Im Rahmen dieses zweiteiligen Beitrags wird auf die brandschutztechnische Bemessung für Brettsperrholzelemente und ‐konstruktionen eingegangen und deren Besonderheit im Vergleich zu Voll‐ und ...Brettschichtholz aufgezeigt. Der zweite Teil erläutert die Nachweisansätze der raumabschließenden Funktion von bekleideten und unbekleideten Brettsperrholzbauteilen, stellt die Prinzipien zur brandschutztechnisch sicheren Detailausbildung dar und gibt Erläuterungen zum Einfluss von Brettsperrholz auf die Branddynamik.
The scientific bases of ensuring fire resistance of reinforced concrete and steel building structures in the conditions of modern extreme influences are laid. The current state of fire safety of ...buildings and structures, as well as approaches, methods and tools for its assessment are analyzed. Analysis of emergencies and fires in the world has shown that the vast majority of them occur in buildings and structures. It is shown that the cause of catastrophic consequences and destruction is the non-compliance of the actual limit of fire resistance of building structures with regulatory requirements. This is due to the imperfection of methods and means of assessing the fire resistance of building structures, including fire-retardant. To overcome the shortcomings identified during the analysis, the paper develops physical and mathematical models of thermal processes occurring in the fire-retardant reinforced concrete structure. Based on the proposed models, a computational-experimental method for estimating the fire resistance of such structures has been developed. The efficiency of the proposed method was tested by identifying the relationship between the parameters of the fire-retardant plaster coating “Neospray” and the fire resistance of fire-retardant multi-hollow reinforced concrete floor. The study of fire resistance of steel structures is proposed to be carried out using reduced samples in the form of steel plates with dimensions of 500×500×5 mm. Based on the proposed models, a calculation and experimental method for estimating the fire resistance of steel structures, as well as an algorithm and procedures for its implementation have been developed. The verification of the efficiency of the proposed method was carried out in the ANSYS software package using the aged coating “Phoenix STS” and the coating “Amotherm Steel Wb” under heating conditions at the temperature of the hydrocarbon fire. The reliability of the developed models and methods is checked. It is established that random errors in temperature measurement significantly affect the accuracy of determining the thermophysical characteristics and limits of fire resistance. In general, the efficiency of the proposed calculation and experimental methods with sufficient accuracy for engineering calculations is confirmed.
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.
•Real-scale fire tests of intumescent coatings applied to steel tension members are presented.•The foaming behaviour and crack formation as well as failure mechanisms of intumescent coatings are described.•The key factors influencing the behaviour of the intumescent coating are identified and assessed.•The requirement and necessity of mechanically loaded tests on tension members are discussed.
Intumescent coating is often used as a fire protection on steel members due to its attractive appearance and ease of use. In the case when the member is fully covered by the coating, the response ...during the fire can be predicted rather accurately. However, if the member is covered only partially, the member's temperature profile and the structural response during the fire are not trivial to define. Partially covered members appear e.g. in cases in which the member is coated on the building site, but some previously installed adjacent structures disturb the coating process. Such partially covered members have been studied in the literature mainly from the temperature point of view, but in the present paper, also the structural behavior during the fire is considered. The paper presents a general procedure how to define the resistance of a partially protected steel member during the fire. As a result, time‐resistance curves are defined for bending, shear and torsion and standard IPE and HEA profiles are used in the example simulations and the results are compared to fully protected and unprotected cases. The finite element method is adopted both for the thermal and structural analyses. The expansion of the intumescent coating is taken into account using the so called effective thermal conductivity, hence the same model can be used for both analyses. The simulated temperature results are validated against experimental and simulation results from previous researches. The results for bending, shear and torsion resistance show, that when compared to the unprotected case, the partial protection increases the resistances and the improvement is at its height during 15‐30 minutes from the beginning of the standard fire.
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•Chitosan and phosphorylated cellulose nanofibrils are layer-by-layer assembled.•The assembly produces an exoskeleton on the complex structure of flexible foams.•Intermolecular ionic ...interactions result in impressive mechanical properties.•The coating prevents foam collapsing and reduces heat release rates.•Unique compositional and structural features result in synergistic interactions.
The layer-by-layer (LbL) assembly of chitosan (CH) and phosphorylated cellulose nanofibrils (P-CNF) is presented as a novel, sustainable and efficient fire protection system for polyurethane foams. The assembly yields a linearly growing coating where P-CNF is the main component and is embedded in a continuous CH matrix. This CH/P-CNF system homogenously coats the complex 3D structure of the foam producing a nano-exoskeleton that displays excellent mechanical properties increasing the modulus of the foam while maintaining its ability of being cyclically deformed. During combustion the CH/P-CNF exoskeleton efficiently prevents foam collapse and suppresses melt dripping while reducing the heat release rate peak by 31% with only 8% of added weight. The coating behavior during combustion is investigated and correlated to the observed performances. Physical and chemical mechanisms are identified and related to the unique composition and structure of the coating imparted by the LbL assembly.
•The temporal changes in the performance of fire protection systems have been investigated.•Event tree and dynamic Bayesian network have been employed to model degradation of fire protection ...systems.•Spatial and temporal escalation of domino effects have been modeled under the impact of fire protection systems.
The propagation of fire in chemical plants – also known as fire domino effects - largely depends on the performance of add-on passive and active protection systems such as sprinkler systems, water deluge systems, emergency shut down and emergency blow down systems, fireproofing, and emergency response. Although such safety barriers are widely employed to prevent or delay the initiation or escalation of fire domino effects, their inclusion in the modeling and risk assessment of fire domino effects has hardly been taken into account. In the present study, the dynamic evolution of fire protection systems has been investigated qualitatively using event tree analysis. To quantify the temporal changes and their impact on the escalation of fire domino effects, a dynamic Bayesian network methodology has been developed. The application of the methodology has been demonstrated using an illustrative case study, considering a variety of fire scenarios, target installations, and firefighting systems.
This work explores the feasibility of using graphene as an effective synergist for intumescent flame retardant (IFR). The flammability test and fire behavior under different fire scenarios are ...investigated. The incorporation of graphene results in different responses of IFR/polypropylene (PP) composites to small fire tests and burning under forced-flaming condition. The addition of graphene weakens the reaction of flame retardant PP to small flame. Lower loading of graphene is observed to improve the swelling of char, resulting in better insulation of the char and decrease in heat and smoke release. The further increase of graphene leads to the worsened fire safety. Flame retardant mechanism and model are proposed on the basis of the analyses of thermal decomposition products and process, and melt viscosity change. This works provides a solution to comprehensively assess the synergistic or antagonistic effect of graphene, and will be beneficial to developing its flame retardant mechanism.
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