Design Spectra - Civil & Environmental Engineering at …civil.utah.edu/~bartlett/CVEEN7330/Design Spectra.pdf · Course Information Lecture Notes Pp. 73 - 75 Kramer Appendix B7 Kramer

Course Information○

Lecture Notes○

Pp. 73 - 75 Kramer○

Appendix B7 Kramer○

Reading Assignment

Responsespectra.pdf (Chopra)○

ASCE 7-05.pdf○

Sakaria time history○

Other Materials

Baseline correct the time history and plot the acceleration,

velocity and displacement records. Use the quadratic function for the baseline correction. (5 points)

□

Determine peak ground acceleration (pga) from the time history.

(5 points)

□

Develop and plot a pseudo acceleration response spectrum for

this record at 5 percent damping using Seismosignal. (5 points)

□

Determine the predominate period. (5 points)□

Scale the record by 1.5 (increase the acceleration values by 50

percent) and replot the pseudo acceleration response spectrum. (5 points)

□

For the Sakaria acceleration time history do the following:

Install Seismosignal software on your computer○

Install the ground motion hazards java program from the United States

Geological Survey (USGS) on your computer

○

http://earthquake.usgs.gov/hazards/designmaps/grdmotion.php

Install Google Earth on your computer and find the latitude and longitude

of the Meldrum Civil Engineering (MCEB).

○

Use these coordinates and USGS java software to find the Ss and S1 values

for the MCEB. (10 points)

○

Assume the MCEB is found on a site class C soil.

Show all calculations and inputs to calculations. Check your solution

against the design spectrum calculated by the USGS java calculator.

Use the Ss and S1 values above and ASCE 7-05 to develop a design

spectrum for the MCEB. (20 points)

○

Homework Assignment #1

© Steven F. Bartlett, 2011

Design SpectraSunday, August 14, 20113:32 PM

Design Spectra Page 1

http://earthquake.usgs.gov/hazards/designmaps/grdmotion.php


Definition - Plot of maximum response (acceleration, velocity displacement

amplitude) of a single degree of freedom system (SDOF) for a particular input ground motion as a function of frequency or period and damping ratio of the

SDOF.

The equation that relate the response of the SDOF to the input ground motion

for a linear elastic, damped system is Duhamel's integral (see Kramer p. 566)

If a response spectrum has been developed, then the spectral displacement Sd,

spectral velocity, Sv and spectral acceleration Sa for lightly damped systems can be approximated by:

Design Spectra (cont.)Monday, January 06, 20142:32 PM



Stiffness and Damping Representation3:32 PM



An acceleration response spectrum, such as that above, is widely used in

geotechnical and structural engineering.

○

It expresses the maximum acceleration response of a single degree of

freedom system (SDOF) as a function of period for a given level of structural damping (usually 5 percent, unless otherwise stated.)

○

The above spectrum is not a design spectrum. It is jagged because it

represents a spectrum for a given time history.

○

Seismosignal is recommended□

Software is usually used to do this conversion.

An acceleration time history can be converted to an acceleration response

spectrum which represents the response of the SDOF for the given input motion.

○

Important Concepts:

Damp. 5.0%

Period [sec]

3210

Response A

ccele

ratio

n [g]

1.8

1.7

1.6

1.5

1.4

1.3

1.2

1.1

1

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

Time [sec]

876543210

Accele

ratio

n [g]

0.8

0.6

0.4

0.2

0

-0.2

-0.4

Acceleration time history (ground surface)

Acceleration Response Spectrum for above time history from SeismosignalTM


Plotting Response Spectra for an Earthquake (cont.)Sunday, August 14, 20113:32 PM


Empirical attenuation relations (CVEEN 6330)○

Building code design spectra (CVEEN 6330 and CVEEN 7330)○

Equivalent Linear Techniques (computer program SHAKE or DEEPSOIL)

(CVEEN 7330)

FEM (finite element methods) (computer program DEEPSOIL)

(CVEEN 7330)

□

FDM (finite difference methods) (computer program FLAC)

(CVEEN 6330 and CVEEN 7330)

□

Nonlinear Techniques (CVEEN 6330 and CVEEN 7330)

Site-specific Ground Response Analyses (CVEEN 6330 and CVEEN 7330)○

Methods of Developing Design Spectra and Design Strong Motion


Representing Earthquake Motion in DesignSunday, August 14, 20113:32 PM


Ss and S1 are obtained from the United States Geological Survey National Strong

Motion Program. The link for this computer program (Java Script) is given in the homework assignment.


Development of Design Spectra using ASCE 7-05Sunday, August 14, 20113:32 PM



ASCE 7-05 (cont.)Sunday, August 14, 20113:32 PM





0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

1.10

1.20

1.30

1.40

1.50

1.60

1.70

1.80

1.90

2.00

2.10

0 0.5 1 1.5 2

Sp

ectr

al accele

rati

on

(g

)

Period (s)

Generic Design Spectrum from ASCE 7-05

ASCE 7-05 Spectrum - Site Class D

Sa =0.4 SDS a T = 0 Sa = pga

To Sa = SDS

Ts = SD1/SDS

Sa = SD1/T




ASCE 7-05 (cont.)3:32 PM


Blank3:32 PM


Documents

Design Spectra - Civil & Environmental Engineering at …civil.utah.edu/~bartlett/CVEEN7330/Design Spectra.pdf · Course Information Lecture Notes Pp. 73 - 75 Kramer Appendix B7 Kramer