BRJ – Volume 55, Number 4, 2007

Building Research Journal
Volume 55, Number 4, 2007

Saidani, M.:
Structural performance of axially loaded concrete-filled steel tubes with different concrete mixes . . . 185

Zuda, L. – Rovnaníková, P. – Rovnaník, P. – Černý, R.:
Effect of aggregates on the properties of alkali activated aluminosilicate composites . . . 197

Mihalka, P. – Matiasovsky, P.:
Water vapour production and ventilation regimes in large panel building flats . . . 209

Ravinger, J. – Psotný, M.:
Residual stresses in steel plate girders . . . 227

Abstracts

Structural performance of axially loaded concrete-filled steel tubes with different concrete mixes
Saidani, Messaoud
Concrete-filled steel tubes are very popular in structural engineering applications. This is due to their excellent structural properties, such as earthquake resistance, high strength and ductility, and large energy absorption. This paper deals with investigating the structural performance of concrete filled steel tubes (CFT’s) with various concrete strengths (mixes) under axial compression. The effects of using different concrete mixes and steel tube material properties are examined. An experimental study is described and evaluated. The results are analysed and compared with those predicted by Eurocode 4. Nine specimens with three different concrete mixes were tested to failure under axial compression by recording the failure load and mode of failure. The columns were 139.7 x 6.3 circular hollow section (CHS) with a total height of 728 mm. All the specimens were tested with 40,45 and 50 N/mm2 concrete strengths.
Keywords: Compression, Composite, Concrete, Steel, Tubes, Columns, Mixes

Effect of aggregates on the properties of alkali activated aluminosilicate composites
Zuda, Lucie – Rovnaníková, Pavla – Rovnaník, Pavel – Černý, Robert
Two alkali activated aluminosilicate composites, one of them with quartz sand aggregates, the second with electrical porcelain are studied in the paper. Compressive and bending strength, water vapor diffusion resistance factor, apparent moisture diffusivity, thermal conductivity and specific heat capacity are determined as functions of previous thermal treatment up to 1 200 °C. The electrical porcelain aggregates are found to be more suitable solution from the point of view of high-temperature resistance of the analyzed composite. The possible explanation of this finding may lie in the better thermal stability of electrical porcelain compared to quartz which changes its volume at 573 °C and 870 °C.
Keywords: aluminosilicates, alkali activation, ground granulated blast furnace slag, electrical porcelain, properties

Water vapour production and ventilation regimes in large panel building flats
Mihalka, Peter –Matiasovsky, Peter
Determination of the air change rate and water vapour production courses in residential buildings represents the problem connected with the inhabitants‘ behaviour. The air change rates and vapour productions in the concrete large panel building flats were determined by the analysis of long-term measurements of the indoor and outdoor boundary conditions. The analysis was made with the use of a system of equations modelling the hygric balance in the indoor space zone with two types of hygroscopic surfaces. The hygroscopicity of the flats was expressed by the effective air mass multiplier identified in the hygric balance equations.

Residual stresses in steel plate girders
Ravinger, Jan – Psotný, Martin
Presented paper offers the simplified equations for the evaluation of the residual stresses. The residual stresses are very important for the evaluation of the properties of the steel thin-walled structures. They play a crucial role in the definition of ultimate load, the stiffness properties and the natural frequency as well.