Optimum design of geometrically nonlinear steel frames with semi-rigid connections using improved harmony search method
Abstract
The improved harmony search method based
optimum design algorithm is presented for
geometrically non-linear steel frames with semirigid
connections. In the analysis of steel frames the
real behaviour of connections are generally
idealized either pinned or fully rigid. The rigid
connection idealization indicates that relative
rotation of the connection does not exist and the end
moment of the beam is entirely transferred to the
column. In contrast to the rigid connection
assumption, the pinned connection idealization
indicates that any restraint does exist for rotation of
the connection and the connection moment is zero.
Although these idealizations simplify the analysis
and design process, the predicted response of the
frame may be different from its real behaviour.
Numerous experimental studies proved that all
beam-to-column connections posses some flexural
stiffness between these two extreme assumptions.
The term semi-rigid is used to express the real
connection behaviour.
The moment-rotation relationship is the most
important factor for the semi-rigid connection
behaviour. The modelling of beam-to-column
connections and predicting the real behaviour of
them have been demonstrated by a number of
experimental and numerical works. Moreover,
experimental studies proved that moment-rotation
curves of semi-rigid connections are non-linear. The
nonlinearity of connection behaviour is due to a
number of factors such as material discontinuity of
the connection subassemblage, local yielding of
some component part and local buckling of a plate
element. Several mathematical models are
developed to curve fit the experimental data of
beam-to-column connections. These models vary
from a linear model to polynomial and exponential
models. In this study, the semi-rigid connections are
modelled with the Frye-Morris polynomial model
because of its easy implementation.
The non-linear analysis of steel frames with semirigid
connections includes both the geometrical nonlinearity
of beam-column members and non-linearity
due to end connection flexibility of beam members.
The columns of frames are continuous and do not
have any internal flexible connections. However, the
beams possess semi-rigid end connections, but have
small axial forces with a geometric non-linearity of
little importance. Based on these considerations, two
types of members are defined to design of steel
frames with semi-rigid connections. These are beamcolumn
member and beam member with semi-rigid
end connections.
Classical harmony search method is recently
developed metaheuristic algorithm which simulates
the process of producing a musical performance.
The harmony search is quite sensitive to the tuning
parameters which are harmony memory size,
harmony memory consideration rate and pitch
adjusting rate. The constant values are used for the
tuning parameters in the pure harmony search
algorithm. Since the values of these parameters are
selected depending on the problem, the efficiency of
the harmony search algorithm is directly affected by
the tuning parameter values. In order to eliminate
the parameter dependent character of the pure
harmony search algorithm, pitch adjusting rate is
updated in each search step. Therefore, the
effectiveness of the classical harmony search
algorithm is increased.
The optimum design algorithm aims at obtaining
minimum-weight steel frames by selecting from
standard set of steel sections such as European wide
flange beams (HE sections). Strength constraints of
Turkish Building Code for Steel Structures (TS648)
specification and displacement constraints are used
in the optimum design formulation. The robustness
of improved harmony search algorithm, in
comparison with classical harmony search and
genetic algorithms, is verified with a benchmark
example. The comparisons revealed that the
improved harmony search algorithm yielded lighter
frames for the presented example.
Geometrik bakımdan lineer olmayan yarı-rijit birleşimli çelik çerçevelerin gelişmiş armoni arama yöntemiyle optimum tasarımı
Abstract
Bu çalışmada geometrik bakımdan lineer olmayan yarı-rijit birleşimli çelik çerçevelerin gelişmiş armoni
arama yöntemi ile optimum tasarımı için bir algoritma sunulmuştur. Armoni arama; müzisyenlerin en iyi
armoniyi bulmak için izledikleri yol ile optimizasyon problemleri arasında benzerlik kuran bir yöntemdir.
Gelişmiş armoni arama yöntem ile optimum tasarım esnasında kullanılan arama parametresinin her arama
işlemi sonrasında güncellenmesi sağlanarak klasik armoni aramadan daha etkili bir yöntem elde edilmeye
çalışılmıştır. Tasarım işleminde amaç gerilme ve deplasman sınırlayıcıları altında minimum ağırlıklı çelik
çerçevenin elde edilmesidir. Gerilme sınırlayıcıları olarak çelik yapıların hesap ve yapım kuralları
yönetmeliğindeki (TS 648) eksenel kuvvet ve eğilmeye maruz çubukların gerilme tahkiki formülleri
kullanılmıştır. Çelik çerçevelerin analizinde hem çerçeve elemanlarının geometrik bakımdan lineer olmama
etkileri hem de kiriş-kolon birleşimlerinin yarı-rijit davranışı hesaba katılmıştır. Gelişmiş armoni arama
yönteminden elde edilen sonuçları kıyaslamak için daha önce genetik algoritma ve klasik armoni arama
yöntemiyle optimum tasarımı yapılmış bir çelik çerçeve kullanılmıştır. Bu kıyaslamalar sonucunda gelişmiş
armoni arama ile daha hafif çerçevelerin elde edildiği görülmüştür.
Details
| Other ID | JA55RG56MA |
|---|---|
| Journal Section | Articles |
| Authors | |
| Publication Date | June 1, 2011 |
| Submission Date | June 1, 2011 |
| Published in Issue | Year 2011 Volume: 2 Issue: 1 |