Campbell Scientific ST350 Strain Transducer for Structural Testing - Manual (Page 5)

Section 1. Introduction
This manual provides information for interfacing the ST350 Strain Transducer
to Campbell Scientific’s Dataloggers. Unless otherwise specified, all part
numbers are Campbell Scientific's.
This manual contains information on sensor specifications, operating
principles, installation, alignment, and calibration. The multiplier and offset
values given here are based on calibration data obtained from the Bridge
Diagnostic’s Calibration Sheet (see example Appendix C).
The most direct approach to quantifying live-load stresses in a structural
member is to record the induced strain. However, it can be tedious work
installing foil strain gages in the field since careful surface preparation and
soldering is often required. Now, most field strain gage installations can be
replaced with the highly accurate ST350 Strain Transducer. These units are
rugged and can be installed in any weather. Since they are pre-wired and easy
to mount, ST350 Strain Transducers will drastically reduce your field
installation time.
1.1 Typical Application
This transducer is typically used for dynamic or event driven stress in structural
members such as bridges or buildings. The ST350 Strain Transducers have
been designed for recording Live Load
strains only. Hence it is assumed that
there will be little to no temperature change during any short time-span testing
sequence.
When a transducer is attached to a structure, it is forced to have the same
deformation as the structure. However, if a temperature increase (or decrease)
occurs, and since the ends of the sensor are "anchored", the transducer will
expand between the end blocks and register compression. The same goes for a
drop in temperature which will register tension. If the sensor is to be mounted
on the structure for a long period of time, it will need to have its "zero" reset
periodically as it drifts around with temperature changes.
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