Mechanical APDL Structural Analysis Guide

The following commands are used to invoke different methods of mode combinations:

Command(s):SRSS,CQC,DSUM,GRP,NRLSUM,ROSE

GUI: Main Menu> Solution

Use the VELO or ACEL label on the mode-combination commands (SRSS,CQC,DSUM,GRP,

NRLSUM,ROSE).

4. Start solution.
   Command(s):SOLVE
   GUI: Main Menu> Solution> Solve> Current LS

6.3. Example Spectrum Analysis (GUI Method)

In this example problem, you determine the seismic response of a beam structure. This problem is
similar to VM70 in the Mechanical APDL Verification Manual.

6.3.1. Problem Description

A simply supported beam of length ℓ, mass per unit length m, and section properties shown in Problem
Specifications, is subjected to a vertical motion of both supports. The motion is defined in terms of a
seismic displacement response spectrum. Determine the nodal displacements, reactions forces, and the
element solutions.

6.3.2. Problem Specifications

The following material properties are used for this problem:

E = 30 x 10^6 psi

m = 0.2 lb-sec^2 /in^2

The following geometric properties are used for this problem:

I = (1000/3) in^4

A = 273.9726 in^2

ℓ = 240 in

h = 14 in

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Spectrum Analysis