Virginia Tech Structural Engineering and Materials Report Series

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Browsing Virginia Tech Structural Engineering and Materials Report Series by Author "Koutromanos, Ioannis"

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    Computational Study of Tension Field Action in Gable Frame Panel Zones
    Wei, Gengrui; Koutromanos, Ioannis; Murray, Thomas M.; Eatherton, Matthew R. (2018-04-01)
    A computational study was conducted to evaluate the extent to which the column panel zone in a gable frame knee joint can develop tension field action when subjected to positive bending (top flange of the rafter is in tension). Past testing was reviewed and used to validate finite element models. The validated finite element modeling approach that utilized shell elements, was then used in a parametric study to evaluate the post-buckling strength of the panel zone beyond the shear buckling strength. In addition, a plastic mechanism model was used to derive an equation for the post-buckling shear strength of the panel zone and the derived equation was validated against the results of the parametric study. The result was a proposed equation for tension field action strength of the panel zone when subjected to positive bending that had an average error of 1% compared to the model results.
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    Experimental Testing of a Reinforced Concrete Structural Wall Under Cyclic Loads
    This report presents the setup and results of an experimental test focused on the seismic performance of a non-ductile reinforced concrete wall. The specimen was a half-scale representation of the lower stories in an 8-story prototype building, constructed in California between the mid-1950s and early 1960s. The cross-section had a barbell shape, with heavily reinforced end pilasters and very light reinforcement in the web region. The specimen was the first in a series of tests, aimed to investigate the strength and failure modes of existing RC wall construction, and also assess the efficiency of different retrofit techniques (the latter will be considered in subsequent tests). Applying lateral displacement cycles of increasing amplitude led to the gradual accumulation of damage. The specimen failed due to the formation of a localized diagonal crack in the web, followed by rupture of several horizontal bars and, ultimately, a sudden shear-crushing failure at the base of the pilaster. The pilaster region also exhibited buckling of the vertical reinforcing bars and rupture of transverse ties. The failure of the specimen was abrupt, occurring at a drift ratio of 1.31%. Computational simulations conducted for the specimen provided further insights on the damage sequence and failure mechanism.