Delivering structural engineering expertise nationwide

February 7, 2024

Written by Stephen Dominguez, PE, SE, Principal-in-Charge, Structural Engineering

For a structural engineering firm to succeed as a national player, it must have a team of knowledgeable professionals well versed in the differing geographical, meteorological and other factors affecting construction approaches around the country.

Designs and project plans created by WT Group’s Structural Engineering team members are developed with a full understanding of local conditions that can impact completed projects. We work with geotechnical report recommendations that frequently vary by region in response to associated soil-bearing capacity, requiring adaptations to soil types ranging from clay to bedrock to sand. Slab subgrade and vapor barrier locations are among the factors that often change based on local geography.

Texas, for example, is rife with “expansive soils,” containing minerals such as smectite clay that is highly absorbent following rain or flooding. When wet, these soils increase in volume and can exert sufficient pressure on structures to cause damage. Across much of the South, footings are shallow and are typically poured monolithically with the concrete slab on grade.

In Illinois and other Midwestern states, snow loads are a key concern, along with other stresses associated with freeze/thaw cycles. Foundations need to be dropped several feet for frost protection, often with the addition of a foundation stem wall between the footing and the building walls. Additionally, different concrete mix and air content are required to accommodate Midwestern freeze/thaw cycles. Midwestern projects may also be subject to significant lateral wind loads from spring and summer convective storms, making the incorporation of wind-load mitigation features into designs a prudent measure.

Of course, Florida and other states bordering the Gulf of Mexico and the Atlantic are particularly vulnerable to high winds exerting severe lateral stresses. In these regions, it is often necessary to have more elements contributing to the lateral force resistance system (LFRS) for new construction to mitigate against anticipated high wind loads.

And then there is California, home to more frequent and severe seismic events than any other part of the nation. Our Structural Engineering team must consider designs, construction techniques and materials to keep the structure from collapsing during a seismic event. Since the seismic force is directly related to the weight of the structure, most of the buildings we design in California are constructed with wood. Not only do wood-shear walls have a positive response to earthquakes, but they are also substantially lighter than other building materials. Other advantages of selecting wood for building design include it being a renewable, cost-effective resource. Wood also stores carbon in its fibers, making it one of the lowest carbon footprint building solutions.

Conversely, most of the commercial buildings we design in the Midwest involve concrete masonry units (CMU) and steel, both of which are great for fire resistance. Other benefits of choosing steel include its high strength, leading to longer framing spans and the ability to fabricate it in a variety of shapes. In addition to fire resistance, concrete and masonry are also strong in compression and work well for insulation against the Midwest’s bitter winters and torrid summers.

Over more than five decades delivering design and engineering expertise to a client list now spanning the nation, WT Group experts have demonstrated a keen ability to adapt to the local geological, meteorological and other requirements affecting customers’ projects. That ability will only become more important in the years ahead as we help clients respond to the changing environmental conditions and new challenges they are certain to face. As a truly national engineering, design and consulting organization, that ability is one of the most important values we bring to the table.