상태평가 결과 기반 고속도로 PSC Box 거더교 상부플랜지 열화․ 손상 실태 고찰
A Review of the Deterioration and Damage of the Top Flange of the Highway PSC Box Girder Bridge based on the Condition Assessment Results
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참고문헌
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초록
PSCB 거더교는 고속도로에서 공용중인 교량의 4%로 많은 비중을 차지하고 있지는 않지만, PSCB 거더교의 약 98%가 1․2종 교량이며 전체 교량 연장의 약 16%(192km)를 차지하는 만큼 유지관리가 매우 중요한 교량 형식 중 하나이다. PSCB 거더교의 손상유형을 분석하기위해 고속도로 공용중 교량의 가설공법, 제설환경 노출등급 비율을 고려한 62개소(477경간) 정밀안전진단 보고서를 선정하여 상세 분석을 수행함과 동시에 실제 열화․손상이 발생한 교량의 현장조사를 수행하였으며, 그 결과 대부분의 열화․손상 원인은 교면포장으로 유입된 우수(염수)가상부플랜지와 계면 사이에 체수되어 콘크리트가 열화되고, 이후 교면포장의 균열 및 파손, 철근의 부식․팽창으로 인한 콘크리트 박락 등으로진전되어 나타난 것으로 조사되었다. 또한, 상부플랜지 하면에 발생한 교축방향 균열 원인은 수화열, 건조수축 등으로 인한 균열로 판단된다. 결론적으로 PSCB 거더교의 특성을 고려한 합리적인 유지관리를 위해서는 시공초기 발생되는 상부플랜지 하면 교축방향 균열 제어를 위한 설계측면의 개선 방안이 제시되어야 할 것이며, 공용중 발생되는 열화는 상부플랜지 열화 이전 교면포장의 유지관리를 통한 선제적 대응과 제설환경 노출등급에 따른 차별화된 유지관리 방안이 제시되어야 할 것으로 판단된다.
Abstract
Although PSCB girder bridges account for 4% of the bridges in use on highways, they do not account for much, but 98% of PSCB girder bridgesare 1sttype and 2ndtype of bridge. Also, the total length of the PSCB girder bridge is 16% (192km) of the total length of the highway bridge. Thus, thePSCB girder bridge can be one of the bridge types where maintenance is important. In order to analyze the damage types of PSCB girder bridges, a detailedanalysis was conducted by selecting 62 places (477 spans) precision safety diagnosis reports considering ratio of the construction method and snow removalenvironment exposure class. Analysis of report and a field investigation was conducted, and as a result, most of the causes of deterioration damage werecaused by rainwater (salt water) flowing into the bridge pavement soaking in between the top flange and the interface. After concrete slab deteriorateoccurred then bridge pavement cracking and breaking increased and exfoliation of concrete occurred by corrosion and expansion of the reinforcing barsoccurred. In addition, the cause of cracks in the longitudinal direction on the bottom of the top flange is considered to be cracks caused by restrained dryingshrinkage. In conclusion, for reasonable maintenance considering the characteristics of PSCB girder bridges, it should be suggested in the design aspectthat restrained drying shrinkage crack on top flange. Also, it is believed that differentiated maintenance method should be proposed according to snowremoval environment exposure class.
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