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Steel tension rod systems consist of tension rods, fork connectors and associated intersection or connecting plates. They are used for truss systems, bracings or suspensions owing to slender design and increased economic efficiency. In case of fire, beside the tension rods themselves, the connection parts require appropriate fire protection. The use of intumescent fire protection coatings prevents a rapid heating of the steel and helps to ensure the load-carrying capacity of the structures. Because the connection components of the tension rod systems feature surface curvature as well as a complex geometry, high demand is placed on the intumescence and thermal protection effectiveness of the reactive fire protection coatings. Experimental studies were carried out to investigate the performance of intumescent coatings applied to the components of tension rod systems. The examined aspects include the foaming and cracking behaviour of the intumescent coatings, the influence of different dry film thicknesses (DFT), the heating rate of the steel connecting parts in comparison to the tension rods, as well as the mounting orientation of the tension rods together with their associated fork connectors. The results show that a decrease in the surface curvature and/or an increase in the mass concentration of the steel components lead to a lower heating rate of the steel. Moreover, the performance of the intumescent coating on tension rod systems is influenced by the mounting orientation of the steel components.
The application of intumescent coatings for fire protection of steel constructions is
increasing. Thanks to the relative thin thickness of the coatings, the typical visual
appearance of the structures can remain essentially unchanged. In Germany, the
applicability of the systems is regulated by the national as well as European technical
assessments. According to the approvals, the application on steel members in tension is
only allowed with limitations. Especially, the application on solid steel rods in tension is
currently excluded from the approval. The paper explains the actual state of the art of the
application of reactive fire protection systems applied to steel structures. Physical and
technical background information are provided. Furthermore, the latest scientific results
of an on-going research project funded by the German National Institute of Building
Technology (DIBt) and conducted by the Federal Institute for Materials Research and
Testing (BAM) will be described.
Purpose – The purpose of this paper is to investigate the performance of intumescent coating on tension rod systems and their components. Steel tension rod systems consist of tension rods, fork end connectors and associated intersection or gusset plates. In case of fire, beside the tension rods themselves, the connection parts require appropriate fire protection. Intumescent fire protection coatings prevent a rapid heating of the steel and help secure the structural load-carrying capacity. Because the connection components of tension rod systems feature surface curvature and a complex geometry, high demand is placed on the intumescence and thermal protection performance of the coatings.
Design/methodology/approach – In this paper, experimental studies were carried out for steel tension rod systems with intumescent coating. The examined aspects include the foaming and cracking behaviour, the influence of different dry film thicknesses, the heating rate of the steel connecting parts in comparison to the tension rods, and the mounting orientation of the tension rods together with their fork end connectors.
Findings – The results show that a decrease in surface curvature and/or an increase inmass concentration of the steel components leads to a lower heating rate of the steel. Moreover, the performance of the intumescent coating on tension rod systems is influenced by themounting orientation of the steel components.
Originality/value – The findings based on fire tests contribute to a better understanding of the intumescent coating performance on connection components of tension rod systems. This subject has not been extensively studied yet.
Intumescent fire protection coatings are used to improve the fire resistance of steel members. Due to slender cross-sections typically used for tension members, high demands are placed on the effectiveness and reliability of the intumescent coatings. This paper describes real-scale fire tests of intumescent coatings applied to steel tension members with circular solid and hollow sections. First, the current regulations for the application of intumescent coatings on steel tension members are discussed. After that, a comparison between the foaming behaviour and failure mechanisms of intumescent coatings applied to steel tension members with different cross-sections and loading conditions is given. Next, the experimental setup and procedure of the performed fire tests are presented. In addition, the influences of various parameters on the performance of the intumescent coating are analysed, including the geometry of the steel profile, dry film thickness of the intumescent coating, load utilisation level as well as the orientation of the member. Based on the theoretical considerations and results of the fire tests, it is evidenced that mechanically loaded fire tests are essential to assess accurately the contribution of intumescent fire protection coatings to the fire resistance of steel tension members with circular solid sections.