![]() ![]() The values of f y and f yt used in design calculations shall not exceed 80,000 psi, except for prestressing steel and for transverse reinforcement in 10.9.3 and 21.1.5.4. The limiting strain of 0.35 percent was chosen as a compromise, considering that the concrete would have some long-term strain from creep and shrinkage, in addition to the short-term crushing strain of 0.3 percent. There was concern that the concrete in a column would crush at levels around 0.3 percent compressive strain and thus, the steel strength based on an f y at 0.5 percent strain would not be fully additive to the concrete strength. At that time, there was little use of Grade 75 reinforcement. But the committee felt it necessary to limit the yield strength f y to that at a strain of 0.35 percent, instead of 0.5 percent as then specified in ASTM. In general, ACI 318 does not override ASTM specifications. This section was introduced in ACI 318-71. Deformed reinforcing bars shall conform to one of the ASTM specifications listed in 3.5.3.1 except that for bars with f y exceeding 60,000 psi, the yield strength shall be taken as the stress corresponding to a strain of 0.35 percent. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |