What does this research mean for the field?

Rotation-invariant ground-motion measures do not remove directionality but rather transform it, and their behavior is controlled by an effective anisotropy of pseudo-spectral acceleration that includes stochastic contributions from directional peak variability. Novelty: ClaimNovelty.METHODOLOGICAL. Consensus alignment: ConsensusAlignment.CHALLENGES_CONSENSUS.

What question did this study set out to answer?

Establish an analytical framework that models directional pseudo-spectral acceleration as a circular stochastic field to derive closed-form expressions for rotation-invariant intensity measures.

September 10, 2026Earthquake Engineering & Structural Dynamics

An Anisotropy‐Aware Framework for Directional Response Spectra and Rotation‐Invariant Ground‐Motion Measures

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Authors

RRRajesh Rupakhety VHVictor Moises Hernández-Aguirre

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Overview

Computational framework demonstrates that rotation-invariant ground-motion measures transform rather than eliminate directionality, highlighting anisotropy as a key driver of seismic hazard metrics.

Key Points

Establish an analytical framework that models directional pseudo-spectral acceleration as a circular stochastic field to derive closed-form expressions for rotation-invariant intensity measures.
Derived closed-form approximations for RotD50, MaxRotD50, and RotD100 by exploiting first admissible angular harmonic dominance in squared directional response.
Validated the derived analytical expressions across multiple periods against a large empirical ground-motion dataset.
Closed-form formulations produced essentially unbiased predictions across all evaluated periods while preserving empirical record-to-record variability.
Effective anisotropy governed max-type measures and elevated RotD100/RotD50 ratios via stochastic directional peak variability, even in motions with weak geometric anisotropy.
Identified pseudo-spectral acceleration anisotropy along principal root-mean-square response directions as the latent state variable controlling rotation-invariant metric behavior.

Cite This Study

Rupakhety et al. (2026) studied this question.

synapsesocial.com/papers/6aa27bbd58559d80afc7529f https://doi.org/10.1002/eqe.70293

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September 10, 2026Earthquake Engineering & Structural Dynamics

An Anisotropy‐Aware Framework for Directional Response Spectra and Rotation‐Invariant Ground‐Motion Measures

View Full Paper

Ask AI

Bookmark

Authors

RRRajesh Rupakhety VHVictor Moises Hernández-Aguirre

Discussion

Member takes

Overview

Computational framework demonstrates that rotation-invariant ground-motion measures transform rather than eliminate directionality, highlighting anisotropy as a key driver of seismic hazard metrics.

Key Points

Establish an analytical framework that models directional pseudo-spectral acceleration as a circular stochastic field to derive closed-form expressions for rotation-invariant intensity measures.
Derived closed-form approximations for RotD50, MaxRotD50, and RotD100 by exploiting first admissible angular harmonic dominance in squared directional response.
Validated the derived analytical expressions across multiple periods against a large empirical ground-motion dataset.
Closed-form formulations produced essentially unbiased predictions across all evaluated periods while preserving empirical record-to-record variability.
Effective anisotropy governed max-type measures and elevated RotD100/RotD50 ratios via stochastic directional peak variability, even in motions with weak geometric anisotropy.
Identified pseudo-spectral acceleration anisotropy along principal root-mean-square response directions as the latent state variable controlling rotation-invariant metric behavior.

Cite This Study

Rupakhety et al. (2026) studied this question.

synapsesocial.com/papers/6aa27bbd58559d80afc7529f https://doi.org/10.1002/eqe.70293

View Full Paper

Ask AI

Bookmark