考虑预应力损失的CFRP布加固钢筋混凝土梁正常使用极限状态可靠度研究
发布时间：2019-03-26 17:50
【摘要】：在考虑预应力损失和二次受力的情况下,对预应力CFRP布加固钢筋混凝土梁,推导了挠度和裂缝宽度的计算公式,并基于改进的蒙特卡罗法和等效线性化方法进行了挠度和裂缝宽度的可靠度计算。可靠度计算结果表明,当预应力损失从500με增加到4000με时,裂缝宽度的可靠指标从7.78减小到0.97;挠度的可靠指标从4.09减小到3.96;预应力损失对裂缝宽度可靠指标的影响更加显著。在未充分卸荷、CFRP布截面面积较小或CFRP布弹性模量较低时,更易加剧裂缝宽度的可靠指标随预应力损失增加而降低的趋势。为防止因预应力损失而影响梁的正常使用,建议采用预应力CFRP布加固钢筋混凝土梁时,尽可能卸荷;选用CFRP布截面面积时,尚应考虑正常使用阶段的功能要求,可适当增加CFRP布的截面面积;同时为了在正常使用阶段充分发挥CFRP布的高强特性,可选择较高弹性模量的CFRP布。
[Abstract]:Considering the loss of prestress and secondary stress, the formulas for calculating deflection and crack width of reinforced concrete beams strengthened with prestressed CFRP sheets are derived. The reliability of deflection and crack width is calculated based on the improved Monte Carlo method and equivalent linearization method. The reliability calculation results show that when the loss of prestress increases from 500 渭 蔚 to 4 000 渭 蔚, the reliability index of crack width decreases from 7.78 to 0.97, and the reliability index of deflection decreases from 4.09 to 3.96. The influence of prestressing loss on the reliability index of crack width is more obvious. When the section area of CFRP distribution is smaller or the elastic modulus of CFRP cloth is lower, the reliable index of crack width is more likely to worsen with the increase of prestress loss, the reliable index of crack width decreases with the increase of prestress loss. In order to prevent the loss of prestress to affect the normal use of the beam, it is suggested that when the reinforced concrete beam is strengthened with prestressed CFRP sheets, the load should be unloaded as much as possible. When the section area of CFRP cloth is selected, the functional requirements of normal service stage should be taken into account, and the section area of CFRP cloth can be increased appropriately. At the same time, in order to give full play to the high strength characteristics of CFRP cloth during the normal use stage, the CFRP cloth with higher elastic modulus can be selected.
【作者单位】： 西南大学;武汉大学;
【基金】：国家自然科学基金(51208078)
【分类号】：TU375.1
[Abstract]:Considering the loss of prestress and secondary stress, the formulas for calculating deflection and crack width of reinforced concrete beams strengthened with prestressed CFRP sheets are derived. The reliability of deflection and crack width is calculated based on the improved Monte Carlo method and equivalent linearization method. The reliability calculation results show that when the loss of prestress increases from 500 渭 蔚 to 4 000 渭 蔚, the reliability index of crack width decreases from 7.78 to 0.97, and the reliability index of deflection decreases from 4.09 to 3.96. The influence of prestressing loss on the reliability index of crack width is more obvious. When the section area of CFRP distribution is smaller or the elastic modulus of CFRP cloth is lower, the reliable index of crack width is more likely to worsen with the increase of prestress loss, the reliable index of crack width decreases with the increase of prestress loss. In order to prevent the loss of prestress to affect the normal use of the beam, it is suggested that when the reinforced concrete beam is strengthened with prestressed CFRP sheets, the load should be unloaded as much as possible. When the section area of CFRP cloth is selected, the functional requirements of normal service stage should be taken into account, and the section area of CFRP cloth can be increased appropriately. At the same time, in order to give full play to the high strength characteristics of CFRP cloth during the normal use stage, the CFRP cloth with higher elastic modulus can be selected.
【作者单位】： 西南大学;武汉大学;
【基金】：国家自然科学基金(51208078)
【分类号】：TU375.1
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