The Wisconsin Commercial Building Code

After 3 days of building code seminars in Madison at the Alliant Energy Expo Center, I am gradually starting to recover. The educational sessions were great, actually: very informative, professionally done with a wide variety of participants and presenters in attendance.

A couple highlights of possible interest to others relating to the State of Wisconsin Commercial Building Code:

Item #1

Adoption of the 2009 version of the I-Codes (IBC, IECC, IEBC, etc.) is hoped to occur by July 1st. This seems to be a "hope" and not an "expectation" for a few reasons:

1. The Safety & Buildings Division will be moving from the Department of Commerce ot the Department of Regulation & Licensing with an expected effective date of July 1st.
2. The proposed changes to the building code need to receive the blessing of the Secretaries of the appropriate department head (now, is that the Commerce Secretary, or the Regs & Licensing Secretary, or more probably both of them?) before becoming finalized.
3. The proposed changes also need to go through the legislative bodies of the State Government before becoming adopted. Anyone heard what they're up to lately? I think they have some higher priorities than a new building code right now, and rightly so.

Item #2

Three Plan Reviewers allegedly retired just last week from the Green Bay plan review office at Safety & Buildings, presumably because of the same reasons for uncertainty outlined above. This leaves the Green Bay office with no plan reviewers left and the State-wide review system which until 18 months ago had 6 offices is now down to just 3: Madison, La Crosse (Holmen), and Waukesha. 18 months ago the single Hayward plan reviewer was laid off, more recently the Shawano office consolidated with Green Bay, and now the "effective" closing of the Green Bay office as all Plan Reviewers there have retired.

Expect plan review to take longer, especially if the spring construction season gets into full swing! Call early for engineering and state plan review so that your summer work doesn't have to become your fall work. Also, remember that for some extra money and with the Owner's signature we can get Permission to Start footings before review is done, but that's as far as you can go without plan review completed by the State.

Any questions, please call me.

Thanks!
Aaron Halberg, P.E.

The Witch of November

"With a load of iron ore - 26,000 tons more
Than the Edmund Fitzgerald weighed empty
That good ship and true was a bone to be chewed
When the gales of November came early."
from "The Wreck of the Edmund Fitzgerald", by Gordon Lightfoot

The short term weather forecast and additional warnings and discussions from the Weather Channel and others, indicate a high probability of damaging winds on October 26th and 27th in the Midwest. The storm pattern and intensity is being compared to the infamous 1975 storm that took down the finest inland ship of the day, the Edmund Fitzgerald, and the lives of the 29 crew members on board.

Although being on a boat or ship during such a wind storm would be scarier to me than the best Haunted House you can imagine, these wind storms are nothing to be taken lightly when you're on land either. Problems with strong winds range from trees falling on transmission lines (power outages) to blocked roads limiting access for rescue vehicles or citizens, all the way to collapse of buildings, loss of property inside and even loss of life for the building's occupants.

If structural engineers seem a little withdrawn in social situations (sorry, that's a stereotype unfairly reinforced as... I.... sit alone in my office writing this blog post), it could be because they spend their time thinking about and planning for this type of nasty event on a regular basis when they are designing buildings. While no building can be considered completely safe from natural forces, a properly designed building will have a much better chance of avoiding damage than an improperly designed building. And if a better designed building does receive damage, it will still be better suited to maintain protection for property and occupants located within the building during the event.

Horizontal winds from storms like this (I'm excluding the high uplift pressures generated by a tornado) act upon on a building and can cause 4 basic types of failure. This illustration was developed by APA, The Engineered Wood Association and illustrates the general failure modes. The uplift shown below could result from horizontal winds passing over a roof shape similar to the uplift created on an airplane wing (the Bernoulli principle) or it could result from the cyclonic action of winds in a tornado although, as I've said, forces from tornado winds are generally not calculated or accounted for directly in building design or building code requirements.




In my opinion, there is also another failure type that might not be its own "General Mode", but it is different than the four shown. Internal Pressurization can occur when a large opening exists on one wall without adequate offsetting openings on adjacent or opposite walls. This creates what I loosely call a "Windsock" effect where you could have a strong wind coming into the building through a large opening and the building itself acts like the windsock with pressure building up on all surfaces whether horizontal or vertical. If the skin of the building or windows in the building shell cannot resist those pressures, local or widespread building failure could occur.

In buildings with large door openings, predicted storms like this one are good reminders to keep these doors closed during wind events like this for a couple reasons. For one thing, they will add some stiffness to the building shell to resist racking. The other thing it does is close off the end of the wind sock to prevent pressurization of the building.

Buildings still under construction are especially vulnerable to wind damage as they generally have some significant amounts of material area in place to capture wind forces, but the walls or systems to transfer that load back into the ground may not be completed, resulting in much higher stresses on certain building elements than a similar wind event would ever cause in the building once the construction of the building is complete. Temporary, or construction, bracing is usually left up to the discretion of the builder to make up for the lack of the completed building structure during this phase, but it has been my experience that this construction bracing, when present at all, is often not installed adequately to resist the loads that the completed building will be capable of.


I hope I am wrong, but I will not be surprised if some buildings under construction are damaged in some way by this impending storm. My hope in writing this post and sending it out to friends and colleagues in the building industry is that this damage can be minimized or eliminated over the next two days.

If you have any questions about this, or any other building engineering questions, feel free to call me!

Aaron Halberg, P.E.