A strength and deformation model for prestressed lightweight concrete slabs under two-way shear

Abstract

Prestressed concrete slabs (PCS) are one of the top choices in many applications, which is due to their significantly improved performance compared to conventional normal-weight concrete slabs (NCS). However, very limited models exist for the two-way shear behavior of PCS, in particular, lightweight ones (PLCS). In this study, a two-way shear mechanical behavior model is developed for PCS, that accounts for all effective parameters and capable of predicting both strength and deformation. An experimental database of PCS was compiled from the literature with emphasis on lightweight concrete. A mechanical model developed by the author for lightweight concrete slabs (LCS) was adapted and modified in order to include the effect of prestressing in terms of the following components: (1) the membrane compression stress; (2) the prestressing eccentricity; and (3) the prestressing vertical component. The extended model was used to predict the behavior of PLCS and prestressed normal-weight concrete slabs (PNCS), which was compared to that using selected design codes and models. The model predicted the rotation accurately and consistently compared to the experimentally measured rotation. The strength predicted using the proposed model was better than existing ones concerning experimentally measured strength, yet it was found to be reasonably safe. However, conclusions are limited to the experimental database.

Shear strength of lightweight and normal-weight concrete slender beams and slabs: An appraisal of design codes

“…However, that exercise would be redundant due to the fact that the ideal relationship is well known to be a straight line and using the different relationships for each figure is not practical and will not allow us to evaluate without bias. In addition, this technique was implemented by many researchers (Kuchman et al, 2019;Bairan et al, 2020;Deifalla, 2021bDeifalla, , 2022. Thus, for Figures 5, 6, 7, 8, 9, 10 & 12, the relationship is a straight line passing through unity, while for Figure 11, it is a 45-degree line passing through the origin point.…”

“…However, that exercise would be redundant due to the fact that the ideal relationship is well known to be a straight line and using the different relationships for each figure is not practical and will not allow us to evaluate without bias. In addition, this technique was implemented by many researchers (Kuchman et al, 2019; Bairan et al, 2020; Deifalla, 2021b, 2022). Thus, for Figures 5, 6, 7, 8, 9, 10 & 12, the relationship is a straight line passing through unity, while for Figure 11, it is a 45-degree line passing through the origin point.

Figure 6.Measured strength versus calculated strength for NC.

Figure 7.Measured strength versus calculated strength for LC.

Figure 8.Variation of safety with respect to d.

Figure 9.Variation of safety with respect to fc'.

Figure 10.Variation of safety with respect to !.

Figure 11.Variation of safety with respect to a/d.

Figure 12.Variation of safety with respect to dg.

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Multivariable Regression Strength Model for Steel Fiber-Reinforced Concrete Beams under Torsion

“…Standard deviation number of samples (11) Such technique was applied in many previous investigations [85][86][87][88]. It is worth noting that applying the principles of reliability is out of scope of this study, it is worthy of future study [89].…”

Evaluation of the Strength of Slab-Column Connections with FRPs Using Machine Learning Algorithms

“…Although the punching shear failure has a sophisticated, complex behavior, other innovative data-driven models are essential for improving prediction accuracy [11][12][13][14][15]. For the last few decades, ML has shown significant improvements in various fields [16][17][18][19], including structural engineering [20][21][22][23].…”