The 3-span continuous beam shown in Figure below has to support the loads shown with a collapse factor of ? = 1.4. Investigate the collapse of each span and determine the corresponding plastic moment capacity M _p . Illustrate all collapse mechanisms together with the corresponding plastic hinges. Identify the critical span and determine the required plastic moment capacity M _p to prevent collapse by any one of the possible collapse mechanism.

Draw the bending moment diagram associated with the critical mechanism.

3m 120kN M 3m 28kN/m 2.5 M 12 m 4m 90kN M 4m