PSI - Issue 42

Rami A. Hawileh et al. / Procedia Structural Integrity 42 (2022) 1198–1205 Hawileh et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction Due to its complexity, study on shear has been extensively carried out in the last decades. Most studies in this area focused mainly on the effect of several parameters on the shear behavior of reinforced concrete (RC) beams. Concrete compressive strength, shear span to effective depth ratio, and longitudinal reinforcement ratio are among these parameters (Thamrin et al. (2016)). The nominal shear capacity of RC beams is calculated, as per most of the current design guidelines, by superimposing concrete contribution to shear capacity ( V c ) and the shear capacity provided by the steel reinforcement ( V s ) (Abu-obeidah et al. (2019); Abuodeh et al. (2020); Mhanna et al. (2021a)) Contribution of steel reinforcement is dependent on the area, yield strength, and spacing of the stirrups intersecting the critical diagonal crack. The transverse reinforcement is assumed to yield when the shear capacity is reached. After that, the critical diagonal crack increases rapidly, and the value of V s remains constant. The contribution of concrete in slender beams (beams with span/depth 2.0 ~ 3.0) comes from three sources, which are shear resisted by concrete in the uncracked compression zone ( V c ), shear transfer by aggregate interlocking at the edge of the diagonal crack ( V a ), and dowel action from the longitudinal reinforcement ( V d ) (Baghi and Barros (2017); Bentz et al. (2006); Ferreira et al. (2014); Koo et al. (2021); Ribeiro et al. (2016); Vecchio and Collins (1986)). Most of the shear design models in the literature were derived exclusively for members with rectangular cross sections. RC beams with T-cross sections are being used for diverse applications in construction industry, such as, bridge decks, building floors/slabs, retaining walls, and parking garages (Ayensa et al. (2019); O. M. Ramadan et al. (2022); O. M. O. Ramadan et al. (2021); Ribas González and Fernández Ruiz (2017)). The advantage of the T-sections is that a portion of the slab acts integrally with the beam and bends along with the beam under the loads to resist acting straining actions. The shear resistance of the RC T-beams, on the other hand, is evaluated by utilizing the area of the beam web only. The contribution of the flanges to the shear capacity is usually ignored in the shear design models. However, recent studies have shown that there is a significant contribution of the flanges to the T- beams’ shear capacity (Giaccio et al. (2002); Mhanna et al. (2019), (2020); Mhanna et al. (2021b); Sarsam et al. (2018); Solanki et al. (2007); Thamrin et al. (2016); Zararis et al. (2006)) . Test results of a study by Ramadan et al. (2022) concluded that the shear capacity of T-sections was notably higher than rectangular sections with same web dimensions by 27-54%, depending on the ratio of flange thickness to total depth. In addition, increasing the width of the flange had less effect on the shear capacity of T-beams compared to increasing its thickness. In another study by Thamrin et al. (2016), the authors tested three T-beams and equivalent three rectangular beams in shear. Results indicated an increase in the shear capacity of the T-beams by 5-20% compared to the rectangular beams, depending on the longitudinal reinforcement ratio. Ayensa et al. (2019) developed 3D finite element models to quantify the contribution of flanges to shear capacity of T-beams. The maximum contribution of flanges was found to be 31.3% of the total shear resisted. In addition, the shear force carried by the flanges increases as their width and depth increase. Shear strength equations available in the design guidelines do not consider the influence of flange of T-sections. Ignoring such a contribution result in a very conservative and uneconomical designs. Therefore, the aim of this study is to evaluate and compare the shear capacity of RC T-beams using shear strength models available in the design guidelines and literature. The data base used to evaluate the shear strength models is composed of 21 RC T-beam specimens (with and without stirrups). In addition, the effect of the geometry of the flange (width and thickness) is assessed. The outcomes of this research will provide better insight on the models that best predict the shear capacity of T-beams, which will aid future studies in developing shear strength empirical equations for RC T-beams. Nomenclature gross area of the section (mm 2 ) longitudinal steel reinforcement area (mm 2 ) ′ top longitudinal reinforcement (mm 2 ) A v total cross-sectional area of vertical stirrups reinforcement (mm 2 ) width of the flange (mm)

flange width (mm) effective width (mm)