Applying external forces gradually to a structure does not cause it to experience any pulse or motion. You can solve structural responses with a simple static equilibrium analysis. That is, the structural elasticity forces and the external forces equilibrate one another.

In reality, however, structures are subject to rapidly applied forces (or so-called dynamic forces), for example, high-rise buildings, airplane wings, and drilling platforms are subject to wind gusts, turbulences, and ocean waves, respectively. These structures are in a state of motion as a result of the dynamic forces. To simulate and solve for the structural responses in a logical manner, a dynamic equilibrium analysis, or a dynamic analysis, is desirable. In a dynamic analysis, in addition to structural elasticity force, structural inertia and dissipative forces (or damping) are also considered in the equation of motion to equilibrate the dynamic forces. Inertia forces are a product of structural mass and acceleration while dissipative forces are a product of a structural damping coefficient and velocity.

When performing a linear dynamic analysis, the application calculates structural responses based the assumption that a structure is linear.

The following sections discuss the steps and requirements to perform different linear dynamic simulations.

• 5.6.1. Eigenvalue Buckling Analysis
• 5.6.2. Harmonic Response Analysis
• 5.6.3. Harmonic Response (Full) Analysis Using Pre-Stressed Structural System
• 5.6.4. Harmonic Response Analysis Using Linked Modal Analysis System
• 5.6.5. Modal Analysis
• 5.6.6. Random Vibration Analysis
• 5.6.7. Response Spectrum Analysis
• 5.6.8. Substructure Generation Analysis