Dimensional analysis of dynamic interaction between adjacent SDOF buildings to forward directivity and fling step pulses

This paper investigates the consequences of well-known characteristics of near-fault ground motions on the seismic response of steel moment frames. Additionally, idealized pulses are utilized in a separate study to gain further insight into the effects of high-amplitude pulses on structural demands. Simple input pulses were also synthesized to simulate artificial fling-step effects in ground motions originally having forward directivity. Findings from the study reveal that median maximum demands and the dispersion in the peak values were higher for near-fault records than far-fault motions. The arrival of the velocity pulse in a near-fault record causes the structure to dissipate considerable input energy in relatively few plastic cycles, whereas cumulative effects from increased cyclic demands are more pronounced in far-fault records. For pulse-type input, the maximum demand is a function of the ratio of the pulse period to the fundamental period of the structure. Records with fling effects were found to excite systems primarily in their fundamental mode while waveforms with forward directivity in the absence of fling caused higher modes to be activated. It is concluded that the acceleration and velocity spectra, when examined collectively, can be utilized to reasonably assess the damage potential of near-fault records.

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Influence of floor system on seismic behavior of RC buildings to forward directivity and fling-step in the near-fault region

Structures ◽

10.1016/j.istruc.2021.01.052 ◽

2021 ◽

Vol 30 ◽

pp. 803-817

Author(s):

Sayed Mahmoud ◽

Ali Alqarni ◽

Joseph Saliba ◽

Amal H. Ibrahim ◽

Magdy genidy ◽

...

Keyword(s):

Seismic Behavior ◽

Rc Buildings ◽

Near Fault ◽

Forward Directivity ◽

Fling Step ◽

Floor System ◽

Fault Region

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Seismic response analysis of intake tower structure under near-fault ground motions with forward-directivity and fling-step effects

Soil Dynamics and Earthquake Engineering ◽

10.1016/j.soildyn.2020.106098 ◽

2020 ◽

Vol 132 ◽

pp. 106098 ◽

Cited By ~ 3

Author(s):

Xi Chen ◽

Yunhe Liu ◽

Binpeng Zhou ◽

Dixiong Yang

Keyword(s):

Seismic Response ◽

Ground Motions ◽

Response Analysis ◽

Seismic Response Analysis ◽

Near Fault ◽

Forward Directivity ◽

Fling Step ◽

Tower Structure

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Strong‐Motion Directionality and Evidence of Rupture Directivity Effects during the Chi‐Chi Mw 7.6 Earthquake

Bulletin of the Seismological Society of America ◽

10.1785/0120190087 ◽

2019 ◽

Vol 109 (6) ◽

pp. 2367-2383

Author(s):

Junju Xie

Keyword(s):

Strong Motion ◽

Clear Correlation ◽

Rupture Directivity ◽

Intensity Measures ◽

Long Period ◽

Forward Directivity ◽

Chelungpu Fault ◽

Fling Step ◽

Motion Directionality ◽

Directivity Effects

Abstract This article investigates the spatial distribution, predominant direction, and variations in the intensity measures (IMs) with orientation for classified pulse‐like and nonpulse motions during Chi‐Chi Mw 7.6 earthquake. The results show evidence of high polarization for long‐period spectral accelerations at relatively large source‐to‐site distances (50–100 km) north of the Chelungpu fault. The polarization of long‐period motions shows a clear correlation with the directivity parameters’ isochrone directivity predictor and ξ, indicating a connection between directionality and rupture directivity. The variation in strong‐motion directionality with the period is also studied. The discrepancy in directionality caused by strong directivity increases with the period from 1 to 10 s, which confirms a clear correlation of period‐dependent directionality with directivity effects. This study finds stronger directionality of pulse‐like motions than nonpulse motions for long periods over 3 s with higher maximum‐to‐median and maximum‐to‐minimum IM ratios. For periods over 3 s, the maximum‐to‐median ratios of pulse‐like motions are higher than the mean prediction of the Shahi and Baker (2014a) model, whereas those of nonpulse motions are lower than the prediction. However, this study does not find simple and clear results for the directions of the maximum component at different periods for pulse‐like and nonpulse motions. Despite clear differences between the unidirectional fling‐step and bidirectional forward directivity pulses, the effects of fling‐step and forward directivity are actually coupled in the waveforms.

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