Extracted text: 18.3 The stairs shown in Fig. 18.23 are to be designed for a live load equal to 100 psf (4.8 kN/m). The stairs are supported by beams, as shown. Design the stairs and the supporting beams for f = 3 ksi (20 MPa) and f, = 60 ksi (400 MPa). olems 723 Beam E Вeam A I'0" 1'0" 5' 0" 6' 0" Beam C l'0" -9' 2"- 10 runs X 11" = 110" Beam B All columns 12" X 11" 8' 3" 9 runs X 11" =99" Beam D Ground level Figure 18.23 Problem 18.3.