A LOW COST MULTI-SENSOR SYSTEM FOR INVESTIGATING THE STRUCTURAL RESPONSE OF BUILDINGS

Early Warning Systems (ETWSs) for the monitoring of buildings and structures are strategic to implement efficient safety actions. Even if very accurate monitoring solutions are available in the market, these are not suitable for the distributed monitoring of large areas due to costs, maintenance and installation needs. In this paper a low cost approach to investigate the seismic response of buildings is presented. The proposed architecture is based on a custom teed network of multi-sensor nodes, equipped with two inclinometers and one biaxial accelerometer. The sensing system is aimed to detect accelerations and tilt angles with a resolution of about 0.02 g (0.2 m/s(2)) and 0.004 degrees, respectively, in the frequency range of (0.5 - 10) Hz. Each multi-sensor node is also equipped with a 16 bit Analog-to-Digital Converter, a micro SD card writer and a rechargeable battery. Performances of the developed multi-sensor node have been deeply investigated by means of a vibrational system. The response of the multi-sensor node to a real seismic stimulation and the comparison with a commercial device will be discussed. Experimental surveys in real sites will be also presented. Two operating modes have been implemented to make the system context-adaptive: continuous data transfer and event triggered. A wireless connection has been exploited to communicate with a remote server. Moreover, a dedicated Wavelet based paradigm has been developed to highlight structural response to seismic sources from other exogenous inertial components. Results obtained during different experimental surveys demonstrate the suitability of the developed system, which open the possibility to develop a low cost early warning approach for the structural monitoring.