Abaqus — Earthquake Analysis //top\\

*STEP, NAME=Seismic, NLGEOM=YES *DYNAMIC, EXPLICIT , 30.0 *BOUNDARY, TYPE=VELOCITY BASE, 1, 1, 9.81 *AMPLITUDE, NAME=EQ_VEL, INPUT=vel.txt *END STEP

*STEP, INC=1000, NLGEOM=YES *DYNAMIC, DIRECT, HAFTOL=1e6 0.01, 30.0, 1e-6, 0.01

ABAQUS offers two primary analysis procedures for earthquake simulation: abaqus earthquake analysis

Explicit time integration (Abaqus/Explicit)

Seismic loading in ABAQUS is typically applied as an acceleration boundary condition at the structure’s base or foundation level. Engineers must first prepare earthquake acceleration time-history data and import it as an amplitude curve in ABAQUS. *STEP, NAME=Seismic, NLGEOM=YES *DYNAMIC, EXPLICIT , 30

Abaqus/Explicit will automatically determine the stable time increment, but ensure it is not too large, which can lead to inaccuracies.

Solves the full nonlinear dynamic equations of motion at discrete time increments using numerical integration (Hilber-Hughes-Taylor operator). Abaqus Procedure: *DYNAMIC, DIRECT (Abaqus/Standard). Solves the full nonlinear dynamic equations of motion

The gold standard for extreme events involving collapse, contact, or high-speed impacts. It handles complex nonlinearities and large deformations more robustly than the implicit solver. 2. Key Steps in the Abaqus Workflow A. Modeling Material Nonlinearity

Define Alpha (mass-proportional) and Beta (stiffness-proportional) factors to avoid over-damping high-frequency modes.