The least permissible clear dimension of the web of thickness $ t $ in the panel of a plate girder is restricted to
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For steel structures like plate girders, always refer to IS 800:2007 for permissible web dimensions and stiffener spacing. The formula $ L_c = 180t $ is key to ensuring web stability.
Step 1: Understand the requirement for web dimensions in plate girders. The clear dimension of the web refers to the distance between adjacent stiffeners or supports in a plate girder. This dimension is crucial for ensuring the stability of the web under shear forces and preventing buckling. According to IS 800:2007, the Indian Standard Code for Steel Structures, the maximum permissible clear span of the web without intermediate stiffeners is given by: $$ \boxed{180t} $$ This ensures that the web remains stable and does not buckle under applied loads. Step 2: Evaluate other options. $ 150t $: Too restrictive; unnecessarily limits design flexibility. $ 160t $: Below the standard limit; may lead to instability. $ 170t $: Closer but still below the safe limit. $ 180t $: Matches IS 800:2007 guidelines; correct value. Step 3: Select the correct option. Based on IS 800:2007, the least permissible clear dimension of the web is: $$ \boxed{180t} $$