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A new direct damage-controlled
design method for plane steel frames under static loading is presented. Seismic
loading can be handled statically in the framework of a push-over analysis.
This method, in contrast to existing steel design methods, is capable of
directly controlling damage, both local and global, by incorporating continuum
damage mechanics for ductile materials in the analysis. The design process is
accomplished with the aid of a two-dimensional finite element program,
which takes into account material and geometric nonlinearities by using a
nonlinear stress-strain relation through the beam-column fiber modeling and
including P-δ and P-Δ effects, respectively. Simple expressions relating damage
to the plastic hinge rotation of member sections and the interstorey drift
ratio for three performance limit states are derived by conducting extensive
parametric studies involving plane steel moment-resisting frames under static
loading. Thus, a quantitative damage scale for design purposes is established.
Using the proposed design method one can either determine damage for a
given structure and loading, or dimension a structure for a target damage
and given loading, or determine the maximum loading for a given structure
and a target damage level. Several numerical examples serve to illustrate
the proposed design method and demonstrate its advantages in practical
applications.
Keywords
continuum damage mechanics, damage control, steel
structures, design methods, beam-column, finite element
method, second order effects, elastoplastic behavior