BRJ – Volume 58, Number 4, 2010

Martin Psotný, Ján Ravinger:
Stability of shallow shell as a ceiling panel . . . . . . . . . . . . . . . . . . . . . . . . . . . .  199 – 208

P. M . Pradhan, P. L. Pradhan, R. K. Maskey:
Lateral resistance of partially infilled masonry wall in concrete frame structures . . . 209 – 220

M. J. Martínez Alvarado, E . Rocha-Rangel, S. D. De LaTorre, M. Díaz-Cruz:
Hydration products derived from ground-blast furnace alkali-activated slag . . . . .  221 – 228

Harun Tanyıldızı, Salih Yazicioglu:
Determination of optimum conditions for bond and compressive strength
of concrete containing mineral admixtures by Taguchi method . . . . . . . . . . . . . . 229 – 242

Abstracts

Stability of shallow shell as a ceiling panel
Martin Psotný, Ján Ravinger

The combination of the shallow thin concrete shell and steel tie is offered as the ceiling panel. The cylindrical shallow shell is approximated as the shallow arch. Big differences between the results from the linear stability solution and geometric nonlinear solution emphasize the necessity of using the full geometric nonlinear analysis including investigation of the effects of initial imperfections. The stable and unstable paths and the bifurcation point have been followed.
Keywords: stability, shallow shell, shallow arch, geometric nonlinear solution, stable and unstable paths, bifurcation point, snap-through effect, initial imperfections

Lateral resistance of partially infilled masonry wall in concrete frame structures
P. M . Pradhan, P. L. Pradhan, R. K. Maskey

The analyses of infilled frame structures are generally done ignoring the presence of brick masonry in the analytical models. The real behavior of such buildings thus will vary during the earthquake events. Researches show that an infilled framed structure actually perform better against earthquake forces, however, when a structure is only partially infilled, the phenomena is again different. The lateral resisting capacity of infilled wall actually restricts the windward column only up to the wall height but above the wall height the free column deforms easily. In this paper, the resistance of partial infilled wall has been analyzed and it is concluded that if the wall height is reduced to less than 50 % of the clear frame height, the resistance increases significantly, thus allowing more shear in the windward column. The equivalent width of partial infill is also recommended.
Keywords: short column effect, partial masonry infill, lateral resistance, strut width

Hydration products derived from ground-blast furnace alkali-activated slag
M. J. Martínez Alvarado, E . Rocha-Rangel, S. D. De LaTorre, M. Díaz-Cruz

Pretending the use of granulated slag from the blast furnace as an alternative cementing compound for the construction of oil wells, a thermal analysis regarding the progress of hydration of the slag, the  same that was activated with NaOH, was conducted. The hydration in those slag experiments during 1, 3, 7, 14 and 28 days was carried out using different analysis techniques. Such as scanning electron microscopy, X-ray diffraction and infrared spectroscopy by Fourier transform. The results show that the hydration products of slag include: hydrated calcium silicate, hydrotalcite, stratlingite, AFt phase (ettringite) and calcite. Likewise, there were observed diffraction peaks corresponding to gehlenite and merwinita crystalline phases that are typical of the granulated blast furnace slag. The presence of these hydration products leads to the potential use of granulated blast furnace slag as viable for being used as cementitious material.
Keywords: hydration products, ground-blast furnace, alkali-activated slag, Portland cement

Determination of optimum conditions for bond and compressive strength of concrete containing mineral admixtures by Taguchi method
Harun Tanyıldızı, Salih Yazicioglu

In this study, the optimum conditions for the bond and compressive strength of concrete were determinate using the Taguchi method. This article adopts Taguchi`s approach with an L36 (211 x 312) to reduce the numbers of experiment. Four control factors (type of mineral admixtures, maximum size of aggregate, rebar diameter, and curing conditions) were used for this study. The specimens were cured in different curing conditions for 28 days. At the end of a curing period, the specimens were tested for the bond and compressive strength. The results showed that based on the Taguchi method, the maximum bond strength of concrete was obtained at 16 mm aggregate grain diameter, 14 mm rebar diameter, water curing and silica fume admixture. Furthermore, the maximum compressive strength of concrete was obtained at 16 mm aggregate grain diameter, water curing and silica fume admixture.
Keywords: concrete, rebar, bond strength, compressive strength, Taguchi method