Enhanced Vibrating Wire Strain Sensor

2007 ◽  
Author(s):  
Dalibor Kuhinek ◽  
Igor Zoric
Keyword(s):  
Strain Sensor ◽  
Vibrating Wire ◽  
Wire Strain

Evaluation of Negative Skin Friction on Bridge Abutment Piles

2021 ◽  
Vol 15 (2) ◽  
Author(s):  
Osama Drbe
Keyword(s):  
Skin Friction ◽  
Pore Water Pressure ◽  
Design Method ◽  
Water Pressure ◽  
Strain Gauges ◽  
Total Stress ◽  
Vibrating Wire ◽  
Negative Skin Friction ◽  
Drag Forces ◽  
Wire Strain

Piles are used to transfer loads of structures to deeper and stronger soil layers through skin friction and/or end bearing. Surcharge loads, site grading, or dewatering may induce downward movement of soil adjacent to piles installed in a compressible medium. This movement creates negative skin friction stresses acting downward at the pile-soil interface, which applies additional loads “drag forces” to the pile causing a maximum axial load in the pile shaft at the “neutral plane”. To evaluate the development of drag forces, a comprehensive field monitoring program was conducted over four years for three instrumented abutment H-piles as part of a three-span bridge project. The soil settlement and changes in pore water pressure in the soil adjacent to the piles due to the construction of an approach embankment were monitored using multiple-point extensometers and vibrating wire piezometers. The piles’ elastic settlement and strains were measured using single-point extensometers and vibrating wire strain gauges. The field measurements are presented and discussed in terms of responses time histories and load distribution along one pile shaft. In addition, the calculated forces from vibrating wire strain gauges are compared with the unified design method prediction considering the total stress method (α-method) for cohesive soils. The results show that the maximum drag force was developed after the complete dissipation of excess pore water pressure and that the location of neutral plane varied during the embankment construction stages. Employing the total stress method in the unified design method provided a reasonable prediction of the drag force and the neutral plane’s location.

scholarly journals Temperature and Strain Correlation of Bridge Parallel Structure Based on Vibrating Wire Strain Sensor

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 658 ◽  
Author(s):  
Lu Peng ◽  
Genqiang Jing ◽  
Zhu Luo ◽  
Xin Yuan ◽  
Yixu Wang ◽  
...  
Keyword(s):  
Sensor Data ◽  
Parallel Structure ◽  
Strain Gauges ◽  
Final Conclusion ◽  
Vibrating Wire ◽  
Traceability System ◽  
Wire Strain ◽  
Time Work ◽  
Long Time ◽  
Dynamic Acquisition

Deformation is a ubiquitous phenomenon in nature. This process usually refers to the change in shape, size, and position of an object in the time and spatial domain under various loads. Under normal circumstances, during engineering construction, technicians are generally required to monitor the safe operation of structural facilities in the transportation field and the health of bridge, because monitoring in the engineering process plays an important role in construction safety. Considering the reliability risk of sensors after a long-time work period, such as signal drift, accurate measurement of strain gauges is inseparable from the value traceability system of high-precision strain gauges. In this study, two vibrating wire strain gauges with the same working principle were measured using the parallel method at similar positions. First, based on the principle of time series, the experiment used high-frequency dynamic acquisition to measure the thermometer strain of two vibrating wire strain gauges. Second, this experiment analyzed the correlation between strain and temperature measured separately. Under the condition of different prestress, this experiment studied the influencing relationship of temperature corresponding variable. In this experiment, the measurement repetitiveness was analyzed using the meteorology knowledge of single sensor data, focused on researching the influence of temperature and prestress effect on sensors by analyzing differences of their measurement results in a specified situation. Then, the reliability and stability of dynamic vibrating wire strain gauge were verified in the experiment. The final conclusion of the experiment is the actual engineering in the later stage. Onsite online meteorology in the application provides support.

Laboratory investigation on Fabry-Perot sensor and conventional extensometers for strain measurement in high performance concrete

2000 ◽  
Vol 27 (5) ◽  
pp. 1088-1093 ◽  
Author(s):  
Marco Quirion ◽  
Gérard Ballivy
Keyword(s):  
High Performance ◽  
Fiber Optic ◽  
High Performance Concrete ◽  
Fiber Optic Sensor ◽  
Vibrating Wire ◽  
Thermal Tests ◽  
Optic Sensor ◽  
Wire Strain ◽  
Fabry Perot ◽  
Concrete Cylinders

Advances in fiber optic sensing technology have made possible the installation of an extremely precise and reliable sensor in small structural members. Because of the high sensitivity and fast response of the sensor, low strain and dynamic strain can be measured. In this study, a Fabry-Perot strain sensor was cast in a high performance concrete cylinder, which had been submitted to simple compression and thermal tests. These results were compared with measurements obtained using external linear variable differential transformers fixed on concrete samples having the same composition as the fiber optic instrumented concrete cylinder. Comparisons were also done with results from tests on concrete cylinders instrumented with embedment vibrating wire and electrical strain gauges. In addition, thermal tests were performed on the different concrete cylinders and samples in order to compare the behaviour of the different sensors in high performance concrete submitted to temperature variations. The results show that the concrete strains measured with the Fabry-Perot sensor are in agreement with strain measurements made on concrete samples. Consequently, the presence of the embedded fiber optic sensor does not influence greatly the mechanical properties of concrete. Furthermore, for high stress levels (0.4 f 'c) and rapid stress changes (0.25 MPa/s), the fiber optic sensor measures with higher accuracy the strains of high performance concrete than the vibrating wire strain gauge.Key words: high performance concrete, sensor, vibrating wire, strain, extensometer, Fabry-Perot, fiber optic, instrumentation.

Experimental Study on Transversal Stress of Precast Simply Supported Box Girder during the Pre-Tensioning and Initial Tensioning Stages

2011 ◽  
Vol 243-249 ◽  
pp. 1689-1693
Author(s):  
Zhang Rui ◽  
Wen Liang Lu
Keyword(s):  
Strain Gauges ◽  
Transverse Strain ◽  
Strain Development ◽  
Vibrating Wire ◽  
Box Girder ◽  
Simply Supported ◽  
Ballastless Track ◽  
Transverse Tensile ◽  
Wire Strain ◽  
Research Findings

Experimental research was conducted on the transverse stress of 32m post-tensioned precast simply supported concrete box girder with ballastless track. Vibrating wire strain gauges were embedded in the key sections to monitor the concrete transverse strain. The concrete strain development law was analyzed. The monitored results showed that there were low transverse tensile stresses and the cracking resistance of the girder was enough during pre-tensioning stage. The research findings provided effective experimental data for design and construction quality control.

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