design and detail the two span continuous welded plate girder to support uniformly distributed load w=1 kip/ft dead load and 3.5 kips/ft live load. assume lateral support at each support and every 20 ft between supports. assume constant depth for girder. use A 572 grade 50steel. use LRFD methods. minimum web thickness is 5/16 inches. assume dead load and live load are acting together.