November 2011 Chapter Meeting: Fires in Structures at NIST: Standards Development through Modeling and Testing
The Northern Virginia Chapter of CSI November Chapter Meeting November 9, 2011Fires in Structures at NIST:Standards Developmentthrough Modeling and Testing Dr. Kathryn Butler Physicist, Fire Research Division Dr. Jiann Yang Director, National Fire Research Laboratory Engineering Laboratory
National Bureau of Standards (NBS)founded 1901 Connecticut Ave. site
Historic Conflagrations The Great Baltimore Fire of 1904
The Standard Fire Test…• Committee P was organized by ASTM in 1905 largely as a result of the Baltimore fire of the year before• By 1906, ASTM Committee P (which would later become C-5 and eventually E-5) proposed a standard specification for testing floors Furnace temperature of 1700 F for all but the first ½ hour• Thinking at the time: Fires were considered to have a single representative temperature and last for up to 4 hours A building assembly passing a test under these conditions could withstand a fire burnout
ASTM Curve vs. Earlier Curves1 1200 2000 1000 1700 Temperature (⁰C) 1600 800 1200 600 800 400 200 1Babrauskas and Williamson (1978) 400 Fire Technology 14:184-194 30 60 90 120 150 180 210 240 Time (min)
The Standard Fire Test…• ASTM E 119 was adopted in 1918 (as ASTM C 19) as a specification for “Fire Tests of Materials and Construction”• Thus, the standard fire curve was prescribed without knowledge of actual temperatures in building fires !
Early History of Fire Research at NBS NBS Federal Triangle fire test NBS column furnace, 1920s
Temperature of a Burning Building • The first systematic effort to measure fire temperatures was begun in 1922 by Simon Ingberg at NBS where he conducted tests to burnout of typical office furnishings (furniture and paper) and measured the temperatures. • Ingberg’s findings include the following: that the fires produced temperature histories quite different from the standard curve the integral of a time-temperature curve defines the fire severity all fires of the same severity have approximately the same effect on a structure the fuel load was the sole variable governing the time-temperature relationship of room fires • Ingberg’s equal area severity hypothesis
Ingberg’s equal area severity hypothesis 2400 1200 2000 1000 Standard Fire Curve Temperature ºC Temperature, ºF 1500 800 Cooling Curve (2 h) Test Fire Curve 600 1000 Threshold 400 Temperature 500 200 0 0 1 2 3 4 5 6 7 8 Time, h
Relationship Between Fire Load and FireSeverity Assumed Combustible Equivalent Fire Load Load Fire (lb/ft2) (kg/m2) (Btu/ft2) MJ/m2 Duration 10 48.8 80,000 907.9 1 h 00 min 15 73.2 120,000 1361.9 1 h 30 min 20 97.6 160,000 1815.8 2 h 00 min 30 146.5 240,000 2723.7 3 h 00 min 40 195.3 320,000 3631.7 4 h 30 min 50 244.1 380,000 4312.6 6 h 00 min 60 292.9 432,000 4902.7 7 h 30 minS.H. Ingberg, “Fire-Resistance Requirements in Building Codes,” Quarterlyof the National Fire Protection Association, Boston, October, 1929
Today – NIST Engineering Laboratory (EL)Strategic Goals:Measurement Science and Standards for:• Disaster-Resilient Buildings, Infrastructure, and Communities• Sustainable and Energy-Efficient Manufacturing, Materials, and Infrastructure• Smart Manufacturing, Construction, and Cyber- Physical Systems
NIST Activities in fire/structure interaction• Performance-Based Design for Fire•••
What is the problem?• Current building codes do not consider fire as a design condition despite significant damage or collapse due to fire in major buildings (e.g., First Interstate Bank Building, One Meridian Plaza, One New York Plaza, WTC 5 and WTC 7).• Instead, required fire ratings of building members and assemblies, derived from standard fire endurance tests (ASTM E119), are specified in building codes. The ASTM E119 test has changed little since its introduction in 1917.• At present, there are no science-based, established measurement tools to evaluate the performance of the entire structure, including connections, under realistic fire loads (e.g., uncontrolled fire).
Performance of Structures Subject to Fire Performance-Based Design for Fire • Identify structural fire safety objectives, functional requirements and performance criteria Analysis of Structural Response to Fire • Determine design fire scenarios and design fires • Evaluate the thermal response of the structure • Evaluate the mechanical response of the structure Reliability-Based Design of Structural Response to Fire • Identify reliability objectives for each limit state • Determine load factor for structurally significantto Fire Experimental Determination of Structural Response fires • Determine material resistance factor for elevated temperatures • Evaluate component and system reliability for fire hazard and limit state
NIST Activities in fire/structure interaction•• Analysis of Structural Response to Fire••
Reliability-Based Design ofStructural Response to Fire Upper Chord
Structural fire performance of composite floor systems• Evaluated 4 structural features for their main and interaction effects on time to damage onset and time to component failures using a 24 factorial design . Studs on Beam Girder Beam Girders Conn Type Framing Length + Double + + Studs +5 m angle Symmetric - No - Single - One- - 15 m studs shear plate sided
Fire Studies • Charleston Sofa Super Store Fire, South Carolina, 2007 • The Station Nightclub Fire, Rhode Island, 2003 • Cook County Administration High-Rise Office Fire, Illinois, 2003 • World Trade Center Fire, New York, 2001 • Astoria Hardware Store Fire, New York, 2001 • Houston Fast Food Restaurant Fire, Texas, 2000 • Keokuk Duplex Fire, Iowa, 1999 • Cherry Road Townhouse Fire, Washington, D.C., 1999 • Vandalia High-Rise Apartment Fire, New York, 1998 • Happyland Social Club Fire, New York, 1990 • First Interstate Bank Building Fire, California, 1988 • Dupont Plaza Hotel Fire, Puerto Rico, 1986Reports available from: http://www.nist.gov/el/disasterstudies/fire
NIST Activities in fire/structure interaction••• Visualization of Fire Dynamics-Thermal Analysis-Structural Response•
Fire Dynamics, Thermal Analysis, and Structural Response Fire Simulation (FDS) Thermal Analysis (ABAQUS) Structural ResponseModels run separately, with each (ABAQUS)providing the boundary conditions for the next …
3-D Visualization… then the results aredisplayed together sothe interaction betweenfire and structure canbe understood Point Probe Cutting Tool
NIST Activities in fire/structure interaction•••• National Fire Research Laboratory
National Fire Research Laboratory (NFRL) Director Dr. Jiann C. YangAssociate Director for Associate Director forStructures Research Fire Research Dr. John L. Gross Dr. Matthew Bundy
National Fire Research Laboratory (NFRL)• Advance real-scale fire measurements (fire sizes, material ignition propensities, fire growth and spread, tenability, fire suppression and detection, and fire fighting)• Enable experimental validation studies of fire models• Conduct experiments to support post-incident disaster and failure studies• Advance structural performance in fires• Enable advances in fire & building codes and standards
Recent Experiments at NFRL Bus Fires Wind Effects on Fire World Trade Center StudyFail Pass Mattress Fires Compartment fires Fire Brands
NFRL Expansion Timeline• Oct 2003 NIST/SFPE Roadmapping Workshop• … 2008 Stakeholder Meetings and Workshops• Oct 2008 15 % Design Completed• Apr 2009 Selected for ARRA funding• Feb 2010 Design Complete• Aug 2010 Construction Contract Awarded• Nov 2010 Construction “Notice to Proceed”• Mid- 2012 Construction Complete• Mid- 2013 Commissioning Complete
Design Objectives• Conduct tests on real-scale structural systems and components – a building two stories high and two bays by three bays in plan.• Apply controlled loads to the test structure to simulate true service conditions.• Create realistic fires (up to 20 MW) that grow, spread, fully-develop and decay.• Characterize the fires (heat release rates) in real time.• Measure response of the structural system and components up to incipient collapse.
Expanded Capabilities will allow NIST to:• Test the performance of real-scale structures under realistic fire and structural loading under controlled laboratory conditions.• Develop an experimental database on the performance of large-scale structural connections, components, subassemblies and systems under realistic fire and loading.• Validate physics-based models to predict fire resistance performance of structures.• Provide the technical basis for performance-based standards for fire resistance design of structures and foster innovation in the building design and construction industry.
National Fire Research Laboratory Expansion Specification Existing Laboratory New Laboratory Total Floor Area 10,800 sq. ft. 21,400 sq. ft. 1 MW (small hood) Fire Capacity 3 MW (medium hood) 20 MW 10 MW (large hood) 60 ft. x 90 ft. x 3.5 ft. thick strong floor Strong Floor/Strong Wall None and 60 ft. x 30 ft. x 4 ft. thick strong wall. Reconfigurable hydraulic loading system, Structural Loading None 55-330 kip actuators; 30 inch stroke
Partnering with the NFRL• The work of the laboratory is focused on the Engineering Laboratory mission: To promote US innovation and industrial competitiveness in areas of national priority by anticipating and meeting the measurement science and standards needs for technology-intensive manufacturing and construction in ways that enhance economic prosperity and improve the quality of life.• The laboratory is led, managed, and operated as a collaborative facility through a public-private partnership between NIST and industry, academia, and other government agencies.• Scientists and engineers from industry, academia, and government agencies work side-by-side with NIST researchers to address significant problems and fill critical knowledge gaps.• International scientists and engineers partner with NIST in areas of mutual interest.• Projects are funded by industry and government, including NIST, on a cost- shared basis.
NFRL Construction Progress The Original Lab Clear Site 2/15/2011 4/15/2011 Excavate Basement Form and Pour Basement and Shear Walls 6/15/2011 8/5/2011
NFRL Construction Progress Form and Pour Basement and Shear Walls Form and Pour Basement and Shear Walls 9/1/2011 9/15/2011 Form Strong Floor, Set 1218 Anchors Prepare for Pouring Strong Floor 10/10/2011 11/1/2011