List of publications
Publication: Effect of the Panel Width Support and Columns Axial Load on the Infill Masonry Walls Out-Of-Plane Behavior (2018)
Preparation and upload by:
Filip Anic, Faculty of Civil Engineering and Architecture Osijek, Josip Juraj Strossmayer University of Osijek
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The present manuscript starts with an extensive state-of-art review of IM walls OOP tests. Experimental activity that was carried out at the Laboratory of Earthquake and Structural Engineering (LESE) composed by two quasi-static OOP tests of full-scale IM walls. The first specimen was built totally supported in the bottom frame’ beam and was subjected to combined gravity load (applied in the to
The present manuscript starts with an extensive state-of-art review of IM walls OOP tests. Experimental activity that was carried out at the Laboratory of Earthquake and Structural Engineering (LESE) composed by two quasi-static OOP tests of full-scale IM walls. The first specimen was built totally supported in the bottom frame’ beam and was subjected to combined gravity load (applied in the top of the frame columns) and cyclic OOP loadings. The second specimen was built partially supported (2/3 panel’ width) in the bottom frame’ beam and was subjected to only OOP cyclic loadings. Due to the lack of further experimental tests in the literature, the main goal of these tests is to present preliminary observations and findings regarding the possible effect of the panel support width and the gravity load on the IM walls OOP behavior. Additionally, a comparative study was performed between these two tests and other three specimens already tested at the LESE laboratory
The IM walls OOP vulnerability when subjected to cyclic loadings can result in important number of collapses/extensive damages that in general increase significantly the risk to the population and the rehabilitation’ costs of the buildings. As reported in the literature, the infill walls, due to the interaction with the surrounding RC frame, can develop higher OOP strength capacity through arching mechanism, which mainly depends of the panel’ slenderness, masonry compressive strength and panel support conditions.
AIM AND SCOPE
The aim of this research is to contribute to increase the understanding regarding the infill panels’ OOP behavior and evaluate the influence of different variables in the panel’ performance, such as: gravity load and panel support condition. For these experimental tests were carried composed by two full-scale infill panels subjected to uniform OOP pressure applied by airbags, subjected to gravity load applied in the top of the frame ‘columns and the other one was built partially supported in the bottom beam. The second goal of this work was to perform a comparative study between these two specimens with other three tests already tested.
DESIGN AND CONSTRUCTION OF THE TEST SPECIMENS:
The experimental work presented throughout this section was carried out with the aim of obtain preliminary results regarding the possible effect of the following two variables in the IM walls OOP behavior:
- Gravity load: Axial load will be applied in the top of the RC frame columns axial combined with the cyclic OOP loading;
- Panel support condition: One specimen will be constructed partially supported (2/3 panel width) in the bottom RC beam. It was pretended with these tests to achieve some insight on this issue and test a very common construction practice adopted nowadays in the southern European countries for correction/elimination of possible thermal bridges.
Summary of the experimental tests performed in tests to comparison:
| | Type | IP | Gravity | Infill panel | Compressive strength | Mortar |
| Specimen | of | drift | load | support | Masonry | Mortar | flexural |
| | test | (%) | (kN) | conditions | (MPa) | (MPa) | Strength |
| M1 | Monotonic | – | 300 | Full | 0.531 | 16.55 | 5.65 |
| M2 | Cyclic | – | – | Full | 0.531 | 5.66 | 2.11 |
| M3 | Cyclic | 0.5 | – | Full | 0.531 | 13.40 | 4.27 |
| M4 | Cyclic | – | 270 | Full | 1.100 | 8.76 | 5.16 |
| M5 | Cyclic | – | – | 2/3 width | 1.100 | 8.76 | 5.16 |
From the test results, it was observed higher effect caused by the reduction of the panel width support which resulted in the panel OOP instability. The OOP strength was significantly reduced, however the arching mechanism provided the sufficient capacity to not occur the panel collapse. It was observed that the introduction of gravity load on the top of the columns modified the cracking pattern. It was also observed a pronounced strength degradation after reached the maximum strength.
From the comparative study it was verified that the monotonic test with application of the gravity load in the frame columns seems to define an envelope of the cyclic tests. It was observed that the variables that affected more the OOP response of the specimens were the existence previous damage and the reduction of the panel’ width support condition. The existence of previous damage (which is more representative of the real behavior of IM panels during an earthquake) revealed to be the most vulnerable condition. It was observed that a panel subjected to a previous IP drift of 0.5% resulted in a reduction of the OOP maximum strength of 60%.
Regarding the influence of the gravity load on the columns prior to carrying out the tests for OOP, revealed to cause a decrease of the panel OOP stiffness. The increase of confinement provided by the gravity load resulted in different cracking pattern when compared with the tests without gravity load.
The definition of the stiffness degradation curve, allowed to visualize that the IM walls begins to loose stiffness quickly for low OOP displacements. This stiffness degradation will is more pronounced depending on the global behavior exhibited by the panel. Larger OOP instabilities are introduced by previous damage and reduction of the panel width support and lead to higher stiffness degradation. It was observed that existence of damage and reduction of the panel’ width support reduced the energy dissipation capacity of the panels due to the lower capacity of the panel to resist to OOP loading demands.
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The creation of these resources has been funded by the ERASMUS+ grant program of the European Union under grant no. 2016-1-DE01-KA203-002905. Neither the European Commission nor the project‘s national funding agency DAAD are responsible for the content or liable for any losses or damage resulting of the use of these resources.