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|Title:||An experimental study of model deep beams. Report 1, Tests on one-quarter scale simply supported beams|
|Authors:||United States. Defense Atomic Support Agency.|
Hampe, Peter A.
Balsara, Jimmy P.
|Publisher:||Weapons Effects Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; N-68-3 rept.1.|
Abstract: The purpose of this study was to determine the extent to which the strength properties of the materials used in environmental (strength) modeling of reinforced concrete deep beams need to be scaled. The first phase of this study was conducted to determine the effect that concrete strength has on shear and flexural failures of model reinforced concrete deep beams. The second phase was conducted to determine if the tensile and compressive reinforcements in these beams can be scaled using bars of intermediate-grade steel, which would result in distorted length and stress scales. This was accomplished by comparing the response of two beams, one reinforced with intermediate-grade steel, and the other with an alloy of magnesium, so that the ratio of the forces developed at yield in the two different reinforcements was near unity. The results of tests of ten simply supported, doubly reinforced concrete deep beams subjected to a concentrated static load are presented herein. Four of the beams had a clear-span-to-effective-depth ratio, i.e. L/d, of 2.00, and six of the beams had an L/d of 4.67. Two of the L/d = 4.67 beams were used to compare the response of a beam reinforced with steel with one that was reinforced with magnesium-lithium bars. The test results indicated that concrete strength has considerable effect on the ultimate load and the mode of failure of the L/d = 2.00 beams, but has less effect on the ultimate load and no effect on the mode of failure of the L/d = 4.67 beams. The comparison study of beams with different reinforcing materials indicated that the tensile and compressive forces in the reinforcements can be scaled properly using either steel or magnesiumlithium bars, although the length and stress scales of the steel bars must be distorted. By including the effects of friction at the supports, the predicted ultimate load in flexure was in reasonably close agreement with the actual load for the L/d = 4.67 and L/d = 2.00 beams. The critical shear can also be predicted fairly accurately for the L/d = 2.00 beams, and the ratio of ultimate shear to critical shear averaged 2.34. The determination of the coefficient of friction of the supports is explained in Appendix A.
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