Seismic Performance Assessment of Steel Diagrid structures in Multi-Story Reinforced Concrete Building
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Date
2020-10
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Addis Ababa University
Abstract
he current trends of construction industry demand tall and lighter structures. These tall
structures are very sensitive to Lateral loads induced by Earthquake, wind or ocean waves
than that of the gravitation loads. To resist the lateral loads several techniques are
available, out of the several techniques available diagrid structures are found as more
structurally efficient over other type of lateral load resisting system in developed countries
recently.
This type of lateral load resisting system (diagrid) has generated a good interest from
architects on aesthetic aspect and structural Engineers by their structural efficiency.
Diagrids or diagonal grids are a structural design approach for constructing buildings that
combine the resistance to gravity and lateral loads into a triangulated system of members
that eliminates the need for vertical columns. If this diagrid system constructed with
optimal configuration, the material consumption will efficiently increase.
This research paper, base the study on the previous researches and accept the structural
efficiency of diagrid structures than the other lateral load resisting system, mainly focused
on the seismic performance evaluation of three different stories (G+10, G+16 and G+22)
with different diagrid angle (53.13˚, 69.26˚, 75.57˚ & 79.22˚) located in two different
ground type (A & C). the results from the twenty-four model cases were compared to
verify the structural efficiency with different structural configuration using design
response spectrum analysis in ETABS 2016 v16.2.1 software for steel diagrid in reinforced
concrete building.
The analysis and design of these twenty-four (24) models of diagrid structures followed
the basic steps and approaches that are operational and practical in real world. Proposed
diagrid structure cases were to be situated in Hawassa, whose seismic zone is categorized
under Zone IV according to the ES EN 1998-1:2015 annex D Table. The lateral load
analysis of the study has been based on the new code ES EN 1998-1:2015. The analysis
has been done using finite element software ETABS 2016 v16.2.1. The performance
evaluation of these twenty-four case studies of diagrid buildings is mainly based on linear
analysis parameters, such as Fundamental vibration period, story displacement and interstory
drift.Based on the model cases considered in this study, Results has showed that Diagrid
structure has difference fundamental vibration period, story displacement and inter-story
drift based on their module angles considered for each case. From the linear analysis of
twenty-four of G+10, G+16 and G+22 story buildings, in ground type A & C with four
different module angles, a two story module or module diagrid angle 53.13˚ has shown a
smaller top displacement, smaller inter-story drift and smaller fundamental time period for
G+10 story building. Whereas module diagrid angle 69.26˚ and 79.22˚ has shown a smaller
top displacement, smaller inter-story drift and smaller fundamental time period for G+16
and G+22 story buildings respectively.
Therefore, according to the linear analysis results and comparative study of this thesis, it
can have concluded that for a better and significantly good performance, finding the
optimal module angle with respect to height to width aspect ratio is very recommendable.
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Keywords
Diagrid Structure system, Module angles, Design response spectrum analysis