Characteristics of horizontal ground motion measures along principal directions

Abstract

Ground motion records are often used to develop ground motion prediction equations (GMPEs) for a randomly oriented horizontal component, and to assess the principal directions of ground motions based on the Arias intensity tensor or the orientation of the major response axis. The former is needed for seismic hazard assessment, whereas the latter can be important for assessing structural responses under multi-directional excitations. However, a comprehensive investigation of the pseudo-spectral acceleration (PSA) and of GMPEs conditioned on different axes is currently lacking. This study investigates the principal directions of strong ground motions and their relation to the orientation of the major response axis, statistics of the PSA along the principal directions on the horizontal plane, and correlation of the PSA along the principal directions on the horizontal plane. For these, three sets of strong ground motion records, including intraplate California earthquakes, inslab Mexican earthquakes, and interface Mexican earthquakes, are used. The results indicate that one of the principal directions could be considered as quasi-vertical. By focusing on seismic excitations on the horizontal plane, the statistics of the angles between the major response axis and the major principal axis are obtained; GMPEs along the principal axes are provided and compared with those obtained for a randomly oriented horizontal component; and statistical analysis of residuals associated with GMPEs along the principal directions is carried out.

Should ground-motion records be rotated to fault-normal/parallel or maximum direction for response history analysis of buildings?

“…Penzien and Watabe (1975) defined the principal axes of a pair of ground motions as the angle or axis along which the two horizontal components are uncorrelated. The principal axis is independent of the vibration period (Goda, 2012) and is not correlated with the MD (Hong and Goda, 2010). Using this idea of principal axis, the effects of seismic rotation angle, defined as the angle between the principal axes of the ground-motion pair and the structural axes along which structural response was studied (Fernandez-Davilla and others, 2000; MacRae and Matteis, 2000; Tezcan and Alhan, 2001; Khoshnoudian and Poursha, 2004;Rigato and Medina, 2007;Lagaros, 2010;Goda, 2012), previous studies demonstrate that the rotation angle of ground motions influences the structural response significantly and that the angle that yields the peak response over all possible nonredundant angles, called θ critical (or θ cr ) depends on the seismic excitation level and character of shaking.…”

Influence of spectral acceleration correlation models on conditional mean spectra and probabilistic seismic hazard analysis

“…For example, the correlation associated with the period pair ρ [ ɛ ( T 1 = 0.1 s), ɛ ( T 2 = 1.0 s)] is equal to 0.88. In this sense, Hong and Goda 18 examined the correlation of spectral accelerations along the principal directions of ground motions (interplate events) recorded at sites along the coast of Mexico. They found that the correlation values remained high even for well‐separated vibration periods.…”

“…In order to answer this question, we compare the applicability of this model and three additional ones, for predicting the observed data from the present study (Figures 4A and 6A). The compared correlation models used in this study are those proposed by Baker and Cornell, 2 Baker and Jayaram, 9 Hong and Goda, 18 and Jaimes and Candia, 19 hereafter referred as BC06, BJ08, HG10, and JC19, respectively. In this regard, Figure 7A–D illustrates the contour plots of correlation coefficients as a function of the vibration periods T 1 and T 2 .…”

“…They suggest that the correlation coefficients depend on the vibration period and type of earthquake. Recently, Jaimes and Candia 19 adapted the functional form proposed by Baker and Jayaram 9 for interplate events focused on the same area and ground‐motion database used in Hong and Goda 18 . The advantage of this correlation model is a better prediction of correlation coefficients for vibration periods widely spaced between them.…”

Site, local, and regional earthquake ground motion characterization and application

“…Sketch of the coordinate system and the variation of SA: (a) coordinate system, (b) SA for T n = 1.5 s, (c) SA for T n = 2.5 s, (d) ratio of A G (T n ,g)/A G (T n , G cr ) for interplate earthquakes, and (e) A G (T n ,g)/A G (T n , G cr ) for inslab earthquakes. (d) and (e) are replots of those given in Hong and Goda (2010).…”