The two-segment statically indeterminate bar in Fig. P3.11-3a has a constant cross-sectional area A = 0.8 in. It is made entirely of material that has an elastic, perfectly-plastic stress-strain behavior illustrated in Fig. P3.11-3b, with y = 36 ksi and E= 30 x 10 ksi. (a) Determine the load Py at which first yielding occurs, and determine the corresponding displacement uy of section B where the load P is applied. (b) Determine the load Pu at which yielding occurs in the re- maining segment of the bar, and determine the corresponding displacement u of section B. (c) Sketch a load-displacement diagram, that is, sketch a diagram of P versus u up to Pu 20 in. (1) 40 in. (2) A B C u (a) A two-segment bar. -Ey Oy E -Oy Ey (b) A stress-strain diagram for an elastic, perfectly-plastic material. n