الفهرس 
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Abstract
High-rise buildings have become increasingly important in the new era, and therefore many
new developments appear in the structural systems of high-rise buildings with increasing
heights around the world. As a result, this study gives light on the systems used in resisting
lateral loads, especially the tube systems, which are characterized by their great efficiency
in resisting lateral loads, and this system has many categories, which are tube-in-tube,
framed, hybrid, and bundled tube.
This study is based on evaluating and comparing the seismic characteristics of these
systems according to the Egyptian and American codes, as well as studying and calculating
the seismic response coefficient (R-reduction factor) represented in the ductility coefficient
and the over-strength coefficient through an analytical study of the tube systems and
comparing the resulting values with the values used in the international codes. But this
study is not limited to that; it also studies the natural frequency and natural period of the
building by creating a Fortran program using the direct stiffness method, Dived and
Conquer, conjugate gradient method to determine the frequency, mode shape and lateral
seismic displacements of the building in an effort to obtain the greatest advantage and
benefit from the tube systems and keep up with modern developments in the field of highrise buildings.
The study was carried out on two buildings, one framed tube and the other mega tube frame
with 15 floors, using software programs, ETABS. The two buildings were designed in
accordance with ECP and ACI, and a pushover analysis was carried out using the two
programs to determine the response modification factor. in addition, in this study we
developing a new solver to perform dynamic analysis for high-rise buildings based on two
numerical methods: the divide-and-conquer method and the conjugate gradient method.
The Divide and Conquer method were used to calculate all the natural frequencies and
mode shapes for tubular-tall buildings, and the displacements due to lateral forces were
calculated using the conjugate gradient method.