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Have you ever wondered, “What is the leading cause of structural demise for communication structures and how can I prevent it from wreaking havoc on my infrastructure?” Probably not, but us structural-engineering-types amuse ourselves with this type of question. The answer, you ask? Weep holes. What?
Well, let’s take a step back. Many structures, and specifically, many lattice tower structures, are constructed from structural members that are tubular or hollow (pipe). One unfortunate fact about structures is that water always finds a way into a hollow space. Even boats take on water and we know that boat engineers try really hard to keep that water out. Fortunately, when designing towers, engineers do not need to hold the water out, they just need to prevent it from collecting. How do they do that? Simply, with weep holes. These small holes in structural members do not significantly impact the strength of the members, but do allow any collected water to drain.
“Why is this important,” you ask? Water does two things when trapped in a pipe: 1.) Water corrodes steel, reducing its strength, and 2.) In most climates, water will freeze during cold months, expanding and potentially causing the tubular members to burst, also reducing their strength. In either of these two cases, the capacity of a tower can be significantly reduced, often without any indication to the owner.
So that is the bad news. The good news is that the leading cause of structural demise for communication structures is one of the easiest problems to correct. A simple inspection to verify that weep holes exist and that they are not plugged can greatly extend the life of a structure. We have seen tower members fabricated with weep holes, only to be installed up-side-down with the hole at the top and no hole at the bottom. This is a great way to let water in and not let it out. The even better news, is that a lack of weep holes is easy to correct. Half a day with a cordless drill solves this problem.
How long has it been since every weep hole on every one of your towers was inspected? Ok, you don’t have to answer that. Every owner should take this situation seriously. Nothing destroys a $20,000 tower faster than the lack of a $5 hole. The Engineering Specialties Group has the expertise to inspect structures and recommend easy fixes such as this to keep your infrastructure function as long as possible.
This article was written by Steve Dorau, project manager and telecom infrastructure group leader.
© Copyright 2011 by the Engineering Specialties Group