Adaptation of torsional constant
See Ref.[1], Chapter 10.1.5., Ref.[2],3.5 and Ref.[3],3.3.4..
When steel sheeting is used, the torsional constant It is adapted for symmetric/asymmetric I sections, channel sections, Z sections, cold formed U, C , Z sections.
The torsional constant It is adapted with the stiffness of the sheeting:
with
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l
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the LTB length
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G
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the shear modulus
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vorhCq
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the actual rotational stiffness of sheeting
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CqM,k
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the rotational stiffness of the sheeting
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CqA,k
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the rotational stiffness of the connection between the sheeting and the beam
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CqP,k
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the rotational stiffness due to the distortion of the beam
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k
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numerical coefficient
= 2 for single or two spans of the sheeting
= 4 for 3 or more spans of the sheeting
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EIeff
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bending stiffness of per unit width of the sheeting
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s
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spacing of the beam
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ba
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the width of the beam flange (in mm)
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C100
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rotation coefficient - see table
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h
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beam height
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t
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thickness beam flange
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s
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thickness beam web
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