4. (10 points) Find the most economic column section for BE (Note: you are asked to design only column BE) in the following loading condition. The ends “A" of simply supported beam AB and cantilever AC rest on the end “A" of AD, which means AD will have to support the load applied on it directly plus the portions of load at A due to beams AC and AB. Assume the loads transferred by the beams AC and AB are vertical.

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