question in Ballast (7)

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lotus0418

February 24, 2021 00:57

Hi guys, I cannot understand the highlighted sentences in below image as follows:

1. In the fist graph, the shear action's arrow is downward, but I think a shear action should be perpendicular to the leg of the end beam;

2. What's "funicular"? And what's the "bending stresses"?

3. What's "the short lengths of the beams near the corners"?

I hope some one can kindly answer my questions. Many thanks in advance.

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  Joseph March 02, 2021 12:59

  1. Shear action occurs along arch (not vertically)

  2. Funicular shape - see link below

  https://www.youtube.com/watch?v=m8nx92UBShM (just watch till 4:15 min)

  If bending stress happens, it needs to be thicker to resist. (like simply support beam - refer the index part of your ballast book for bending stress)

  3. Take a look "the short lengths of the beams near the corners" in this link below ( see Fig 8.30 (b)) 

  https://www.civilengineeringx.com/structural-analysis/structural-steel/arched-roofs/ 

   

  If you have extra time, see this slide also in this link below(page 12 & 16)

  https://www.slideshare.net/SusmitaPaul12/shell-structure

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  Joseph March 02, 2021 13:21

  Owner hire an architect to build gas station in downtown, DC using thin shell funicular shape barrel vault for the roof.

  What is the force not present in the roof of this gas station.

  1) shear 2) tension 3) compression 4) bending

  answer) 4

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