ISO TR 24679-2:2017 pdf free download.Fire safety engineering — Performance of structure in fire — Part 2: Example of an airport terminal.
Introduction
ISO TR 24679-2 is an example of the application of ISO 24679-1. It preserves the numbering of subclauses in ISO 24679-1 and so omits numbered subclauses for which there is no text or information for this example. Therefore, the following two points should be kept in mind.
a) ISO TR 24679-2 Is not intended to provide uniform technical provisions for the user, but rather demonstrate how ISO 24679-1 is applied in compliance with the related standards of China.
b) Fire service intervention has been considered when defining the maximum heat release rate of the design fire in this case because the fire brigade is dedicated and is approximately 1 km away from the airport terminal. It is completely legal in China to consider the fire service intervention, which may not be the case in other countries. Therefore, when taking any reference from this document, attention should be paid to the requirements of the related national standards.
It should be noted that this example does not follow every step described in ISO 24679-1, but rather follows its principles as applicable to the building regulatory in China.
4 Design strategy for fire safety of structures
The built environment is an airport terminal that has been provided with automatic fire alarm system, sprinkler system, fire hydrant and smoke control system, etc. Furthermore, the fire service brigade dedicated is located approximately 1 km away from the airport terminal. Consequently, their intervention has been taken into account in definition of fire scenarios. The heat release rates (HRR) of combustible products, which could be found at the different locations of the terminal, have been defined by fire tests. An advanced model has been used to define the thermal action in different volumes of the studied terminal. The thermomechanical behaviour of the principal structure of the terminal, based on advanced and simplified methods, is carried out in function of the real thermal actions defined previously.
This case study Is intended to illustrate the steps given in Iso 24679-1. Therefore, the following design process has been adopted.
5 Quantification of the performance of structures in fire
5.1 Step 1: Scope of the project for fire safety of structures
This is the initial step in a fire safety design process for a new or an existing built environment. Below are the main items included in this step.
5.1.1 Built environment characteristics
This airport terminal (see Figure 1) Is 80 m deep, 252 m long and 22,13 m high. It has two stories above the ground and one underground, with a total floor area as about 7,1 x 104 m2. More details are given in Annex A. The airport terminal has been provided with automatic fire alarm system, sprinkler system, lire hydrant and smoke control system, etc.
The column, beam, floor structures on first floor are reinforced concrete. The column and roof structures on the second floor are steel. In case of fire, the flame and hot smoke may endanger the integrity and stability of steel structures on the second floor. Therefore, the purpose of this case study is to calculate the mechanical performances of the steel elements in the event of fire so as to determine if the trial plan is feasible.
5.1.2 Fuel loads
Fuel load analysis
Fuel load is the essential factor to analyse the full developed fire. Therefore, combustibles inside the terminal, including their amount, properties and location should be understood thoroughly before analysing the fire scenario.
In this case study, fuel loads is classified as
a) dead load,
b) live load, and
c) temporary load.
The fuel loads of this airport terminal have been defined based on the survey and investigation done by University of Science and Technology of China (see Reference 171). See Table 2 for the detail.
The structure consists of a series of parallel portal steel frames. For simplification, each of the frames is generally considered as an independent structural assembly with no out-of-plane deformation when doing the engineering calculation. Therefore, only a single steel frame has been calculated. When doing the structural analysis under fire condition, only the above-mentioned loads were considered. For example, the effects of change of the pressure inside the terminal caused by fire or the Impact of water used for firelight ing have not been considered.
5.2 Step 2: Identify objectives, functional requirements and performance criteria for fire safety of structures
The objectives, functional requirements and performance criteria are defined according to the statements in related codes and standards of China.
ISO TR 24679-2 assesses the fire safety of the main and secondary portal frame of an airport terminal. Therefore, the performance criteria are defined according to the requirements of CECS 200, which Is a technical code of China Association for Engineering Construction Standardization.
According to the related national codes and standards of China, the fire safety objectives of this airport terminal should address
— the life safety (occupants Inside the airport terminal and fire fighters), and
— conservation of property and continuity of operations.
In order to fulfil the fire safety objectives, the functional requirements of the steel structure should be:
— no serious damage to the structure or successive collapse in case of fire.
Therefore, efforts should be put on how to prevent or limit the partial structural failure in case of fire so as to protect the life safety of the occupants and fire fighters, and how to prevent or limit the structural deformation or collapse so as to reduce reconstruction cost and ensure the continuity of operation and not to increase the cost or difficulties of the after-fire restoration.
According to the statements in CECS 200, one of the following performance criteria shall be met.
The structure consists of a series of parallel portal steel frames. For simplification, each of the frames is generally considered as an independent structural assembly with no out-of-plane deformation when doing the engineering calculation. Therefore, only a single steel frame has been calculated. When doing the structural analysis under fire condition, only the above-mentioned loads were considered. For example, the effects of change of the pressure inside the terminal caused by fire or the Impact of water used for firelight ing have not been considered.
5.2 Step 2: Identify objectives, functional requirements and performance criteria for fire safety of structures
The objectives, functional requirements and performance criteria are defined according to the statements in related codes and standards of China.
ISO TR 24679-2 assesses the fire safety of the main and secondary portal frame of an airport terminal. Therefore, the performance criteria are defined according to the requirements of CECS 200, which Is a technical code of China Association for Engineering Construction Standardization.
According to the related national codes and standards of China, the fire safety objectives of this airport terminal should address
— the life safety (occupants Inside the airport terminal and fire fighters), and
— conservation of property and continuity of operations.
In order to fulfil the fire safety objectives, the functional requirements of the steel structure should be:
— no serious damage to the structure or successive collapse in case of fire.
Therefore, efforts should be put on how to prevent or limit the partial structural failure in case of fire so as to protect the life safety of the occupants and fire fighters, and how to prevent or limit the structural deformation or collapse so as to reduce reconstruction cost and ensure the continuity of operation and not to increase the cost or difficulties of the after-fire restoration.
According to the statements in CECS 200, one of the following performance criteria shall be met.