Experimental Study on Shear Performance of Poplar LVL Beams with Opening in Bending-Shear Region
Bibliographic record
Abstract
To investigate the shear performance of Italian poplar laminated veneer lumber (LVL) beams with opening in the bendingshear region, six standard specimens were designed and tested under four-point bending.The shear failure mechanisms of the LVL beams with opening under various parameters were analyzed.The results show that the unperforated beam experiences bending failure due to tensile cracking at the mid-span.In contrast, beams with circular opening experience longitudinal shear failure at the ends due to stress concentration around the opening perimeter.The maximum transverse tensile strain around the opening perimeter forms an angle of approximately 45° or 225° relative to the longitudinal axis of beam, consistent with the crack initiation angle.As the diameter-to-height ratio increases to 0.5, both cracking and ultimate load capacities of the beams with circular opening significantly decrease, exhibiting more brittle shear failure.When the diameter-to-height ratio increases from 0.3 to 0.4 and 0. 5, the ratio of cracking to ultimate load capacity increases from 0.79 to 0.80 and 0.81, respectively.Using carbon fiber reinforced polymer (CFRP) wrapping around the openings effectively suppresses crack propagation and enhance the structural performance of the perforated beams.For the beam with a diameterto-height ratio of 0.4, the ultimately load decreases by 17.9% and 5.22%, respectively, for one and two layers of CFRP wrapping, compared to the unperforated beam.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 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) | 0.002 | 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 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".