The Possibility of a Continuous Monitoring of the Horizontal Buildings’ Rotation by the Fibre-Optic Rotational Seismograph AFORS Type

Abstract

The design and investigation of the Autonomous Fibre-Optic Rotational Seismograph – AFORS as a system used for a continuous monitoring of the horizontal buildings rotation is presented in this chapter. Since AFORS utilizes the Sagnac effect for a direct measurement of rotational components it operates without any reference system designed to work during earthquakes. The presented system contains a special autonomous signal processing unit (ASPU) which optimizes operating of the rotation motions measurement, whereas a newly applied telemetric system based on the Internet (FORS-Telemetric Server) allows for a remote AFORS control. The laboratory investigation of the system named AFORS-2 indicated that with theoretical linear changes of sensitivity it keeps the accuracy no less than \( 4.8{\cdot}10^{-9} \) to \( 6.1 {\cdot} 10^{-8} \mbox{rad/s} \) in the frequency band from 0.83 to 106.15 Hz. In our opinion the above results are very optimistic for the future application of AFORS for the continuous monitoring of any rotational moving of the multi-storey buildings as well as the investigation of an in-plane irregularity. The first experimental results of the AFORS-2 operation in a real multi-storey building in Warsaw, Poland are also presented. On this basis the investigation of a new low cost system type AFORS is presented as the chapter conclusion.