Mini-crane (aka engine hoist) design.... strength questions
Hello all! This is my first post, so please delete/move if I made a mistake on placement. Thank you for any advice you can lend. Here's what I'm doing...
I am pouring a concrete slab to place a car lift on. I am also trying to incorporate an engine lift, or at least ability to add one, into the slab. 1. I am going to bury a tube/pipe 4 feet deep into the ground, the top of it being flush with my concrete slab. The hole will be dug with a 10 inch diameter and filled with concrete around the pipe and then integrated into the slab surface. I will then have a 14 foot tall pipe that will set/sleeve into that pipe whenever needed for lifting stuff(engines, heavy equipment, anything). Meaning, 4 feet will be in the ground, 10 feet above ground. I am hoping to do this with a 4" diameter vertical tube/pipe but I need to see if it can hold the load safely. I want to design the lift to safely pick 1000lbs(most use will be far less than that though). From the amature research I've been doing, I am using bend moment to determine stress the pipe must endure. IE: Pipe is 10ft tall(sticking out of ground) with a 10ft long horizontal I beam. When lifting 1000lbs at the furthest point on the horizontal I beam(10ft out) I get a bend moment of 10,000lbs at the point where the vertical tube enters the sleeve in the ground or where the top I beam attaches to it. I am going to double that number for a safety factor, meaning I need the vertical tube to be spec'd at 20,000ft lbs of bend moment. Sound roughly correct? Now here's my main question........ How do I calculate the bend moment a pipe/tube can take? The tubes I'm looking at using are 4" outer diameter, with either a 1/4" or 3/8" wall. Both wall thicknesses have a tensile strength of 70,000psi and a yield of 60,000psi. Is there a way to calculate the bend moment strength based on tensile or yield strength? Thanks a ton!