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应用于桥梁工程的碳纤维增强复合材料(CFRP)筋通常受循环荷载作用,导致其力学性能的退化,这将影响桥梁结构的受力。为了考察循环荷载作用对CFRP筋力学性能的影响,首先利用静载试验对CFRP筋的初始力学性能进行了检测,然后结合静载试验结果并利用疲劳试验考察了各阶段循环荷载作用对CFRP筋弹性模量、松弛及抗拉强度的影响。研究结果表明,极限拉力作用下CFRP筋的弹性模量较初始状态高约5%,对于CFRP筋构件的变形对结构内力有较大影响的结构,在设计阶段建议适当地考虑CFRP材料的非线性问题;桥梁工程中,经200万次正常使用设计循环荷载作用的CFRP筋,其弹性模量和松弛性能较初始状态未发生明显退化,经应力幅为4.3%的极限抗拉强度的循环荷载作用后,CFRP筋的抗拉强度提高了1.2%,但应力幅提高至7%的极限抗拉强度时,其抗拉强度与初始状态相比无明显变化。
Carbon fiber reinforced composites (CFRP) tendons used in bridge engineering are often subjected to cyclic loading, resulting in the degradation of their mechanical properties, which will affect the force of the bridge structure. In order to investigate the effect of cyclic loading on the mechanical properties of CFRP bars, the initial mechanical properties of the CFRP bars were tested by static load tests. Then the fatigue tests were carried out to investigate the effect of cyclic loading on the CFRP bars’ elasticity Modulus, relaxation and tensile strength. The results show that the elastic modulus of CFRP tendons is about 5% higher than that of the initial state under the ultimate tensile force. For the structure where the deformation of the CFRP tendons greatly affects the internal force of the structure, it is suggested that the nonlinearity In the bridge project, the CFRP tendons designed by cyclic loading of 2 million times of normal use have no obvious degradation of the elastic modulus and relaxation property compared with the initial state. The cyclic loading of the ultimate tensile strength with the stress amplitude of 4.3% , The tensile strength of CFRP tendons increased by 1.2%, but the tensile strength of CFRP tendons did not change significantly compared with the initial state when the stress amplitude was increased to 7%.