Civil Engineering and Architecture 10(5): 1916-1930, 2022 http://www.hrpub.org DOI: 10.13189/cea.2022.100516 Aspect Ratio and Relative Beam-Slab Stiffness Effects on the Long-term Deflection of Flat Plates and Beam Supported One-Way Slabs Karwan Khalid Ismael * , Sarkawt Asaad Hasan Department of Civil Engineering, Erbil Engineering Technical College, Erbil Polytechnic University, Iraq Received April 8, 2022; Revised May 6, 2022; Accepted June 21, 2022 Cite This Paper in the following Citation Styles (a): [1] Karwan Khalid Ismael, Sarkawt Asaad Hasan , "Aspect Ratio and Relative Beam-Slab Stiffness Effects on the Long-term Deflection of Flat Plates and Beam Supported One-Way Slabs," Civil Engineering and Architecture, Vol. 10, No. 5, pp. 1916-1930, 2022. DOI: 10.13189/cea.2022.100516. (b): Karwan Khalid Ismael, Sarkawt Asaad Hasan (2022). Aspect Ratio and Relative Beam-Slab Stiffness Effects on the Long-term Deflection of Flat Plates and Beam Supported One-Way Slabs. Civil Engineering and Architecture, 10(5), 1916-1930. DOI: 10.13189/cea.2022.100516. Copyright©2022 by authors, all rights reserved. Authors agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License Abstract This study investigates the ACI 318-19 two-way slab provisions for the long-term deflection control in flat plate slabs with an aspect ratio ranging between 1 to 3 at different panel locations (interior, edge, and corner) with a large span of 5.0 m, 7.5 m, and 10.0 m. Further, the study examines the effects of the relative beam-slab stiffness of the beams provided at the two long sides of flat plat slabs of aspect ratio greater than two using ACI318-19 recommended one-way slab thickness. The paper uses the Finite Element SAFE software to calculate the long-term deflection (LTD) by using nonlinear analysis (long-term cracked analysis) that considers concrete creep and shrinkage of two-way slabs and one-way slabs for different beam-slab stiffnesses and aspect ratios. The aspect ratio of a flat plate slab had a considerable effect on the LTD, where for slab panels of the same long span length and variable aspect ratio, as the aspect ratio gets smaller (square slab), the LTD increases, a behavior that ACI318-19 two-way slab deflection control procedures overlook. So, the deflection under the beams is within the ACI318-19 long-term deflection limits for different panel locations (interior, interior, exterior, and exterior edge). In addition, this part has been conducted to recommend a minimum relative beam-slab stiffness for the supporting beams. Keywords Flat Plate Slab, One-Way Slab, Aspect Ratio, Long Term Deflection, Permissible Deflection, Relative Beam-Slab Stiffness, Minimum Thickness of Slab 1. Introduction A flat slab is a two-way reinforced concrete slab without beams, drop panels, or capitals and transfers loads straight to the supporting concrete columns. In this type of slab system, it is recognized that deflection is a critical aspect, where the slab might experience excessive deflection resulting in cracks in the supported partitions walls. In two-way flat plat slabs, ACI318-19 provisions do not consider the aspect ratio (large span (L1)/short spans (L2)) as a parameter in the recommended minimum slab thickness. The slab thickness depends on the large span only. For example, for an exterior flat plat slab panel of 10 x 10 m and 10 x 5 m, ACI318-19 recommends the same slab thickness (ℓn/30, ℓn is the clear span length). This indicates that if the long span does not vary, the recommended slab thickness remains constant regardless of how the small span length changes. Further, the situation becomes even more uncertain with the flat plate aspect ratio exceeding 2. Therefore, as an attempt to apply the minimum thickness recommended by Table 8.3.1.1 (minimum thickness of two-way slabs without edge beam) of ACI318-19 to an exterior flat plat slab (for example) with an aspect ratio greater than 2,
Aspect Ratio and Relative Beam-Slab Stiffness Effects on the Long-term Deflection of Flat Plates and Beam Supported One-Way Slabs
May 19, 2023
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