FIRE PERFORMANCE OF CONCEALED WOOD-STEEL-WOOD CONNECTIONS WITH PERPENDICULAR TO GRAIN REINFORCEMENT
Notice bibliographique
Résumé
The use of wood as a construction material for high-rise and non-residential buildings has significantly increased over the past decade around the world.This trend leads to a need to conduct research on timber connections to meet the fire-resistance ratings required by building codes.Timber connections are typically the weakest link in heavy timber structures subjected to a fire.Recent research has shown that the predominant failure modes of concealed connections, which is the connection type most used in the industry, at both ambient and elevated temperatures are perpendicular-to-grain tensile splitting and parallel-to-grain row shear out.The majority of research on the use of reinforcement to strengthen concealed connections against such failure modes has been conducted at ambient temperatures.There are only a very few studies that deal with the behaviour of concealed connections with reinforcement in fire.This study aimed to investigate the fire behaviour of these connections by considering the effects of parameters such as the number of bolts, bolt pattern and load ratios.The connections used for this study were fire-protected glulam beam-to-column reinforced concealed connections loaded perpendicular-to-grain resulting in bending moment on the connection.Eight (8) full-scale fire tests were conducted involving four different connection configurations.All metal connecting components, i.e., bolt heads and nuts, and steel plate edges were fire protected using wood plugs and strips, respectively.The connections were designed in accordance with the Canadian engineering design in wood standard, CSA O86-14, and the fire tests were conducted in compliance with the CAN/ULC-S101 standard procedure.The specimens were reinforced perpendicular-to-grain with six (6) or eight (8) fully-threaded selftapping screws (STS) depending on their bolt number, and exposed to elevated temperatures that follow the CAN/ULC-S101 standard fire time-temperature curve while being constantly Abstract ii loaded perpendicular-to-grain with a transverse load.The load ratios applied during fire testing were 60%, 100% and 130% of the ultimate design load capacity of the weakest unreinforced connection configuration.A 1oad ratio of 100% was applied on four specimens consisting of four-and six-bolt connection configurations.Thereafter, two specimens with four-bolt connection configurations were subjected to a load ratio of 60% while the remaining two specimens with six-bolt connection configurations were subjected to a load ratio of 130%.The test results showed that the failure times of all the tested beam-to-column concealed connections were more than 50 minutes, which is higher than the 45 minutes rating prescribed in the National Building Code of Canada for combustible construction.Specimens with the two rows of bolts symmetrically positioned near the top and bottom sides of the beam cross-section (bolt pattern P1) performed better than specimens with the bottom row raised to the mid-height of the beam section (bolt pattern P2).The results showed that increasing the number of bolts from four (4) to six (6), improved the failure time by a factor of 1.25 and 1.07 in bolt patterns P1 and P2, respectively.Increasing the load ratio from 60% to 100% and from 100% to 130% decreased the failure time of the connections.The wood strips and plugs used to protect the metal parts of the connections prevented the wood around the T-stub flange from charring.The brittle failure modes frequently encountered in unreinforced concealed connections were prevented by the application of self-tapping screws and the specimens experienced a gradual failure in deflection.
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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 | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| 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) | 0,003 | 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 ».