In a structural design, it is necessary to obtain an appropriate geometric shape
for the structure, so that it can carry the imposed loads safely and economically.
This can be achieved by the use of Structural Shape Optimization (SSO) procedures,
in which the shape and/or the thickness of the components of the structure are
varied to achieve a specific objective satisfying certain constraints. Many structures
gain considerable rigidity (stiffness) by the modification of their thickness variation
and structural shape. Such rigid structures have higher resistance against
deformation and may, therefore, be considered structurally more efficient.
The SSO of rectangular plates with prescribed movement directions of
shape design variables was studied by Rupesh and Ramana (2008a; 2008b and
2010), with strain energy and stress leveling index minimization as objectives. Hinton et al. (1991a and 1991b), Ramana and Hinton (1993), Hinton et al. (1993), Hinton and Ramana (1993a, 1993b and 1993c), Hinton et al. (1994), Ozakca and Taysi (2003) and Ramana and Hinton (1994a and 1994b) have presented
a comprehensive study covering the static and free vibration analysis and
optimization of prismatic and axisymmetric shell structures. Hartman and Neumann
(1989), Cheung and Cheung (1971 and 1972), and Sisodiya and Ghali (1972)
have analyzed the box girder bridges using Finite Strip method.
The Finite Element (FE) optimization of structures was studied by Mohr
(1994). Much of the literature is available on the shape
optimization, and many researchers dealt with the
SSO with different objective functions and geometric constraints. However, in
many cases, the optimum shapes of structures, particularly box girder
bridges, are obtained using the Finite Strip method completely. To the authors' knowledge, no work
has been reported on the analysis and optimization of box girder bridges using the
FE method completely. |
