화재 사건과 기술기준 -건물 화재에 대한 공학적 분석-

Dr.–Ing. Wee Kyong KIM

2018 KEPIC-Week, Busan

2018.8.28~31

Introduction and Fire Dynamics

Ignition and Prevention Factors

Fire Growth / Flame Spread

Fire Suppression, Detection and Alarm

Fire Confinement / Structural Integrity

Smoke Movement / Management

Egress Systems and Tenability Analysis

1. Introduction

Definitions of failure

Failure is an unacceptable difference between expected and observed performance

ASCE Technical Committee on Forensics

Distortion, breakage, deterioration or other fault in an item, component, system, assembly or structure that results in unsatisfactory performance of the function for which it was designed

NFPA 921, Guide for Fire and Explosion Investigations

※ Definition of fire investigation

The process of determining the origin, cause, and development of a fire or explosion

1. Introduction

Classifications of failure

Design

Installation

Inspection, testing and maintenance

Equipment malfunction

Training / operation / administrative controls

Communication

1. Introduction

Origin and Cause issues

Most of the focus in fire investigation is on the

cause of ignition

What started the fire?

Potential cause of action against responsible parties

Was the fire intentionally set (arson)?

Criminal prosecution

Denial of insurance coverage

1. Introduction

Engineering issues

What physical / chemical / operational factors permit a fire or explosion?

What factors permit a small fire to grow large and cause unacceptable damage or injury?

Flammability of materials

Fire detection and alarm notification

Fire suppression

Smoke management / control

Fire confinement / structural integrity

Means of egress

1. Introduction

Role of Codes and Standards

Fire codes and many fire safety standard : Prevention

Fire test/FP system installation standards : Mitigation

Building codes :

Describe fire safety systems and features that should be in place to mitigate the consequences

Reference Fire test/FP system installation standards to assure compliance with the code’s performance objectives

Building codes, Fire codes and many fire safety standard

Are used to evaluate whether an appropriate standard of care has been applied in design, installation, operation and maintenance of building and fire protection systems

1. Introduction

Reasons for post-fire analyses

Identify criminal activity,

Assess responsibilities

Provide feedback for improvements to manufactures, designers and regulators

Reduce risk (insurance)

Identify trends (data)

Learn from past mistake to prevent reoccurrences in the future

Determine Origin and Cause and provide feedback to

Protect property(reduce damages), Save lives and prevent injuries, conduct research to improve codes, standards, regulation, Reduce impact on environment, protect firefighters

2. Fire Dynamics

Stages and elements of enclosure fires

Fire plume/ceiling jet,

Enclosure smoke filling,

Pre-flashover

Post-flashover

Data needs for fire scenario reconstruction,

Fire patterns and their analysis,

Fire Modeling tools, uses and limitations

2. Fire Dynamics

Case study : MGM Grand Hotel Fire (80.11.21)

https://en.wikipedia.org/wiki/MGM_Grand_fire

세 번째로 큰 호텔 화재 : 85명 사망, 650명 부상

화재원인 : ‘The Deli’ Restaurant(소켓의 접지불량)

문제점 : 상주지역(SP 면제:화재시 비상주지역), 가연성물질, 수직 관통부, 연기 확산(HVAC), 비상구잠금

Fire reconstruction is based heavily on issues addressed by FPEs

Large scale fire testing supported has been used.(화재전파속도 : 4.6~5.8 m/s)

Response of materials to fire, Fire pattern analysis,

Fire dynamics / modeling

3. Ignition and Prevention Factors

Introductory concepts : 점화원과 가연물

Fire Origin and cause considerations + propagation

Ignition sources and their control (Che/Mech/Elec)

NFPA 1, 51B, 54, 58, 70, 86, 211

Materials first ignited : 물질 상태(기액고) 및 형상(고)

Thin solids : 𝒕𝒊𝒈 =𝑻𝒊𝒈−𝑻𝒐

𝒒 𝒏𝒆𝒕" /𝝆𝒄𝜹

Thick solids : 𝑡𝑖𝑔 =𝜋

4𝑘𝜌𝑐

𝑻𝒊𝒈−𝑻𝒐

𝒒 𝒏𝒆𝒕"

2

Ignition factors : 설계, 설치, 행정통제,검사 및 기기

오동작

3. Ignition and Prevention Factors

Case study : The Station nightclub fire (03.2.20)

100명 사망, 250명 부상,

화재원인 : 불꽃이 벽마감재에 점화

PU foam as interior finish : Life Safety Code

Use of pyrotechnics without proper permits/training : 행정통제

Overcrowding / exit capacity / arrangement

Lack of early suppression

Summary

최초 점화된 가연물을 점화시키기 위한 점화원 능력

최초 점화된 가연물의 점화 용이성

최초 점화된 가연물에 노출되는 점화원 인자 : 설계/시공/행정

4. Fire Growth / Flame Spread

Introductory concepts :

화재예방실패 다음 단계는 성장속도 제한

Interior finishing (조기화재성장), floor

(Flashover), Furnishing and decorations (점화 용이/조기 화재성장)

4. Fire Growth / Flame Spread

Material flammability properties / regulation

Ignition properties : Effective Thermal properties(thin, thick), Ignition temperature, Heat release rate properties(연소열, 증발열)

Performance expectations for flammability

Case study : North Central High School

적재된 체육관 매트에서 발화 급속 성장 구조적 손상

Flammability Characteristics of gym mat and Bleachers(관중석)

NFPA 101 : HRR < 100 kW matt 평균 HRR 50 MW

5. Fire Detection and Alarm

Introductory concepts :

Performance expectations for fire detection systems

Performance expectations for fire Alarm and communication systems

Case study : Signature Foods plant (1998년 1월 2일) :

냉동창고, 열감지기(57℃) dry-pipe/preaction SP,

야간 고온수 청소작업으로 회로 차단(고질적인 문제)

설계,시공, ITM, 오동작 등 다양한 형태로 감지 및 경보계통 손상

화재경보 기록은 fire reconstruction에 매우 유용한 자료(R type)

6. Fire Suppression

Performance expectations for fire suppression systems

진압/제어 + 감지/경보

Factors associated to system failures

Case study :

River Cities Business Park (01.2.20)

SP system 손상 : 적재물 배열, 20만 gal 물탱크 전복, 기타 원인?

Commercial Cooking Fire

설계/시공/유지관리 미흡, 소화약제 탱크 미동작(안전플러그)

Refuse Recycling Facility

Over 200 sprinklers opened???

7. Smoke Movement and Management

Introductory concepts

Stack effect, Wind effects, Fire-induced buoyancy and expansion, Mechanical ventilation

Performance expectations for smoke management systems

Case study : Cook County Administration Building(03.10.17)

6명 사망, 21명 부상,

Open door to store room(화재지역) / Locked doors in stairways / Smoke in occupied stair

FDS, CONTAMW Simulations,

NIST 사건조사 참여 : NIST BFRL website “SP-1021” 참조

But for deaths of 6 civilian in stairway, CCAB fire may have been considered a fire protection success despite lack of SP protection

8. Fire Confinement / Structural Integrity

Introductory concepts : Building Type I ~ V

3-hr ratings means no failure 3 hours of real fire exposure

Performance expectations for fire barrier

Performance expectations for structural elements

Test standards : assemblies, doors, windows fire stops……

Case study : First Interstate Bank(88) / One Meridian Plaza(91) / WTC(01)

공통점 : office furnishings, open floor plans, fire spread to multiple floors

차이점 : FIB(재사용), OMP(재사용불가), WTC(붕괴)

Fire resistance of steel-framed structure : Temperature, long-span floor(열팽창 크기), 중력방향으로 견디는 연결부

Pressure Reducing valve 문제점

9. Egress Systems / Tenability Analysis

Introductory concepts : ASET > RSET

Egress system issues :

재실자 대비 출구크기 및 수량, 이동거리, 문, 계단/

복도….

Tenability analysis issues

Case study : MGM Grand fire