FIRE PERFORMANCE OF CONCEALED WOOD-STEEL-WOOD CONNECTIONS WITH PERPENDICULAR TO GRAIN REINFORCEMENT
Bibliographic record
Abstract
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.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".