Ultimate Strength of Beams Reinforced With Steel Having No Definite Yield Point


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Title: Ultimate Strength of Beams Reinforced With Steel Having No Definite Yield Point

Author(s): Peter D. Heimdahl and Albert C. Bianchini

Publication: Journal Proceedings

Volume: 71

Issue: 12

Appears on pages(s): 600-603

Keywords: beams (supports); building codes; deformed reinforcements; flexural strength; high strength steels; rein-forced concrete; strength; tests; yield point.

Date: 12/1/1974

Experimental evidence is presented of the conservative nature of the provisions of the ACI Building Code (ACI 318-71) in predicting the ultimate strengths of beams reinforced with steel with no well-defined yield point. Tests to failure were conducted on a total of 16 beams of various percentages of reinforcement. Eight of the beams were reinforced with high strength steel with a sharply defined yield point, and the others were reinforced with steel for no definite yield. A general theoretical method of calculating ultimate beam strength, for which no limiting strain criterion was involved, was used to corroborate experimental A Code modification which accounts for the strength increases realized in tests of beams reinforced with steel with no definite yield was developed. The Code was modified by extending the assumed concrete failure strain to 0.004 and by using the steel stress corresponding to a strain of 0.005 rather than 0.0035 on the actual stress-strain curve. Predictions according to the modifications are most accurate at 75 percent of the balanced reinforcement ratio and conservative for lower reinforcement ratio. [Authors]