“We change the connection here from a rigid weld to a pinned joint with viscous dampers,” she said. “It’ll break the resonance. We’ll shift the natural frequency to 2.6 Hertz. The roof will be stiffer, but we’ll add a slight camber to the rib for the visual.”

Lena leaned back, a small smile playing on her lips. SAP2000 hadn't just given her a problem; it had given her the solution. She highlighted the node and opened the section designer.

For ten seconds, the model was serene. Then, at 12.3 seconds, Node 347’s red dot began to shiver. By 15 seconds, the shiver became a quake. The lines representing steel members turned from blue to yellow to a deep, warning crimson. Finally, with a silent, digital scream, Node 347 vanished from the model, and the entire eastern wing of the virtual roof collapsed into a pile of magenta lines.

“It’s not the wind,” she said, zooming in. “Look at the mode shape.”

The screen displayed an animation. The beautiful, static wireframe of the terminal began to vibrate, ever so slightly, in a slow, rhythmic sway. Node 347 wasn't just a point of high stress; it was the fulcrum of a harmonic oscillation.

Now, SAP2000 was telling her a story it had hidden before.