Studies Toward the Development of a Continuous Position Monitoring and Discontinuous Repositioning System of a Motorway Bridge

A two-part electronic system was designed to monitor and maintain the alignment of a bridge which is to be constructed in clay terrain. Previous bridges constructed along this Motorway in Southern Italy were closed for beam misalignment resulting from pillar displacement. The current two-part system was developed to provide a means to continuously monitor the position of the pillars and restore deck-pillar realignment when pillar displacement is detected. The monitoring system measures relative pillar position using a new multiple laser system. The repositioning system is composed of a number of computer controlled mechanical actuators bearing six degrees of freedom. A hydraulic piston coupled to a ring nut gear will be used for lifting, and will hence be intrinsically safe, since this configuration will not allow retrograde motion in case of power failure. Each actuator will allow motion along three perpendicular directions and spherical rotation about a point, to permit rotations of the bridge beams with respect to the pillars during deck-pillar realignment.