If you’re wondering what structural monitoring is, you’re not alone. This article will give you a basic understanding of structural monitoring and discuss some of the methods available. These include fiber optic sensors, strain gauge rosette, and real-time 3D deformation. In addition, you’ll learn about the benefits of using such technology.
Structures are subjected to a variety of stresses. Thermal expansion, for example, can affect the stability of a structure and lead to the deformation of elements. In earthquake-prone areas, acceleration can also impact a structure. Wind loads also affect the design of tall buildings and long-span bridges. Structural monitoring can help determine when an element may break and allow timely intervention. Monitoring can be as simple as measuring vibrations or sophisticated as using remote structural monitoring systems.
While structural health monitoring involves periodically sampling response measurements, this process is also effective for existing structures. The placement of sensors allows observers to determine the health and life expectancy, enabling them to estimate the remaining life expectancy of a structure. In addition to improving the safety of existing structures, structural health monitoring can also determine the integrity of structures following earthquakes. The benefits of structural health monitoring are numerous, not the least of which is the reduction of construction and maintenance activities. In addition, using sensors to monitor structures allows engineers to assess their integrity and safety and move towards performance-based design philosophy.
Fiber optic sensors
Fiber optic sensors can monitor structural health and detect deformation for buildings and bridges. This technology is based on the principle of low-coherence interferometry, a method that measures the difference in length between two optical fibers. One fiber is mechanically coupled to the structure to monitor its deformation, while the other is free and acts as a temperature reference. Both fibers are installed in the same pipe, with the measurement basis set anywhere between 200mm and 10m. This system has a resolution of 2 micrometers and an accuracy of less than 2% of the observed deformation throughout years of operation.
Fiber optic sensors must have mechanical coupling with the host structure to achieve accurate measurements. Optical fiber sensors must be able to resolve temperature changes and compensate for cross-sensitivity. Moreover, fibers should be intact and micro-bent only when necessary. For long-term measurements, they must be free from cracks and microcracks. A reference fiber with a constant length is needed for long-term performance.
Strain gauge rosette
A strain gauge rosette is a device of multiple measuring elements bonded together on a common carrier. They are arranged to have different measuring axes and measure strains caused by biaxial stress conditions. Two measuring elements perpendicular to one another are referred to as 90-degree rosettes. If multiple rosettes are used, they can be arranged in a half-bridge or full-bridge configuration.
A strain gauge rosette is a data logger that measures the shear and tension forces on a structure. The information is gathered through strain gauges mounted on a steel rail. The rosette has three strain gauges: a, b, and c, and the Rosette Analysis tool in iTestSystem estimates the primary strain, angle, and stress.
Real-time 3D deformation
Deformation is a major determinant of the structural stability of architectural heritage sites. Conservators monitor and analyze deformations to devise adaptable conservation plans. However, existing geodetic approaches cannot measure three-dimensional (3D) deformations of buildings. Point-based instruments have a limited range and are time-consuming. Therefore, they are not ideal for monitoring the stability of heritage structures. The real-time 3D deformation structural monitoring method allows for accurate measurement of tunnel shapes, dimensions and structures in the construction zone. The method involves using high-accuracy automated total stations with auto-target recognition and dedicated control boxes that contain specialized software. The data gathered by these sensors are then analyzed and displayed through real-time 3D deformation graphics. In this way, researchers can understand the deformation of a building or bridge in real-time.
The new paradigm of structural monitoring and early warning systems introduced in this paper can be used in various applications. The proposed method is based on the concept of lower upper bound estimation. The lower and upper bound of WI is calculated based on time-domain features of structural monitoring data. This method also allows optimizing the kernel parameters of the RVM to achieve the lowest lube. This approach can also be applied to smart city applications, such as city safety monitoring and infrastructure supervision.