How much force is there to lift an object?

By inspection the weight is centered at the center of gravity of the solid block, or in the middle of the span, 12.5 ft. So just divide the weight by 2 to get the reaction at both ends, or 12500kg. If the object were a different shape then the cg would be in a different location and a different analysis using reactions and moments would be required. But if you need to lift it at a certain rate other than very slowly then a different analysis would be also required using F=ma