WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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Publisher: search.filters.publisher.American Concrete Institute

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  • Article
    Citation - WoS: 63
    Correlating Rheology of Self-Consolidating Concrete To Corresponding Concrete-Equivalent Mortar
    (American Concrete Institute, 2009) Erdem, Tahir Kemal; Khayat, Kamal H.; Yahia, Ammar
    The investigation reported in this paper seeks to develop a methodology to evaluate the rheological parameters and thixotropy of self-consolidating concrete (SCC) using those of concrete-equivalent mortar (CEM). The mixture proportioning of CEMs are derived from their corresponding concrete mixtures by eliminating the coarse aggregate fraction and replacing it by a certain mass of sand of the same surface area. SCC mixtures with water-cementitious material ratios (w/cm) of 0.35, 0.38, and 0.42 and coarse aggregate-total aggregate volume ratios (CA/A) of 0.44 to 0.53 were investigated. The mixtures with a w/cm (if 0.38 and 0.42 incorporated low and moderate dosages, respectively, of a viscosity-modifying admixture to enhance stability For each SCC, the dosage of high-range water-reducer (HRWR) was varied to cover a wide range of slump flow consistencies ranging between 570 and 730 mm (22.4 and 28.7 in.). All SCC mixtures were proportioned with 450 kg/m(3) (758.5 lb/yd(3)) of ternary silica fume-ground granulated blast-furnace slag cement. A simple method is also proposed to determine the HRWR demand of SCC from that of the corresponding CEM. Test results showed that a good correlation can be established between the yield stress, plastic viscosity, and thixotropy of SCC and their corresponding CEM mixtures. Both thixotropy and plastic viscosity of SCC mixtures and their corresponding CEM mixtures are shown to vary primarily with variations in the w/cm and relative volume of coarse aggregate.
  • Article
    Citation - WoS: 277
    Citation - Scopus: 345
    Effects of Shear Mechanisms on Impact Behavior of Reinforced Concrete Beams
    (American Concrete Institute, 2009) Saatçi, Selçuk; Vecchio, Frank J.
    A well-instrumented experimental program was undertaken to contribute to our understanding of the effects of shear mechanisms on the behavior of reinforced concrete (RC) structures under impact loads and to provide data for verification of methods developed for the impact analysis of such structures. Eight RC beam specimens, four pairs, were tested under free-falling drop-weights, impacting the specimens at the midspan. All specimens had identical longitudinal reinforcement, but varying shear reinforcement ratios, intended to investigate the effects of shear capacity on the impact behavior. A total of 20 impact tests were conducted, including multiple tests on each specimen. The test program was successful in providing a substantial amount of high-quality impact test data. The test results showed that the shear characteristics of the specimens played an important role in their overall behavior. All specimens, regardless of their shear capacity, developed severe diagonal shear cracks, forming a shear-plug under the impact point. © 2009, American Concrete Institute.
  • Article
    Citation - WoS: 78
    Citation - Scopus: 88
    Nonlinear Finite Element Modeling of Reinforced Concrete Structures Under Impact Loads
    (American Concrete Institute, 2009) Saatçi, Selçuk; Vecchio, Frank J.
    The methods available in the literature for the analysis of reinforced concrete (RC) structures subjected to impact loads generally exhibit some deficiencies in aspects relating to applicability, practicality, and accuracy. The shear-dominant behavior of RC members under impact loads creates another significant shortcoming, because modeling the shear behavior of RC has long been a challenging issue. This study aims to present and verify a nonlinear finite element analysis procedure employing the Disturbed Stress Field Model, based on a smeared rotating crack approach, as an advanced method of modeling shear behavior under impact conditions. The proposed methodology has a wide range of applicability, and displays fast solution time while providing extensive and accurate information on structural behavior. The methodology was tested by analyzing a set of RC beams subjected to impact loads. A high level of accuracy was demonstrated in various comparisons between test and analysis results, including peak and residual displacements, crack profiles, and reinforcement strains.