Fatigue Tests on Prestressed Concrete I-Beams

by John M. Hanson, (M.ASCE), Asst. Mgr.; Struct. Res. Sec., Res. and Development Div., Portland Cement Assn., Skokie, IL,
Cornie L. Hulsbos, (F.ASCE), Chmn.; Dept. of Civ. Engrg., The Univ. of New Mexico, Albuquerque, NM,
David A. VanHorn, (M.ASCE), Chmn.; Dept. of Civ. Engrg., Lehigh Univ., Bethlehem, PA,

Serial Information: Journal of the Structural Division, 1970, Vol. 96, Issue 11, Pg. 2443-2464

Document Type: Journal Paper


Six fatigue tests of prestressed concrete I-beams containing web reinforcement are reported. Each beam was initially subjected to a high overload, and then subjected to 2,000,000 cycles of a design equivalent repeated loading. The beams failed by either flexural or shear fatigue. The flexural fatigue life of the test beams was less than expected from available information on the fatigue strength of strand. The tests demonstrated that prestressed concrete beams have a remarkable shear fatigue resistance. Prestressed beams, with enough web reinforcement to develop their flexural capacity, can be subjected to overloads which cause extensive cracking without subsequent danger of a shear fatigue failure under design loads. Shear fatigue failures do not occur suddenly. There is considerable warning, as indicated by increasing deflection and increasing inclined crack width, before failure occurs. In these and other tests, shear fatigue failures did not occur when the range in inclined crack width was less than 0.006 in. under application of repeated loads.

Subject Headings: Fatigue tests | Shear failures | Concrete beams | I beams | Flexural strength | Failure analysis | Prestressing | Shear tests

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