Old beam...how to determine what type it is 1

[jimtheengineer10]

I have been asked to determine the uniformly distributed load an existing beam can handle. The building was constructed in 1929 and the only notes on the plans regarding the beam are that it is a 15" 42plf beam. The beam is about 50' above the floor and I was able to climb above the beam on some wooden slats and take some measurements but I couldn't get exact measurements as I had to reach quite a way down to the beam. Looking in my LRFD book I see there is an S shape that is S15x42.9. I can't find any W beams that seem to match up.

How would you handle this? Is there a way to figure out exactly what type of beam this is or do I just need to make some assumptions and run the calcs based on my measurements/assumptions and then state my assumptions in my report? Thanks.

 

[WWTEng]

Sounds like S15x42.9. There is marked difference between S & W shapes, were you able to verify that visually?

 

[woodman88]

First off you need more information about the shape of the beam. Per my Data Book for Civil Engineers copyright 1945, 51 & 60 an Amer. Std Beams has a 15I section with wt= 42.9, S=58.9, t=0.41, d=15, b=5.5, t'=.62

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[JAE]

You might look through slideruleera's website (member here at Eng-Tips) as he has posted some good resource information:

http://www.slideruleera.net

 

[topsisu]

From Slideruleera's website, look at AISC "Iron and Steel Beams 1873 to 1952" (page 20 in my hardbound version). Several choices for a 15" American Standard Beam 42.0 plf. Remember, the yield strength may only be 30 ksi. Study the footnotes for the years rolled.

 

[msquared48]

I fully agree with the last two posts. And remember, back in the 20's they had to use silderules, so do go there.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[jimtheengineer10]

Ok, I have looked through the "Iron and Steel Beams 1873 to 1952" book and I want to make sure I am reading it correctly.

On page 20 (in the pdf from slideruleera's page) there are three rows with a 42plf weight. For the bottom row there there is only one number in column 1 which is 28. If I look at the top of page 20 and find the number 28 it says to see page 18. I go to page 18 and at the top the number 28 has a PE 1898, PE 1900 and PE 1901. This means that the beams was manufactured by A&P Roberts Company (Pencoyd Iron Works) correct?

Do I get the yield strength from the yield strength would be on page 6? Would I look under the ASTM A9 or Buildings row?

Thanks for all the help.

 

[topsisu]

Your interpretation of the footnotes match mine. You may also look at AISC Design Guide 15 which replaced the book. My original copy of a 1915 Cambria Steel manual lists an allowable fiber stress of 16000 psi. The AISC DG 15 says the AISC specification for 1923 list the allowable stress as 18000 psi.

 

[jimtheengineer10]

Is there a table that gives the φMn values or do I have to calculate those?