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Re: dynamic analysis - Tacoma Narrows - pushover analysis?

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On Jun 8, 2005, at 8:26 AM, refugio rochin wrote:

Cannot a pushover analysis take the place of a dynamic analysis.
Sometimes this is the more complicated method, and takes into
account the ductility of the structure much more readily than a
time-history or spectrum analysis, no?
Two different things. The pushover analysis is non-linear quasi-static, so the dynamic loading characteristics have to be fudged into the applied loading. Ordinary linear dynamics doesn't apply to non-linear behavior, except with some fudging on the spectra.

You can do a dynamic pushover analysis using time-history methods, but it's a huge pain in the ass and has a whole litany of approximations of its own, not the least of which is getting a realistic but practicable load set. You can generate a synthetic earthquake record from a response spectrum, but it's not a very satisfactory process, and only a statistical artifice.

Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw(--nospam--at)   | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania 1864)

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