I want to use a lever beam point, two meters away from the middle of the fulcrum, to lift two tons half the weight of I-beam with much?
Your problem is the most basic cantilever beam. There is a whole formula in the mechanics of the material. The formula is not written to you. In the Baidu library, look for the mechanics of the PDF book and see the part of the calculation by yourself. You give something incomplete, so you have a cantilever beam, the most basic pivot distance from both ends of the length, you gave one. What material do you use, don't you say?. The use of low alloy steel or carbon structural steel, or stainless steel, is unknown.
Generally, stainless steel needs the worst stress, slightly better carbon steel, and low-alloy steel is the best. But in low alloy steels, the steels with higher strength tend to have lower toughness and worse toughness. They require severe deflection and overall instability, but will reduce the load-carrying capacity of the steel, increase the size and waste the material.Generally on the market, the common Q235-B, Q345, more. The parameter you are giving is incomplete. I wonder if you could estimate the coefficient of the lifting dynamic load If the dynamic coefficient of the 1.65 of the general equipment lug is concerned, the overall instability will be a destructive factor. You're more reliable than 20A or 20b i-beam. I think it would be safer to smash 250B I-beam if I often throw it crosswise. But the weight of 2 and a half tons is very low. Not very tall. The steel structures I make often hoist more than 60 tons.
There are so many controls on the beam damage to your present situation. The maximum principal stress ratio of 1 beams should be less than 0.7; the overall stability torque of the 2 beams is less than the flexural strength after the weighted coefficient of safety. The local stability of the 3 beam is less than the flexural strength after weighting. The maximum deflection of the 4 beam is less than L/300 or L/400. 5, the overall loading times should be less than the number of fatigue cycles, probably by 1000 times the following, more than 1000 times the load is considered unsafe.
