Protezione dal fuoco di strutture metalliche

La protezione dal fuoco per l'acciaio strutturale è fondamentale nel design degli edifici. Questa ricerca esplora l'importanza dei rivestimenti intumescenti nel mantenere la resistenza dell'acciaio durante gli incendi e permettere un’eventuale evacuazione in sicurezza.
Lo studio sottolinea la necessità di misure di protezione antincendio negli edifici, incluse strategie attive (come sprinkler e porte antincendio) e passive (come i rivestimenti intumescenti). I rivesti- menti intumescenti reagiscono chimicamente quando esposti al fuoco, espandendosi per formare uno strato protettivo che rallenta il surriscaldamento dell'acciaio, consentendo l'evacuazione sicura.
Inoltre, i cicli di pitturazione con intumescente non solo offrono protezione antincendio ma prevengono anche dalla corrosione, sono testati rigorosamente secondo gli standard internazionali e offrono diversi livelli di protezione. Solitamente includono un primer per la resistenza alla corrosione e una finitura per l'aspetto estetico e la protezione degli strati sottostanti
In conclusione, la scelta dei rivestimenti protettivi antincendio appropriati è cruciale per garantire la sicurezza degli occupanti negli edifici in acciaio, mantenendo la resistenza strutturale e migliorando il comportamento al fuoco.

Fire Protection of Structural Steel: The Role of Active and Passive Strategies

The protection of structural steel in buildings is a critical aspect of modern construction. Steel, known for its strength and versatility, serves as a fundamental material in many designs. However, its vulnerability to high temperatures during a fire necessitates the implementation of effective fire protection measures to ensure the safety and integrity of buildings. This chapter introduces the importance of fire protection, highlighting the dual roles of active and passive fire protection strategies.

Active fire protection measures, such as sprinklers, fire alarms, and fire doors, aim to detect, sup- press, and control fires. These systems are designed to respond immediately upon fire detection, mitigating the spread and intensity of flames. While essential, active measures alone are insuffi- cient to protect the structural integrity of steel under prolonged exposure to high temperatures.

Passive fire protection, on the other hand, involves integrating fire-resistant materials and designs into the building's structure. These measures do not require activation and work continuously to slow the spread of fire and smoke. Among the most critical passive protection strategies are intu- mescent coatings, which expand to form an insulating char layer when exposed to heat, thus pre- serving the load-bearing capacity of steel.
Intumescent coatings represent a key advancement in passive fire protection, they are lightweight and thin, expanding up to 50 times their original thickness when heated in a fire.

This expansion forms a protective char barrier that insulates the steel from heat, significantly delaying the tem- perature rise and preventing structural failure for a denoted period of time (i.e. fire resistance rating).

The distinction between fire retardant and fire-resistant coatings is essential in understanding their respective roles. Fire retardant coatings are designed to reduce the flammability of materials and slow the spread of flames, whereas fire-resistant coatings, such as intumescent coatings, provide insulation to structural elements, maintaining their integrity under high temperatures.

This paper explores the necessity of comprehensive fire protection strategies that integrate both active and passive measures. While active systems play a crucial role in life safety by detecting and suppressing fires, passive measures like intumescent coatings are vital for ensuring the structural integrity of buildings during a fire. The effectiveness of intumescent coatings in maintaining the load-bearing capacity of steel structures, combined with their lightweight nature and aesthetic flexibility, makes them an indispensable component of modern fire protection strategies of struc- tures.

In the following chapters, we will delve into the fundamentals of fire protection, the composition and mechanisms of intumescent coatings, the distinctions between fire retardant and fire-resistant coatings, and the standards and testing protocols that ensure their efficiency.

Additionally, we will examine application techniques, case studies, and the dual role of these coatings in providing both fire and corrosion protection. Finally, we will explore future trends and innovations in fire protec- tion technology, emphasizing the ongoing research and development efforts aimed at enhancing the performance and sustainability of intumescent coatings.

Fundamentals of fire protection in buildings

Fire protection in buildings is an intricate field that combines various strategies to prevent, control, and mitigate the impact of fires. This chapter provides an overview of the fundamentals of fire protection, highlighting the importance of both active and passive measures in ensuring building safety and integrity.

Active fire protection measures are systems designed to detect and combat fires as they occur. These include fire alarms, sprinklers, smoke detectors, and fire suppression systems. Fire alarms and smoke detectors are critical for early detection, alerting occupants and emergency services of the presence and location of a fire. Sprinklers and fire suppression systems work to control and extinguish fires, thereby preventing their spread and reducing the heat release rate. These systems are essential for protecting lives and property, but they are reactive in nature and depend on time- ly activation and proper maintenance to function effectively.

Passive fire protection measures, in contrast, are built into the structure of a building and are designed to prevent the spread of fire and smoke, as well as to protect the structural integrity of the building. These measures include fire-resistant walls, floors, and doors, as well as firestopping systems and intumescent coatings. Passive fire protection is proactive, providing continuous protection without the need for activation.

Structural steel, while strong and versatile, is particularly vulnerable to high temperatures. At approximately 500°C for beams in bending and 200°C for columns in compression (as referenced in Figure 3.2 of Eurocode EN 1993-1-2:2005 [1]), steel begins to lose its strength and rigidity, compromising the structural integrity of the building. This is where passive fire protection, specifically intumescent coatings, becomes crucial. Intumescent coatings provide a thermal barrier that insulates the steel from the heat of a fire, delaying the temperature rise and allowing more time for evacuation and firefighting efforts.

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L'intera memoria è in lingua inglese.

La presente relazione è stata presentata in occasione del XXIX Congresso CTA, svoltosi a Milano il 26 e 27 settembre 2024.