List of publications
Publication: Innovative systems for masonry infill walls based on the use of deformable joints: combined in-plane/out-of-plane tests (2016)
Brick and Block Masonry
Preparation and upload by:
Filip Anic, Faculty of Civil Engineering and Architecture Osijek, Josip Juraj Strossmayer University of Osijek
Publication abstract (click to enlarge):
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Within the INSYSME Project, funded under the 7th Framework Program by the Commission of the European Communities and aimed at developing innovative systems for masonry enclosure walls, the University of Padova and ANDIL (Italian Association of Clay Bricks and Roofing Tiles Producers) proposed a construction system named DRES (Damage Reduction Enclosure System). The system is made of a single-le
Within the INSYSME Project, funded under the 7th Framework Program by the Commission of the European Communities and aimed at developing innovative systems for masonry enclosure walls, the University of Padova and ANDIL (Italian Association of Clay Bricks and Roofing Tiles Producers) proposed a construction system named DRES (Damage Reduction Enclosure System). The system is made of a single-leaf clay masonry wall, with three horizontal deformable joints within the clay unit rows, to be employed in RC frame buildings in regions prone to medium/high intensity earthquakes. To understand the behaviour of this system, an experimental campaign on four real-scale, one-bay, one-storey RC frames infilled with both partial and full enclosure walls, was performed. The tests combine cyclic in-plane and monotonic out-of-plane loading of the specimen. Two variants of the DRES system and a reference plain masonry enclosure were first tested in the in-plane direction and then in the out-of-plane direction. An additional specimen infilled with two partial enclosures, one built with DRES and one with plain masonry, was first tested in the out-of-plane direction and then, after removal of damaged walls from the bare frame, tested in the in-plane direction. An analysis, in terms of strength, ductility parameters and damage, of the in-plane and the out-of-plane test results is carried out.
The recent earthquakes that occurred in Central Italy, in L’Aquila in 2009 and in Amatrice in 2016, have shown, once again, how infill panels and partitions, widely used as non-structural elements in reinforced concrete frames, are significantly vulnerable when subjected to seismic actions. Moreover, they highly affect the structural behavior and seismic response of typical, multi-story buildings, strongly influencing their repair costs due to the inevitable damage they usually undergo during seismic events. Therefore, they should be designed to withstand earthquakes forces, both in-plane and out-of-plane, so to ensure the safety of the occupants. In addition to seismic performance, infill panels play the primary role of providing comfort to occupants through adequate thermal and acoustic insulation.
AIM AND SCOPE
The main purpose of this paper is to experimental evaluate, by means of quasi-static cyclic procedures, the combined in-plane and out-of-plane performances of the proposed system. The experimental program consisted of 4 combined in-plane/out-of-plane tests on specimens composed by fullscale one-bay, one-storey infilled R.C. frames.
DESIGN AND CONSTRUCTION OF THE TEST SPECIMENS:
Four specimens were made of full scale, one-bay, one-storey reinforced concrete frame with a 4150 mm clear span and a 2750 mm height. The R.C. frame was considered as being part of a reference 3 storey R.C. frame building designed in high ductility class, according to DM 14/01/2008. The frame is composed by two 300 x 300 mm columns and a 500 x 250 mm top beam, reinforced respectively with 8 phi 22 and 8 phi 16 longitudinal steel bars. In order to comply the strength hierarchy, particular attention was given to the top beam reinforcement design, taking into account the axial preload applied to perform cyclical in-plane tests. The choice to adopt full-scale specimens was made to avoid any scaling effect due to the relative stiffness ratio of the RC frame and infill wall.
These frames were infilled with different enclosure solutions:
− 1st was infilled with two walls separated by an
opening, one plain masonry wall (1.PI.MJ) and one DRES-V1 wall (1.PI.R1)
− 2nd frame was infilled with a full DRES-V1
− 3rd frame was infilled with a full DRES-V2
− 4th frame was infilled with a full plain masonry
enclosure wall (4.FU.MJ).
In full solutions the enclosures are 2750 mm high and 4150 mm wide so as to occupy the whole span of the R.C. frame. Conversely, in partial solutions the R.C. frame is filled with two 2750 mm high and 1450 mm wide enclosures, detached from the columns through the interposition of an air layer of about 30 mm.
| Specimen | Infill | Infill type | Test type | dr,max % |
| 1.PI.R1 | Partial | DRES-V1 | OoP only | – |
| 1.PI.MJ | Partial | Plain | OoP only | – |
| 1.BF.30 | – | – | IP only | 3.0 |
| 2.FU.R1 | Full | DRES-V1 | IP + OoP | 2.4 |
| 3.FU.R2 | Full | DRES-V2 | IP + OoP | 2.4 |
| 4.FC.MJ | Full | Plain | IP + OoP | 2.4 |
University of Padova in collaboration with ANDIL developed an innovative enclosure system, named DRES (Damage Reduction Enclosure System), to improve the seismic performances of masonry enclosures in R.C. buildings. In order to evaluate the effectiveness of this system, combined in-plane and out-of-plane tests were performed on four real scale, one bay R.C. frames infilled with two versions of DRES enclosures and with plain masonry enclosures.
Enclosures were first cyclically tested in the inplane direction until 2.4% drift and then monotonically tested in the out-of-plane direction. As reference, two partial enclosures were first tested in the out-of-plane direction and then, after removal of damaged enclosures, the remaining R.C. frame was tested in the in-plane direction until 3.0% drift. Test results showed that DRES-V1, among all, was able to better reduce the damage during in-plane deformations, thanks to the sliding of masonry strips along deformable joints. However, it should be noted that this behaviour had the side effect of heavily reduce the infill stiffness, not allowing the full exploitation of the joint deformability and introducing permanent deformations after in plane displacements.
DRES-V2 was able to overcome these limitations, optimising the interaction phenomena between R.C. frame and enclosure during in-plane deformations, doubling the inter-storey displacements required to reach the maximum strength and considerably reducing the masonry damage compared to a plain masonry system. Due to the optimal in-plane behaviour, even out-of-plane performances of DRES-V2, in terms of both strength and initial stiffness, were excellent.
RECOMMENDATIONS FOR FUTURE RESEARCH
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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.