Characterizing rotational components of earthquake ground motion using a surface distribution method and response of sample structures

This paper discusses the origins of torsion and its effect on the response of structures with a focus on the contribution of experimental data. The fact that torsion increases the stresses in structures, augmenting strain and damage during earthquakes, was confirmed in the 1960s. Over the years, the torsional response of structures has mainly been analysed through numerical studies, because few buildings are equipped with translational sensors, and even fewer are equipped with rotational sensors. This is likely to change as building instrumentation becomes more widespread and new generations of rotational sensors are developed. Therefore, this paper focusses on a number of scientific questions concerning the rotational response of structures during earthquakes and the contribution of experimental data to the understanding of this phenomenon.

Section: Experimental and Numerical Observation Of Torsionmentioning

confidence: 99%

The Torsional Response of Civil Engineering Structures during Earthquake from an Observational Point of View

Guéguen

2021

“…Even though most of these effects can be explained to result from pure translational ground-motion and are likely caused by the asymmetry of the constructions, there are indications that this is not always the case [15,102]. In fact, the structural response of buildings to rotational motions is widely unknown [103]. Despite indications that damage caused by rotational motions might be significant [104][105][106][107][108][109][110], earthquake hazard assessment was until recently almost exclusively based on the analysis of translational motion.…”

Section: Earthquake Engineeringmentioning

confidence: 99%

Seismological Processing of Six Degree-of-Freedom Ground-Motion Data

Sollberger

Igel

Schmelzbach

et al. 2020

Recent progress in rotational sensor technology has made it possible to directly measure rotational ground-motion induced by seismic waves. When combined with conventional inertial seismometer recordings, the new sensors allow one to locally observe six degrees of freedom (6DOF) of ground-motion, composed of three orthogonal components of translational motion and three orthogonal components of rotational motion. The applications of such 6DOF measurements are manifold—ranging from wavefield characterization, separation, and reconstruction to the reduction of non-uniqueness in seismic inverse problems—and have the potential to revolutionize the way seismic data are acquired and processed. However, the seismological community has yet to embrace rotational ground-motion as a new observable. The aim of this paper is to give a high-level introduction into the field of 6DOF seismology using illustrative examples and to summarize recent progress made in this relatively young field. It is intended for readers with a general background in seismology. In order to illustrate the seismological value of rotational ground-motion data, we provide the first-ever 6DOF processing example of a teleseismic earthquake recorded on a multicomponent ring laser observatory and demonstrate how wave parameters (phase velocity, propagation direction, and ellipticity angle) and wave types of multiple phases can be automatically estimated using single-station 6DOF processing tools. Python codes to reproduce this processing example are provided in an accompanying Jupyter notebook.

“…Accessibility to sensitive rotation sensors turns into the possibility of conducting not only theoretical works but also practical research in the field of geophysics, mining, and earthquake engineering. In the beginning, most of the research works were related to measurement of strong-motion seismology in far-field [18][19][20][21][22][23]. This is due to the fact that records of earthquakes with high magnitude allow determining the rotation rate and the general characteristics of 6-DOF (six-degrees-of-freedom) motion.…”

Section: Introductionmentioning

confidence: 99%

Near-Field Measurement of Six Degrees of Freedom Mining-Induced Tremors in Lower Silesian Copper Basin

Fuławka

Pytel

Pałac-Walko

2020

The impact of seismicity on structures is one of the key problems of civil engineering. According to recent knowledge, the reliable analysis should be based on both rotational and translational components of the seismic wave. To determine the six degrees of freedom (6-DoF) characteristic of mining-induced seismicity, two sets of seismic posts were installed in the Lower Silesian Copper Basin, Poland. Long-term continuous 6-DoF measurements were conducted with the use of the R-1 rotational seismometer and EP-300 translational seismometer. In result data collection, the waveforms generated by 39 high-energy seismic events were recorded. The characteristic of the rotational component of the seismic waves were described in terms of their amplitude and frequency characteristics and were compared with translational measurements. The analysis indicated that the characteristic of the rotational component of the seismic wave differs significantly in comparison to translational ones, both in terms of their amplitude and frequency distribution. Also, attenuation of rotational and translational components was qualitatively compared. Finally, the empirical formulas for seismic rotation prediction in the Lower Silesian Copper Basin were developed and validated.