Cantilever spar cable-stayed bridge Cantilever spar cable-stayed bridge A cantilever spar cable-stayed bridge is a modern variation of the cable-stayed bridge. This design has been pioneered by the structural engineer Santiago Calatrava in 1992 with the Puente del Alamillo in Seville, Spain. In two of his designs the force distribution does not depend solely upon the cantilever action of the spar (pylon); the angle of the spar away from the bridge and the weight distribution in the spar serve to reduce the overturning forces applied to the footing of the spar. In contrast, in his swinging Puente de la Mujer design (2002), the spar
Pontoon effect Pontoon effect The pontoon effect refers to the tendency of a vessel whose flotation depends on lateral pontoons to capsize without warning when a lateral force is applied. The effect can be sudden and dramatic because pontoon boats usually cannot rely on the righting effect of a keel (which contains ballast). The vessel is stable and self-righting up to the point that the centre of gravity shifts past the centre of buoyancy of the ship and the vessel rapidly capsizes. The pontoon effect is theoretically possible whenever the vessel's entire weight exceeds the buoyancy of the pontoon(s) on either side.