低干缩延性材料-混凝土复合梁抗弯性能

Flexural performance of LSECC-concrete composite beam

摘要:

为研究延性材料对普通混凝土的增强增韧效果,本文采用低干缩高延性纤维增强水泥基复合材料(LSECC)与普通混凝土复合的方式,从试验与模拟两个方面研究了复合梁的抗弯性能．结果表明,在梁底复合低干缩延性材料后不仅可以提高梁的抗弯承载能力,还大幅提升了梁的延性．当LSECC的强度比上层混凝土的强度高时,复合梁的峰值荷载受LSECC层厚的影响明显,随着层厚的增加而增大．当上层混凝土的强度较高时,复合梁的峰值荷载随LSECC层厚度的变化不明显．基于开裂强度和材料应力裂纹宽度关系的抗弯模型可良好地预测不同材料复合梁的弯曲性能,模型结果与实测值吻合良好,可用于组合结构优化设计．

Abstract:

To investigate the effect of ductile material on strength and ductility improvement of concrete, the flexural performance of LSECC-Concrete composite beam, in which the ductile fiber reinforced cementitious composite with characteristic of low shrinkage (LSECC) was used at the tensile part of the beam, was studied by both experiments and theoretical simulation. The results show that the concrete beam combined with ductility material at the bottom of beam can achieve a high ductility and enhance load carrying capacity. The strength of the LSECC and plain concrete, as well as the thickness of LSECC layer used in the composite beams can greatly influence the strength and ductility of the beam. Based on cracking strength criteria and stress-crack opening relationship, a model to simulate bending performance of composite beam is developed, which can well predict the flexural behavior of composite beam. A seasonable agreement between model and test results is observed and the model may be used in optimization of the composite structures.