Assessment of The Design and Performance of Primary and Secondary Seismic Members Of Reinforced Concrete Dual System
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Date
2017-12
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Journal ISSN
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Publisher
Addis Ababa University
Abstract
From recent earthquake experiences, buildings with structural walls do have satisfactory
performance against collapse. However, this is not always true for dual structures composed
of both structural walls and frames resisting seismic actions. This begs for a detailed study on
the performance of dual structures. Some studies show that the elastic response of dual
buildings is mainly governed by the wall response and the frame contribution could be
neglected, which then makes them a secondary seismic member. This scenario is reversed
while the members are within their inelastic nature. These variations make it difficult to
select and identify primary and secondary members based on stiffness limitation specified in
codes which is only based on the linear response of the members. Without clearly identifying
the distinction between these members in a structure, and without clearly knowing the
boundary between these seismic members it is difficult to follow the simplified approaches of
analysis in practice, in which lateral load is resisted by some selected and properly detailed
members.
Hence, to address the effect of considering frames as secondary seismic members in RC wallframe
system,
comparative
analysis
among
sample
dual
system
buildings
has
been
carried out
in
the following thesis work. Efforts have been made to evaluate the overall seismic
performance of the buildings using non-linear push over analysis method. For each building
under study two cases are examined. In the first case frames and shear walls are designed and
detailed as primary seismic members. In the second case however, frames are designed as
secondary seismic members and shear walls are designed and detailed to be primary seismic
resistance contributors. The results of non-linear push over analysis were obtained for each
case in the form of capacity curves, global yielding point and performance point, plastic
hinge formation patterns, and base shear distribution among frames and walls.
The observation of these results shows that the overall seismic resistance capacity of
buildings reduces when frames are considered as secondary seismic members. In conclusion
of this study; in RC wall-frame dual system, it is important to design both frames and walls as
primary seismic members.
In addition, frames take up larger bases shear in the inelastic range than what is estimated in
the linear analysis, which makes it incorrect to regard these members as secondary seismic
members according to most building codes specification of base shear resistance proportion between primary and secondary members. To minimize the effect of neglecting frames as
secondary members, the stiffness limitation specified in code should be revised.
Description
Keywords
Reinforced Concrete, Seismic Members, Reinforced Concrete Dual System