碳纤维布加固松木梁受弯试验

为研究碳纤维布加固矩形松木梁的受弯性能,通过抗弯性能试验,并结合有限元数值计算,研究了弹性模量、碳纤维布层数、初始裂缝与抗弯承载力之间的关系; 在给定的2种初始裂缝情况下,采用虚拟裂纹闭合法进行应力强度因子计算,并使用最大周向应力准则作为断裂判据; 基于试验数据和有限元计算结果,提出碳纤维布加固松木梁抗弯承载力的计算公式。结果表明:松木梁经碳纤维布加固后,其抗弯承载力提高幅度为12.9%～34.5%; 松木梁截面应变沿高度方向的分布基本符合平截面假定; 当碳纤维布弹性模量在加固松木梁弹性模量30倍以内时,随着碳纤维布弹性模量的增加,木梁的抗弯承载力显著升高,但超过这一限值后,提高速度逐渐减慢; 计算得出松木梁在考虑初始裂缝情况下的抗弯承载力削减幅度为6.5%～27.3%,并且刚度有一定程度降低; 综合考虑计算结果与经济效应,可以认为加固矩形松木梁时使用3层或4层碳纤维布加固最为合理。

Experiment on Flexural Behavior of Pine Wood Beams Strengthened with CFRP Sheets

In order to study the flexural behavior of rectangular pine wood beams strengthened with CFRP sheets, the relationships between modulus of elasticity, number of layers of CFRP sheets, initial cracks and the flexural bearing capacity were studied based on the flexural behavior test and finite element numerical calculation. With the consideration of the two initial cracks, the virtual crack closure method was used to calculate the stress intensity factor and the maximum circumferential stress criterion was used to judge the fracture. Based on experimental data and finite element calculation results, the formula for calculating flexural capacity of pine wood beam strengthened with CFRP was proposed. The results show that the flexural capacity of pine wood beams strengthened with CFRP is improved by 12.9%-34.5%. The distribution of strain along the height of wood beam section basically conforms to the assumption of plane section. When the elastic modulus of CFRP is less than 30 times of the elastic modulus of strengthened pine wood beam, the flexural capacity of pine wood beams increases significantly with the increase of CFRP elastic modulus. After exceeding the limit, the speed of increase slows down gradually. With the consideration of the initial cracks, the flexural capacity of the pine wood beam is reduced by 6.5%-27.3%, and the stiffness is reduced by a certain extent. Considering the calculation results and economic effects comprehensively, it can be concluded that it is most reasonable to use 3 layers or 4 layers of CFRP to strengthen rectangular pine beams.