Subsystem of structural health monitoring system (SHM)

Building tilt and elements displacement control

Nowadays tall structures are widely spread. However, even though such structures have a wide range of advantages, they belong to the high-hazard class of structures and require constant structural monitoring.

The ground foundation of high structures is exposed to considerable impact. If the ground settlement is uneven or there is a structural fault, then there will be witnessed changes in the building’s dimensional characteristics: deviation from the vertical axis, displacement of structural elements, etc.

“Building tilt and elements displacement control” subsystem is used for timely detection of bearing structures tilt that can lead to the transition of the building state from operational into failure state.

Подсистема мониторинга крена и смещения

The subsystem is based on the use of ZET 7X54 and ZET 7140-S digital sensors, which enable tilt dynamics and bearing elements displacement control.

Digital tilt meters are placed on the controlled elements (slabs, walls, bearing ceiling structures, beams, etc). As for the digital sensors – it is recommended to install them in the areas, where the elements relative displacement is most likely to take place.

Basic characteristics

Controlled parameter Displacement Displacement Tilt
Module/digital sensor type ZET 7140-S + ВС 701-17 ZET 7080-I + REFTEK
ZET 7180-I + REFTEK
ZET 7054
ZET 7154
Measuring unit µm mm degree
Measuring range -2500…+2500 1…200 -15…+15
Recordable changes (min) 5 0,05 0,01
ALARM – min. threshold level 50 1 0,12

In the course of its operation, the “Building tilt and elements displacement control” system compares the registered values to the threshold values of warning and alarm levels. If the threshold values are exceeded, a “Warning” signal (beige line in the diagram) or a “Danger” signal (the red line in the diagram) is formed.

Показания инклинометров ZET 7X54 по оси X с отображением пороговых значений в программном обеспечении ZETLAB
Показания инклинометров ZET 7X54 по оси Y с отображением пороговых значений в программном обеспечении ZETLAB

Signals from the sensors are transferred to data acquisition node via Ethernet interface. Then the data is transferred to the server for further storage. Each of the registered signals is compared with threshold values. In the case if the threshold level is exceeded, there is formed an alarm notification for the operator.

Threshold level values (for structure tilt and elements relative displacement) are calculated in accordance with the applicable technical documentation for the particular structure type.

Nowadays there are a lot of two-axial measuring modules for tilt control. Let us compare the most popular tiltmeters with ZET 7X54 digital inclinometers.

Инклинометры цифровые СМИК. БСГ

Digital tilt meters

ZET 7X54 Digital tilt meters
Manufactured by ZETLAB Company

Измерители угла наклона двухкоординатные ИН-Д3

Tilt angle meter

All these instruments are used for tilt angle and object displacements measurements in two axes (they are included into National Register of measuring instruments, have digital output and high precision).

However, ZET 7X54 digital tiltmeters have a number of advantages if compared to similar products available at the market:

  • metrological self-check function– it is possible to check and evaluate metrological specification in the course of measurements performance without de-installation of the sensor;
  • LED indication – enables on-site visual diagnostics and operability check;
  • “Set to zero” function allows to calibrate the tiltmeters for each of the axes, thus preventing critical tilt of the platform from the set coordinates.

Infrormation on dimensional and geometry characteristics shows the final result of structural deformation. The data obtained does not reveal the deformation dynamics and changes that occur in the ground foundation. Hence, it is reasonable to implement this system as an addition to the Structural health monitoring system (SHM).