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Teguchi - I have reviewed calculations by others on a number of occasions with regard to the 5% rule in IBC (3402.2 in IBC 2000). A relatively small load (roof-mounted antennas and radio equipment) was being added to roof framing members. The design engineer showed that the increase in load over...

Teguchi wrote: "IBC 2003 states under chapter 34 - 3403.2 - Additions and alterations ... not increase the force ... more than 5%. synopsis - Code allows a 5% overstress for existing structures. For new construction, this is a no-no except for as-built pile cap designs." No, I don't believe...

Thank you all for your thoughtful input. This instance involves analysis of existing telecommunication towers regarding their capability of supporting additional antennas. I have a number of examples of other engineers using a 105% maximum. I am going to decline providing them with a signed...

It seems to be standard structural engineering practice to allow up to 5 percent overstress in structural design. It's been this way since I graduated college in 1980 and I've seen the practice commonly used in the tower analysis field for the last 15 years. I've been asked my opinion by a...

Thank you all for your input. I have read all of the other threads and there seems to be a consensus that split washers are not effective. I'm not sure I can agree, however. I routinely inspect telecommunication towers, which obviously see cyclical wind loads to an extreme degree. Hundreds or...

I found the requirements in EIA/TIA-222, Structural Standards for Steel Antenna Towers, to be interesting. Both revisions of this standard reference AISC Manual of Steel Construction. Revision F of the standard has been in effect since 1996. It states: "Where high-strength bolts are used and...

Sorry to not be more clear. I am not interested in opinions on their effectiveness, but I welcome opinions/interpretation of AISC requirements. Thanks.

Thanks Cory. I did read a few of those threads prior to posting, but they do not address my question, which specifically is whether AISC allows lock washers on A325 bolts or not. I also searched AISC's site and Googled to no avail. I have inspected close to 800 telecommunications towers and...

I was recently told that lock washers (a.k.a. split washers) were not allowed on A325 structural bolts. Their reasoning was the following in AISC's 9th Ed. of ASD (page 5-266): "(e) Washers. Flat circular washers and square or rectangular beveled washers shall conform to the current...

Communication tower manufacturers such as PiROD and ROHN list breaking strengths of EHS and Bridge Strand cables in their catalogs. I don't know about bridge applications, but in telecommunications the EIA/TIA standard requires a factor of safety of 2.0 for guys and components.

Dave Atkins & adk covered this well. I would only add a couple suggestions: When I took a PE review course prior to taking the exam, I received a "Civil Engineering Reference Manual" by M.R. Lindeburg. I've found this book to be quite useful in that it covers basic information on a...