Title: Plastic Strain in Prestressed Concrete Beams Under Sustained Load
Author(s): John N. Cernica and M. Jean Charignon
Publication: Journal Proceedings
Appears on pages(s): 215-222
Fourteen concrete beams were loaded under sustained load at the third-points for 1 year. The beams were identical except for the type of coarse aggregate. All 14were loaded with a load equal to 45 percent of the average ultimate of six beams tested under stort-time static load. Strain was measured at the center of the beam (a section of pure bending) at four different depths of the beam, viz., top, upper third, lower third, and bottom. The results show that under sustained loading the time-rate of plastic compressive strain in the concrete is initially rapid and then gradually decreases in both the slag and lime-stone beams. Furthermore, at the end of 1 year, the plastic compressive strain was a little over twice the elastic strain as measured by SR-4 strain gages.