الفهرس 
LITERATURE REVIEWOnly 14 pages are availabe for public view
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Abstract
In the past decade, the use of hollow flange beams (HFB) has found many
applications in the building industry and it has been used in many projects
instead of the common C and Z cold-formed sections. The unique shape of
HFB, comprising two torsionally stiff hollow flanges and a slender web, is a
double-edged weapon. As it overcomes most of the disadvantages of open coldformed
sections,
it
is
the
main
reason
for
limiting
the
bending
capacity
of
HFB
to
its lateral distortional buckling (LDB) capacity. The current study aims at
optimizing the cross sectional configurations of HFBs for performance
improvement. Also, an investigation to alleviate LDB using web stiffeners with
different configurations is performed.
A brief introduction and literature review of previous works in the field of
hollow flange beams is presented. Also, a summary on the cold-formed works
and different welding processes is introduced. The finite element model used to
solve the current problem is presented and validated by comparing its results
with experimental results found in the literature. The model takes into account
material and geometric non-linearities as well as the initial geometric
imperfections and the residual stresses.
84 models are performed to study the configuration of the HFB taking
variable parameters as; flange depth-to-flange width ratio, width of plate
performing the HFB section and beam span. A comprehensive parametric study
is conducted to study the best geometric configuration of hollow flange beams
against LDB. Values for the hollow flanges aspect ratios ranging from 0.67 to
0.80 are recommended for better cross sectional utilization A comparison between finite element results and the current design rules
is conducted and found that the current rules are conservative when dealing with
HFB. A modification to the HFB slenderness equation, presented in the
AS/NZS-4600 (2005) standards, is proposed to accurately predict the bending
strength of the HFBs.
The finite element study is extended to study the effect of adding web
stiffeners to the HFBs. 59 models are performed in this study using the
proposed best section configuration. The spacing between stiffeners as well as
stiffener depth and thickness are taken as the variable parameters. The obtained
results revealed that the gain in bending strength of the HFB is directly
proportional to both the web ratio and the unsupported length of HFBs. New
equations that accurately predict the bending capacity of strengthened HFBs are
also proposed.
Finally, a summary of the work carried out in this thesis along with
general conclusions obtained from the study and recommendations for future
studies in same field are presented.
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