報告書番号

N12013

タイトル（和文）

鉄筋腐食が生じた鉄筋コンクリート製ボックスカルバートの耐荷特性評価－地震により発生したひび割れの影響に関する実験的検討－

タイトル（英文）

Evaluation on load-carrying capacity for cacked RC box-culvert with reinforcing steel corrosion - Experimental study on effects of cracking damage caused by earthquake -

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，ひび割れを有するRCボックスカルバートの腐食性状を明らかにするとともに，鉄筋腐食が耐荷特性に及ぼす影響を評価することを目的として，実環境を想定した電食と実規模載荷実験を実施し，耐荷性能評価におけるひび割れの考慮方法を検討したものである。この結果，RCボックスカルバートでは，荷重が再分配されるため，主筋の平均腐食量が約10%までの範囲では，初期ひび割れの程度にかかわらず，最大荷重の低下割合は腐食がない場合と比べて数%であることを示した。また，鉄筋降伏が生じないひび割れ程度であれば，既報で提案した劣化進行過程に対応した残存耐荷性能評価法が，ひび割れに起因する鉄筋腐食に対しても適用可能であることが確認された。

概要 （英文）

The purpose of this paper is to evaluate the effects of reinforcing steel corrosion on load carrying capacity of a RC box-culvert with cracking damages, which were assumed to be caused by a big earthquake.
We conducted a series of cyclic loading tests using RC box-culvert full-scale specimens whose reinforcing steels were artificially corroded by the electrolytic corrosion method. From the experimental results, it was recognized that load carrying capacities of the box-culvert specimens with corroded reinforcing bars slightly decreased under the conditions of average corrosion ratios of 3 to 12%, and that the local deterioration due to steel corrosion in a specimen caused only a minor effect on the ultimate strength of a RC box-culvert. It was the reason why the small decrease of steel volume does not cause the decrease of load carrying capacity directly because the development of plastic hinges at the corner parts of a RC box-culvert contributed to the redistribution of sectional forces. However, the deformation at the deteriorated parts of the specimens due to steel corrosion became larger in the case that the steel corrosion started from cracks caused by the force corresponding to the yielding of steels.
Based on these results, we suggested a table of reduction factors applied to the estimation of threshold values for verifying the structural sound function of RC box-culverts with deterioration due to steel corrosion.

報告者

キーワード