旭硝子財団助成研究成果報告2022

62/90

松川　和人70Kazuto MATSUKAWA石山　央樹71Hiroki ISHIYAMA劣化した鉄筋コンクリート柱の長期安全性評価に関する研究(2020採択)Research on Long-term safety evaluation for reinforced concrete columns deteriorated by corrosion of reinforcing bars(Project 2020)木造建築物における各部位劣化時の建物構造性能の定量評価(2018採択)Quantitative Evaluation of Wooden Building Structural Performance with Each Part Degradation(Project 2018)58旭硝子財団　助成研究成果報告（2022）次世代へより良い建築ストックを引き継いでいくためには，劣化した建築物の適切な安全性評価が必要である．本研究では，その端緒として，鉄筋コンクリート造柱が鉄筋腐食した場合の長期荷重（軸力）保持能力を部材実験により評価した．その結果，質量減少率30％程度の鉄筋腐食ではおよそ10％以下程度の軸力保持能力低下にとどまるが，これに加えてかぶりコンクリートが剥落した場合は，20％もの軸力保持能力の低下が確認された．これらの実験結果は，既存の軸耐力推定モデルと整合的であり，劣化部材であっても適切なモデル化により構造性能評価が可能であると明らかになった．In order to hand over better building stocks to the next generation, it is necessary to properly evaluate the structural safety of deteriorated buildings. In this study, as a first step, the long-term load (axial load) carrying capacity of reinforced concrete columns with corroded steel bars was evaluated through structural experiments. The results showed that the axial force carrying capacity decreased by 10% or less when the weight loss ratio of reinforcements was about 30%, and by approximately 20% when the cover concrete was spalled. These experimental results are consistent with existing models for estimat-ing axial capacity. The appropriate models will therefore contribute to the structural performance evalu-ation of deteriorated buildings.木造建築物における各部位劣化時の構造性能を定量評価するため，実物件における劣化事例収集，木材含水率と釘の腐食速度の関係検証，木ねじの形状と腐食が引抜性能に及ぼす影響の実験的検証，木材腐朽と木ねじ発錆が同時に発生した時の構造性能の実験的検証，木材腐朽と釘の発錆を伴う面材耐力壁の構造性能の解析的検討を行った．その結果，腐朽した木材に打たれた釘は発錆が著しいこと，木材含水率が30％を超える領域では釘の腐食速度が大きいこと，木ねじが錆びると胴部の割合が大きなものは耐力が上がること，木ねじのせん断耐力に及ぼす影響は木材の腐朽が大きいこと，木材腐朽および釘の発錆が柱において生じると二次剛性が大きく低下することがわかった．The following studies were conducted to quantitatively evaluate the structural performance of wooden build-ings with deterioration of each part. 1) Collection of deterioration cases, 2) Experimental verification of the relationship between wood moisture content and nail corrosion rate, 3) Experimental verification of the effect of screw shape and corrosion on pullout performance, 4) Experimental verification of structural performance with wood decaying and screw rusting simultaneously, 5) Analytical investigation of the structural perfor-mance of shear wall with wood decay and nail rusting. As a result, the following were clarified. 1) Nails driv-en into decayed wood are significantly rusted. 2) Nails corrosion rate is higher when the wood moisture con-tent exceeds 30 %. 3) Pull out load of screw is increased with rust when body length of screw is large percentage. 4) Wood decaying has a significant effect on the shear strength of wood screws. 5) Secondary stiffness of shear wall is significantly reduced with wood decaying and nail rusting on columns.