FOUNDATIONS RESPONSE UP TO PLASTIC COLLAPSE OF PORTAL STEEL FRAMES BUILT ON SANDY SOIL

Experimental study was carried out on steel portal frames of 30 cm spa n and 20 cm height built on sandy soil. Various footing dimensions wer e tested and the settlement and rotation of the footings were measured . During loading, some frames have collapsed through the formation of enough plastic hinges to form a plastic collapse mechanism indicating the conservative design of their footings. The footings of these frame s were subjected to small deformations. Other frames were subjected to large deflection and sway before reaching the theoretical plastic col lapse load, indicating the unconservative design of their footings. Th e footings of these frames were subjected to large settlements and rot ations. This paper shows that Hansen's equation is a little conservati ve in the design of footings in order to minimize the deformations of the footings at the plastic collapse of superstructures.