High Strength Bolting Keeps Nucor Building Systems Secure

At Kemp Construction Company our custom metal building design and solutions are all centered around the benefits of working with Nucor Building Systems.

Nucor Building Systems has been a metal building construction industry leader for the design and manufacture of custom-engineered metal building systems for well over 25 years.

Their avid focus on customer service, price, and premium quality materials has allowed Nucor Building Systems to grow and expand within all of North America.

While most of this discuss is applicable to most metal building systems, please note that since Kemp Construction has such a strong relationship with Nucor Building Systems some information is not accurate for other brand — even if they are owned by NBS, or, one of its subsidiaries.

The components of a Nucor steel metal building system

Pre-engineered buildings are factory-built buildings of steel that are shipped to site and bolted using high-strength bolts and nuts at critical joints.

Great speed is achieved because while the foundations and floor slab are being constructed, the structural system consisting of the beams and columns are being fabricated in the factory by Nucor Building Systems.

The foundations for pre-engineered metal buildings are made with conventional concrete systems. Most commonly these concrete systems are of the open foundation variety.

The concrete as we discussed on another blog post is critical to the safety of the metal building, briefly here is why…

The impact of wind on by metal building structures

Nucor Building Systems are usually quite large in stature, and as a result, similar to other large building structures — they tend to attract a fair amount of wind force from different directions.

Roof damage can be caused by high wind air pressure below the roofing assembly when the air pressure is greater than the air pressure above the building’s roof.

As this force of wind passes over the roof of your metal building, the pressure directly above the surface of the roof decreases.

Simultaneously, internal air pressure is increased due to air infiltration, which typically comes from planned openings like garage doors, windows, or manufacturing exhaust vents.

Of course, Nucor Buildings Systems are adaptable to a number of energy-efficient insulation systems from basic fiberglass to rigid board and insulated metal panels, even prismatic skylights can help maximize energy savings by significantly reducing building operating costs.

Nonetheless, this powerful cause and effect of wind creates a net upwards phenomena known as “uplift”.

Since Nucor Building System are active members of the MBMA Energy Committee and the U.S. Green Buildings Council, and help to set the bar concerning energy efficient buildings and green construction practices, their metal building systems have a published rate of 89% or higher recycled content which leads to structure weight of as little as 50 kg per square meter.

In other words, Nucor Building Systems steel building can be an exceptional choice for your LEED® projects, as the building are of high-quality weather-proof design and light-weight. Please, note the foundation(s) and floor slab is not included in the estimate.

Despite top notch grade Nucor Building Systems material, and excellence of Kemp Construction design and installation the need to combat uplift was of a concern to the Nucor Building Systems engineers.

The solutions to uplift on Nucor Building Systems

Every Nucor metal building has at its foundations custom designed with joint assembly points for the purpose of firmly anchoring the entire structures to the ground with bolts, preventing them from being blown away by the uplift effect of wind.

sidewall and endwall fasteners Nucor
Image Source: Nucor Building Systems; Product and Engineering Manual; Section 10.0 Anchor Bolt Details; Last Revision 08/28/09 by: DLC, CHK, AES, Detail Name if Applicable – AB0020PE.DWG 10.0.5 AB0020PE – Sidewall OR Endwall Column Setback

Nucor Building Systems do not stop there, they also exceed the standards set by FM Approvals.

According to Roof Contractor Magazine:

FM Approvals is a nationally recognized testing laboratory that tests and certifies building materials, fire protection and electrical equipment that can help prevent or reduce property damage.

Those products and services that meet FM Approvals’ rigid testing criteria become FM approved and bear the “FM” diamond certification mark.

Setting a firm foundation

The flooring of a typical metal industrial or steel storage building is usually a thick (about 6″ to 8″ ) concrete grade slab that rests directly on the prepared earth beneath it.

The concrete can be topped with a thin, abrasion resistant smooth coating called an epoxy floor or polyurethane floor if desired.

This style of construction is ideally suited to industrial buildings and warehouses; it is cost-effective, very fast to erect, and can also be dismantled and moved to another site – more on that later.

The Nucor Steel Building has these same features with the added benefit of its own supplier of welded wire reinforcement, Harris Supply.

As a result Nucor concrete foundations and slabs are reinforce with a full range of industry leading and advanced innovations in epoxy coated WWR where rebar and/or steel remesh products are needed.

Nucor Column Bolted To Concrete Foundation Floor
Image Source: Nucor Building Systems; Product and Engineering Manual; Section 10.0 Anchor Bolt Details; Last Revision 08/28/09 by: DLC, CHK, AES, Detail Name if Applicable – AB0020PE.DWG 10.0.5 AB0030PE – Column At Finished Floor

Dried into the concrete foundation and slabs are 1.25″ industrial grade Nucor steel fasteners anchor bolt with a projection of 3” above the bottom of the baseplate, see image above for details.

Column and Bolts Below ConcreteGrout thickness needs to be added to the projection where grout is used in ensure a precise fit and to hide the column base and anchoring bolts [see image below].

Nucor Building Systems require that the Nucor Anchor Bolt Setting Plan be used in lieu of the Architect’s Anchor Bolt Setting plan at all times.Baseplate with grout

The Metal Building Structure and Secure Design

The columns and beams of Nucor Building Systems consist of custom-fabricated I-beam sections that have an end plate with precision cut holes for bolting at both ends.

These I-section members are constructed by cutting Nucor steel plates of the desired thickness, and welding them together to assure joint integrity, and eliminate cracks.

Welding the section is another design feature to combat uplift as discussed earlier. 

The cutting and welding of the I-beam sections is manufactured via cutting edge automation. These industrial robots offer a high degree of speed and accuracy; the robots of overseen by human operators who will simply feed a CAD drawing of the beams into the machines, and then monitor the robots as they handle the task.

Once the foundations and floor are dried solid and pass inspection, the steel columns are shipped to Kemp Construction at the build site.

Upon arrival the painted steel sections, we utilize cranes to lift the sections into proper place and begin what we consider the most critical part of metal building construction …

… the fastening of I-beam section members to each other, and securing them to the concrete foundation and protruding Nucor structural fastener anchor stud bolts.

Pneumatic Torque Wrench for metal building construction

In large buildings, construction can start with two cranes working inwards from both ends; as they come together, one crane is removed and the other finishes the job.

The Role of Nucor Fasteners In Metal Building Safety

The proper tensioning, or tightening, of high strength structural bolts is essential at the slip-critical (or slip-resistant) joints of metal frames, and is the secret sauce to achieve engineered strength of a Nucor Building System.

If engineered strength is not attained, resistance to wind, snow, seismic loads, and other factors may cause the building frame to distort or worse fail.

Unfortunately, even though Nucor Building Systems has its own supplier of 6 different types of industrial fasteners as seen listed below, anchor bolts and nuts are not supplied by Nucor as part of the building order.

Nuts and Bolts - Nucor Fasteners
Image Source: Nucor Product Reference Guide

Of course, the nuts, washers, and bolts in and of themselves do not ensure a secure metal building; the method of torquing the fasteners is the true hero.

Nonetheless, the industrial fasteners was must withstand the applied force of torque in the first place.

According to Guy Avelon, owner of GT Technical Consultants;

A critical bolt failure can make all the difference between a high performance system and a broken high priced device. It takes just a single compromised bolt to cause untold damage to both the system and the very facility the system is located.

Nucor Structural BoltsThat said, insufficiently tightened fasteners may result in loosening of nuts on stud over time, and ultimately ceasing to contribute to the metal building frame stability.

Since each piece of the Nucor Building system is very much alike they are able to be fastened with a consist type and size of fastener at various points, and thus only 6 types of fasteners are required.

Fastening materials included for contractors

Nucor supplies all it approved builder, like Kemp Construction (3) sets of 11” X 17” anchor bolt setting plans on all building orders.

Usually, each connection calls for six to twenty bolts to be installed. Bolts are to be tightened to exactly the right amount of torque using various wrenches.

BERT with 3' Projection
All anchor bolts are ASTM F1554 Grade 36 unless noted otherwise. Nucor sizes the anchor bolt for shear and tension at the column base.
However, it is important to know that all aspects of the foundation design including anchor bolt embedment length and development to the concrete is not by Nucor.
Instead, the responsible architect or engineer for a specific project must see to it that the concrete is done by a professional who is qualified for this type of work.
Anchor Bolt Details
Image Depicts: Anchor Bolt Details

Now remember earlier we mentioned that the I-beam section members had open end plates for bolting them into the concrete?

While most of the other sections of a Nucor Building System can be fastened with manual spud wrench, the foundation structure should be fastened at minimum with a high quality Milwaukee or Ingersoll Rand type of impact wrench.

TTP Metal Steel Nucor Building Systems

However, for maximize benefit and precision a controlled tightening device like a TTP 1 Pneumatic TorcGun which ranges from hex size 1″ to 2 3/8″ is highly recommended by Kemp Construction especially on 1 1/2 inch to 2 1/2 inch bolt hex.

Approved Procedures for Tensioning Bolts

There are two generally accepted methods for tensioning high strength bolts on metal framed buildings. These are:

Manual Torquing“Turn-of-the-nut” method.

Bolt is tightened as snug as possible with a 14″-16″ spud wrench similar to the ones manufactured by Klein Tools.

A mark is made on a point of the nut and on the frame at the same point. Using a 4′-6′ cheater bar or using an impact wrench, the nut is tightened two points past the mark on the frame.

Calibrated Tigthening of Pre-Engineered Metal Building BoltsCalibrated wrench method.

The nut and bolt is paired tightened using a calibrated wrench, (not a common torque wrench), and is tightened to the manufacturer’s specifications.

Other methods approved by the manufacturer or project engineer may be used with prior approval of the Building Official.

After final tightening, we recommend the fastener be distinctively marked with paint or light colored indelible marker, to indicate the nut and bolt has been fully torque within specification.

Anchoring The Safety of Metal Building

As we have shown you, pre-engineered metal buildings require a firm foundation, welded integrity of seams, and precision bolting of its components to each other and the concrete base and slab.

Doing so prevents “uplift” created by wind force to damage the roof and wall sections.

The cement mix and steel rebar play an essential part in the laying on the concrete foundation and slabs.

Spud wrenches and impact wrenches are used to fasten most bolts, however, the 3″ anchor bolt extending from the base of the concrete are recommended to be tightened with a calibrated pneumatic torque wrench to achieve maximum accuracy.

Should you have any questions, comments, or thoughts regarding this post; High Strength Bolting Keeps Nucor Building Systems Secure, or any other matter please contact Kemp Construction, for a Nucor Building System quote call us at (574) 773-4994 .

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