The elevator shaft is rectangular 4'6" x 1'8". The elevator lifts Lime pebble and the elevator is approx. 128' tall. They would like to cut an access door near the bottom of the elevator. They would like the door to be installed on both sides of the casing which the width of the side is 4'6". They would like a 5' tall by 3' wide door. I contacted the supplier because I found draings of access doors on elevators but would like to calculate double check the stiffeners required around the opening. I found material on a silo (round) but I am uncertain about calculations on the rectangular.