네트워크 RTK 기반 현수교 동적거동 모니터링 시스템

Abstract

The bridge is one of the most important infrastructure in the national economy. Increasing volume of traffic and logistics led by economic growth, as well as the recent interconnection between locations with geographical remoteness, called for long-span cable bridges. As the result, a number of such bridges are complete or being built, however, construction-oriented approach leaves the maintenance part short of attention for existing bridges. Maintaining cable bridges and suspension bridges is of much significance especially because of their large scale, architectural importance and complex structural behavior. Commonly used sensor-based monitoring systems for bridge health evaluation tend to be affected by the size of structure and weather conditions. Resulting data loss subsequently causes discontinuity of displacement information, which leads to low efficiency in precise behavior analysis of bridges. This emphasizes the necessity of a more accurate monitoring system that can analyze dynamic behavioral characteristics of long-span cable bridges with qualities such as cost effectiveness, durability and data acquisition stability. Having seen the benefits of GNSS-based dynamic behavior monitoring systems, some advanced countries have already adopted them to large scale structures as a solution that can replace sensor-based monitoring systems. To achieve a GNSS-based dynamic behavior monitoring system with enhanced stability and reliability, a data processing technology that can improve the accuracy of GNSS, along with customized software specific to the bridge environment rather than formerly generic software, had to be developed. Furthermore, a reasonable data filtering technology has been unprecedentedly implemented through multipath modeling in order to acquire more reliable real-time displacement data of GNSS and to eliminate multipath error which is dominant in the bridge environment. Recent development of high sample rate receivers enabled us to build a bridge monitoring system that can analyze various dynamic behavior modes and process GNSS data up to 50Hz, where conventional products handle no more than 20Hz. After applying this system to Kwangan bridge and comparing it to the results from the existing sensor-based measurements, we concluded that the system is applicable and economical, which makes us to expect it to be widely used in analyzing dynamic behavior of suspension bridges.