科研之友
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摘要
Residual displacements of single-degree-of-freedom systems due to ground motions with velocity pulses or fling step displacements are presented as a function of period T and of its ratio to the pulse period T-p. Four hysteretic behaviors are considered: bilinear elastoplastic, stiffness-degrading with cycling, stiffness-cum-strength degrading, with or without pinching. When expressed in terms of T/T-p, peak inelastic and residual displacements due to motions with a pulse or fling appear similar to those due to far-fault motions, if the response to far-field records are expressed in terms of the ratio of T to the record's characteristic period. However, as the latter is usually much shorter than the pulse period of motions with fling, the range of periods of interest for common structures becomes a short-period range under fling motions and exhibits very large amplification of residual and peak inelastic displacements. Similar, but less acute, are the effects of motions with a velocity pulse. Wavelets of different complexity are studied as approximations to near-fault records. Simple two-parameter wavelets for fling motions overestimate peak inelastic displacements; those for pulse-type motions overestimate residual displacements. A more complex four-parameter wavelet for motions with a velocity pulse predicts overall well residual and peak displacements due to either pulse- or fling-type motions; a hard-to-identify parameter of the wavelet impacts little computed residual displacements; another significantly affects them and should be carefully estimated from the record. Even this most successful of wavelets overpredicts residual displacements for the periods of engineering interest.
- 出版日期2016-7-25
