Plastic Hinging at the Intersection of Beams
G. C. Ernst
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Principal object of investigation was to determine the amount of concentrated plastic rotation developed at the connection between beams and columns. Thirty-three tests were conducted, some at a slow loading rate, some at a fast loading rate equivalent to that, prescribed for concrete cylinders. Steel ratios of 0.01, 0.03 and 0.05, column widths of 6, 12, 18, 24, and 36 in., and nominal concrete strengths of 3000 and 4000 psi were used. Concentrated plastic rotation at concrctc crushing and at maximum moment, is markedly reduced when the steel ratio cxcecds 0.01, and is also less for a fast loading rate. Theoretical moments agreed satisfactorily with experimentally determined moments in all casts. At concr&e crushing for the 0.05 steel ratio under fast loading, concentrated plastic rot,ation was virtually negligible. It seems necessary, therefore, to consider the effect of steel ratio and rate of loading in cases for which the ultimate capacity of a structure is dependent, upon a redistribution of moment produced by concentrated plastic rotations.