Vibrating Wire Embedment Jointmeter
The Vibrating Wire Embedment Jointmeter is ideal for monitoring movement of joints in mass-concrete structures.
The jointmeter comprises two parts: a socket and a main body. The socket is a detachable end that is cast into the first lift of concrete. The main body is a protective outer case which houses a vibrating wire displacement transducer and screws into the socket. Once screwed into the socket, it is cast into the second lift of concrete.
The transducer has a vibrating wire sensing element which is anchored at one end and connected to a spring loaded push rod at the other end.
Any movement applied to the push rod causes the spring to contract or elongate, causing an increase or decrease in the vibrating wire tension. This tension is directly proportional to the movement applied and therefore the opening or closing of the joint.
- Highly accurate and robust; accuracy unaffected by cable length
- Connecting cable is strong, screened and flexible and can be used in lengths in excess of 1000m
- Option to fit a thermistor
- Over-voltage surge arrestor fitted to protect
- against electrical damage
- Waterproof and sealed to 7 bar pressure
- Accommodates shear movement
- Over 30 years of expertise in the design and manufacture of Vibrating Wire instrument technology
- Very good longterm stability
- Suitable for remote reading and datalogging
- Thermistor option enables examination of temperature effects
The socket is installed in the first lift of concrete, using an installation plug to prevent concrete entering the socket.
Before the second lift of concrete is cast the main body is screwed into the installed socket, extended sufficiently (most commonly to its mid-point) to allow for expected joint movement, welded or tied to the rebar and then the second lift of concrete is cast.
When both lifts of concrete are complete, the jointmeter is now firmly anchored into each concrete lift and will measure opening or closing of the joint. The sensing transducer is smaller than the protective body of the jointmeter, therefore a degree of shearing motion is accommodated by universal joint connections within the unit.
The Vibrating Wire Embedment Jointmeter is ideal for monitoring movements of joints in mass-concrete structures.
Typical applications include:
- Abutments, slabs, foundations and retaining walls
- Tunnels or shaft linings; arch, gravity and buttress dams
- Monitoring construction joints