Structural Analysis II Section A6.10
**
Section
I.9
Shear
Stress
Distribution and
Angle of
Twist for
Multiple-Cell
Thin-Wall
Closed
Sections
**

In the figure above the area outside of the cross section will be designated
as **cell (0)**. Thus to designate the exterior walls of
cell (1), we use the notation** 1-0**. Similarly for cell (2) we use **
2-0** and for cell (3) we use **3-0**. The interior walls will be
designated by the names of adjacent cells.
From section A6.9, the torque of this multi-cell member can be related to
the shear flows in exterior walls as follows

For elastic continuity, the angles of twist in all cells must
be equal

The direction of twist chosen to be positive is clockwise.

NOTE: Since the exterior walls in each cell have equal shear flows, we can
factor the shear flow out and multiply it by the sum of the quotient S/t of
the exterior walls.

The above equations for angle of twist together with the torque equation
provide a total of 4 linear equations which can be solved simultaneously for
the 3 unknown shear flows (i.e., q1, q2, and q3) and 1 unkown angle of twist.

EXAMPLE
PROBLEMS

- Example 1 Shear flow distribution,
Maximum shear stress, and angle of twist in a two-cell section

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Pure Torsion
To Section
I.8
To Section I.10