Title: Deflection of Partially Prestressed Beams Under a Combination of Long-Time and Short-Time Loading
Author(s): E. W. Bennett and K. H. Lee
Publication: Symposium Paper
Appears on pages(s): 185-214
Keywords: beams (supports); cracking (fraturing); cyclic loads; deflection; loads (forces); partial prestressing; prestressed concrete.
A series of nine partially prestressed concrete beams was tested by a combination of a long-time load with intermittent cycles of short-time load over a total period of about one month. Additional tests were made of three of the beam types under the long-time load alone. The load-deflection-time relationships are discussed and a method of calculation of deflection is described which takes account of the "tension stiffening" effect of the concrete between the cracks. The ACI 318-83 recommendations are also checked against the results and found to be satisfactory for initial short-time loading but unconservative for a combination of long-time and intermittent cyclic loading.