Finite Element Modelling of Anchorage to Concrete Systems at Different Strain Rates
Notice bibliographique
Résumé
Demand for flexibility in design and faster construction times has resulted in the increasing use of fasteners in a variety of concrete structures.These structures are exposed to static and dynamic loading conditions.Furthermore, these structures can be exposed to high strain rate loading such as encountered in impact and blast loads.Thus, anchorage systems used to fasten elements to concrete structures are also exposed to the high strain rates of loading which can be tensile and shear loads.If not adequately designed and constructed, anchorages can fail in a catastrophic manner and pose significant threat to building safety and the life of building occupants.Behaviour of anchors embedded into concrete and subjected to static load has been widely investigated experimentally.However, despite the fact that many structures that contain anchorage systems are exposed to dynamic loads, the research in this vital area is limited.Currently, no guidance is available in design codes for the anchorage response under high strain rate loading.The American Concrete Institute and Concrete Capacity Design methods are recommended for anchorage system subjected to static and low cycle dynamic loading only.Hence, there is a need to develop a design method to predict the anchorage response and capacity under impact and blast loading.The project presented in this thesis aims to investigate the tensile and shear behaviour of cast-in-place, adhesive and undercut anchors subjected to different strain rates using LS-DYNA software.Numerical models of the anchorage systems with different design parameters were developed and mesh sensitivity analyses were carried out to determine mesh sizes that best simulated the experimental results obtained from the literature.The iii ultimate static capacity results were verified with the design methods.Effect of strain rate, embedment depth, and anchor diameter on the tensile and shear failure loads was investigated.Failure modes for the anchorage systems were also examined at different strain rates.Concrete cone breakout diameter and failure cone angles were investigated.A relation between the ultimate loads and the strain rates was investigated and dynamic increase factors (DIF) for design were determined.Regression analysis was performed to predict a relation that accurately represents the finite element results.Results of the tensile and shear loading of the anchorage to concrete systems show that anchorage to concrete system capacity increases with an increase in the strain rates.The failure mode of the anchorage systems is influenced by the strain rate.Maximum DIFs of 1.74, 1.13 and 1.58 were obtained for the cast-in-place, adhesive and undercut anchors under tensile load respectively where concrete cone breakout failure mode was observed.Maximum DIFs of 1.17, 1.13 and 1.44 respectively were obtained for the cast-in-place, adhesive and undercut anchors exhibited steel failure mode.The maximum DIFs were 1.15, 1.18 and 1.45 respectively for the anchors subjected to shear load where steel failure was observed.
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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 | 0,001 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,001 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,002 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,003 | 0,001 |
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 ».