Diverse Member Cross Section Cost Comparison

[vava1]

Anyone know of an effective way of comparing diverse steel and aluminum members for simple beam support to give the best dollar for strength. Have flexibility in design for choosing cross sections, mainly looking at I-beam, channel, round, square and rectangular tubing. Thank you. Vava1

 

[MechEng2005]

The loading needs to be taken into account.

I have attempted similar, by creating a spreadsheet listing many structural steel shapes and properties (i.e. cross-sectional area, moment of intertia, etc). Then, by inputting the loading, the spreadsheet would calculate the shear/moment for the span, determine the maximum stress in the member. This list can then be used to determine options of what will work. It would be easy enough to add a "cost" column to determine the cheapest acceptable member.

However, I think a spreadsheet that allows entering a wide array of loading, and contains the hundreds of structural steel members, would be quite large and complex. Typically, I have a single spreadsheet that allows for only a single loading, and modifying it to a different situation is cumbersome to say the least.

-- MechEng2005

 

[civilperson]

Dollars per volume/allowable stress.

 

[youngstructural]

I hope you mean to compare steel to steel, and aluminum to aluminum...

When designing to a given siatuation, the cheapest is typically the lightest. Further, more in depth, comparisons are not easy; That's why there are so many shapes available.

The shapes that are offered by the steel mills are based on being as material efficient as possible while minimising any "additional" works required, such as stiffeners.

There are several good threads on efficient/economical design; I suggest you do a search. I will, however, be very interested to read other people's remarks.

Regards,

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[vava1]

Would there be any need to account for the section modulus and/or modulus of elasticity - say comparing cost effectiveness of steel 46ksi rect tubing vs an 35ksi aluminum alloy I-beam?

 

[agostage]

I would say yes giving that many designs are serviceability and deflection controlled.