Load bearing of 2 alluminum square tubing

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Discussion Overview

The discussion revolves around the load-bearing capacity of 2-inch aluminum square tubing (AA6061 T6) with 1/8 inch walls, specifically in the context of constructing a bike frame. Participants explore the implications of static versus dynamic loads and the structural considerations necessary for safety.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant seeks to understand the weight that an 8-foot length of 2" aluminum tubing can bear before bending, expressing discomfort with mathematical concepts.
  • Another participant provides a specific allowable midspan point load of 2100 N for a simply-supported beam, but does not clarify the conditions under which this applies.
  • A different participant emphasizes the importance of defining the type of load (static vs. dynamic) and the support conditions (simply-supported vs. cantilever) before calculating load capacity.
  • Concerns are raised about the safety of the proposed bike frame design, particularly regarding dynamic loads and the potential for injury if the structure fails.
  • One participant mentions the need for additional clarification on what "P" represents in the context of load calculations.
  • The original poster expresses a desire to use aluminum for weight considerations but contemplates switching to steel due to concerns about bending under load.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the load-bearing capacity of the aluminum tubing, and there are multiple competing views regarding the safety and structural integrity of the proposed bike frame design. The discussion remains unresolved, particularly concerning the implications of dynamic loading.

Contextual Notes

Participants highlight the need for clarity on load types and support conditions, indicating that the calculations may vary significantly based on these factors. There is also an acknowledgment of the potential risks associated with improper construction.

Who May Find This Useful

This discussion may be of interest to individuals involved in structural engineering, DIY bike frame construction, or those exploring the properties of aluminum materials in load-bearing applications.

sirhart
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load bearing of 2" alluminum square tubing

im trying to build a load bearing beam out of 2" alluminum tubing 1/8 in walls can anyone tell me the weight a length 8feet long could bear befor bending its aa6061 T6 what would it hold befor bending? keep in mind math is not my cup of tea lol
 
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forgot to mention its square tubing aa6061 T6 2" square 1/8 in walled
 
For a simply-supported beam subjected to static loading, the allowable midspan point load would be P = 2100 N.
 


i apriciate the help but like i said befor i don't even know what P stands for me and math are sworn enemies lol. but thanks for the help
 


Well, there are many different types of loads that could be supported...and in so many different fashions.

Is this like a structural beam which is pretty much rigidly supported at two ends and has a point load in the middle (or at multiple spans)? Is it a cantilever? These are all questions you'll have to answer before you can do the math.


See here for a basic mathematical explanation of everything you'd want to know about beams.

See http://www.aaronklapheck.com/Downloads/Engr112_Handouts/ENGR112%20Solutions/05-01ChapGere[1].pdf for good examples with equations and solutions.

Click here for just the formulas for different cases.

Hope that helps.
 
Last edited by a moderator:
sirhart: P in post 3 is the applied, transverse, midspan point load as shown http://img27.imageshack.us/img27/1302/beam01.png . Let us know if this is not what you were asking about.
 
Last edited by a moderator:


basically i am atempting to build a 4 tired bike frame since my knee is no longer strong enulf to catch me on a normal bike i thought i might put an extra seat on it for my 7 year old daughter to come along. i needed the frame to span about 6 feet from axle to axle 8 feet in all. was hoping to use aluminum for weight issues but may have to use steal. just trying to figure if it would of bend with two people riding it. didnt want to get hurt riding along and pop I am on the ground lol
 


sirhart said:
im trying to build a load bearing beam out of 2" alluminum tubing 1/8 in walls can anyone tell me the weight a length 8feet long could bear befor bending its aa6061 T6 what would it hold befor bending? keep in mind math is not my cup of tea lol

sirhart said:
basically i am atempting to build a 4 tired bike frame since my knee is no longer strong enulf to catch me on a normal bike i thought i might put an extra seat on it for my 7 year old daughter to come along. i needed the frame to span about 6 feet from axle to axle 8 feet in all. was hoping to use aluminum for weight issues but may have to use steal. just trying to figure if it would of bend with two people riding it. didnt want to get hurt riding along and pop I am on the ground lol

You are asking for advice on how to build something that could get your daughter hurt if it's not done correctly? You didn't even specifiy early on that this was going to be a dynamic load, with peak loads significantly above the static load (potholes)!

Sorry, this is not a good subject for the PF. Thread is closed.
 

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