EE's were setting new Ibeam support in plant. Ibeam was being supported by come-a-long and strap at top and was caught at bottom by 1/2"" plate. Ibeam stopped at top by another Ibeam, EE attempted to dislodge it by lifting on it in a crouched position and threw out his back. EE complained of pain and layed on floor. EE was placed on backboard and taken to hospital.