Problem

Design the lateral system for a 12-story concrete building in San Diego to ASCE 7-22 and ACI 318, and prove it holds up: irregularities, drift, diaphragm forces and ductile wall detailing.

Approach

Modeled in RAM Structural System and SAP2000 per ACI and LATBSDC, with Equivalent Lateral Force and Modal Response Spectrum workflows alongside drift, diaphragm force and irregularity verifications.

Hard part

Getting past the code's simplified section assumptions. A nonlinear fiber-section model in SAP2000 captured confined concrete and steel behavior at the wall boundaries, showing the ACI interaction diagrams were generally conservative.

Result

18 in by 30 ft walls in 8 ksi concrete with Grade 80 steel. Critical first-floor walls and boundary elements detailed in spColumn for seismic ductility, with every factored load combination inside the strength envelope.