Seismic Performance of Gravity Load Designed Reinforced Concrete Frames with Unreinforced Masonry Infill Walls
Bibliographic record
Abstract
A significant portion of the existing building stock constructed prior to the enactment of modern seismic design provisions consists of Gravity-Load-Designed Reinforced Concrete (GLDRC) frames and unreinforced masonry infill walls which were used as partition walls in those buildings. Common construction practice before modern seismic design codes appeared, allowed the use of columns lap splices above the slab in each floor or above the foundation. The splices were typically 20 to 24 longitudinal bar diameters in length. Shear reinforcement was in the form of stirrups with 90-degree bends and spaced at half the depth of the frame member. As a result, the section at the base of these columns is unconfined and susceptible to shear failure or to a premature failure of the lap splices before yielding of the longitudinal bars, under reversed cyclic loadings in the event of an earthquake. The masonry infill walls used as partitions were often ignored by design engineers since such walls were considered as non resistant architectural elements. However, lessons learned from past earthquakes and from several tests performed have shown that those walls tend to interact with the bounding frame when the structural system is subjected to moderate or severe earthquake ground motions and that such interaction may not be beneficial to the performance of the structure. This paper presents the results of a series of tests, one monotonic and several shake table tests, conducted on two similar 1/2 scale gravity-load-designed reinforced concrete frames containing an unreinforced masonry infill wall built using hollow concrete blocks. One specimen was subjected to a static monotonic lateral loading and the other to prescribed simulated ground motions at different intensities to identify the interaction between the reinforced concrete frame and the masonry infill wall, the degradation in stiffness, and failure mechanism. The tests were conducted at the Earthquake Engineering Research Facility at the University of British Columbia in Vancouver, Canada.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".