June 24, 2025

Rethinking Tall Building Design

In structural engineering, few design challenges are as rewarding—or as unforgiving—as the tall building. While gravity systems and code checks form the backbone of any structural project, once a structure rises beyond ten or fifteen stories, a shift occurs. Wind and seismic forces begin to dominate. Story drift and torsional irregularities become non-negligible. Load paths grow increasingly indirect. And design decisions, if not carefully made early on, can have exponential consequences higher in the structure. Tall buildings are not simply “bigger” versions of short ones. They behave differently. And understanding those differences is essential for any engineer working in an urban environment where building vertically is often the only viable path forward. Modeling for Reality, Not Just Code The foundation of any successful tall building design lies in the model—its assumptions, resolution, and degree of abstraction. Many engineers begin with simplified representations: rigid diaphragms, idealized connections, and linear material properties. This is practical and often sufficient for early design phases. But as the building increases in height and complexity, those assumptions may start to mask critical behaviors. Semi-rigid diaphragm modeling, for instance, allows engineers to capture in-plane flexibility of floor systems—especially important in buildings with irregular cores, open floor plans,…

Read More