纤维增强聚合物布加固裂纹木梁的稳定性

Stability of Cracked Timber Beam Reinforced with Fibre Reinforcement Polymer Sheet

梁中横向裂纹等效为无质量内部转动弹簧,假定纤维增强聚合物(FRP)布与梁表面紧密粘贴,建立了考虑轴向压力二阶效应FRP布加固裂纹梁线性弯曲的控制方程,并得到其显式解析通解.在此基础上,研究了FRP加固简支裂纹木梁的稳定性,通过数值求解方程,分析了纤维增强聚合物(CFRP)布含量、裂纹深度和位置以及数量等因素对CFRP布加固简支裂纹杉木梁临界载荷的影响,结果表明:CFRP加固可明显减小裂纹深度和数量等对裂纹杉木梁临界载荷的影响,且裂纹处弯矩较大或裂纹较深时加固效应愈加显著;CFRP加固裂纹木梁临界载荷随CFRP布加固层含量的增加而增加,但当CFRP布含量达到一定值后,进一步增加CFRP含量对CFRP加固裂纹梁临界载荷提高并不明显.

Regarding the transverse crack in beam as a massless inner rotation spring and assuming that tightly bonding between the beam surface and fiber reinforced polymer(FRP) sheet, the governing equation of linear bending of FRP-reinforced cracked beam with the effect of second-order axial pressure was established, and its general explicit analytical solution was derived. On this basis, stability of the simply-supported cracked beam reinforced with FRP-sheet is investigated, and influences of content of carbon fiber reinforced polymer(CFRP), crack depth, location and number on critical load of cracked fir timber beam were analyzed by solving equation numerically. It is shown from results that the influences of the crack depth and number on the critical load of cracked fir timber beam can be reduced evidently with the CFRP reinforcement, and the reinforcement effect is more remarkable when the bending moment at the crack location is larger or crack is deeper. And the critical load of the CFRP-reinforced cracked beam is increased with increase of the content of the CFRP reinforcement layer, but the critical load increase of the CFRP-reinforced cracked beam is not obvious when the content of the CFRP reinforcement layer reaches to some level.