الفهرس 
The LITERATURE OF REVIEW
Gravity LoadsOnly 14 pages are availabe for public view
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Abstract
This chapter summarizes the work presented in the thesis and concludes the
results of it to develop recommendations for future studies according to the Egyptian
Codes, ECP-203(2007) and ECP-201(2012) to develop new structural system design
provisions.
6.2 Summary
This study is mainly concerned with the behavior of braced concrete columns over
reinforced concrete shear walls in high-rise buildings which used to resist loading in
high-rise buildings and lateral forces from wind and earthquakes instead of using shear
wall all over the height of the building. Parametric studies are carried out for six main
systems that are modeled in three dimensions as residential buildings with different
parameters and geometry. ETABS (v 15.2.2) is used to model and analyze this systems
using three dimensional linear analysis. The six systems are studied under the effect of
several parameters such as number of stories and the existence of bracing members
between columns or just tie beam. Their effect on bending moment values, shear force
and normal, as well as story displacement, and inter-story drift are analyzed.
Comparisons between the results show the difference between values and the
indifference between others values including the percentage of saving.
6.3 Conclusions
The main conclusions in this research are presented as follows:
1. Using columns with connecting beams and bracing (Truss system) as a structural
system in high rise buildings enhance the general behavior of RC shear walls.
2. The developed finite element models were found to be highly suited for the
analysis of high rise buildings, both in case of using solid shear walls, and in case
of using the equivalent truss system. 3. The equivalent truss system behavior showed that it is recommended to use this
system in the whole building height, and not in a limited number of floors at the
building top, in order to avoid high shear force variations at the level where the
system changes from “shear wall” to “truss”.
4. Use of a combined system of shear walls, and equivalent trusses in a building was
tested, and showed that the “equivalent truss system” carries less moment than the
“shear walls”. In addition, the shear force carried by the “truss system” is much
less than that carried by the “shear walls”, indicating that the majority of the forces
carried by the truss system are carried at the top floors.
5. In practical application in an actual building case, analysis results showed that the
transformation of shear walls into an equivalent truss system has the effect of
increasing the overall building stiffness, and reducing its total lateral drift at top,
when framing action exists in the whole building.
6. Models modified to minimize the above-mentioned framing action showed that the
truss system working on its own, without significant framing action in the building
is less stiff than the “shear wall” case. It is therefore recommended that
replacement of the shear walls by an equivalent truss system should be combined
with significant framing action in the building. For every building under design,
the two models should be analyzed, and decision to use the equivalent truss system
should be based on the amount of saving produced in the overall building cost.
7. Analysis of the actual building was performed using both equivalent static and
response spectrum methods. The analysis results showed that both models
produced similar results. The replacement of shear walls by equivalent truss
systems resulted in an approximately 5% reduction in building weight, which
reflected almost exactly in a similar reduction of about 5% in the base shear
observed in case of “Equivalent Static” analysis, and “Response Spectrum”
analysis.
8. Application of the proposed system showed to an actual case showed an
economical advantage. A reduction of 38% of concrete quantities in the shear
walls was observed for 20 story building, about 45% for 15 story building, and
about 46% for 10 story building.
9. Similar Reduction in steel quantities of about 11%, 19% and 38% for 20, 15, and
10 story buildings were observed respectively.