EX4.4 - CEE 415 Example 4.4 Design a doubly reinforced...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
CEE 415 1 Example 4.4 – Design a doubly reinforced section for negative bending moment in the indicated girder at the face of the first interior column of the floor plan shown on the last page. We cannot use the ACI moment coefficients for this case because of the concentrated loads applied to this girder from the floor beams. For an initial calculation of the weight of the girder (web), assume it has a depth of 26 in. and a width of 14 in. Calculations indicate that the reduced live load for this design section is 30 psf. Assume f ´ c = 4000 psi and f y = 60 ksi. From RISA analysis, M u = 610 k-ft = 7320 k-in. Start design process with 1 3 0.0189 0.019 cy ff ρβ ≅= Then, ω = ρ (f y /f ´ c ) = 0.285 and, R = ω f c ’ (1 - 0.59 ω ) = 0.948 ksi 0.95 ksi Now, assuming φ = 0.9, the required value of b d 2 = (M u / φ )/R = 8560 in. 3 Select b 0.6 d, so d [8560/0.60] 0.33 = 24.3 in. (round to 23.5 in.) ( h = 26 in.) Then, with d = 23.5 in, b 8560/(23.5) 2 = 15.4 in. (round to 16 in.) No need to adjust M u . Selection of A s = ρ b d = (0.019)(15.4")(23.5") = 6.92 in.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/29/2011 for the course CEE 415 taught by Professor Wight during the Spring '11 term at University of Michigan.

Page1 / 3

EX4.4 - CEE 415 Example 4.4 Design a doubly reinforced...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online