報告書番号

N08023

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３)- 鉄筋腐食が生じたＲＣボックスカルバートの耐荷特性評価 -

タイトル（英文）

Structural Performance Evaluation on Aging Underground Reinforced Concrete Structures (Part III) - Evaluation on load carrying capacity for RC box-culvert with corroded reinforcing bars-

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，鉄筋腐食を伴う実規模ＲＣボックスカルバートの損傷破壊過程を把握するとともに，鉄筋腐食が耐荷特性に及ぼす影響を評価したものである．載荷実験結果に基づいて，ＲＣボックスカルバートでは，隅角部付近で鉄筋降伏や斜めひび割れなどの損傷が生じても，塑性ヒンジが形成され荷重が再分配されるため，主筋の最大腐食量が約15％の腐食程度でも局所的な鉄筋腐食が曲げ耐力に及ぼす影響は小さいことを明らかにした．また，塩害環境下の一般的な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力の関係を対応付けて整理した結果，劣化期に至らない範囲では曲げ耐力はほとんど低下しないが，せん断耐力は腐食ひび割れの発生する加速期以降に低下する傾向にあり，潜伏期に比べて最大で約85％になることを示した．

概要 （英文）

The purpose of this paper is to assess damage mechanism for RC box-culvert with corroded reinforcing bars and to evaluate effects of reinforcing steel corrosion on load carrying capacity based on experimental results. We conducted a series of full-scale cyclic loading tests on RC box-culvert specimens that were artificially corroded by stay current corrosion. In experimental results, maximum strength of the box-culverts with corroded reinforcing bars shows slight decrease under the condition of maximum corrosion ratio 15%, and the locally material deterioration has minor effect on ultimate strength of RC box-culverts. It was because that plastic hinges were developed if steel yielding or shear cracks occurred around the corner parts and the loads were redistributed from the damage parts to the other parts. Then, as an application of experimental results, we developed relationships between the structural performance of RC box-culverts and chloride induced deterioration progress as is widely accepted in maintenance practice for civil engineering reinforced concrete structures. As a result, the degradation ratio of deformation capacity became larger than that of maximum strength with the increase of corrosion degree. Moreover, stayed as that of in sound condition except deterioration stage, while the minimum degradation ratio of shear strength in acceleration stage to that in initiation stage was approximately 85%.

報告者

キーワード