钢纤维高强混凝土有腹筋梁受剪试验研究
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摘要
本文对22根钢纤维高强混凝土梁进行均布荷载作用下的受剪性能试验，重点通过研究不同基体混凝土强度等级、不同钢纤维体积含量、不同配箍特征值以及不同钢纤维品种对结构受剪性能的影响，来探讨钢纤维在高强基体下对于结构的受剪性能的基本作用。试验结果表明：
1．与普通基体情况相似，钢纤维的掺入没有在根本上改变高强混凝土梁的受剪传力机制，梁的破坏形态依然表现剪压破坏、剪拉破坏等典型受剪破坏特征。
2．钢纤维高强混凝土对于改善梁结构的初始斜裂荷载作用，并不明显；但在裂缝出现以后，对抑制裂缝在宽度上的进一步发展作用十分明显，较好的体现了“晚、细、密”三大特征。
3．钢纤维的掺入在一定程度上提高了梁体在各受力阶段的受力性能，并且高强基体下钢纤维对梁破坏时的极限承载力的增强作用，与普通基体下的情况相比，由于其与基体间的粘结性能更好而更为明显。
根据试验分析，同时吸收国内外关于这一领域的研究成果，并考虑与《混凝土结构设计规范》相衔接，本文提出钢纤维高强混凝土梁在均布荷载作用下的受剪承载力计算建议公式和与混凝土规范相衔接的计算公式。通过对回归公式的计算承载力与试验实测承载力进行比较，两个公式的符合性较好，并且对于不同工况的试件，可靠度水平基本一致。
试验结果还表明，不同的钢纤维品种对于梁结构在均布荷载下的受剪承载力增强作用，在体积掺量相同的情况下相差不大。进而本文在此基础上提出关于混凝土和钢纤维分项的统一计算表达式。
另外，试验过程中发现不同的钢纤维在基体强度较高的时候，存在不同程度的拉断情况，建议在高强基体下，选择钢纤维品种时，考虑这一影响因素。
In this paper, results of an experimental and analytical investigation on shear behavior of 22 steel fiber reinforced high-strength concrete beams under even loads are presented. The study explores the effects of concrete strength, contents of stirrup, ratio by volume of steel fiber and types of steel fibers on shear behavior of beams. The tests show:
1. For high strength concrete, steel fiber cannot drastically change the mechanism of the beam's shearing behavior, so its failure pattern is still within the typical ones: shear-compress , shear-tension and so on.
2. The steel fiber cannot obviously improve the loads corresponding to the first inclined cracks. But after the appearance of cracks, steel fiber has significant effect on restriction of the extension of the crack's width. The process of the fracture and the crack shape show the following three characters: "late, thin and thick".
3. To some extent, steel fiber can improve the beam's strength capacity, and the enhancement of ultimate strength of steel fiber beams with high strength concrete is greater than that with plain strength concrete because of the better bond between the high strength concrete and steel fibers.
According to tests and researches acquired at home and abroad, and also consistent with the Code For Concrete Structures Design, the formulae for shear capacity of high strength steel fiber reinforced concrete beams under even loads are derived. Good consistency is achieved between the calculated result and the test one. For each specimen, approximate reliability of the results given by the two equations is presented.
The following conclusions can also be drawn according to the tests: Given the same contents but different types of steel fiber, the enhancement of shear capacity of beams shows little difference. Based on this, a unified formula for the loads subentry considering concrete and steel fiber is given.
In addition, certain extent of rupture of steel fiber is found in the high strength concrete beams. It is suggested that for high strength concrete, the problem of rupture of steel fiber should be considered.
1．与普通基体情况相似，钢纤维的掺入没有在根本上改变高强混凝土梁的受剪传力机制，梁的破坏形态依然表现剪压破坏、剪拉破坏等典型受剪破坏特征。
2．钢纤维高强混凝土对于改善梁结构的初始斜裂荷载作用，并不明显；但在裂缝出现以后，对抑制裂缝在宽度上的进一步发展作用十分明显，较好的体现了“晚、细、密”三大特征。
3．钢纤维的掺入在一定程度上提高了梁体在各受力阶段的受力性能，并且高强基体下钢纤维对梁破坏时的极限承载力的增强作用，与普通基体下的情况相比，由于其与基体间的粘结性能更好而更为明显。
根据试验分析，同时吸收国内外关于这一领域的研究成果，并考虑与《混凝土结构设计规范》相衔接，本文提出钢纤维高强混凝土梁在均布荷载作用下的受剪承载力计算建议公式和与混凝土规范相衔接的计算公式。通过对回归公式的计算承载力与试验实测承载力进行比较，两个公式的符合性较好，并且对于不同工况的试件，可靠度水平基本一致。
试验结果还表明，不同的钢纤维品种对于梁结构在均布荷载下的受剪承载力增强作用，在体积掺量相同的情况下相差不大。进而本文在此基础上提出关于混凝土和钢纤维分项的统一计算表达式。
另外，试验过程中发现不同的钢纤维在基体强度较高的时候，存在不同程度的拉断情况，建议在高强基体下，选择钢纤维品种时，考虑这一影响因素。
In this paper, results of an experimental and analytical investigation on shear behavior of 22 steel fiber reinforced high-strength concrete beams under even loads are presented. The study explores the effects of concrete strength, contents of stirrup, ratio by volume of steel fiber and types of steel fibers on shear behavior of beams. The tests show:
1. For high strength concrete, steel fiber cannot drastically change the mechanism of the beam's shearing behavior, so its failure pattern is still within the typical ones: shear-compress , shear-tension and so on.
2. The steel fiber cannot obviously improve the loads corresponding to the first inclined cracks. But after the appearance of cracks, steel fiber has significant effect on restriction of the extension of the crack's width. The process of the fracture and the crack shape show the following three characters: "late, thin and thick".
3. To some extent, steel fiber can improve the beam's strength capacity, and the enhancement of ultimate strength of steel fiber beams with high strength concrete is greater than that with plain strength concrete because of the better bond between the high strength concrete and steel fibers.
According to tests and researches acquired at home and abroad, and also consistent with the Code For Concrete Structures Design, the formulae for shear capacity of high strength steel fiber reinforced concrete beams under even loads are derived. Good consistency is achieved between the calculated result and the test one. For each specimen, approximate reliability of the results given by the two equations is presented.
The following conclusions can also be drawn according to the tests: Given the same contents but different types of steel fiber, the enhancement of shear capacity of beams shows little difference. Based on this, a unified formula for the loads subentry considering concrete and steel fiber is given.
In addition, certain extent of rupture of steel fiber is found in the high strength concrete beams. It is suggested that for high strength concrete, the problem of rupture of steel fiber should be considered.
引文
1．朱清江．高强高性能混凝土研制及应用[M]，北京：中国建筑工业出版社，1999．
2．陈肇元，朱金铨，吴佩刚．高强混凝土在建筑工程中的应用[M]，北京：清华大学出版社，1991．
3. Ashour, Smair A.;Hasanain, Ghazi S.;Wafa, Faisal F. Shear behavior of high-strength fiber reinforced concrete beams[J]. ACI Structural Journal, 1992, 89(2).
4．赵国藩，彭少民，黄承逵．钢纤维混凝土结构[M]．北京：中国建筑出版社，1999．
5．章文纲，程铁生，王威龙．钢纤维混凝土抗剪性能研究[A]．钢纤维混凝土结构设计与施工规程专题研究报告[C]，大连：1990．
6．CECS38：92，中国工程建筑标准化协会标准．钢纤维混凝土结构设计与施工规程[S]．
2．陈肇元，朱金铨，吴佩刚．高强混凝土在建筑工程中的应用[M]，北京：清华大学出版社，1991．
3. Ashour, Smair A.;Hasanain, Ghazi S.;Wafa, Faisal F. Shear behavior of high-strength fiber reinforced concrete beams[J]. ACI Structural Journal, 1992, 89(2).
4．赵国藩，彭少民，黄承逵．钢纤维混凝土结构[M]．北京：中国建筑出版社，1999．
5．章文纲，程铁生，王威龙．钢纤维混凝土抗剪性能研究[A]．钢纤维混凝土结构设计与施工规程专题研究报告[C]，大连：1990．
6．CECS38：92，中国工程建筑标准化协会标准．钢纤维混凝土结构设计与施工规程[S]．