A Generalized Span–Depth Ratio Model for Minimum Thickness Design of Flat Plate Slabs Incorporating ACI Deflection Criteria

This study proposes a unified span–depth ratio model aimed at optimizing the minimum thickness of reinforced concrete flat plate slabs, addressing the limitations of the simplified span-to-depth ratio provisions in ACI 318. The existing code does not fully consider critical parameters such as panel...

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Main Author: Bahman Omar Taha
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Buildings
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Online Access:https://www.mdpi.com/2075-5309/15/13/2157
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author Bahman Omar Taha
author_facet Bahman Omar Taha
author_sort Bahman Omar Taha
collection DOAJ
description This study proposes a unified span–depth ratio model aimed at optimizing the minimum thickness of reinforced concrete flat plate slabs, addressing the limitations of the simplified span-to-depth ratio provisions in ACI 318. The existing code does not fully consider critical parameters such as panel aspect ratio, reinforcement ratio, support conditions, concrete strength, and long-term deflections due to creep and shrinkage. To overcome these shortcomings, a generalized analytical model is developed based on fundamental deflection theory, incorporating both immediate and time-dependent behaviors. The model is validated through numerical simulations applied to interior, edge, and corner slab panels subjected to various geometric configurations, loading scenarios, and reinforcement levels. Results from the parametric study indicate that deflection control improves significantly with higher reinforcement ratios and lower aspect ratios, leading to more efficient slab designs. Comparisons with ACI 318 guidelines reveal that the proposed model provides enhanced accuracy, particularly for irregular slab geometries and stringent deflection limits (e.g., L/480). The findings highlight that conventional code-based thickness limits may underestimate slab depth requirements in many practical scenarios. The study advocates for integrating deflection-based considerations into the preliminary design stage, offering structural engineers a more robust and practical tool to ensure serviceability while optimizing material use.
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spelling doaj-art-07fea86d7e2745739533d60a7d9e80bd2025-08-20T03:28:37ZengMDPI AGBuildings2075-53092025-06-011513215710.3390/buildings15132157A Generalized Span–Depth Ratio Model for Minimum Thickness Design of Flat Plate Slabs Incorporating ACI Deflection CriteriaBahman Omar Taha0Department of Technical Civil Engineering, Erbil Technical Engineering College, Erbil Polytechnic University, Erbil 44001, IraqThis study proposes a unified span–depth ratio model aimed at optimizing the minimum thickness of reinforced concrete flat plate slabs, addressing the limitations of the simplified span-to-depth ratio provisions in ACI 318. The existing code does not fully consider critical parameters such as panel aspect ratio, reinforcement ratio, support conditions, concrete strength, and long-term deflections due to creep and shrinkage. To overcome these shortcomings, a generalized analytical model is developed based on fundamental deflection theory, incorporating both immediate and time-dependent behaviors. The model is validated through numerical simulations applied to interior, edge, and corner slab panels subjected to various geometric configurations, loading scenarios, and reinforcement levels. Results from the parametric study indicate that deflection control improves significantly with higher reinforcement ratios and lower aspect ratios, leading to more efficient slab designs. Comparisons with ACI 318 guidelines reveal that the proposed model provides enhanced accuracy, particularly for irregular slab geometries and stringent deflection limits (e.g., L/480). The findings highlight that conventional code-based thickness limits may underestimate slab depth requirements in many practical scenarios. The study advocates for integrating deflection-based considerations into the preliminary design stage, offering structural engineers a more robust and practical tool to ensure serviceability while optimizing material use.https://www.mdpi.com/2075-5309/15/13/2157flat plate slabminimum thicknessspan/depth ratioaspect ratiolong-term deflection
spellingShingle Bahman Omar Taha
A Generalized Span–Depth Ratio Model for Minimum Thickness Design of Flat Plate Slabs Incorporating ACI Deflection Criteria
Buildings
flat plate slab
minimum thickness
span/depth ratio
aspect ratio
long-term deflection
title A Generalized Span–Depth Ratio Model for Minimum Thickness Design of Flat Plate Slabs Incorporating ACI Deflection Criteria
title_full A Generalized Span–Depth Ratio Model for Minimum Thickness Design of Flat Plate Slabs Incorporating ACI Deflection Criteria
title_fullStr A Generalized Span–Depth Ratio Model for Minimum Thickness Design of Flat Plate Slabs Incorporating ACI Deflection Criteria
title_full_unstemmed A Generalized Span–Depth Ratio Model for Minimum Thickness Design of Flat Plate Slabs Incorporating ACI Deflection Criteria
title_short A Generalized Span–Depth Ratio Model for Minimum Thickness Design of Flat Plate Slabs Incorporating ACI Deflection Criteria
title_sort generalized span depth ratio model for minimum thickness design of flat plate slabs incorporating aci deflection criteria
topic flat plate slab
minimum thickness
span/depth ratio
aspect ratio
long-term deflection
url https://www.mdpi.com/2075-5309/15/13/2157
work_keys_str_mv AT bahmanomartaha ageneralizedspandepthratiomodelforminimumthicknessdesignofflatplateslabsincorporatingacideflectioncriteria
AT bahmanomartaha generalizedspandepthratiomodelforminimumthicknessdesignofflatplateslabsincorporatingacideflectioncriteria