b.

Design of a Beam Subject to Torsion.

Problem:

Design the beam in Example Problem a. for a uniformly

distributed torsional load.

Given:

(1) Example Problem a, L, d, and vu.

(2)

Unbalanced support shears of roof slabs.

Solution:

(1) Determine torsional load d distance from the face of

support.

(2) Find torsional stresses using Equation (47a>.

(3) Determine shear and torsional capacity of unreinforced web

from Equations (48) and (49).

(4) Find required area of web reinforcing for shear stress

using Equation (45>.

(5) Find required area of web reinforcing for torsional stress

using Equation (51).

(6) Calculate total web reinforcing.

(7) Check minimum tie reinforcing area and maximum tie

spacing.

(8) Determine required area of longitudinal steel using

Equation (54a) or (54b).

(9) Determine distribution of bending and longitudinal steel

at beam section.

Calculation:

Given:

(1) Beam of Example Problem a., L = 240 in, d = 27.125 in, and

vu = 202.7 psi.

(2) Unbalanced support shear from two adjacent slabs

vs = 320 lb/in along the edge of the beam.

Solution:

(1) Design torsional load.

L

Tu = ( - d) x Vs x arm

2

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