Modular construction is reshaping how buildings are designed and delivered — and cold-formed steel (CFS) is proving to be a critical part of that evolution. Its high strength-to-weight ratio, dimensional consistency, and compatibility with offsite fabrication make CFS framing a natural fit for modular systems.
But one challenge demands careful engineering attention: ensuring adequate lateral stiffness and seismic resistance in modular assemblies, particularly when units are stacked. A 2025 study published in Structures addresses this directly — and its findings have meaningful implications for how engineers should approach CFS wall design in modular projects.
What the Research Shows
“Lateral stiffness of modular steel structures infilled with cold-formed steel walls” (full article)
The study’s key findings:
- CFS infill walls significantly increase the lateral stiffness of modular steel frames
- Connection detailing — specifically how CFS walls are fastened to the frame — directly affects lateral performance
- A simplified model using axial springs to represent studs accurately predicts system behavior, validated by quasi-static full-scale testing
- Openings such as doors and windows reduce stiffness, but the effect can be addressed through deliberate design choices
The takeaway for structural engineers: infill CFS walls aren’t just partitions — they’re active structural contributors to lateral system behavior, and their connections need to be designed accordingly.
Designing These Systems with SteelSmart®
SteelSmart® System is built to support precisely the kind of nuanced CFS design this research highlights. The software integrates TSN’s full connector and framing library, allowing engineers to design and specify systems that account for drift, deflection, and lateral load transfer within a single workflow.
DriftTrak®
Allows in-plane lateral drift and vertical deflection at the head of wall, enabling modular and panelized systems to accommodate building movement without compromising connection integrity. SteelSmart® System’s Curtain Wall module supports DriftTrak specification alongside complete stud layout design.
VertiClip® SL & SLB
Transfer horizontal forces while allowing vertical deflection of the stud relative to the structure — behavior that directly parallels the energy-dissipating stud action modeled in the study. These connectors are part of TSN’s product library within SteelSmart® System.
X-Brace Shear Wall (StiffWall®)
SteelSmart® System includes a dedicated X-Brace Shear Wall module for designing TSN’s StiffWall system, providing engineers with a direct path to specifying flat strap bracing for panelized CFS wall assemblies that need to resist lateral loads.
Design Takeaways for Modular Engineers
The research reinforces several principles that should inform how engineers approach CFS wall design in modular applications:
- Treat infill walls as structural elements, not just enclosures — especially in stacked modular systems where lateral performance is cumulative
- Specify engineered connectors that account for both in-plane drift and out-of-plane deflection, rather than relying on generic fastening details
- Use software that reflects real structural behavior — SteelSmart® System is built around TSN’s tested and load-rated product line, giving engineers the tools to design with performance and constructability in mind from the start
A Software Platform Built for These Challenges
As modular construction grows in complexity, the demands on CFS design software grow with it. SteelSmart® System gives structural engineers the analytical tools and TSN product integration needed to tackle lateral stiffness challenges in modular framing with confidence — from initial member sizing through connection specification and documentation.