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$10\mathrm{.}4.$ Select the lightest $W$ section for the two$-$span continuous beam of the accompanying figure. Use $F_y=60$ksi. The concentrated loads are $12$kips dead load and $60$ kips live load. Lateral support is provided at the vertical supports and under the concentrated load. Specify alternative lateral support if necessary in order to use maximum plastic strength in the design.

Problem $10\mathrm{.}4$