본 연구에서는 음향 방출 기법을 사용하여 강연선(7-wire strand)의 손상을 감지하기 위한 기초 실험을 수행하였다. 강연선은 주로 교량에 추가적인 인장력을 제공하기 위해 널리 사용되는 건설 자재이다. 프리스트레스 교량 또는 사장교가 대표적인 경우이다. 그러나 교량 노화가 급격히 진행되면서 강연선 부식 문제가 대두되고 있다. 이러한 이유로 케이블 점검을 위한 다양한 비파괴 방법이 연구되고 있고 현장 적용 이 시도되고 있다. 비파괴 방법 ??중 하나인 음향 방출 기법은 케이블 손상 및 파단을 감지하는 효과적인 기술로 알려져 있다. 본 연구에서는 음향 방출 기법의 교량에 대한 적용 가능성을 평가하기 위해 강연선의 손상에 따른 음향 방출 신호 특성을 인장 실험을 분석 하고, 현장 적용을 위한 최적 센서 주파수 타입을 선정하였다. 결과적으로, 음향 방출 기법을 활용하여 향후 교량 케이블의 부식 파단 및 파단 징후를 감지 할 수 있다 고 여겨진다.

In this study, the durability rating was evaluated to evaluate the safety of bridges considering the factors affecting the corrosion of cables in cable-stayed bridges and suspension bridges. Corrosion factors were considered for salinity, sulfur dioxide concentration and relative humidity. In addition, the durability level was calculated by applying the corrosion rates given in KS D ISO 9223 ~ 9226.

It is important to operate appropriate measurement system of cable bridges for the efficient construction and maintenance. The main results of study on the optimal construction detail method of measurement for individual cable bridge are described. In this paper, the basic guidelines for the cable bridges measurement system is presented such as sensor classification, installation location and performance standard for the installation of the optimal measurement system of cable bridges on expressways.

케이블지지교량에서 케이블은 하중을 지지하는 주요 부재로, 케이블 장력은 교량의 건전성과 안전도 평가에 있어서 매우 중요한 변수이다. 케이블의 장력을 추정하는 기법으로, 로드셀 및 유압잭 등을 이용하여 케이블의 응력을 직접 측정하는 직접법과 케이블의 형상조건과 계측된 동특성을 활용하여 장력을 역산하는 진동법이 가장 많이 활용되고 있다. 최근 들어 케이블 내부 강재의 응력변화로 인하여 유발되는 자기장 변화를 탐지하는 EM 센서의 연구 및 활용이 증가하고 있다. 본 연구에서는 리프트오프 테스트, EM 센서 및 진동법(Vision-based System, Accelerometer)을 적용하여 장력을 측정하고 그 결과를 비교 분석하였다.

현수교 주 케이블은 케이블 밴드의 볼트 축력에 대한 정기적인 유지 관리가 매우 중요하다. 현수교 케이블 밴드의 볼트 축력은 시간이 경과함에 따라 케이블 소선의 크리프 현상, 볼트의 릴렉세이션, 하중 변동, 케이블 소선의 재배열 등으로 인해 축력 감소 현상이 발생하게 된다. 본 연구에서는 국내 현수 교량(SR대교)의 케이블 밴드가 시간이 경과하면서 발생하는 축력 감소 현상에 대해 그 원인 및 감소량 등에 대한 현장 측정 및 이론적 검토, 안전율 검토, 장기적인 이력 관리 등을 수행하였다. 그 결과, 케이블 밴드 볼트 축력 감소는 주 케이블 소선에 사용된 아연 도금층의 소성 변형에 크게 영향받는 것을 확인하였으며, 이에 대한 이론적 체계 및 장기 이력 관리에 대한 적용성을 확립하였다.

This paper aims to evaluate the safety of the cable supported bridges under the occurrence of damages on cable system. There are more than 50 cable supported bridges currently built in the Korean peninsula and efficient and systematic maintenance and management are in great demand. However, safety of the bridges cannot be under estimated and should be properly evaluated. In this paper, two bridges (one cable-stayed bridge and one suspension bridge) in South Korea were investigated their safety based on the damage scenario of cable system. FEM analysis for safety evaluation of the two bridges was conducted and the results were explained. The result could be used by operators and owners of bridges for the future maintenance and management.

This study is the National R&D project which has been carried out since 2016 with governmental support. The main objective of this study is to enhance technical and economical competitiveness on cable bridge through providing total solution for the major field issues in overseas market. In this paper, methodology and promotion strategy of the study are introduced and future research plan is also explained.

This paper introduces and summarizes damage cases of cable for cable supported bridges. The damage cases of similar bridge types may become an important database in the maintenance and management of cable supported bridges in the future. It will also be used as a base material for improving and developing the technology of inspection and maintenance of cable supported bridges.

Earthquake safety assessment software of the cable-stayed bridge using the seismic acceleration measurement date was developed. Various safety assessment indices for evaluation structural safety and serviceability of bridges are discussed. A systematic approach is proposed to process the raw data for generating appropriate safety assessment indicators. The software for structural state evaluation includes (i) format conversion of raw data, (ii) noise filtering, (iii) generation of assessment index, (iv) state evaluation. Determination of the limit state included in the condition evaluation step is discussed and an example of the graphic user interface of the software is shown.

This paper introduces and summarizes damage cases of cable for cable supported bridges. The damage cases of similar bridge types may become an important database in the maintenance and management of cable supported bridges in the future. It will also be used as a base material for improving and developing the technology of inspection and maintenance of cable supported bridges.

Earthquake safety assessment software of the cable-stayed bridge using the seismic acceleration measurement date was developed. Various safety assessment indices for evaluation structural safety and serviceability of bridges are discussed. A systematic approach is proposed to process the raw data for generating appropriate safety assessment indicators. The software for structural state evaluation includes (i) format conversion of raw data, (ii) noise filtering, (iii) generation of assessment index, (iv) state evaluation. Determination of the limit state included in the condition evaluation step is discussed and an example of the graphic user interface of the software is shown.

This study was conducted to build an emergency action plan (EAP) for cable-supported bridges in South Korea. First, accidents happened on Cable-supported bridges were investigated and categorized based on the types. Second, accident scenarios were built-up regarding the types. Two bridges were selected for planning the emergency action following the accident scenarios. The emergency action plan established in this study could be used for the management of cable-supported bridges in the future.

본 연구는 현수교에 설치된 주케이블 제습시스템의 효율성에 대한 검증을 수행한 것으로서, 송기 시스템 본체, 주케이블 내부, 대기중에서 온도 및 습도 등의 데이터를 측정하여, 교량에 설치된 제습시 스템의 작동 유·무를 고려한 습도변화량 등을 분석하였다.

Acceleration measurement is widely employed, because acceleration sensors generally have low noise and cost effective. To determine cable tension, FFT analysis of measured acceleration data is widely used. This study proposes a stay cable measurement system using acceleration data to determine the cable tension and vibration amplitude. A small light-weight wireless sensor is also proposed to increase the applicability.

Structural performance of cable-bridge has been evaluated based on the field load test and the measurement monitoring system of existing Nielsen arch bridge. The measured acceleration data was converted to the displacement of girder and the tension of cable in the process of numerical integration and maximum frequency detection algorithm..

A cartridge type sensor head was fabricated to detect the level of corrosion in steel cables with consistent or varying cross sections by assessing the LMA (Loss of Metallic Area) damage. Two coil sensor cartridges were made to cater to cables with up to 70mm and 150mm. The developed system was verified through lab experiment using a tapered steel cable specimen, and through a field test conducted in cable bridge. The result showed that the developed system is capable of assessing a cable with varying cross section.

The thermal load must be considered to design cable supported bridges as a variable load. The thermal load recommended by Korean design code might be different to real temperature distribution in the bridges because the thermal load proposed by Korean design code is referred to Eurocode, etc. Therefore this study proposes the temperature distribution of cable supported bridges In Korea based on measurements.

In this study, several vibration characteristics of model bridge due to changes in cable tension are experimentally analyzed. In order to achieve the study, acceleration responses are measured from the model bridge for several cable tension case. The values of features extracted by frequency transform method are increased due to tension-loss.