Safety of Threatened Buildings Safety of Threatened Buildings ProgramProgram

William Grosshandler Building and Fire Research Laboratory

National Institute of Standards and Technology Gaithersburg, MD

Fire Resistive Materials WorkshopJuly 14, 2005

Threats to Safety in Public & Commercial Buildings

• Traditional fire hazards

• Combined hazards

• Terrorist threats

• Performance envelope of structures

Fire & Emergency Service

Academics

Industry Suppliers

Stakeholders and Partners in R&D Program for Safety of Threatened Buildings

Reduced Threat

Construction Industry

Fire Safety Engineering

Codes and Standards Organizations

Structural Engineeringand Design

Government Agencies

Insurance,Testing labs

Public/Groups

What is Safety of Threatened Buildings Program?

• Part of the NIST post-9/11 response plan

• Extension and enhancement of pre-9/11ongoing R&D

• Objective: To provide a technical foundation that supports improvements to codes, standards, and practices that reduce the impact of extreme threats to the safety of buildings, their occupants & emergency responders.

• Anticipated Major Outcomes: Increased Structural Integrity Enhanced Fire Resistance Improved Emergency Egress & Access Building & Emergency Equip. Standards & Guidelines

3/04

Components of Safety of Threatened Buildings Prgm

Prevention of Progressive Collapse; PI: H.S. LewTo develop and implement performance criteria for codes and standards, tools, and practical guidance for prevention of progressive structural collapse.

• No progressive collapse provisions in current U.S. bldg. codes• Lack of design tools• NIBS workshop (DTAP)

Increased Structural Integrity

Definition of Progressive Collapse: Spread of structural failure by a chain reaction, disproportionate to a localized triggering failure.

Loss of gravity load capacity of structural system

Inability of the structural system to redistribute the load

Project Goal: To prevent loss of lives and injuries due to progressive collapse of buildings.

Initiating events

• Impact

• Explosion

• Blast

• Fire

Fire Resistance of Building Partitions; PI: Dick Gann Technical basis for accurate measurement & prediction methodologies for inclusion of fire resistance properties of walls, floors & ceilings in performance-based fire safety design

Fire Protective Coatings for Structural Steel; PI: Dale Bentz• Predictive criteria for selection of fire protective coatings to accelerate development of materials with reduced vulnerability to extreme events.

Components of Safety of Threatened Buildings Prgm

Fire Resistance of Uncoated Structural Steel; PI: Frank Gayle • Develop efficient test method for evaluating fire resistance of steel• Benefits of FR steel not adequately tested under ASTM E119

Enhanced Fire Resistance

Fire Safe Building Structures; PI: John Gross To develop and implement verified and improved standards, tools, methodology and guidance for the fire safety design and retrofit of concrete and steel structures.

• Ability to confine a fire for time sufficient to allow occupant evacuation

• Standards successful in reducing fires that have caused loss of life/property - limited value for quantitative design

• Benefit to public safety - putting fire resistance description of partitions on an absolute basis

Fire Resistance of Building Partitions:

Approach:• Conduct real scale tests of wall assemblies• Develop model of time to failure modes --

Heat, smoke, and flames• Establish apparatus needed for model input data• Develop and validate method(s) at minimum scale for obtaining

thermal and failure data on assemblies

Wall Location

0

250

500

750

1000

0 600 1200 1800 2400

Time ( s )

Tem

per

atu

re (

°C

)

M - Exposed

E - Exposed

M - Int Exposed

E - Int Exposed

M - Int Unexposed

E - Int Unexposed

M - Unexposed

E - Unexposed

NAFTL Round Robin:• Compare behavior of different vertical furnaces • Data used by labs to assess relative performance of their furnaces• Data used by NIST to develop relationship between furnace behavior and actual fires - understand cracking/failure of gypsum boards

Exposed Face

Unexposed Face 304.8 cm

304.

8 cm

0.9525 cm

0.9525 cm

9 sc

rew

s (3

0.5

cm o

.c.)

92 m

m

28.5 mm22 gauge

60.9

cm

182.

8 cm

Vertical FurnaceUL Northbrook

Gypsum Non-Load BearingWall Partition

Global Collaboration on Prediction of Structural Fire Performance:

• Objective - To establish a global collaboration to conduct identified research that addresses outstanding technical issues needed to perform engineering analysis of structural reaction to fire.

• Approach - Establish a consortium of research labs and funding sources who would address the issues in a coordinated program leading to a generally accepted engineering method. Organization and coordination of the program would be done through CIB W14 as an independent international body.

Collaboration Partners:

Task Lead Organization Participating Labs

Coordination CIB W14

Technical Direction NIST all

Fire/structure simulation NIST & BRE CTICM, SINTEF & NIST

Full-scale tests of connections

ABRI CSIRO

High heating rates CTICM BRANZ

High temp properties BRI NRCC, SP & NIST

High thermal gradients CSIRO SINTEF

Cooling phase SKLFS BRANZ

Symposium NIST all

Working - plan awaiting funding - no response

Components of Safety of Threatened Buildings Prgm

Occupant Behavior and Egress PI: R. Peacock Reliable predictions of time to egress

Improved Emergency Egress & Access

Emergency Use of Elevators; PI: R. Bukowski Technical and procedural means to allow use of elevators during emergencies for evacuation of occupants with disabilities from, and for first responder access to, high rise buildings

Components of Safety of Threatened Buildings Prgm

Developing, Managing and Disseminating Building Information During Emergencies; PIs: K. Reed, S. Treado, W. Healy • Services that enable ready access to building systems data by first responders; • Managing heterogeneous wireless sensor networks in buildings;• Ensuring secure dissemination of building information to emergency responders.

Technologies for Building Operations in CBR Attacks PI: Andy Persily Analysis tools and guidance for assessment and subsequent reductions in vulnerability of buildings to CBR attacks

Cost-effective Risk Management Tools; PI: Bob Chapman User-friendly tool for building owners/managers to aid in selection of cost- effective strategies for management of terrorist and environmental risks

Building & Emergency Equipment Stds & Guidelines

Implications for Standards

Test methods for mechanical and thermal properties of fire proofing materials

• gypsum• SFRM• intumescents

Test methods for performance of partitions in fire

Test methods for performance of structural materials in fire• high temperature steels• high strength concrete• composites (organic and inorganic)

Test methods for strength of connections at fire temperatures.

Issues specific to ASTM E119

Time as the Unit of Rating

• Rating system should be immune to misinterpretation.

• ASTM E119 is a prescriptive standard; units of time imply absolute level of performance which has not been justified by analysis, actual fire tests, nor historical record.

• Express rating on non-dimensional relative scale that is continuous (not discreet) and easily converted to large data base on fire resistance that already exists.

Issues specific to ASTM E119

Resolution and Uncertainty of Rating

• Account for variability in test method and test specimen that are beyond control of best laboratory practices.

• Different laboratories conducting tests on two specimens designed to be identical will produce a time to failure that differs by some amount, which should be default value for uncertainty.

• Alternative methods for evaluating resolution and uncertainty could involve replicate tests or historical data.

Issues specific to ASTM E119

Running Test to Failure

• Need for improved measurement techniques.

• Collect data on all performance criteria relevant to the application of the construction element:

temperatures throughout element deflections throughout element penetration of flame through element

• Record and make available all results as function of time.

• Establish rating based upon multiple criteria.

Need for National Structural Fire Resistance Laboratory

To enable structural fire resistance to be rigorously evaluated so that safety benefit of improvements to related building fire codes and standards can be demonstrated to all major stakeholders.