Basic Steel Frame Structure

Center Column Joint at Top

A simple, four bay office building is being considered for additional equipment storage facility at the construction company where you work. The company would like to use the steel I-beams currently in storage at the company for the center columns. The list of available I-beams are given in the table at the left.

What is known:

• Young's modulus, E, is 200 GPa.
• Dead load on the roof is 300 kg/m².
• Live load on the roof is 250 kg/m².
• A factor of safety of 2.5 is required for all loads.
• Columns are rigidly fixed to the ground.
• Columns are assumed to be fixed at the top due to the rigid beams.
• Yield stress in compression is 250 MPa.

What I-beam should be specified for the center column to minimize the total weight of the building? Chose only from the list at the left.

• Roof loads, dead and live, need to be combined for total design load.
• Roof load needs to be distributed to each of the columns.
• Assume failure will be buckling.
• Use Euler's formula for fixed-fixed columns.