In this study, weight optimization of two dimensional steel frames is carried out in
which the flexibility of beam-to-column connections and the soil-structure
interaction are considered. In the analysis and design of steel frames, beam-tocolumn
connections are assumed to be either fully rigid or perfectly pinned.
However, the real behavior of beam-to-column connections is actually between
these extremes. Namely, even the simple connections used in practice possess some
stiffness falling between these two cases mentioned above. Moreover, it is found
that there exists a nonlinear relationship between the moment and beam-to-column
rotation when a moment is applied to a flexible connection. These partially
restrained connections influence the drift (P- effect) of whole structure as well as
the moment distribution in beams and columns. Use of a direct nonlinear inelastic
analysis is one way to account for all these effects in frame design. To be able to
implement such analysis, beam-to-column connections should be assumed and
modeled as semi-rigid connections. In the present study, beam-to-column
connections are modeled as &ldquo / end plate without column stiffeners&rdquo / and &ldquo / top and seat
angle with web angles&rdquo / . Soil-structure interaction is also included in the analysis.
Frames are assumed to be resting on nonlinear soil, which is represented by a set of
axial elements. Particle swarm optimization method is used to develop the optimum
design algorithm. The Particle Swarm method is a numerical optimization technique
that simulates the social behavior of birds, fishes and bugs. In nature fish school,
birds flock and bugs swarm not only for reproduction but for other reasons such as
finding food and escaping predators. Similar to birds seek to find food, the optimum
design process seeks to find the optimum solution. In the particle swarm
optimization each particle in the swarm represents a candidate solution of the
optimum design problem. The design algorithm presented selects sections for the
members of steel frame from the complete list of sections given in LRFD- AISC
(Load and Resistance Factor Design, American Institute of Steel Construction).
Besides, the design constraints are implemented from the specifications of the same
code which covers serviceability and strength limitations. The optimum design
algorithm developed is used to design number of rigid and semi-rigid steel frames.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12612281/index.pdf |
| Date | 01 August 2010 |
| Creators | Dogan, Erkan |
| Contributors | Saka, Mehmet Polat |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | Ph.D. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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