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Three i-sections are used as test specimens under beam loads: a w18×50, a w18×158, anda plate girder with a thin flange. All tests use the same span and unbraced length and all beams aremade of the same type of steel. It is found that each beam undergoes a different failure mode. One failsin local buckling, one in lateral-torsional buckling (ltb), and the last by a plastic hinge mechanism.write the failure mode under the correct section and explain your reasoning.