Page 274 - Handbook of Civil Engineering Calculations, Second Edition
P. 274
PRESTRESSED CONCRETE 2.59
7. Verify the value of F i,min by checking the critical stresses
At support: f bi 2338 lb/sq.in. (16,120.5 kPa); f ti 190 lb/sq.in. ( 1310.1 kPa). At
midspan: f bf 0.85(2338) 374 2038 425 lb/sq.in. ( 2930.4 kPa); f tf 2250
lb/sq.in. ( 15,513.8 kPa).
BEAM WITH DEFLECTED TENDONS
The beam in the previous calculation procedure is to be prestressed by means of tendons
that are deflected at the quarter points of the span, as shown in Fig. 35a. Evaluate the al-
lowable unit superimposed load, the magnitude of the prestressing force, the eccentricity
e 1 in the center interval, and the maximum and minimum allowable values of the eccen-
tricity e 2 at the supports. What increase in capacity has been obtained by deflecting the
tendons?
FIGURE 35
