الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Diagrid system is a structural system in which all external vertical columns are eliminated, leaving just triangular-shaped formed by inclined columns on the building’s façade creating a
unique view for the structure. Diagonal members can carry lateral loads and gravity loads due to
the triangular configuration by the axial force in diagonal members. The application of exterior
diagonals improves the esthetics of the building which in turn attracts the attention of architectural
and structural designers of tall buildings. Progressive collapse is the propagation of a local failure
from one element to another that causes the collapse of the building or a large part of it due to the
loss of one or more load-carrying elements. Recent research focused on the structural performance of diagrid structures whereas the
optimization of structural patterns of the diagrid system against progressive collapse has rarely
been investigated in the literature. The main objective of this study is to perform numerical
analysis to investigate the effect of the important parameters on the progressive collapse of the
diagrid system such as the inclination angle of diagonals, the number of stories, and the location
of removed diagonals. Finally, the difference between the two analytical methods, linear and
nonlinear are thoroughly investigated. ETABS software is used in the analysis model.
A parametric study is performed by modeling and analyzing a set of models considering
36, 48, and 60 storeys. To determine the optimum angle for the diagrid structural system, four
different inclination angles are studied, 50.2º, 67.4º, 74.5º, and 82.1º with 2, 4, 6, and 12-storey
modules, respectively. The progressive collapse-resisting capacity of diagrid buildings was evaluated based on arbitrary column removal scenarios according to UFC4-023-03-2009
guidelines and procedures using Alternate Load Path Method (APM). The results generated due
to the variation of the above-mentioned parameter were compared in terms of storey displacement,
inter-storey drift, storey shear, and percentage of increase in structure weight to find the optimum
angle which increase the capability of diagrid structure against progressive collapse. All models
were redesigned to detect the most practical and cost-effective angle to enhance the progressive collapse-resisting capacity. Linear and Non-linear static analyses have been performed to make a
complete assessment of the analysis. It is found that the diagrid system with 36, 48, and 60 stories
with an angle 74.5° provides less storey displacement and the lowest inter-storey drift which reflects more stiffness to the diagrid system, also consumes less tonnage of steel. Diagrid system
is more vulnerable to progressive collapse when corner braces are damaged. The Diagrid structure system is compared with the conventional braced Frame system. The study is performed by
considering the weights of diagrid structural systems with different diagonal angles with the
conventional columns/bracing system. It is found that the diagrid system with an inclination angle of 74.5° saves about (30% - 50%) of the structural building weight compared to the conventional system and when the number of stories increases, the percentage of saving in weight decreases.Non-linear static analysis (NSA) provides an accurate and optimum design with lower steel weight than linear analysis. NSA produces a reduction in steel weight by about 45% compared to the LSA.