受压区高度对碳纤维加固桥梁的有效性影响

采用理论分析及有限元模拟2种方法,研究了《公路桥梁加固设计规范》中粘贴碳纤维抗弯承载力公式的连续性及承载力提高问题,得出了几种情况下的ΔM-h、ΔM-ρ曲线。结果表明:混凝土受压区高度x不同的2个承载力计算公式,当x等于fξb时仅在梁高小于500 mm或配筋率为1.6%左右时连续,而其余情况则发生跳跃;当fξbh大于等于x和小于ξbh0时,对梁高小于600 mm的构件采用粘贴碳纤维提高抗弯承载力效果并不明显,而当梁高及原构件配筋率愈大时加固效果才愈明显;当x小于fξbh时,计算得的加固后截面承载力却小于加固前的承载力,这显然与实际情况并不相符,因而需对此做进一步地深入研究。

Influence of depth of compression zone on effectiveness of strengthened bridges with carbon fiber sheets

Theoretical analysis and finite element modeling were adopted to study the continuity of equations for the flexural capacity of structural members by bonding carbon fiber sheets and the strengthening effect of such method in specifications for strengthening design of highway bridges(Chinese Code).A family of ΔM-h and ΔM-ρ curves were obtained under different conditions.The results indicate that if x is equal to the parameter of ξfb,only when the height of a flexural member is less than 500 mm or its longitudinal reinforcement ratio is around 1.6%,the equations are continuous,otherwise jumps occur between the equations;if x is not less than the ξfbh and less than ξbh0,when the height of flexural member is less than 600 mm,the bonding carbon fiber sheets have no marked strengthening effect,whereas with the increase in the height of member and its longitudinal reinforcement ratio,the strengthening effect becomes more prominent;if x is less than ξfbh,the flexural capacity calculated with corresponding equations in the Code is even less than that of the original members without strengthening,which is clearly contrary to the fact,and to which further studies is to be conducted.2 tabs,12 figs,13 refs.