July 22, 2025

Designing Light-Framed Structures: Tips for Wood & CFS

Light-framed construction has become increasingly prevalent in mid-rise and modular development, driven by its cost-efficiency, speed of construction, and adaptability. But with flexibility comes complexity. Engineers designing with wood and cold-formed steel (CFS) must navigate a unique set of challenges: diaphragm behavior, segmented shear walls, buckling sensitivity, and code-specific checks that differ from traditional hot-rolled steel or reinforced concrete structures. This article explores practical modeling and design approaches for light-framed buildings, focusing on how structural engineers can balance constructability, analysis clarity, and compliance with governing codes. Diaphragm Behavior: Not Always Rigid In light-framed buildings, flexible diaphragms are often assumed due to the nature of wood sheathing or light-gauge decking. However, as buildings increase in size and irregularity, this assumption deserves scrutiny. Flexible diaphragm assumptions work well in rectangular buildings with regular framing, but irregular load paths or large openings may require semi-rigid modeling to capture torsional behavior. Engineers should consider the influence of diaphragm stiffness when assigning lateral forces, especially in hybrid systems where part of the structure may be stiffer or tied into concrete cores. In projects where semi-rigid diaphragm analysis was warranted, integrating tools like finite element meshing helped visualize how in-plane stiffness impacted overall response—particularly in designs…

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