{{Test Problem
name = Acceleration load |
description = Demonstrate acceleration load and relative/absolute acceleration, velocity and displacement. |
keyword = acceleration; cantilever |
program = SAP2000 |
version = V12.0.1 |
status = finalize |
id = ok/acceleration}} |
Purpose
- illustrate how acceleration load is applied to the model
- illustrate absolute/relative acceleration, velocity and displacements
- verify SAP2000 results against those obtained from spreadsheet ("acceleration to displacement record" SAP2000 tool)
- check one actual acceleration record (ALTADENA-1)
- check one sinusoidal acceleration record with 10 cycles
Model Overview
The attached file contains a massless cantilever with a vertical force applied at the top of the cantilever. This vertical force was considered as a source of mass. Time history function "SINE" with sinusoidal variation of the applied acceleration was defined and used in a time history load case.
Plotting absolute accelerations, absolute velocities, or absolute displacements against time at a restrained joint enables you to obtain the applied (ground) acceleration and corresponding time history of velocities and displacements. For the test model, these values are plotted in the graph below:
The values in the above graph match values calculated "manually" in the attached Excel file (as per Prof. Wilson: Static & Dynamic Analysis of Structures, Appendix J, Equation J.2). Our test problem shows that the displacement is not zero at the end of the time history record and therefore the acceleration time history data would need to be corrected to have zero displacement at the end of the record.
Since the absolute displacement at an unrestrained joint is a sum of (1) input (ground) displacement, which is calculated from input acceleration, and (2) relative displacement calculated from the time history analysis, I would recommend making a correction to your input acceleration such the displacement is zero at the end of the record.
To Do
{{To Do
who = ok |
comment = correct the acceleration record}} |
See Also
Attachments
File | filename = Acceleration test problem hand calcs.pdf | title = hand calculations(PDF format)File | filename = Acceleration test problem sapfile model A V12.0.1.zip | title = V12.0.1 sapfile - model A(zipped SDB file)File | filename = Acceleration test problem spreadsheet.zip | title = spreadsheet calculations(zipped Excel file)
