Seismic Microzonation of Great Toronto Area and Influence of Building Resonances on Measured Soil Responses
Notice bibliographique
Résumé
A pilot seismic microzonation of the Greater Toronto Area (GTA) is used to establish the conditions and limitations of geophysical methods for site response investigations in city conditions. Maps of fundamental soil resonant frequencies, amplifications at these frequencies and interpolated average shear wave velocity of top 30 m of soil profile (VS- 30) used in soil classification were compared to the maps of drift thickness and surficial geology for the GTA. The non-applicability of the interpolated VS-30 map for site classification between measured test points is indicated. It is also shown that the soil response cannot be estimated properly using VS-30 values only. In order to enhance the capability of the horizontal-to-vertical-spectral-ratio (HVSR) method to resolve the fundamental soil resonances, a procedure and a computer program were developed for separation of ambient vibrations from nearby traffic as well as distant sources using the recorded waveforms before calculating the HVSR. A portable seismic station was developed for field HVSR waveforms recordings. It was also used for identification of building vibration modes. The influence of building vibrations on the HVSR result was investigated considering a benchmark building before construction started and after its completion. This influence is expressed as suppression or split-up of HVSR resonance if the building and soil resonances are close. This effect spreads out to distances comparable to the maximum dimension of the building. The experimentally obtained building resonant frequency at first vibration mode was found to be significantly higher than that calculated using empirical equations proposed by building codes, while the damping factor was less than the prescribed value. Additionally, the concept of using the HVSR inside a building to identify its resonances was examined using recorded waveforms, but the results did not confirm applicability of the HVSR for this purpose. The limitations and initial conditions that are necessary for successful implementation of refracted shear wave seismic profiling (SH-profiling) and multi-channel-analysis-ofsurface- waves (MASW) methods for application in urban areas are discussed. The problems with interlaying low velocity soil layer are pointed out. The soil response functions obtained from the microzonation studies using low intensity seismic sources differ from the response during an earthquake. An approach to estimate the changes of soil response in relation with expected Peak Ground Velocity (PGV) and Intensity of Modified Mercalli Scale (IMM) is proposed. The results were found to be in agreement with strong motion data from the epicentral area of a strong earthquake. It was concluded that the results from seismic microzonation studies should be considered in conjunction with models that simulate the change in dynamic characteristics of soil and buildings during expected earthquake events.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».