Experimental Study of the In-Plane Behaviour of All-Masonry Infilled Frame Systems under Lateral Loading
Date
2020-12-08T14:01:57Z
Authors
Hosseini, Seyedali
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Abstract
This study is part of on-going experimental research, aiming to further investigate the in-plane behaviour of concrete masonry infills bounded by reinforced masonry frames (all-masonry infilled frames). A total of six all-masonry infilled frame specimens was tested under in-plane loading applied at the frame top beam level to specimen failure. The parameters studied included vertical loading, infill aspect ratio, presence of interfacial gaps, and cyclic loading. Two levels of vertical load were studied where the vertical load was applied through frame columns and held constant while the lateral load was monotonically increased to the specimen failure. In the infill aspect ratio study, two specimens with different aspect ratios (one squat and one slender) were constructed and tested under monotonic lateral loading. The last two specimens had window openings and pre-defined gaps and were tested under cyclic lateral loading.
Description
Load vs. displacement response, failure mode, and ultimate load for each specimen were obtained and discussed in detail. The performance of specimens was compared with previous studies conducted in the same research group. The experimental results were also used to evaluate the validity of stiffness and strength provisions contained in CSA S304.14 and TMS 402/602.16 masonry design standards.
The final failure mode for the infilled frame specimens was observed to be predominated by severe diagonal cracking extending into the boundary columns. Except for the specimen with side gaps and tested under cyclic loading, no evident corner crushing was observed. An increase in the vertical load resulted in an increase in the ultimate load but less ductile behaviour of specimens. When the vertical load was applied through frame columns vs. frame top beam, the above-mentioned trend was more pronounced. As the infill aspect ratio increased, the stiffness of the infilled frame decreased, and uplift at the specimen loaded side increased, indicating an increase in flexural behaviour in an otherwise shear action dominated behaviour. However, the ultimate strength appears to be controlled still by the length of the diagonal strut. The side gaps had a more effect on the specimen’s stiffness while the top gap had more detrimental effect on the specimen’s ultimate load. The comparison with previous studies showed that behaviour, strength, and ductility of all-masonry infilled frames are similar to, and in some cases, slightly better than infilled RC frames under either monotonic or cyclic loading. In general, CSA S304-14 tends to overestimate the stiffness in comparison with TMS 402/602. In the case of strength prediction, CSA S304 performed better than TMS 402/602, with predicted values closer to the test results.
Keywords
All-Masonry Infilled Frame System, In-plane lateral loading, Monotonic lateral loading, Cyclic lateral loading