This product should be installed and operated only by qualified personnel. Its misuse is potentially dangerous. The Company makes no warranty as to the information furnished in

this manual and assumes no liability for damages resulting from the installation or use of this product. The information herein is subject to change without notification.

1 DESCRIPTION ..................................................................................................... 1

1.1 STRAIN GAUGE .................................................................................................. 2

1.2 READINGS ........................................................................................................... 2

2 INSTALLATION PROCEDURE ............................................................................ 2

2.1 GAUGE LENGTH ADJUSTMENT ........................................................................ 3

2.2 ATTACHMENT OF ANCHOR BLOCKS ................................................................ 4

2.2.1 WELDING ONTO METAL SURFACE ............................................................ 4

2.2.2 BOLTING TO STEELWORKS ....................................................................... 5

3.2 MB-6T LINEAR READINGS (N) ............................................................................ 7

4 SPECIFICATIONS................................................................................................ 8

5 MISCELLANEOUS............................................................................................... 9

5.1 CONVERSION FACTORS .................................................................................... 9

5.2 THERMISTOR: TEMPERATURE READING ...................................................... 10

The SM-5B vibrating wire strain gauge is used to measure surface strains over long

periods of time under adverse environmental conditions. The SM-5B strain gauge is

intended primarily for long-term measurements on steel structures such as arches, joists

and prefabricated tunnel linings. It is also used to monitor strain changes on concrete or

rock surfaces using mounting blocks grouted or embedded in the surfaces.

The gauge consists of a length of high strength wire clamped at both extremities into two

threaded end pieces. Two hex nuts on each threaded end piece are used to fasten the

study. They are welded, bolted, bonded or mechanically clamped in place. A waterproof

removable coil/magnet assembly fits on a construction at the center of the stainless steel

mounting blocks are shown in Figure 1.

Figure 1: SM-5B vibrating wire strain gauge description and dimensions

To mount the gauge on steel structures, the anchor blocks are set onto the spacer bar

(described below), to provide the required spacing before they are welded to the structure.

After welding, the spacer bar is removed and replaced by an actual gauge with a separate

coil/magnet assembly mounted over the gauge to excite the gauge and measure the

response. The wire is tensioned to the required level using the nuts mounted on the

reading shown plotted against the LINEAR reading.

Figure 2: SM-5B strain range vs period

1.2 READINGS

The SM-5B vibrating wire strain gauge can be read with the MB-6T or MB-6TL portable

readout units or with the SENSLOG Data Acquisition System.

2 INSTALLATION PROCEDURE

SM-5B gauges are supplied fully sealed with the coil/magnet assembly separate, and with

the wire pretensioned. The SM-5B coil/magnet assembly also contains a thermistor which

is read using the MB-6T readout. It is suggested that a preliminary check of both the

vibrating wire and the thermistor be carried out to verify the gauge lead cable and readout.

Connect the wire leads to the readout box as follows:

A complete description of the readout procedure is contained in the MB-6T or MB-6TL

instruction manuals.

The correct resistance readings between the conductors in the lead cable are:

to be measured; refer to Figure 2. When in doubt, set the initial reading to mid-range.

where:  = strain change in strains in the surface under study

To determine the strain change in the instrumented structure from LINEAR readings, the

following equation is applied:

where:

= strain change in strains in the structure