Filtern
Erscheinungsjahr
- 2018 (3) (entfernen)
Dokumenttyp
Sprache
- Englisch (3) (entfernen)
Schlagworte
Organisationseinheit der BAM
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.
In this paper, a nonlinear three-dimensional finite element (FE) model was developed and validated to study the effect of seismic damage location on the response of concrete filled tube (CFT) columns at fire after earthquakes. Three analyses were conducted consecutively in the modelling, namely, cyclic, thermal and structural. Results of the cyclic loading analysis comprising residual deformations were applied as the Initial condition to the thermal-stress model, replicating the seismic performance of column.
Following, a nonlinear sequentially coupled-thermal stress Analysis was carried out to investigate the fire response of CFT columns after the seismic event. Three damage scenarios were contemplated, considering any possible potential damages that could be generated by the earthquake loading on CFT columns. The accuracy of the proposed FE model was examined by comparing the numerical results with that of available tests on fire and cyclic loading. By means of the validated model, the performance of damaged CFT columns was then investigated under fire after earthquakes. The level of damage was assumed as a high damage level, presuming that the column reached 50% of ist lateral resistance while still maintaining its overall stability after the earthquake. The results were presented broadly, including the axial deformation history as well as the fire resistance time for CFT columns. To have a comprehensive insight on the influence of damage location in columns, the fire response of damaged specimens was compared with that of an intact one.
In this study, a nonlinear three-dimensional finite element (FE) model was developed and validated to investigate the response of concrete filled tube (CFT) columns subjected to post-earthquake fires. Three steps were considered successively in the modelling, namely, cyclic, thermal and structural analyses. Outputs from the cyclic loading including residual deformationswere imposed as an initial condition to the thermal-stress model, imitating the seismic response of the column. Subsequently, a nonlinear sequentially thermal-stress analysis was conducted to simulate the fire response of column after the earthquake. The proposed FE model was validated by comparing the simulation resultswith the observations of full-scale fire and cyclic tests available in the literature.
The validated numericalmodelwas then used to study the behavior of CFT columns under the combined action of earthquake and fire as a multi-hazard event. Three probable seismic damage scenarios were considered in the column, namely, middle length, bottom and top end region damages. The level of damage was assumed as a high damage level, presuming that the column reached 50% of its lateral resistance while still maintaining ist overall stability after the earthquake. The results showed that the top and bottom end region damages have not significantly influence the fire response of the damaged column. Besides, the column with the middle span damage performed a lesser fire resistance time owing to the coincidence of damage location to that of onset of global buckling.