Investigation of Soft Stories in Buildings with Hollow Block Slab

Year 2018, Volume: 13 Issue: 1, 37 - 44, 01.03.2018

Ozan Ince Humeyra Sahin Kursat Esat Alyamac Zulfu Cinar Ulucan

Abstract

Hollow
block slab is a floor slab system that consists of a thin slab and joists. In hollow
block slab system, nonstructural materials are used between joists. Hollow
block slab usually consists of wide and shallow beams. Because of low beam
height in this system, its lateral stiffness is less than beam floor systems.
Because hollow block slab has low lateral stiffness, using of this slab type increases
soft-story risk in buildings that have
soft-story risk. Therefore, in building with hollow block slab should be detailedly
investigated regarding soft-story. For
this reason, in this study buildings with stores of 5, 8 and 11, which constructed
with hollow block slab were numerically investigated for different ground story
height. According to analysis, lateral drift ratios was obtained for each story. As ground story height increased, the
lateral drift ratios of ground story with hollow block slab were increased nearly between 33% and 50%. As
the number of stories increased, the lateral drift ratios have approached upper
limit which is recommended by TEC-2007. The high values of lateral drift ratios
in ground stories increase soft-story risk. This situation has a negative
effect on building performance under lateral loads. For improving this negative
effect shear walls was added to the systems and analysis was repeated. Because
shear walls have decreased lateral drift ratios of ground stories nearly
between 40% and 60%, negative effect of increment in ground story was
decreased. It is agreed on that in high
seismic zone, buildings with hollow block slab should be designed as a frame-wall system for better building
performance.

Keywords

Hollow block slab, Soft-story, Lateral drift ratio, Reinforced concrete building

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