Post-disaster emergency monitoring system and data analysis for a continuous rigid frame bridge in mountain area

Bridges are subject to deterioration over time and unexpected disasters, such as traffic-induced fire, explosion, etc. Considering the sensor equipment and maintenance cost, the lightweight monitoring system is highly demanded for in-service small and medium-span bridges or bridges with an emergent request, such as post-disaster monitoring. This paper introduced a real practice of the post-disaster emergency monitoring system designed for a continuous rigid frame bridge in a mountain area in China. Considering bridge structural mechanical features and budget limits, the dynamic deformation of the bridge girder and bridge pier inclination are two major monitored objectives to timely identify the bridge deformation and dynamic features. Moreover, to precisely identify structural performance, the temperature variation is an indispensable monitoring content. Hence, this system consists of only three types of sensors, including the photoelectric deflection meter, the inclinometer, and the temperature–humidity sensor. In detail, this 330 m continuous rigid frame bridge with five spans, 45 + 80  \(\times\) $\times$  3 + 45 m, is entirely and efficiently monitored using 8 sensors. The entire system was installed within four days after the traffic-induced fire accident. The dynamic deflection is recorded to evaluate the structural load capacity and dynamic features considering the temperature variations. Three months’ measurements are interpreted and discussed in this paper, which can prove the non-contacted deflection meters are practical for long-term monitoring. But limits exist for the sensors’ stability, because of the considerable temperature difference in mountain areas, which will affect the meters’ supports. In summary, the efforts of this paper contribute to the research and practice gap of lightweight and emergency monitoring systems, especially for post-disaster requests. Based on a three-month data survey, we demonstrate the stability and feasibility of the proposed post-disaster monitoring system for bridge safety assessment.