为研究超高性能混凝土(UHPC)柱偏心受压性能,完成了7个UHPC柱和1个高强混凝土(HSC)柱的偏心受压试验;通过改变UHPC的钢纤维体积掺量以及偏压柱的偏心距及配箍率,分析试件在竖向荷载作用下的破坏形态、承载能力及变形能力.试验结果表明,UHPC柱在偏心受压作用下的破坏形态为大偏心受拉破坏和小偏心受压破坏;大偏心受拉破坏为受拉区纵筋屈服、裂缝细密,受压区UHPC被压裂;小偏压受压破坏为受拉区纵筋未屈服、裂缝细微且数量少,受压区UHPC被压碎.由于钢纤维的"桥联"作用,受拉裂缝得到有效的抑制,且数量明显增多、宽度减小;UHPC大偏压柱荷载-挠度曲线有较平缓的下降段,表现出良好的延性;与HSC柱相比,UH-PC柱开裂荷载提高了44.5%和59%,极限荷载提高了30.2%和58.9%,随钢纤维体积掺量的增加,UHPC柱极限荷载提高13.3%~58.9%,破坏挠度提高14.3%~146.5%,随配箍率的增加,极限荷载提高6.2%~11.4%,破坏挠度提高14%~14.8%,通过增加钢纤维体积掺量及配箍率能有效的提高UHPC柱的承载能力和变形能力;基于UHPC较高的抗拉强度,考虑对受拉区的贡献,采用等效矩形应力图简化计算,提出UHPC偏心受压柱的承载力计算公式.计算值与试验值吻合良好.可为工程应用提供理论依据.%To study the eccentric compression performance of ultra-high performance concrete (UHPC) columns,seven UHPC columns and one high-strength concrete (HSC) column were tested.Variation parameters include:the steel fibers volume of UHPC,load eccentri-city and stirrup ratio of columns.The failure mode,bearing capacity and deformation capacity of the specimens with vertical loading were studied,and the following conclusions were drawn.It is demonstrated that the failure mode of UHPC eccentric compression columns includes large eccentric tension failure and small eccentric compression failure.Large eccentric tension failure mainly showed the following three characteristics:the tensile longitudinal reinforcements were yield,fine cracks appeared in tension zone and the UHPC in compression zone was crushed.However,small compression eccentric failure mainly showed the following two character-istics:less and slighter cracks appeared in tension zone and the UHPC in compression zone was crushed,without the yield of tensile longitudinal reinforcements.Due to the "bridging" effect of steel fibers,the development of cracks were delayed,the number of cracks increased significantly,and the width decreased.The load-deflection curves of large eccentric columns shows a gentle descending sec-tion,which shows that the specimens have good ductility.Comparing with HSC column,the cracking loads of UHPC columns in-creased 44.5% and 59%,and the ultimate loads increased 30.2% and 58.9%.With the increase of steel fiber volume,the carrying capa-city of UHPC columns increased by 13.3%~58.9%,and the failure deflection increased by 14.3%~146.5%.With the increase of stirrup ratio,the carrying capacity of UHPC columns increased by 6.2%~11.4%,and the failure deflection increased by 14%~14.8%.The increase of steel fiber volume and stirrup ratio has an effective effect on improving bearing capacity and deformation capability of UHPC columns.Due to the high tensile capacity of UHPC,the contribution of UHPC tensile strength to carrying capacity was considered in bearing capacity formula.And an equivalent rectangular stress diagram was used to simplify the calculation.The theoretical calculation results agree well with the test results.It can provide a theoretical basis for engineering application.
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