Eurocode 1: Actions on structures – Part 1–2: General actions – Actions on structures exposed to fire Part of the One Stop Shop program Annex E (informative) →Fire load densities

Introduction Fire load density evaluation FLD used is a “design value” based on –Measurements or –Values given in national regulations Determined by –Classification of occupancies and/or –Individual project analysis

Design value The design value of the fire load: Characteristic fire load density per unit floor area Combustion factor Fire activation risk factors for Compartment size and Type of occupancy Fire-fighting measures risk factor

Determination of fire load densities Fire load density needs to be determined taking into account –Type of building / occupancy –Protected fire loads –Calorific value of fuel This process is used to determine the value of for previous equation

from occupancies For a large number of buildings, e.g. offices, residencies, hotels, and the paper industry, In which case, Table E.4 may be used to determine the value of Separate fire load densities within the building should be added to the tabular value if necessary

from basic principles To obtain we must obtain a value for Compartment area Characteristic fire load Amount of combustible material Net calorific value Optional factor for protected loads

Combustion factor Having determined a value for we next need a value for - the combustion factor The value of 0.8 is taken for cases mainly consisting of cellulosic fuels In other cases the combustion behaviour should be looked at as a function of occupancy and type of fire load

Fire activation risk factors 1.Due to size of compartment: 2.Due to type of occupancy: The factors vary from just under 1.0 to just over 2.0 – the particular value used is taken from Table E.1 included in the Annex

Fire-fighting measures risk factors This factor is a function of active fire- fighting measures Takes into account –Fire suppression systems –Automatic fire detection and alarm systems –Manual fire suppression systems The values for the individual factors are given in Table E.2

Worked example Work out the design fire load for a 6,500m 2 office space, with no additional fuels present in the space. –The office is sprinkler protected –Heat detectors are the only source of A&D system within the space –No other special provisions are present apart from the normal fire-fighting measures

Worked example - workings From Table E.4, we can see the value of can be taken as 420 MJ/m 2 This value may be taken because the value of is 1.0 (Table E.1) The value of can be taken as 0.8 The value of is 2.0, as it is between the 5,000 and 10,000m 2 brackets (Table E.1)

Worked example - workings The value of is therefore averaged from 0.61, 0.87, and 1.0 which results inhaving a value of 0.83

Worked example - answer Putting these values back into the original equation gives us a design value of the fire load for our test case scenario highlighted in the worked example as: MJ/m 2