(Solved): A plate girder beam is supported by load bearing stiffener (internal) in the mid span at both side ...

A plate girder beam is supported by load bearing stiffener (internal) in the mid span at both sides of the web as shown below. The intermediate transverse stiffeners are used to provide lateral torsional restraint to this beam. Determine radius of gyration \( \left(r_{w s}\right) \) in \( \mathrm{mm} \) of web and load bearing stiffener (internal). The design information of this beam and load bearing stiffener (internal) are given below: Design Information: - Thickness of the flange, \( \mathrm{t}_{\mathrm{f}}=15 \mathrm{~mm} \) - Thickness of the web, \( t_{w}=7 \mathrm{~mm} \) - Depth of the plate girder, \( d=1250 \mathrm{~mm} \) - Load bearing stiffener's outstand, \( b_{\mathrm{es}}=200 \mathrm{~mm} \) - Load bearing stiffener's thickness, \( \mathrm{t}_{\mathrm{s}}=25 \mathrm{~mm} \) - Intermediate transverse stiffeners are provided at \( 1500 \mathrm{~mm} \) spacing - Design reaction, \( \mathrm{R}^{*}=300 \mathrm{kN} \) - Stiff bearing length, \( b_{\mathrm{s}}=200 \mathrm{~mm} \) - Effective area of web and load bearing stiffener, \( A_{w s}=11540 \mathrm{~mm}^{2} \) - \( f_{y w}=320 \mathrm{Mpa} \) - \( f_{y f}=300 \mathrm{Mpa} \) - \( f_{y s}=280 \mathrm{Mpa} \) - Form factor, \( \mathrm{k}_{\mathrm{f}}=1 \) - Member section constant, \( a_{\mathrm{b}}=0.5 \) - \( b_{b f}=b_{s}+5 t_{f} \)