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All Posts By

Steve Petracek

07.30 2024

Optimize Site Adapted Prototypes for Efficient and Compliant Design

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July 2024

by Steve Petracek

Site Adapted Prototypes

On the design side of a project, everyone loves a prototype. Okay, maybe not everyone, but making a project or its details can be prototypical, the more efficiently a project can be designed. However, adapting a prototype to a specific site requires careful consideration. Questions may include: How does the building integrate with the site’s layout? How do planning, zoning, and energy codes influence both aesthetics and functionality? And where are the utilities situated, considering they often don’t align with the optimal building corners?

On the structural side of the project, The main elements affecting structural design at any site are variable loadings: snow, wind, and seismic forces. Foundations can vary as much as the loading types, each presenting unique challenges. The complexity of foundation design increases with soil types like clay, silt, sand, or any combination thereof, not to mention site leveling and frost depth. In conclusion, addressing these variables with a well-adapted prototype ensures structural integrity and cost-efficiency.

Snow

Snow is effectively a variable live load, and while many of us enjoy it, it can significantly impact a structure’s design. For reference, a standard roof live load is 20 pounds per square foot (PSF) across the country. In regions like Florida, southern Texas, and southern California, there is no snow loading. However, places like Maine and Alaska can experience ground snow loads of up to 100 PSF. Site-specific locations in mountainous regions, such as Colorado and Idaho, can have localized loads well over 100 PSF. Consulting the building official in these areas is highly recommended but not always sufficient. Building officials often suggest contacting local fabricators to determine the typical design load used in the region.

Wind

Wind pressure can be applied as a broad loading, or in other words, one design covers a significant area of the country. Almost everywhere in the country, anytime you step outside, you can feel a breeze. For wind to be considered severe in the US, it must reach a speed of 58 mph with most storms only reaching 39 to 46 mph per the National Oceanographic and Atmospheric Administration (NOAA). Therefore, one design may be able to cover 90% of the prototype locations. Unless the project is in a hurricane zone, the code wind speed in the US is predominately 115 mph or less for a Risk Category II structure. For a Risk Category III, the wind speed jumps to 122 mph, well above all but the most severe cases.

Seismic

Location is significant in seismic design, with forces determined by the structure’s weight. Plate tectonics and the Ring of Fire in the Pacific significantly affect the west coast and Alaska. But one can’t forget the Madrid fault in southeast Missouri that in 1811 it shook and was felt in Hartford, CT and Charleston, SC.  The lighter the structure, the smaller the seismic force. For most lightweight structures built with wood or cold-formed steel framing, 90% of the designs are completed with a single approach since the structure is relatively light. However, some variations make seismic design unique at each site compared to wind. Beyond the previously mentioned weight concern and building height, framing type plays a significant role in the design effort. Concrete shear walls, moment frames, and braced frames are in a long list of framing options that require different levels of detail, depending on the maximum considered earthquake. And then there is the soil type unique to each site that plays a significant role. Solid or soft, each one resists the load in a different way.

Geotechnical

Geotechnical information varies significantly across the United States, impacting building costs. To break this variation down, I will address them as two foundation types: shallow and deep. Shallow foundations are the typical spread footings located approximately in the upper 10′ of the soil. Deep foundations are some version of piers or piles and extend deeper than 10′. Depending on the structure’s mass, a conservative value for spread footings that work in most places may add avoidable additional costs.

An assumed bearing pressure of 1,500 psf compared to an actual bearing pressure of 2,000 psf could reduce the footing size and material costs by 25%. The nice thing about spread footings is that an adjustment to them can be made easily and quickly, depending on the complexity of the foundation system. 

There is no point in making the effort for deep foundations to create a prototype design. There are too many variables. Better results will be achieved by designing deep foundations on individual projects.

Grouping

For a prototype design, the larger the grouping, the quicker the updates or design adjustments can be made. Of course, the design envelope size will vary, depending on the framing material and type. Structural steel and concrete typically have extra capacities based on code minimum or functional requirements. For example, an HSS2x2 post may work, but an HSS4x4 is used because of the connection preferences. Cold-formed steel and wood are typically not loaded to their maximum capacities, and higher loads can be applied to allow for a larger design window. 

With all this said, prototype design can be very efficient for a client and a time saver for the designer. There will always be a design element in every project, but if the layout and framing of a structure don’t change, design effort is reduced, saving time and money.

The body having jurisdiction has the final say. Each municipality is different, and many have unique requirements, so even with the best planning, changes could still be possible.

Conclusion

Adapting prototypes to specific sites involves a careful balance of design efficiency and compliance with local codes and environmental conditions. By understanding the impact of site layout, planning, zoning, and structural variables such as snow, wind, and seismic loadings, architects and engineers can create designs that are both functional and cost-effective. Effective communication with local building officials and fabricators is crucial to ensure that the design loads and foundation requirements are accurately addressed.

Ready to optimize your next project with site-adapted prototypes? Contact our team of experts today to ensure your design meets all site-specific requirements efficiently and effectively. Let’s bring your vision to life!

Steve Petracek, Principal

05.30 2024

How To Overcome Structural Challenges: FEC Conversion – Chapter 3

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October 2023

by Steve Petracek, Principal

The Engineering Side of Things

Now that we have seen the architectural view of a Family Entertainment Center (FEC) conversion, the next logical step is to jump into the structural aspects. The benefits of an FEC conversion may be lost, if the modifications to the structure can’t be made. I have learned the best thing is to be flexible. Typically, we can achieve the outcome in most cases, but maybe not as planned originally.

The most intrusive element in the structure is the demising wall. Below are some general structural approaches to addressing existing demising walls. These tactics are dependent on the size and location of openings. Possible options include:

  • CIP conc: A solid wall, typically used to carry gravity and lateral loads, has the potential to add openings without excessive work.
  • Precast: Another solid wall system used to carry gravity and lateral loads, usually in widths of 8′ to 10′ sections. These are easier to modify as removing a complete section is possible; coordination of openings with the panel joints is required.
  • Tilt Wall: The same approach as used with CIP concrete.
  • CMU: Concrete Masonry Units are like concrete walls, but with unreinforced cells, intermittent steel reinforcing has an added challenge for wall capacity and use of anchor types.
  • Steel: The easiest and possibly the most troublesome at the same time. Typically, it is never an issue to remove the infill light gauge framing to enlarge the volume. In some cases, though, an X-brace is in the wall. Both the steel columns and X-bracing, which is a pretty cool feature, will need to remain.

The auditoriums themselves are typically straightforward, with the auditorium seating platforms able to be removed completely. Whether framed with structural steel, light gauge, or foam, reclaiming auditorium space is typically straightforward and requiring only demolition. Removing or filling a sloped floor is a simple fix to create a level surface at the required elevation.

Some difficulty comes into play with using the space under the mezzanine framing. There usually are columns between the demising walls to accommodate mezzanine offsets, steps, or reduce beam spans. In most cases, removing mezzanine columns can be completed with the correct reinforcing. Typically, removing one column requires two columns to be added.

To keep costs lower and downtime less, the location of the new framing is critical. The best solution is to design the new framing as the shoring element and the final condition framing. Having a contractor on board during the initial design phase is beneficial as they can provide guidelines or limitations on what they can do. Such as the maximum lifting weight, achievable framing lengths, and numerous other construction coordination requirements they are in control of that will push costs up or down.

Framing around kitchens is always a challenge. Owners want an open floor plan, with a preference for kitchen operation. That can be a problem based on the column interferences mentioned above. Coordination with a kitchen vendor early on to work on keeping unobstructed paths is recommended. Additionally, added kitchens require new rooftop equipment, typically supported by existing roof joists. In most cases, these joists do not have much additional capacity beyond their original design, requiring coordination with kitchen equipment to locate them efficiently and safely.

In summary, with Family Entertainment Centers becoming the next big thing, retrofitting an existing theatre is an excellent opportunity to bring in additional revenue. Bowling, arcade/redemption, axe throwing, laser tag, etc. provide diverse revenue streams that can be established for year-round, all-day business and an existing auditorium is an excellent place to find the space.

Steve Petracek, Principal

06.24 2022

Structural Definitions

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by Steve Petracek, Principal

JUNE 24, 2022

Communication can be very difficult. I could think I am saying one thing, but you might hear something completely different. It happens all the time in normal day-to-day conversations. How about when the subject is work-related and specific terms are used? The terms may be straightforward, but many people put different meanings or nuances to them. As some of you may know, I am also in the Navy Reserves and as I write this, I am in DC working on a reorganization of units, and a key phrase we keep falling back to is “words matter”. Meaning, that specific words need to be used at certain times, and they must be chosen carefully so that others understand them, and you can get your expected results.
Let me help with a better understanding of some technical words:

MEMBER – I used the word member almost a dozen times below, and not always in the same context. And in this case, it is exactly as Merriam-Webster describes it, “one of the individuals composing a group”.

DECK – This is the first line of the load path as it carries the floor and roof and transfers the load to the beams. In addition to carrying the gravity load, it works to carry the lateral load to the lateral resisting members.

BEAM – This is basically any horizontal member. Structurally, I would call the beam the first member supporting a floor or roof. Which leads to the next definition, the girder.

GIRDER – Typically horizontal or predominately horizontal member that supports beams.

TRUSS – A built up section to reduce the weight of the member and span a longer distance than a typical W-shape beam or girder. Very beneficial in creating long and open spaces but more depth is required.

COLUMN – Typically a vertical member but not always at 90 degrees to the foundation. Columns will carry the loads of the beams and girders.

FOOTING – or Foundation but never footer (section at the bottom of a page) or footin’ (not sure what that is). It is the bottom of all load carrying members and used to distribute the load to the soil. It carries both gravity and lateral loading.

BRACE – This is a diagonal member that is used to brace or support other members. These can be X-braces, single diagonals, and K-braces among other types. These are the vertical members that typically get in the way of openings or blocking some form of opening and are used to, in most cases, resist lateral load created from wind, seismic, or seating loads.

STRUT – A horizontal member that resists a force in line with itself. These are typically located in the plane of a diaphragm. It helps transfer the load from the diaphragm across an opening to a load carrying member such as a shear wall.

SHEAR WALL – Constructed of CMU or concrete and works also as a load bearing element. Typically, they are around the perimeter of the building and in theatres, is sometimes used as a demising wall.

TOP OF STEEL – This can be confusing. Top of steel is measured as the top of the structural steel such as a beam or girder. It is not the top of the steel joist sitting on a beam. Coordination for the top of steel elevation is left to the fabricator in coordination with the joist supplier verifying joist seat depth.

I know this is not as exciting to most as it is to me, but this should help anyone on a construction site, or when dealing with engineers and architects.

The best story I have heard was from a fellow coworker that was out on a site visit talking with the contractor about the steel framing. Structural engineer site visits are early and there is minimal framing up in some locations. In one location the contractor kept describing the issue he was having with the beams. As the engineer surveyed the site, all she saw were columns. When she stated there were no beams out there, the response was, “they are right there, those vertical beams.” Then she understood. Once we all have the same definitions, we can better support and help each other.

Have more questions about structural vocabulary, or stories about coordination that you would like to share? Ask! Email me at spetracek@tkarch.com

Steve Petracek, Principal

11.11 2020

Freedom is Never Free

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November 11, 2020

I am Steve Petracek, a Principal at TK Architects and a CDR in the US Navy Reserves and I want to say thank you and express my thoughts on this Veteran’s Day.  I am in the Navy Reserves and only a few months short of achieving the 20-year mark, but I have no retirement plans.  The military has helped me grow in ways I couldn’t see 20 years ago.  There have been some good times and some bad times, but all of them have helped shape me into the person I am today.

I joined the Navy in May of 2001, only months before the 9-11 attacks.  My wife and I had discussed the time and effort it would take, but we had no idea what lay before us.  I have only completed two deployments during my time.   My first tour was to Kuwait in 2006-2007 for eight months, with my second one to Afghanistan in 2012-2013 for 12 months, with each providing unique experiences.

In Kuwait, I was a lieutenant tasked to provide engineering management for small construction projects in the state’s eastern part.  My home was Camp Arifjan, and my focus was on overseeing projects that provided safety and resource staging for our troops.  I had the continual support of the Kuwait military in all I did.  I can’t imagine letting any other sovereign nation establish a base on US territory, yet they did and were very thankful.

My trip to Afghanistan was an entirely different story.  I was the operations officer for the battalion, and I started this position a year before our unit was to deploy.  What the means is I was responsible for training and preparing 550 people through classes and field exercises to face the austere and hostile environment Afghanistan was at that time.

For any of you who have seen “Band of Brothers,” a bond does form with people who endure hardships together.  Shortly after leaving Afghanistan, I read a quote that best describes the deployment.  It has stayed with me, and the further I get from my time there, the more real it rings, “I am homesick for a place I never wanted to call home.”  The bonds created there are forever locked in me that time will never take away.

I have been blessed in many ways.  I have a wonderful family that has supported me and been there every step of my journey, as well as an understanding and appreciative company that has bent over backward to help any way they can.  As my family will attest, these 19+ years have not always been easy.  The time away is difficult, and each of us changed in ways we didn’t think.  We have ridden the rollercoaster through numerous hills.  The best and worst times followed each other closely.  The joy of coming home from a year’s deployment was followed immediately by anger and resentment.  We never went back to the way we were, but we always found a path through the hardships.

There is so much more I could say, and if you ever want to listen to it, I would love to grab a cup of coffee and talk about it.  Good or bad, I am thankful for the opportunities to serve my country.  I am so very grateful for what my country has provided me, and it has been my pleasure to give back in some measure.

Non sibi sed patriae.

Steven Petracek