Effect of Diaphragm Discontinuity in Seismic Response of Multi Storey Reinforced Concrete L-Shape Building
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Date
2020-06-08
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Addis Ababa University
Abstract
Most recent seismic code put criteria for classified buildings to account the effect come shape
regularity. In the present research the buildings taken are regular in elevation and irregular in
plan (L-shape). After checking elevation regularity and fundamental period of vibration
satisfaction, the equivalent lateral force method of analysis used for analysis of earthquake
resistant buildings. Analysis was carried out reinforced concrete framed building where
parametric study made to structure exhibiting different opening location-shape planer with varied
projections and varied story height based on capacity design principle. Seismic design makes
use of energy absorption and dissipation to reduce the design forces in order to achieve economy
by properly accounting behavior factor based on code recommendation. Diaphragm discontinuity
plays a great role on the response of building when the building exposed to different types and
direction of loads. It affects the performance, top story displacement and base shear of building.
In this study, the evaluation of diaphragm discontinuity for elevation regular and plan irregular
ductile reinforced concrete structures using nonlinear analysis is investigated. The evaluation
was carried out by designing elevation regular and plan irregular structures for different
parametric condition (opening location, story height and projection lengths) with the provision of
the Ethiopian seismic code and by checking their performance through non-linear analysis using
CSI ETABS. In this study parametric study has been conducted using same parameters including
seismic location, ground type, and ductility class, loading condition, behavior factor and material
type for all models. Moreover, the evaluation of diaphragm discontinuity using different models
under the same conditions along with performance comparison of structures designed for same
ductility class (DCM) were carried out and the findings results are concluded as follows:- For
same stories on different slab opened down positions the top story displacement decreases when
pushed to both x-and y-direction, especially at the slab opened at the projection part and the
comparison values clearly states that for the slab opened down at an angle, main part and
projection part, the base shears have decreased respectively when pushed to the x-direction and
y-direction. For same stories on different projection lengths, the top story displacement increased
by the same percent when pushed to x-direction and decreased when projection length increase
to pushed to y-direction and the base shears decreased almost by same percent for all projections
when pushed to x-direction and while the projection length increased, the base shears decreased
respectively when pushed to y-direction. For different stories on same slab opened down
positions, the slab opened down in all stories led the top story displacement to be decreased
approximately by the same percentage when pushed to the x direction and when the story level
increased, the top story displacement decreased when pushed to y-direction and the base shears
decreased almost by same percent when pushed to the x-direction and the base shears decreased
when story height increased respectively, when pushed to the y-direction.
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Keywords
Diaphragm, Projection, Opened down, pushover