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Validation of the martlet wireless sensing system through dynamic testing of full-scale reinforced concrete frames

The adoption of wireless sensing technology by the structural health monitoring community has shown advantages over the cable-based systems, such as convenient sensor installation and low system cost. Recently, one new generation of wireless sensing platform, named Martlet, has been collaboratively developed by researchers at the University Michigan, Georgia Tech, and Michigan Tech. Martlet adopts a Texas Instruments Piccolo microcontroller running up to 80MHz clock frequency, which enables Martlet to support high-frequency data acquisition and high-speed onboard computation. Meanwhile, the extensible design of the Martlet printed circuit boards conveniently allows stacking-up of various sensor boards.

In order to obtain accurate high-resolution acceleration data and meanwhile reduce the sensor cost, one Martlet sensor board, named integrated accelerometer wing, is developed and validated by large-scale experiments. The integrated accelerometer wing adopts a commercial-off-the-shelf MEMS (microelectromechanical systems) accelerometer and contains an onboard signal conditioner performing three basic functions, mean shifting, anti-aliasing filtering and signal amplification. One distinct feature of the signal conditioner is the on-the-fly programmable cut-off frequency and amplification gain factor. To validate the performance of Martlet and the integrated accelerometer wing, experiments are carried out on a full-scale two-story, one-bay concrete frame structure located at Georgia Tech structures lab. Dynamic structural responses due to various loading conditions are measured by the wireless sensing system. In the experiments, a blend of Martlet units and Narada units (the precursor wireless sensing system developed prior to Martlet), supporting more than sixty acceleration channels, are deployed on the columns, girders and slabs of the structure. Excitations are sequentially introduced by one small modal shaker installed on the first elevated slab, and one large shaker on the second elevated slab.

Such dense instrumentation helps to investigate the accuracy and robustness of the wireless sensing system under complex circumstances possibly encountered in the field. The performance of the wireless sensing system is compared with a high-precision cabled sensing system by placing cabled and wireless sensors side-by-side at critical locations of the frame structure. The field test results demonstrated that the performance of the wireless sensing system is comparable to that of the counterpart cabled system. Moreover, using data collected by such dense deployment of wireless sensors, detailed modal characteristics of the frame structure are identified for high-resolution finite element model updating.

Author(s):

Xinjun Dong    
Georgia Institute of Technology
United States

Tim Wright    
Georgia Institute of Technology
United States

Dapeng Zhu    
Georgia Institute of Technology
United States

Yang Wang    
Georgia Institute of Technology
United States

Reginald DesRoches    
Georgia Institute of Technology
United States