (LSC) Goals and Objectives Prescriptive: o Protection of occupants not intimate with initial fire development o Improvement of survivability of occupants intimate with initial fire development o Added benefit to non-fire emergencies and crowd movement o Provide occupant protection during time to evacuate, relocate, or defend in place o Maintain structural integrity

22 PBD - OVERVIEW Meet prescriptive goals and objectives Limit exposure to instantaneous or cumulative untenable conditions (4 methods) Establish design specifications, inputs, assumptions, building safety features Determine design fire o o Realistic Challenging with respect to initial fire location, early rate of growth in fire severity, and/or smoke generation Design Fire Scenarios (8 Scenarios)

23 PBD FIRE SCENARIO Performance Criteria: Method 2, LSC o Complete building evacuation before hot gas layer extends less than 6 ft above floor (ASET > RSET?) Design Scenario: Scenario 2, LSC o Ultrafast-developing fire in the primary means of egress with interior doors open at the start of the fire o Focus on reduction in number of means of egress o Can all occupants escape before being exposed to smoke? Design Fire: electronics section in front of primary entrance and exit

24 PBD EGRESS: NFPA CALCULATION Increase by 100: confusion, searching for new exit Decrease to 0 due to inaccessibility Methodology and data from NFPA Handbook, 20 th edition

25 PBD EGRESS: PATHFINDER Calculation of movement time, not including premovement time 3208 occupants randomly spread throughout room Single doors: 36 Double doors: 72 Walls placed around tables, displays, and racks as obstructions All interior doors open OCCUPANTS FIRE BLOCKING EXIT t = 0s

26 PBD EGRESS: PATHFINDER Occupants moving toward doors Jams occurring at doors OCCUPANTS FIRE BLOCKING EXIT t = 30s

27 PBD EGRESS: PATHFINDER Most occupants have reached an escape route OCCUPANTS FIRE BLOCKING EXIT t = 60s

28 PBD EGRESS: PATHFINDER All occupants are experiencing jamming at doors Floor is completely cleared FIRE BLOCKING EXIT t = 120s

29 PBD EGRESS: PATHFINDER Very few occupants remain Maximum egress time: 191s t = 180s

30 PBD EGRESS: PATHFINDER RESULTS Occupants Occupants Inside Costco During Evacuation OBSERVATIONS Evacuation complete 3.2 min after begins Including 1.7 min maximum pre-movement time and 1.2 factor of safety, total time = 5.3 minutes Close agreement with NFPA method results (5.5 min) Note: linear evacuation rate supports egress time is limited by exit capacity of exits rather than travel time to exits Time (s)

31 PBD CFAST ENVIRONMENT & LAYOUT SINGLE-WIDE AND DOUBLE- WIDE EMERGENCY EXITS AROUND PERIMETER DETECTION DEVICES LOCATION OF FIRE MAIN ENTRY AND EXIT

32 DESIGN FIRE FIRE INPUT PARAMETERS P6 FIRE Full scale test 2 pallets of 12 boxed computer monitors 1m x 1m x 1m, side by side Soot and CO yields from polystyrene Ignition using kw line burner Modeled as t 2 fire reaching steady burning after 25s SFPE Handbook Table

33 PBD DETECTION AND ALARM 700 Heat Detector Temperatures in Design Fire - CFAST Temperature (⁰C) PEAK HRR REACHED STEADY STATE BURNING Hot Gas Heat Detector 1 Heat Detector 2 Heat Detector 3 Heat Detector HEAT DETECTOR ACTUATION = 5s Delay has negligible impact on 1.7 min pre-movement time Time (s)

34 DESIGN FIRE CFAST SIMULATION T = 0s T = 10s Initial temperature at 22 ⁰C Plume develops quickly Hot gas layer forms immediately

35 DESIGN FIRE CFAST SIMULATION T = 20s T = 30s Hot gas layer has reached ceiling Smoke already gathering at the ceiling Peak HRR is reached Temperature of hot gas layer rapidly increasing Interface height: 8.87m

36 DESIGN FIRE CFAST SIMULATION T = 60s T = 120s Temperature of hot gas layer continues to increase Interface height: 8.67m Smoke layer remains high Interface height: 8.3m Alarm and pre-movement time periods have passed. Occupants are now moving to exits. Some have exited already.

37 DESIGN FIRE CFAST SIMULATION T = 240s T = 300s Average lower layer temperature increasing (29 ⁰C) Interface height: 7.63m Interface height: 7.32m After 5 minutes, all occupants have reached an exit and are evacuating

38 DESIGN FIRE CFAST SIMULATION Hot Gas Layer Height and Layer Temperatures in Design Fire 1 - CFAST Simulation T = 330s Layer Height (m) Temperature (C) All occupants have exited building Final interface height: 7.18m Final lower layer temperature: 32.2 ⁰C Time (s) Layer Height Upper Layer Temperature Lower Layer Temperature

39 PERFORMANCE BASED DESIGN SUMMARY ASET > RSET: SUCCESS Extremely rapid heat and smoke production offset by massive volume of compartment Impact of smoke development unlikely to put occupants at risk Overall performance from life safety perspective: very good ASSUMPTIONS Sprinklers do not activate demonstrate safe egress is possible given worst case scenario Peak HRR maintained during steady burning period o Fuel source large enough to supply continuous burning for entire duration of building egress Occupants spread evenly to all available exits during egress o If gathering occurs near one exit with another exit available, occupants travel to available exit

40 CONCLUSION Prescriptive requirements for structural design, alarm and detection system, egress, and sprinkler system were considered. Structural, A&D, egress requirements were satisfied Recommendations made for sprinkler compliance (system redesign, pump, secondary water source) Performance-based analysis using Pathfinder egress modeling software and CFAST 7 with real-life (albeit, exaggerated) fire test data showed that the life safety criteria of ASET>RSET was satisfied with large margin, even with highly challenging design fire.

41 RECOMMENDATIONS Determine if pump is required for sprinkler system Examine impact of staff trained to help with egress Explore more complex modeling in Pathfinder: response times, seeking new exits, travel speeds Compare CFAST and FDS smoke height interface results Performance based design for protection of property and valuables FDS to model alternative suppression systems, examine cost impact

42 THANK YOU!