Tutorial $5$: Steel Beam and Column Design

Question $1$:

An existing bungalow is to be converted into an art studio and gallery by constructing an extension to the rear of the structure. To facilitate this extension, a new steel beam to be inserted to support both the existing and new roof structure. A cross section of the building is shown in Figure $1$ indicating key dimensions and the location of the new beam.

Design Details:

Characteristic permanent load $($on plan$)$ including beam self$-$weight, $g_k=2\mathrm{.}5k\frac{N}{m^2}$

Characteristic variable load $($on plan$),q_k=1\mathrm{.}5k\frac{N}{m^2}$

Clear Span of Beam between centres of Bearing $=6\mathrm{.}5m$

Assume that the existing roof truss structure and the proposed new structure do not provide lateral restraint to the compression flange of the beam.

At the supports at either end the beam is fully restrained against torsion, its compression flange is fully restrained, and both flanges free to rotate on plan.

:$-....*$

$($i$)$ Use the appropriate Design Table from the TATA Steel Blue Book to demonstrate that the UKB section in Figure $1$ has sufficient capacity by checking its resistance to:

a$.$ Bending,

b$.$ Lateral Torsional Buckling,

c$.$ Deflection $($assume the beam supports a brittle finish$).$

$($ii$)$ What reduction factor was applied to the moment capacity of the UKB section when determining its resistance to lateral torsional buckling?

$($iii$)$ Comment on the efficiency of the above design.

$($iv$)$ Determine the lightest UKC section suitable. Check lateral torsional buckling and deflection only. Compare the weights of the UKB and UKC sections sized.