How to do engineering calculations?

   / How to do engineering calculations? #11  
the depth of the beam is the major key to strength,

most likely you can make a small and light weight addition on your current ramps that will nearly eliminate the problems, if the ram is not bent.
if you can straighten it out, use a 1/2 to 5/8" rod and put a few spacers, for a web, (flat, rod, small angle, etc.), and make a rod that will truss the under of the ramp most like a nice bow will be fine, I would say about 6" in the center, and then use the short pieces to fill in for a web, in the truss,

the pictures are not ideal but represents what I am trying to say,

years ago I made a moving ramp, abut 3 foot wide and 20 foot long, use some rebar for truss and it was made out of one inch square tubes and the 1/2 rebar truss I had two points in it to widen the truss, now I know it would not have most likely supported a 3000 pound machine, but it was not designed to, but the truss can strengthen them greatly and not add a lot of weight,

if all else a flat iron 1/8 on the bottom edge of the angle and increase it depth to 6" and trim the ends so it can work same as the angle to the earth would be (just a solid web),
 

Attachments

  • truss.jpg
    truss.jpg
    5 KB · Views: 158
  • TRUSS_PUTLOG.jpg
    TRUSS_PUTLOG.jpg
    26.6 KB · Views: 133
   / How to do engineering calculations? #12  
search around for a program called 'beam boy'. You can pick your shape/thickness and length and type of loading/support. It will tell you the peak stress and the deflection.

For smart phones, try 'epicFEM'.
 
   / How to do engineering calculations? #13  
the depth of the beam is the major key to strength,

most likely you can make a small and light weight addition on your current ramps that will nearly eliminate the problems, if the ram is not bent.
if you can straighten it out, use a 1/2 to 5/8" rod and put a few spacers, for a web, (flat, rod, small angle, etc.), and make a rod that will truss the under of the ramp most like a nice bow will be fine, I would say about 6" in the center, and then use the short pieces to fill in for a web, in the truss,

the pictures are not ideal but represents what I am trying to say,

years ago I made a moving ramp, abut 3 foot wide and 20 foot long, use some rebar for truss and it was made out of one inch square tubes and the 1/2 rebar truss I had two points in it to widen the truss, now I know it would not have most likely supported a 3000 pound machine, but it was not designed to, but the truss can strengthen them greatly and not add a lot of weight,

if all else a flat iron 1/8 on the bottom edge of the angle and increase it depth to 6" and trim the ends so it can work same as the angle to the earth would be (just a solid web),
Trusses are the strongest and lightest structure you can build. Something like in the first photo should do the trick for you and not be too terribly heavy. Just make sure the ends are welded securely. I would use 3/4" solid A36 steel rod for the truss with a tensile of 36,000 PSI it would have to stretch or break prior to the ramp bending.
 
   / How to do engineering calculations? #14  
the depth of the beam is the major key to strength,
First thing to fail on a beam is the flange. That's why engineers will have you add plate / flatbar to the flanges if the beam is in question.

A "PE" used this analogy to explain to me how a beam fails under load. Take a yardstick, support the ends, push down in the center of the yardstick, what happens? The yardstick bows out to one side or the other. It doesn't go straight down. It bows out to the side until it buckles. So if you beef up the flanges of the beam. Or box the beam in some how. The trick is to keep the beam from bowing to the side. The web has little effect to the strength on the beam.
 

Attachments

  • Flange Stiffeners.jpg
    Flange Stiffeners.jpg
    93 KB · Views: 184
  • Yard stick.JPG
    Yard stick.JPG
    242.1 KB · Views: 168
  • Yard stick bow.JPG
    Yard stick bow.JPG
    233 KB · Views: 151
   / How to do engineering calculations? #15  
simple --> go to school like the rest of us!

I am very leery of trying to explain how to perform calcs over the internet for various reasons. Your best bet would be to simply overbuild whatever your trying to do. Copying another design is also a pretty safe route to take. Steel shapes are rathering fascinating because depending on the loading and connections there are several different failure modes that could occur and each one needs to be examined to determine which one controls in a specific example.


Many individuals like asking about bridges and what size beam do I need? Simple question, not an easy answer. Everyone runs to the online calculators without knowing what they are actually looking at. They have no idea if the answer is reasonable or accurate. Close enough is usually the name of the game, or using whatever they were given for a good deal. I'm not trying to be critical, just trying to explain an engineer's point of view.


Shieldarc, the DEPTH of the web is critical to the strength of the beam. A simple "I" or "W" shape that acts like a simple machine if you will. Each piece contributes a unique attribute to the structural shape and is chosen for that exact reason.
 
   / How to do engineering calculations? #16  
So why does the same height W-shape take more weight than the same height S-shape?
 
   / How to do engineering calculations? #17  
First thing to fail on a beam is the flange. That's why engineers will have you add plate / flatbar to the flanges if the beam is in question.

A "PE" used this analogy to explain to me how a beam fails under load. Take a yardstick, support the ends, push down in the center of the yardstick, what happens? The yardstick bows out to one side or the other. It doesn't go straight down. It bows out to the side until it buckles. So if you beef up the flanges of the beam. Or box the beam in some how. The trick is to keep the beam from bowing to the side. The web has little effect to the strength on the beam.


The contributions of parts of an i-beam is a chicken/egg phenomena. All of the tension/compression strength is in the flanges. However, all of the shear strength, which is what holds it together, is in the web. The maximum shear is dead center in the web, in fact. If you can't handle the shear load in the web associated with the tension/compression in the flanges, they may as well be noodles. So the whole cross-section of the i-beam is important and matters. You can't have one characteristic without the other.
 
   / How to do engineering calculations? #19  
Reading a book on welding should be enough to get me a job as a pressure welder??:)
 
   / How to do engineering calculations? #20  
Why read a book when you have the internet and youtube? All you would ever need to know...


Seriously, they are many things you can learn and do on your own with the help of the internet. Building a skyscraper is not one of them however :)
 

Tractor & Equipment Auctions

2018 John Deere 524K-II Articulated Wheel Loader (A50322)
2018 John Deere...
2014 Ford Escape S SUV (A48082)
2014 Ford Escape S...
2018 Ford Explorer AWD SUV (A48082)
2018 Ford Explorer...
UNUSED Grey Metal Roof Panels (A50860)
UNUSED Grey Metal...
GENERATOR HOUSE POWERED BY TWIN (60 SERIES)  DETROIT 14.0L ENGINES (A50854)
GENERATOR HOUSE...
2003 International 4300 Flatbed Truck w/ Liftgate - Inoperable - 7.6L DT466 Diesel Engine (A51039)
2003 International...
 
Top