報告書番号

N08083

タイトル（和文）

経年劣化した鉄筋コンクリート製地中構造物の構造性能評価に関する検討(その６)- 鉄筋腐食を考慮した照査用限界値推定法の提案 -

タイトル（英文）

Structural Performance Evaluation on Aging Underground Reinforced Concrete Structures(PartVI) -An estimation method for threshold value in performance verification taking reinforcing steel corrosion-

概要 （図表や脚注は「報告書全文」に掲載しております）

本研究は，鉄筋腐食が生じたＲＣボックスカルバートの耐荷性能評価に用いる材料劣化の力学モデルの適用性を検証した上で，鉄筋腐食を考慮した照査用限界値推定法を提案したものである．鉄筋腐食したＲＣボックスカルバートの載荷実験に対する有限要素解析結果に基づいて，既提案による材料劣化の力学モデルは，主筋の最大腐食量が約15%までの範囲において，耐荷力評価に適用可能なことを確認した．さらに，腐食程度や腐食箇所などをパラメータとした一連の有限要素解析結果および既往の実験結果などを総合的に勘案して，塩害環境下の劣化進行過程における劣化程度とＲＣボックスカルバートの耐荷性能を対応付ける劣化係数を求めた．これらの結果に基づき，1)材料劣化の力学モデルを用いた構造解析による方法，2)健全時の構造解析結果に劣化係数を乗ずる方法，の２つの照査用限界値推定法を提案した．

概要 （英文）

This paper discusses applicability of material degradation model due to reinforcing steel corrosion for RC box-culverts with corroded reinforcement and an estimation method for threshold value in performance verification reflecting reinforcing steel corrosion. First, In FEM analyses, loss of reinforcement section area and initial tension strain arising from reinforcing steel corrosion, and deteriorated bond characteristics between reinforcement and concrete were considered. The full-scale loading tests using corroded RC box-culverts were numerically analyzed. As a result, the analyzed crack patterns and load-strain relationships were in close agreement with the experimental results within the maximum corrosion ratio 15% of primary reinforcement. Then, we showed that this modeling could estimate the load carrying capacity of corroded RC box-culverts. Second, a parametric study was carried out for corroded RC box culverts with various sizes, reinforcement ratios and levels of steel corrosion, etc. Furthermore, as an application of analytical results and various experimental investigations, we suggested allowable degradation ratios for a modification of the threshold value, which corresponds to the chloride induced deterioration progress that is widely accepted in maintenance practice for civil engineering reinforced concrete structures. Finally, based on these findings, we developed two estimation methods for threshold value in performance verification: 1) a structural analysis method using nonlinear FEM included modeling of material degradation, 2) a practical method using a threshold value, which is determined by structural analyses of RC box-culverts in sound condition, is multiplied by the allowable degradation ratio.

報告者

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