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  • Effects of the effective width of slabs on the seismic response of cantilever RC walls : macro topic - concrete, masonry, steel, timber structures [Elektronski vir]
    Isaković, Tatjana ; Janevski, Antonio
    Reinforced concrete walls are one of the most commonly used and one of the most efficient types of structural systems resisting seismic load. Usually, they are interconnected by a floor system ... consisting of slabs and beams. Sometimes, the beams are omitted, and the walls are linked only by slabs. Such walls are considered cantilever walls. Typically, it is believed that their connection is relatively weak and that their resistance mainly depends on their flexural resistance. It is generally supposed that the flexural strength of the slabs is negligible compared to that of the walls and that slabs connect the walls only as rigid diaphragms. It is further supposed that the coupling level provided by the slabs is small. Most modern codes accept these assumptions. Recent experiments on RC walls sometimes call these assumptions into question. For specific wall configurations, such as elevator shafts, the coupling level provided only by slabs is not negligible, particularly when the significant effective slab width can be activated. In such cases, the resisting system can differ from the cantilever walls. Consequently, the effects of the seismic excitations can be considerably different from that expected in the design, causing unexpected types of damage (shear damage and failure of walls and buckling of the flexural reinforcement), which were observed in recent earthquakes. In the paper, the seismic response of walls which are relatively strongly coupled only by slabs is analysed. Basic large-scale shake table experiments' findings that were used to identify the main parameters causing notable coupling are presented. The sensitivity study of the tested specimen illustrates the importance of the main parameters influencing the coupling level, such as the strength and stiffness of walls and slabs and their ratios, the effective width of slabs, and the rotations of foundations. It is demonstrated that considerable coupling can activate the considerable frame action, which makes the structure stiffer, increasing the total base shear. Moreover, owing to the frame action, a considerable increase of compression axial forces can occur in single piers simultaneously, causing considerable redistribution of shear forces between piers. To be able to generalise the observations of the shake-table experiment, a parametric study has been performed, varying the ratio of the strength and stiffness of slabs and walls. The results of this study confirmed that considerable coupling of slender walls can be provided only by slabs without RC beams. It has been demonstrated that in strongly coupled piers, shear forces can be considerably larger than the design shear forces determined based on the elastic analysis of cantilever walls and that in such walls considerable redistributions of shear forces can occur due to the considerable frame action.
    Source: Proceedings of the 18th World Conference on Earthquake Engineering [Elektronski vir] : 30th June to 5th July 2024, Milan, Italy (Str. 1-12)
    Type of material - conference contribution ; adult, serious
    Publish date - 2024
    Language - english
    COBISS.SI-ID - 201370627

    Link(s):

    https://proceedings-wcee.org/wcee18.html

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