Fire-fighting systems: guidelines seismic vulnerability reduction systems
The guidelines developed by the Ministry of Interior, Department of the Fire Department provide criteria and operational guidelines to reduce the seismic vulnerability of firefighting equipment.
Recent earthquakes, in fact, have shown that the damage recorded by the non-structural components, such as mechanical, electrical, plumbing and fire, resulted in the unavailability of many buildings, even when the structures were left intact.
In some cases, the damage of the piping systems has resulted in significant losses of water and consequent flooding as well as the interruption of essential services. such as fire protection or gas leaks with danger of fire and explosion.
Of infrastructure and strategic buildings, in which the essential functions must be able to be provided without interruption since from the immediate post-quake, is therefore required an adequate seismic protection for sprinkler installations designed to ensure their continued operation.
They must, at the same time, be guaranteed appropriate levels of security (eg no component must collapse causing damage to occupants or obstruct escape routes and facilities of the gas supply must not result in losses) and fire-fighting systems should not, because the earthquake, activated in the absence of fire resulting in unusable condition of buildings or portion thereof.
Are defined in these guidelines as the minimum requirements for seismic safety conditions deemed necessary to obtain and installation features that ensure, as needed, the safety of people, the maintenance of functionality, the early restoration after the earthquake.
Provides guidance preventive to avoid situations of difficulty or danger to persons in the event of earthquake-related evacuabilità of the places and the generation of induced effects associated with the risk of fire, such as releases of hazardous substances or flammable.
These guidelines are aimed to define the requirements for seismic safety of the plants connected to fire safety with regard to the various installation scenarios (hazard of the site and the strategic function of the installation).
Studies carried out as a result of earthquakes have highlighted damage situations applicants and, in particular:
external to the buildings:
- Breaking or crushing of buried pipelines due to subsidence or liquefaction effects which have caused soil compaction;
- Inadequate supplies of water in terms of volume and pressure, caused by damage to the water system.
inside the buildings:
- Rupture of the vertical pipes (risers) due to strong inter-shifts; detachment from its anchor points of the brackets for pipes;
- Extraction of the elements between the anchor hooks and structure of the building due to earthquake loading, sprinkler head crashes due to the impact with structural or non-adjacent elements (eg. Ceiling panels);
- Impairment of tight connections and pipe joints;
- Damage to pipelines crossing seismic joints are not designed to withstand differential movements;
- Tear of pipes due to detention for clamping the walls penetrated;
- Piping systems suspended floor or ceiling, do not adequately braced, under the seismic action have fluctuated heavily loaded anchor points and determining impact damage on both pipes on the heads;
- Partial collapse of the pipes to rupture and release the hooks from the media because of the cyclical nature of large displacements;
It was also found that gas leaks from pipes have helped to aggravate the consequences of the earthquake of life and property.
It is, therefore, of paramount importance to ensure the maintenance of the sealing of the pipes and joints or, in case of leakage, the prompt interruption of the inflow of gas.
Fire-fighting systems, in particular, should be considered "life saving" and then designed taking into account this feature.
These plants are normally inactive but must promptly and correctly operate in case of necessity, to avoid serious risks to people and / or substantial economic damage.
Especially in strategic buildings in which we want to preserve the post-earthquake operation and avoid consequential damage caused by uncontrolled leakage of water, particular attention must be paid to the control of the oscillations produced by the seismic shaking and differential movements of the pipes with respect to the structure which are anchored.
It is necessary that the different components are provided with adequate structural strength and that it is assessed the ability of maintaining function.
At present technical standards have not been enacted for the protection of buildings from fires caused by earthquakes.
In the most recent technical rules issued as a result of Ordinance 3274/03 and subsequent NTC 2008, the issue is addressed only indirectly by controlling the level of structural damage.
The NTC 2008 then prescribe that all structural components without structural function, the disruption can cause damage to persons, shall be verified to the seismic action, together with their connections to the structure.
For plants the signs are limited to defining the design seismic action, and to require the sealing of gas pipelines with the introduction of shut-off valves on large supplies and the constraint of the luminaires.
24/04/2012
----------------------------------------
Translated via software
----------------------------------------
Source:
Italian version of ReteArchitetti.it