Structural Fire Safety

Fire  risk  assessment  has  always  been  a  challenging  issue.  furthermore,  performance  based  approaches  to fire  engineering  showed  that  risk  based  decisions  and  fire  scenarios  are  a  fundamental  element  of  the  fire  safety strategy assurance.
In particular, a correct assessment of the risk allows all the involved stakeholders to identify a  specific  strategy  among  a  pool  of  possibilities.  Risk  assessment is  the  perfect  tool  to  identify
comparable  fire  protection  strategies  and  to  measure  fire  risk  reduction  associated  to  the  single  specific  prevention and protection measures composing each different fire strategies.
This approach implies the need to abandon a classic, not even conservative approach, that in many cases linked the total fire load to the fire risk level, despite specific dynamics, layouts, prevention measures and risk management issues during time.
During the years, a number of different methodologies have been developed: for specific cases, for industrial or civil buildings, to adopt a method enforced by the local law and regulations acts, etc. Methods have been based  on  matrices,  indexes,  check-lists,  etc.  Present  paper  illustrates  a  method  developed  by  the  authors  taking into account several international recognized methods; even coming back to methodologies developed in early seventies.
The Method is named “FLAME” (Fire risk Assessment Method for  Enterprises), it goes back  to  the  fire  safety  fundamentals  against  a  generalized  approach  to  fire  safety  engineering  based  on  complex
and time -consuming  methods like CFD that deals only with the ‘consequences’ aspect of the fire risk (that is indeed characterized also by frequency estimation) using as reference scheme the “Fire Safety Concept Tree” explained in detail in the NFPA 550 Standard. In order to identify the most appropriate fire safety strategy it is important  to  identify  the  associated  fire  risk  that  the  strategy  is  intended  to  mitigate  to  a  certain  level. Alternative  solutions  can  be  evaluated
considering the  risk reduction operated by  different  strategies  and  by
different elements composing the fire strategies themselves and also costs with a modern ALARP approach.
A clear advantage is the possibility to get an overview of the whole fire risk as the cumulative risk assessed by  the  model  and  not  solely  related  with  the  consequences  evaluation  of  a  limited  number  of  fire  scenarios (usually the most obvious ones). Risk level assessment leads to the identification of the fire scenario (or a pool of) that governs and limits the specific situation, declined for both humans and structures (assets) considering  that the two vulnerabilities could be linked to different fire risk scenarios.
The method has been tested against different buildings occupancies. In the present case results of the FLAME method application to hospitals and health-care facilities are reported. A fire compartment-based risk estimation has been conducted on an overall of  about  300  compartments  (overall  size  of  about  60000  m 2).  Coherence  has  been  found  among  risk estimation  by  FLAME  parametric  code  and  prescriptions  of  the  Italian  fire  code.
There  is  good  agreement when assessing the RSET with the method proposed in FLAME, dealing with the occupants’  behaviour and the actual characteristics of occupants in clinics or hospitals and difficulties due to poor mobility or incapacity to understand emergency cue.

The protection of human life and the prevention of irreparable damages in case of fire have
become a compulsory requirement and a trend research topic. In strategic structures it is important
to limit deformations in order to guarantee the building serviceability also in case of
fire.
In this work the authors develop a procedure to estimate the deformations of a simple frame
subjected to fire. By means of the SAFIR code a nonlinear structural analysis has been considered
as a benchmark for structures under standard fire conditions. Hence, “effective temperatures”
have been determined imposing the equality of deformations obtained by linear
calculation and the ones obtained by SAFIR. The results show an acceptable error percentage
taking into account the coarse approximations involved in the procedure.
The “effective temperatures” method allows early assessments of the serviceability limit state
of complex structures partially subjected to fire.

An efficient numerical approach is developed in this paper for heat transfer analysis of insulated steel members exposed to fire, characterized by one-dimensional conduction through an insulation layer. The numerical schemes make use of Green's function solutions of diffusion equations, and consequently no spatial discretization is involved. Two types of time-varying boundary conditions, namely, the essential (Dirichlet) and the natural (Neumann), are treated individually. Computational models are developed for boundary conditions of each type, in which the choice of sampling time does not have the numerical stability requirement imposed. The numerical algorithm can be implemented in an Excel spreadsheet for engineering use.

The use of a new class of renewable liquid polyfurfuryl alcohol (PFA) resins has been investigated for use in composite applications for mass transport. PFA resins originate from the hemicellulose fraction of agricultural waste materials and with their char building potential posses an intrinsic resistance to fire and high temperature.

At the edge of today modern world, the human dependencies towards electricity are very significant. There are several sources for empowering the generation of electricity and one of them is by the gas-fired power plant. Gas-fired power plant is utilizing natural gas which is mainly composed of methane in its process for production of electricity. Safety is a common factor involved in and out of the plant respectively. The objective of this work is to evaluate the consequences of fire breakout inside the plant using ALOHA simulation software and followed by Quantitative Risk Calculation approach. There are several factors studied in this work such as the size of leakage aperture, pipeline pressure, pipeline temperature and wind speed. Positive responses are given by the leakage size and pipeline pressure while negative response for pipeline temperature. Stagnant response is given by the wind speed factor respectively. At the time of worst case scenario in the plant the formation of jet fire are thoroughly studied. Since there are settlements around the plant, the effect of jet fire is range out to the distance of 50m, 100m, 200m, 300m and 400m. The heat radiation intensity at the respective distances is 12.1 kW/m 2 , 3.04 kW/m 2 , 0.754 kW/m 2 , 0.342 and 0.196 kW/m 2 respectively.

Português:
O incêndio sempre representou um risco às edificações, comprometendo a segurança estrutural e humana. É de interesse da engenharia civil a análise de edifícios em situação de incêndio, para que se possa prevenir o colapso prematuro da estrutura.Este trabalho tem como objetivo analisar, numericamente, a variação de temperatura nas seções transversais de vigas de concreto armado em situação de incêndio, levando em consideração a compartimentação do ambiente em chamas e material celulóstico como combustível. O estudo utiliza o software ANSYS 16 com verificação do transiente do gradiente térmico na peça. Foram utilizados modelos tridimensionais para a obtenção dos gradientes e determinação da envoltória de 500ºC. Os resultados foram comparados com a ISO 834, NBR 14323 e EUROCODE 1-2,os quais apresentam ábacos com as máximas temperaturas das seções transversais das vigas e linhas isotermas pré-estabelecidas. Encontrou-se uma pequena divergência na angulação das isotermas em comparação com os ábacos analisados, espera-se que em decorrência da discrepância de fatores utilizados nas simulações e no ábaco.
English:
Fire has always represented risk to buildings, compromising structural and human safety. It is an interest of structural engineering the analysis of buildings under fire conditions to prevent the premature collapse of the structure. This paper has the objective to numerically analyze the temperature range in transversal sections of reinforced concrete beans under fire circumstances, considering ambient divisions and cellulosic fuel. The study uses the software ANSYS 16 within verification of the transient thermal gradient in the beam. There was used three dimensional models to obtain the gradients and determine the 932 Fahrenheit envelopment, including thermal structural analysis. The results were compared to ISO 834, NBR 14323 and EUROCODE 1, which shows graphs with the maximum temperatures of the beams sections, and some pre-established isothermal lines. There was found a little divergence in the angulation of isothermals in comparison with the analyzed graphs, it is thought to be caused by the discrepancy of the simulation and the graph used data.

RESUMO A arquitetura europeia edificada no estado catarinense se tornou um símbolo da evolução de um povo que, refugiado de sua terra natal, conseguiu se instalar e se desenvolver no Brasil. Hoje, além de ser um símbolo cultural, turisticamente diversas cidades catarinenses possuem sua economia fomentada no turismo das edificações construídas por imigrantes, como é o caso, por exemplo, da arquitetura austríaca de Trezes Tílias, alemã de Blumenau, ou Japonesa de Frei Rogério. Porém um aspecto preocupante se refere a precariedade de algumas residências que, além da deterioração decorrente das intempéries possuem estruturas em madeira que estão suscetíveis a disseminação do fogo em caso de acidente. Um aspecto relevante considerado nesta pesquisa é que, atualmente, há uma grande quantidade de edificações rurais no meio Oeste do estado de Santa Catarina que conservam este tipo de arquitetura. Assim, por instalações elétricas precárias, ou fagulhas de fogo geradas externamente, estas edificações encontram-se vulneráveis a propagação de um incêndio. Com isso o presente trabalho, através de um levantamento bibliográfico, buscou reunir os principais autores que discorrem acerca da temática, enaltecendo soluções viáveis do olhar da arquitetura para potencializar a segurança contra incêndio em casas construídas em madeira para conscientizar, principalmente, a população rural. Palavras-chave: edificações em madeira; prevenção contra incêndio; arquitetura vernacular; edificações europeias; edificações rurais.

The fire safety of the existing structures is very important from the international socioeconomic point of view and has high social impact for civil, industrial, and commercial buildings. The verification of the minimum fire resistance of civil structures is done through some
regulations, drafted to ensure occupant and rescue teams safety as well as a limited structural damage. These national fire rules are not always easily applicable to existing buildings. The purpose of the research activity is to provide guidance about the structural analysis of existing buildings exposed to fire, with particular reference to steel buildings protected with intumescent coatings.

When exposed to high temperatures, the structural members and frames have their bearing capacity compromised because the physical characteristics and material resistance used in the structures deteriorate during exposure to fire, resulting in a considerable loss of strength and stiffness. In this context, the present work carries out a whole thermomechanical analysis of steel members and frames using the Finite Element Method (FEM) inelastic formulation based on the Refined Plastic Hinge Method (RPHM) coupled with the Strain Compatibility Method (SCM). The use of SCM allows for a more realistic analysis against the design codes prescriptions. So even under high temperatures, SCM is used for both evaluation of bearing capacity and stiffness parameters. To do this, the steel behavior used in the structure numerical modeling must be described in a consistent manner through its constitutive relationship. A comparison of the results obtained here with the numerical and experimental results available in the literature suggest the effectiveness of coupling SCM/RPHM and that such a methodology can provide reliable analyses of steel members and frames subjected to high temperatures.

I numerosi incendi che si innescano e danneggiano
le strutture hanno rivoluzionato, da una parte,
molte procedure sulla prevenzione definendo metodologie
gestionali più efficaci e stanno, dall’altra,
portando ad affinare procedure investigative
codificate atte a ridurre il rischio di errori/omissioni
durante le indagini.
Lo scopo di questo articolo è quello di esporre
una metodologia codificata di Structural Fire Investigation
(Investigazione sugli aspetti strutturali in
caso di incendio) atta ad individuare le cause scatenanti,
pregresse e latenti, che hanno determinato
l’evento accidentale.
L’iter investigativo, associato a determinate operazioni
strutturali e forensi che partono dalla raccolta
delle informazioni iniziali al repertamento e
controllo documentale per poi completarsi con le
verifiche computazionali, sicuramente aiuta a determinare,
in maniera rigorosa, le cause e l’origine
di un incendio. La modellazione degli incendi con
il software del NIST, Fire Dynamics Simulator
(FDS) e l’analisi strutturale con vari codici di calcolo,
permettono di verificare determinate ipotesi
maturate durante il repertamento e di avvalorare
scientificamente l’analisi semiotica rilevata sulla
scena, fornendo dati forensi utili in fase dibattimentale.
Quindi un’attività investigativa pianificata, permette
a qualsiasi utente, (VV.F., personale delle Forze
dell’Ordine, Consulente, Perito, CTU o Libero
Professionista), di svolgere indagini in maniera appropriata
secondo una linea guida che permette
di non tralasciare controlli a volte rilevanti per la
stesura della documentazione complessiva in forma
di report finale.