预应力碳纤维布加固钢筋混凝土梁受弯性能的试验研究

【作者】 孔琴；

【导师】 刘立新； 徐有邻；

【作者基本信息】 郑州大学 ， 结构工程， 2005， 硕士

【摘要】 工程实践及试验研究表明,利用碳纤维布加固混凝土受弯构件时,碳纤维布高强度的特点仅在梁中主筋屈服后才得以充分发挥,而在主筋屈服前,碳纤维布所起的作用有限。因此,它对提高被加固构件的开裂荷载及屈服荷载作用不是十分明显,对受弯构件在正常使用阶段的性能的改善也有限。为了更加充分而合理地利用碳纤维布高强度的特点,本试验采用预应力技术,克服CFRP的缺陷,提高加固效果。 试验证明,无论梁初始是否处于开裂状态,预应力的施加提高了碳纤维布在各个阶段的发挥效果。无论是抗裂、延缓钢筋屈服还是提高构件极限承载力,预应力碳纤维加固梁的性能均优于非预应力碳纤维加固梁;并且,在初始状态钢筋未屈服的情况下,已经开裂的梁经过加固,其承载力相当于甚至优于梁在未开裂情况下直接加固的程度。外加给碳纤维布的预应力是通过布与梁之间的粘结胶层传递给梁体的,U形箍只是起到了保护作用,良好的粘贴才是保证构件承载力有效提高的关键所在。 理论分析和数值计算结果表明,由于对预应力碳纤维布施加了预应力,提高了碳纤维强度发挥的程度,也相应地提高了被加固梁的承载力,减小了正常使用状态下的裂缝宽度和挠度,本文建议的张拉度在30%左右。在计算预应力碳纤维加固梁的极限承载力时,碳纤维应变取0.01是比较合理的值。本文还针对工程实际提出关于开裂弯矩计算方法,并对预应力损失进行了初步研究,提出相应的计算公式。更多还原

【Abstract】 Engineering practice and experimental research show that strengthening action of CFRP mainly is fully taken after the steels yield ,however,deficiently before that.Thus the action that CFRP enhance cracking load and yield load of the beams strengthened with CFRP isn’t apparent and the improvement to the performance in bending in the regular service course is limited.To make full use of the strength of CFRP,the prestressing technology is used in the experiment to overcome the disadvantage of CFRP and improve strengthening action of CFRP.The test shows that prestress can improve the performance of CFRP in all course. Prestressed CFRP can exert its full contribution to the beams strengthened with CFRP. If the steel bars in initial state do not yield ,whether the beam is cracked or not , bearing capacity is similar.Prestressing force is transferred to the concrete through bond. U style stirrups only take the action of pretection and the key what can ensure the the strengthening action of CFRP is good bond between CFRP and concrete.Academic analyse and calculation show that bearing capacity is enhanced and the width of cracks and the deflection in the regular service course is limited for prestressing force can improve the exertion of CFRP. 30 percent of the strength of CFRP is proper prestressing value.0.01 is the proper number of strain of CFRP when the ultimated moment is calculated.This paper put forward a technics on cracking moment. Preliminary research effort on the losses of pretress is taken and the calculation formula is put forward accordingly.更多还原