Title:
Long-Term Deflection of High-Strength Concrete Beams
Author(s):
Kent A. Paulson, Arthur H. Nilson, and Kenneth C. Hover
Publication:
Materials Journal
Volume:
88
Issue:
2
Appears on pages(s):
197-206
Keywords:
beams (supports); compressive strength; creep properties; deflection; high-strength concretes; loads (forces); shrinkage; Materials Research
DOI:
10.14359/2008
Date:
3/1/1991
Abstract:
A large body of experimental evidence is now available to confirm that the creep coefficient of high-strength concrete under sustained axial compression is significantly less than that of ordinary concrete. Thus, the ratio of time-dependent deflection to immediate elastic deflection of high-strength concrete beams under sustained loads should also be lower. However, the long-term deflection multipliers of the 1989 ACI Building Code do not account for concrete strength as a variable. Experimental results are reported for nine beams with nominal concrete compressive strengths over a range to 12,000 psi, loaded over a 12-month period. These tests confirm the significant differences between beams using high-strength concrete and those using normal strength concrete. Based on these and other tests, modifications to the present ACI Building Code method of predicting long-term deflections are suggested.