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（1 湖南大學(xué)土木工程學(xué)院，長(zhǎng)沙 410082；2 工程結(jié)構(gòu)損傷診斷湖南省重點(diǎn)實(shí)驗(yàn)室（湖南大學(xué)），長(zhǎng)沙 410082）

［摘要］為研究長(zhǎng)細(xì)比效應(yīng)對(duì)BFRP（玄武巖纖維增強(qiáng)復(fù)合材料）約束完好及損傷混凝土軸壓力學(xué)性能的影響規(guī)律，首先對(duì)3組不同長(zhǎng)細(xì)比的素混凝土圓柱體試件進(jìn)行軸壓預(yù)加載，考慮了3種不同程度初始損傷，隨后采用3種BFRP層數(shù)包裹加固并再次進(jìn)行軸壓試驗(yàn)。結(jié)果表明，損傷混凝土經(jīng)BFRP約束后其抗壓強(qiáng)度和變形能力仍能得到有效改善，但損傷等級(jí)對(duì)BFRP約束混凝土的強(qiáng)度、初始彈性模量等力學(xué)性能具明顯不利的影響。通過直觀分析與多因素析因分析，發(fā)現(xiàn)BFRP約束完好及損傷混凝土的極限強(qiáng)度具有長(zhǎng)細(xì)比效應(yīng)，隨著長(zhǎng)細(xì)比的增加，極限強(qiáng)度逐漸下降，而極限應(yīng)變則無明顯規(guī)律。值得注意的是，隨著約束層數(shù)的增多，長(zhǎng)細(xì)比效應(yīng)對(duì)強(qiáng)度的影響可能有所下降，而隨著損傷等級(jí)的加重，長(zhǎng)細(xì)比效應(yīng)對(duì)強(qiáng)度的影響反而可能會(huì)增加?？紤]約束層數(shù)與損傷等級(jí)對(duì)長(zhǎng)細(xì)比的交互效應(yīng)，建立了考慮長(zhǎng)細(xì)比效應(yīng)的極限強(qiáng)度模型，模型預(yù)測(cè)結(jié)果與試驗(yàn)結(jié)果吻合良好。

［關(guān)鍵詞］FRP約束； 長(zhǎng)細(xì)比效應(yīng)； 初始損傷； 強(qiáng)度模型； 混凝土圓柱體

中圖分類號(hào)：TU375-3文獻(xiàn)標(biāo)識(shí)碼：A文章編號(hào)：1002-848X(2020)24-0091-08

Slenderness ratio effect of BFRP-confined damaged concrete cylinders

MA Gao1,2, CHEN Xiaohuang1

(1 College of Civil Engineering, Hunan University, Changsha 410082, China;2 Hunan Provincial Key Lab on Damage Diagnosis for Engineering Structures (Hunan University), Changsha 410082, China)

Abstract:To investigate the slenderness ratio effect on the axial compression mechanical behavior of BFRP-confined undamaged concrete and damaged concrete, three groups of plain concrete cylinders with different slenderness ratios were pre-loaded under axial compression loading. Three damaged  levels were considered. The damaged concrete cylinders were wrapped with three kinds of BFRP layers and subjected to axial compression loading again. The test results show that the compression strength and deformation capacities of the damaged concrete can be effectively improved after BFRP confinement. However, the damaged levels had a noticeable adverse effect on the mechanical properties of BFRP-confined concrete (e.g. strength and initial elastic modulus). Through intuitive analysis and multifactorial analysis, it is found that the ultimate strength of BFRP-confined concrete had slenderness ratio effect. With the increase of slenderness ratio, the ultimate strength decreased, while the ultimate strain had no obvious trend. It should be noted that the effect of slenderness ratio on strength may decrease with the increase of confinement layers, while increase with the increase of damaged levels. An ultimate strength model was proposed for BFRP-confined damaged concrete with considering the interaction effect between the confinement layers and damaged levels on slenderness ratio. The proposed model showed a good agreement with the experimental results.

Keywords:FRP-confinement; slenderness ratio effect; initial damage; strength model; concrete cylinder

* 國家自然科學(xué)基金項(xiàng)目（51878268），湖南省自然科學(xué)基金項(xiàng)目（2020JJ4195）。

作者簡(jiǎn)介：馬高，博士，副教授，Email:magao@hnu.edu.cn。