Dear Sir,

Software used : PV Elite V. 4.0

In calc. Of a tall silo under wind design code of UBC , the combined load stress report shows stress Ratio >> 1.0 near to 11.0 for load case of IP+WF+CW , whereas for the other load cases the ratio
is < 1.0 and okay. An investigation results in the stress due to load WF ( wind moment ( filled ) ( no CA ) goes with Beta 3 as defined in the program HELP ) is the key point . Also UBC code donot consider “ Beta 3 “ .

You are kindly requested to instruct how to cope the problem .

B.Regards

A. Mehrabani
Sen. Mech. Engineer

Nargan Co.

Dear Sir,

You are correct in stating that UBC does not directly consider the effect of structural damping as do many of the other wind codes. To be consistent with other wind codes, we allow these values to be entered.

If the stress ratio is greater than 1, I would determine which of the stress components is causing the problem. The program adds the stress components using linear superposition. I might suggest that you send in your file to us for further evaluation if necessary.

------------------
Scott Mayeux
COADE Inc.