ART 3.0 - Strong-Motion Analysis and Research Tool

Section Index: 3.1 Installing ART 3.2 Setting up sensor information 3.3 Starting ART

Chapter 3. Getting Started

The material in this chapter covers the installation, configuration and invocation of ART 3.0.

3.1 Installing ART

ART is included in the standard Scream! distribution for Windows, which is available for free download.

ART uses the Matlab runtime library for its mathematical routines. This is supplied as part of the installer and may be freely distributed.

To download Scream!, send an e-mail to scream@guralp.com, including information about your institution and the type(s) of equipment you are using.

To install the package, download the scream installer using the instructions with which you will have been provided and then run the installer. There is a check-box for ART 3 on the "Optional components" screen:

Tick this check-box and then click to proceed with the installation.

3.1.1 A post-installation action…

ART is a compiled MATLAB program. To comply with the MathWorks license, its support files are delivered as a compressed archive. The very first time that the program is run, the archive is uncompressed, which requires administrative authority. (Subsequent invocations use the previously uncompressed files.)

To avoid permissions problems, manually invoke ART once as administrator. To do this, open windows explorer by keying + and navigate to the folder into which ART was installed. Right click-on ART3.exe and select “Run as administrator” from the context menu:

Windows will respond with a User Account Control screen:

Click to continue. A command window will briefly appear and then disappear. ART should then be usable by any user, as described in the rest of this manual.

Note: Failure to carry out this step can result in the error message

"??? Undefined function or variable 'matlabrc'"

3.2 Setting up sensor information

Before it can analyse data from your instruments, ART needs to know detailed calibration information for each one.

Note: If you start ART from within Scream! (as in section 3.3.2) without setting up the relevant sensor information, you will receive an error message saying:

A VPC= entry for {SYSTEM_ID-SERIAL} was not found in calvals.txt

and you should follow the procedure in this section before re-trying.

The calibration information must be provided in a file called calvals.txt, which should be kept in the ART/Scream! program directory. You can create and edit this file from inside Scream! by right-clicking on the digitiser's icon ( ) in the main window and selecting Calvals...

The file is divided into sections, each beginning with a title in square brackets. The title gives the System ID and serial number (as given by the first four characters of the Stream ID) for the digitiser which produces the data stream.

For example: to add calibration information for a digitiser with System ID GURALP outputting streams DEMOZ2, DEMON2, DEMOE2, etc., you would add a section beginning with the line

[GURALP-DEMO]

If you move an instrument from one digitiser to another, you will need to update the calvals.txt file to reflect the change.

To set the serial number of the instrument, include the line

Serial-Nos=serial-number

Scream! cannot tell what instrument is connected to the digitiser. This line is provided to help you remember which set of calibration values you have used, and to provide a title for calibration graphs. If you attach a different instrument to the same digitiser, you will need to enter new calibration values to reflect the new instrument.

To set the sensitivity of the digitiser, include the line

VPC=sensitivity

VPC stands for voltage per count, measured in units of μV/count. This is sometimes given as μV/Bit on the digitiser calibration sheet.

To set the sensitivity of the calibration channel, include the line

CALVPC=sensitivity

as for the other digitiser channels.

To set the value of the calibration resistor, include the line

CALRES=resistance

Güralp Systems digitisers normally use a 51 kΩ resistor (CALRES=51000).

To set the sensor type, include the line

TYPE=model-number

e.g. 3T, 5T, etc..

To set the response of the sensor, include the line

RESPONSE=response-type unit

The values you can use are given in the table below.

Sensor	Sensor type code (response-type)	Units (V/A)
5TC, 5TD or 5T, DC – 100 Hz response	CMG-5_100HZ	A
40T-1 or 6T-1, 1 s – 100 Hz response	CMG-40_1S_100HZ	V
40T-1 or 6T-1, 2 s – 100 Hz response	CMG-40_2S_100HZ	V
40T-1 or 6T-1, 10 s – 100 Hz response	CMG-40_10S_100HZ	V
40T, 20 s – 50 Hz response	CMG-40_20S_50HZ	V
40T, 30 s – 50 Hz response	CMG-40_30S_50HZ	V
3T or 3ESP, 30 s – 50 Hz response	CMG-3_30S_50HZ	V
40T, 60 s – 50 Hz response	CMG-40_60S_50HZ	V
3T or 3ESP, 60 s – 50 Hz response	CMG-3_60S_50HZ	V
3T or 3ESP, 100 s – 50 Hz response	CMG-3_100S_50HZ	V
3T or 3ESP, 120 s – 50 Hz response	CMG-3_120S_50HZ	V
3T, 360 s – 50 Hz response	CMG-3_360S_50HZ	V
3TB or 3V / 3ESP borehole, 30 s – 50 Hz response	CMG-3B_30S_50HZ	V
3TB or 3V / 3ESP borehole, 100 s – 50 Hz response	CMG-3B_100S_50HZ	V
3TB or 3V / 3ESP borehole, 120 s – 50 Hz response	CMG-3B_120S_50HZ	V
3TB or 3V / 3ESP borehole, 360 s – 50 Hz response	CMG-3B_360S_50HZ	V
3TB or 3V / 3ESP borehole, 360 s – 50 Hz response	CMG-3B_360S_100HZ	V

Some English descriptions are also accepted, e.g. “120s velocity or “100Hz acceleration” but this is not a free-format field.

To set the sensitivities (or gains) of the sensor components, include the line

G=vertical-sens,N/S-sens,E/W-sens

These values are given on the sensor calibration sheet. For velocity sensors, they are given in units of V/ms-1). The gain of an accelerometer is expressed in V/ms-2). Because Güralp Systems sensors and digitisers use differential inputs and outputs, the sensitivity is quoted as 2 × (single-ended sensitivity) on the calibration sheet.

To set the coil constants of the sensor components, include the line

COILCONST=ZCC,NCC,ECC

Where ZCC is the vertical coil constant, NCC is the North/South coil constant and ECC is the East/West cost constant. These values are given on the sensor calibration sheet.

To set the local acceleration due to gravity, include the line

GRAVITY=acceleration

You should give this value in V/ms-2, if you know it. If you miss out this line, Scream! will use a standard average g value of 9.80665 V/ms-2.

3.2.1 Examples

The calibration information for a Güralp 3T weak-motion velocity sensor might look like the following:

[GURALP-3T]

Serial-Nos=T3X99

VPC=3.153,3.147,3.159

G=1010,1007,1002

COILCONST=0.02575,0.01778,0.01774

CALVPC=3.161

CALRES=51000

TYPE=3T

RESPONSE=CMG-3_30S_50HZ V

GRAVITY=9.80122

Güralp 5TD accelerometers use 1 Ω calibration resistors, and their coil constant is set to unity. Older 5TD instruments, based on Mk2 digitiser hardware, do not have calibration input facilities, and thus the CALVPC entry is omitted. For example:

[GURALP-5T]

Serial-Nos=T5585

VPC=2.013,2.028,2.036

G=0.256,0.255,0.255

COILCONST=1,1,1

CALRES=1

TYPE=5T

RESPONSE=CMG-5_100HZ A

GRAVITY=9.81089

3.3 Starting ART

ART can be started in two ways, either from SCREAM or by double clicking on the ART icon.

3.3.1 Start from the ART icon

Double-clicking on the ART icon ( ) will start the application and cause the main ART window to open.

Clicking on the ‘Import data’ button at the top of the left-hand column of the main ART window opens up a file selection window from which a GCF time-history can be selected to import and analyse.

3.3.2 Starting from SCREAM

Within Scream!, open a WaveView window displaying the event you are interested in. Click on the Pause icon to stop the traces moving then, using the mouse, select the parts of the time-histories that you want to analyse while holding down either the or keys.

If you use the key, the first and last streams in the selected area will be analysed. This is useful for picking two streams from many for comparison. If you use the key, a contiguous set of streams are selected.

When the or key is released, a pop-up menu will appear (after a short delay) asking which add-on program you want to run. Select ART and the main ART window will open with the selected time-histories automatically loaded.

The picture below shows a Scream! WaveView window with two streams selected (using the key).

The second illustration shows the selection of two non-adjacent streams for comparison. To do this, hold down the key and drag a box from the start-time on the first stream to the end time on the second stream.