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- Beitrag zu einem Tagungsband (22) (entfernen)
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- Constitutive equation (3)
- Fire (3)
- Creep (2)
- Fire engineering (2)
- Fire resistance (2)
- Acoustic emission (1)
- Carbon fibre reinforced plastics CFRP (1)
- Circular (1)
- Column (1)
- Columns (1)
Organisationseinheit der BAM
For the evaluation of the fire resistance time of structural elements thermal and mechanical loadings are applied to the specimen. Up to now the monitored data is represented in tabular form and simple plots. In the following a visualization system to show the data in its geometrical context is discussed.
Substrukturtechnik: Eine hybride Prüfmethode - Überblick mit Anwendung im Brandingenieurwesen
(1999)
Im Gegensatz zu realen Bränden werden Bauelemente bei klassischen Brandversuchen als Einzelbauteile ohne Wechselwirkung mit dem umgebenden Gebäude betrachtet. Um einen Brandversuch realistischer durchführen zu können, ist die Entwicklung spezieller experimenteller Methoden erforderlich. Als Beitrag zur Verbesserung der Situation wurde die Anwendung der Substrukturtechnik, einer speziellen hybriden Prüfmethode, die aus dem Erdbebeningenieurwesen bekannt ist, auf das Brandingenieurwesen übertragen.
In contrast to real fires in classical fire resistance tests building elements are considered as stand alone elements without interaction with the surrounding building. In order to run a fire test in a more realistic fashion the development of special experimental techniques is required. As a contribution to overcome the situation the application of the substructuring method, a special hybrid method known from earthquake engineering, has been adopted to fire engineering. The paper gives a presentation of the concept including a short description of utilized system components.
Experimental and numerical study of high performance concrete columns subjected to fire loading
(2009)
Damage and strength reduction of a high performance concrete due to thermomechanical stresses
(2008)
In fire resistance tests, building elements are considered as stand-alone elements without interaction with the surrounding building. As a contribution to overcome the situation, the application of the substructuring method has been adopted to fire engineering. The paper gives some remarks on the aforementioned experimental method. The analysis is based on the results of two built-in column fire resistance tests, i.e. one test with an unprotected column at the ground floor of the 8-storey steel framed building at Cardington and another test at BAM with an unprotected column and simulated axial restraining stiffness by the substructuring method.
Although identified on the basis of so-called instationaiy creep-tests the constifrvtive model of Eurocode 3 (EN 1993-1-2, 2010) - hereinafter refened to as EC3 - represents a non-linear rateindependent relationship between stress and meclianical strain. I.e. the experimentally observed phenomenou of creep at constant stress but linear time varying temperature is described only through the temperature dependence of the material parameters characterizing the EC3 constitutive model. As a consequence some important phenomena cannot properly be described: E.g. creep or relaxation at constant temperature, creep or relaxation at non-monotonic temperature rates or sensitivity of the instationary creep process on the temperatme rate.
An intermediate-scale fire testing approach on the structural integrity of lightweight materials
(2013)
Carbon or glass über composites and Sandwich structures, the lightweight materials of choice for aviation, naval, offshore and construction show an enormous energy saving potential. Their combination of excellent specific mechanical properties, high corrosive resistance and thermal insulation properties in combination with various adoptable fabrication techniques leading to mass and fuel cost reduction. The most limiting single factor for a wider use of fibre reinforced plastics (FRP) in particular as elements for structural application is believed to be their fire behaviour (Mouritz and Gibson, 2006). FRPs promote burning by themselves consuming the stabilizing polymeric matrix while embedded fibers (glass, carbon) persisting the flame (Mouritz et ah, 2006). Already at elevated temperatures (100 - 200 °C) the matrix softens with a loss in mechanical properties (Perret et al., 2011, Mouritz and Gibson, 2006). For this reason the stability of the structural component is decreased severely. Fire behavior becomes the major hazard to worry about, increasingly demanding targetoriented investigation, suitable testing and tailored development.
Experimental approaches in the bench-scale have been proposed to investigate the structural integrity in the past (La Delfa et al., 2009, Gibson et al., 2010, Seggewiß, 2011, Mouritz and Gardiner, 2002, Schartel et al.). Ascribed to the small-scale neither the mechanical properties nor the effects of fire may be represented satisfactorily. Flence, the task is to perform more realistic investigations under adequate compressive loads in fully developed fires, based on suitable specimen sizes. Also (La Delfa et al., 2009)) have announced that it is evident that larger scale test of composites are needed. The aim of this study is to present a developed intermediate-scale test setup to perform more realistic investigations (Hörold et al.). Mechanical loading is generated by a column furnace in terms of compression due to a more severe response of specimens in fire tests (Seggewiß, 2011, Gibson et al., 2012, Feih et al., 2008, Feih et al., 2007). An oil burner used to determine the burnthrough resistance of thermal/acoustic insulation materials provides fire directly onto one side of the specimen (Federal Aviation Administration, 2003). Generating a fully developed fire the NexGen burner offers a homogenous heat flux of ~ 180 kW/m2. The intermediate-scale is addressed by specimen sizes either 500 x 500 mm or 1000 x 500 mm with a maximum thickness of 50 mm. The specimen attachment is realized by a compression device that was designed to apply the compressive loads, figure 1. The test setup for specimens with component like dimensions allows realistic investigations up to structural failure in absence and presence of fire load. A first test series was carried out with different levels of loading while the fire remained unchanged. Failure mechanisms, temperature distributions, diversity of FRPs regarding fiber, matrix, lay-up and core as well as flame retardant Systems are in the scope of investigation.