Mechanical APDL Structural Analysis Guide

6.9. Example Multi-Point Response Spectrum (MPRS) Analysis (Command or Bat ch Method)

In this example problem, you determine the seismic response of a three-beam frame using Mechanical
APDL commands.

6.9.1. Problem Description

A three-beam frame is subjected to vertical motion of both supports. The motion is defined in terms
of seismic acceleration response spectra. A multi-point response spectrum analysis is performed to de-
termine the nodal displacements.

6.9.2. Problem Specifications

The following material properties are used for this problem:

Young’s modulus = 1e7 psi

Density = 3e-4 lb/in^3

The following geometric properties are used for this problem:

Cross-sectional area = .1 in^2

Area moment of inertia = .001 in^4

Beam height = .1 in

Beam length = 100 in

6.9.3. Problem Sketch

Figure 6.3:Three-Beam Frame

h h h

SupportMotion

2ndSpectrum

SupportMotion
1stSpectrum

ℓ

ℓ ℓ

Y

X

6.9.4. Command Listing.

It ems prefaced by an exclamation point (!) are comments.

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Example Multi-Point Response Spectrum (MPRS) Analysis (Command or Batch

Method)