Formwork for Concrete Structures by R.L.Peurifoy and G.D- By EasyEngineering.net

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Forms for Columns 285
FIGURE 10-1 Forms for square column.
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with the depth of the area below the surface of the concrete. For
concrete weighing 150 lb per cu ft, the maximum pressure is given
by Eq. (10-1).
Chapter 5 presented the equations for determining the allowable
span length of form members based on bending, shear, and deflection.
The terms in the equation include the physical properties, the
allowable stresses, and the uniform load w, measured in lb per ft. For
clarity, the equations from Chapter 5 are repeated here.
For lumber, the allowable span lengths with multiple supports
are as follows:
For bending, l b
= [120F b
S/w] 1/2 (10-3)
For shear, l v
= 192F v
bd/15w + 2d (10-4)
For deflection, l ∆
= [1,743EI/360w] 1/3 for ∆ = l/360 (10-5)
For deflection, l ∆
= [1,743EI/16w] 1/4 for ∆ = ¹⁄16 in. (10-6)
For Plyform, the allowable span lengths over multiple supports
are as follows:
For bending, l b
= [120F b
S e
/w b
] 1/2 (10-7)
For shear, l s
= 20F s
(Ib/Q)/w s
(10-8)
For deflection, l d
= [1,743EI/360w d
] 1/3 for ∆ = l/360 (10-9)
For deflection, l d
= [1,743EI/16w d
] 1/4 for ∆ = ¹⁄16 in. (10-10)
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