计及界面损伤的纤维片材加固砼梁的弯曲破坏分析

BENDING FAILURE ANALYSIS FOR FIBER SHEET-STRENGTHENED CONCRETE BEAMS ACCOUNTING FOR INTERFACIAL DAMAGE

对四点弯曲荷载作用下含微裂缝的纤维片材加固钢筋砼梁,建立一种计及梁中裂缝和纤维片材与梁跨中界面发生损伤的分层剪滞模型,并采用复合材料力学中的细观统计破坏理论,研究了纤维片材断裂模式下的纤维应力重新分布和极限承载力,定量获得了纤维应力集中、纤维片材与砼梁之间的界面损伤区长度和极限承载力与界面剪切强度的关系。结果表明,应力集中随界面剪切强度的增加而增加;界面损伤区长度随界面剪切强度的增加而减小;极限承载力随界面剪切强度的增加是先增大后减小;适宜的界面黏结,极限承载力最高。

For fiber sheet-reinforced concrete beams with a crack under four-point bending,a layering shear-lag model accounting for the crack in beams and interfacial damage between sheet and concrete in mid-span was established,and micro-statistical failure theory of composite mechanics was adopted to study the fiber stress redistributions and failure loads at sheet rupture mode.The variation of the fiber stress concentrations,lengths of interfacial damage area between fiber sheet and concrete and the failure loads as a function of the interfacial shear strength was obtained quantitatively.The results show that the stress concentrations are increased,the length of interfacial damage area is reduced and the failure load is first increased and then decreased,as the increase of the interfacial shear strength.Obviously,the failure load of members is the highest if an interfacial cohesion is suitable.