Influence of the inclination angle of self-tapping screws on the fire performance of CLT-concrete composite floor slabs
Bibliographic record
Abstract
In this study, four full-size slab-type timber-concrete composite (TCC) floor assemblies were experimentally examined under standard fire exposure. The main objectives of the study are to investigate the influence of the inclination angles of the self-tapping screws (STS) utilized as shear connectors on the fire performance of TCC floor slabs, achieve a 2-h fire resistance as a result of the composite action between a supporting cross-laminated timber (CLT) panel and a top concrete layer, and ultimately verify the residual strength of the TCC slabs after 2-h standard fire exposure. Each slab specimen comprises a 143-mm thick, 5-ply CLT panel topped with a 90-mm thick normal-strength concrete layer. The overall dimensions of each test assembly were 5300 mm long and 900 mm wide, with a 5000 mm clear span. Screws were installed following the shear flow direction at two different inclination angles (i.e., 30° and 45°), with each specimen duplicated. TCC floor assemblies were exposed to elevated temperatures following the CAN/ULC-S101 standard fire time-temperature curve while subjected to four-point flexure. The experimental results show that all test assemblies surpassed the 2-h fire resistance time with an average residual wood thickness of 48 mm. However, after 2 h of standard fire exposure, the 30° STS installation angle resulted in better performance of the TCC floor slabs with lower midspan deflections than a 45° installation angle. In addition, the residual strength tests conducted after the 2-h standard fire exposure show that a TCC floor slab with STS installed at 30° may produce an ultimate moment as much as 12 % greater than when the STS are installed at 45°. • Timber-concrete composite (TCC) slab-type floor assemblies offer advantages over beam-type assemblies due to exposure to one-dimensional charring from underneath only. • TCC floor assemblies can be designed to meet the required 2-h fire resistance rating, essential for creating tall, mass timber buildings with acceptable fire safety measures. • Appropriate design can enhance the fire resistance of CLT panels by converting a simple timber slab to an advanced TCC floor system by adding shear connectors and a top concrete layer. • After a 2-h standard fire exposure, the 30° STS installation angle resulted in better performance of the TCC floor slabs with lower midspan deflections than a 45° installation angle. • Residual strength tests showed that a TCC floor slab with STS installed at 30° may produce an ultimate moment as much as 12 % greater than when the STS are installed at 45°.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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) | 0.000 | 0.000 |
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 teacher head, 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".