“…(3) critical shear crack theory (CSCT). In addition, shear studies in terms of types of concrete include, but are not limited to, lightweight concrete (LC), ultra-high-performance concrete (UHPC), and fiber-reinforced concrete (FRC) have been documented (Deifalla et al, 2020b;Tong et al, 2020;Ababneh et al, 2020;Shaban et al, 2020;Ridha et al, 2018).…”
Section: Introductionmentioning
confidence: 99%
“…Several theories are being used for the analysis of specimens under shear (ASCE-ACI, 1999; Cavagnis et al, 2020; Bentz et al, 2006; Muttoni et al, 1997), namely, (1) modified compression field theory (MCFT); (2) simplified modified compression field theory (SMCFT); and (3) critical shear crack theory (CSCT). In addition, shear studies in terms of types of concrete include, but are not limited to, lightweight concrete (LC), ultra-high-performance concrete (UHPC), and fiber-reinforced concrete (FRC) have been documented (Deifalla et al, 2020b; Tong et al, 2020; Ababneh et al, 2020; Shaban et al, 2020; Ridha et al, 2018). Figure 1.Reinforced concrete under shear loading a) failure cracking pattern and b) resistance mechanism (ASCE, 1999).…”
Lightweight concrete (LC) is a viable alternative for conventional normal weight concrete (NC). It has a reduced weight and similar properties. However, shear provisions design codes are way behind for the case of the LC compared to the NC. This study evaluates the shear design of NC and LC specimens. First, an extensive experimental database of these specimens under shear was compiled. Then, selected shear provisions of design codes were outlined and applied for strength calculations. The calculated strengths were evaluated considering the experimentally measured ones to assess these design codes' overall accuracy and consistency. In addition, the effect of selected parameters (depth, concrete strength, flexure reinforcement ratio, shear span to depth ratio, and nominal maximum aggregate size) on the safety of the design was assessed. The third draft of the Eurocode was the most accurate and consistent for the shear design of LC and NC specimens. Finally, the Eurocode shear provisions draft was adapted, refined, verified, and proposed for the shear design of LC beams and slabs.
“…(3) critical shear crack theory (CSCT). In addition, shear studies in terms of types of concrete include, but are not limited to, lightweight concrete (LC), ultra-high-performance concrete (UHPC), and fiber-reinforced concrete (FRC) have been documented (Deifalla et al, 2020b;Tong et al, 2020;Ababneh et al, 2020;Shaban et al, 2020;Ridha et al, 2018).…”
Section: Introductionmentioning
confidence: 99%
“…Several theories are being used for the analysis of specimens under shear (ASCE-ACI, 1999; Cavagnis et al, 2020; Bentz et al, 2006; Muttoni et al, 1997), namely, (1) modified compression field theory (MCFT); (2) simplified modified compression field theory (SMCFT); and (3) critical shear crack theory (CSCT). In addition, shear studies in terms of types of concrete include, but are not limited to, lightweight concrete (LC), ultra-high-performance concrete (UHPC), and fiber-reinforced concrete (FRC) have been documented (Deifalla et al, 2020b; Tong et al, 2020; Ababneh et al, 2020; Shaban et al, 2020; Ridha et al, 2018). Figure 1.Reinforced concrete under shear loading a) failure cracking pattern and b) resistance mechanism (ASCE, 1999).…”
Lightweight concrete (LC) is a viable alternative for conventional normal weight concrete (NC). It has a reduced weight and similar properties. However, shear provisions design codes are way behind for the case of the LC compared to the NC. This study evaluates the shear design of NC and LC specimens. First, an extensive experimental database of these specimens under shear was compiled. Then, selected shear provisions of design codes were outlined and applied for strength calculations. The calculated strengths were evaluated considering the experimentally measured ones to assess these design codes' overall accuracy and consistency. In addition, the effect of selected parameters (depth, concrete strength, flexure reinforcement ratio, shear span to depth ratio, and nominal maximum aggregate size) on the safety of the design was assessed. The third draft of the Eurocode was the most accurate and consistent for the shear design of LC and NC specimens. Finally, the Eurocode shear provisions draft was adapted, refined, verified, and proposed for the shear design of LC beams and slabs.
“…Consequently, deformation in the form of twisting becomes more pronounced. Furthermore, inclined torsion induced cracks tend to propagate rapidly and are wider and more unsightly than flexural cracks [ 39 , 40 ].…”
Torsional behavior and an analysis of steel fiber reinforced concrete (SFRC) beams are investigated in this paper. The purpose of this study is twofold: to examine the torsion strength models for SFRC beams available in the literature and to address properly verified design formulations for SFRC beams under torsion. A total of 210 SFRC beams tested under torsion from 16 different experimental investigations around the world are compiled. The few strength models available from the literature are adapted herein and are used to calculate the torsional strength of the beams. The predicted strength is compared with the experimental values measured by the performed torsional tests and these comparisons showed room for improvement. First, a proposed model is based on optimizing the constants of the existing formulations using multi-linear regression. Furthermore, a second model is proposed, which is based on modifying the American Concrete Institute (ACI) design code for reinforced concrete (RC) members to include the effect of steel fibers on the torsional capacity of SFRC beams. Applications of the proposed models showed better compliance and consistency with the experimental results compared to the available design models, providing safe and verified predictions. Furthermore, the second model implements the ACI code for RC using a simple and easy-to-apply formulation.
“…The usage of lightweight concrete slabs in Tall buildings provides up to a 30% reduction in the concrete slabs' own weight, just result in significant savings in the overall cost of construction. In addition, the usage of prestressed concrete slabs extends to various applications, in particular prestressed lightweight concrete slabs (PLCS), however, fail quite suddenly with little warning as shown in Figure 1 (Aguilera, 2020;Deifalla, 2020aDeifalla, , 2020bDeifalla, , 2020cDeifalla et al, 2020aDeifalla et al, , 2020b. For two-way shear of prestressed concrete slabs (PCS), design methods are different in the considered parameters as shown in Table 1 and Appendix B (ACI-318, 2019;Cle´ment et al, 2014;EC2, 2004;ECP-203-18, 2018;MC, 2010).…”
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.
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