预应力CFRP布加固低强度混凝土方柱的力学性能

Mechanical Properties of Low Strength Concrete Square-columns Strengthened with Prestressed CFRP Sheets

为了研究预应力碳纤维增强复合材料(CFRP)布加固低强度混凝土轴心受压柱的力学性能,按截面配筋率不同设计制作了3组12根混凝土方形截面柱,混凝土强度均为C20,每组包括3根利用预应力CFRP布加固的混凝土柱和1根未加固的普通混凝土柱。通过对每组柱的静载试验,得到了试验柱极限承载力、轴向位移等试验数据,并利用有限元软件ANSYS建立了分析模型,对预应力CFRP布加固低强度混凝土柱进行了研究。结果表明:预应力CFRP布加固的混凝土柱在纵向受力钢筋屈服后,预应力CFRP布对混凝土的环向预压作用能够明显提高加固柱的极限承载力,且承载力提高幅度受截面配筋率及CFRP布张拉控制应力影响;对于配筋率较低的混凝土柱,利用预应力CFRP布加固后柱的承载力提高幅度随CFRP布预拉应力的提高而增大;同时能够明显提高混凝土的极限压应变,增大加固柱的轴向变形;采用预应力CFRP布加固技术能够使CFRP布较早地参与受力,充分发挥其高强度特性。

In order to study the mechanical properties of reinforced concrete columns strengthened with prestressed carbon fiber reinforced polymer （CFRP） sheets under axial compression, three groups of concrete columns, total of 12, were made according to different reinforcement ratios, and the concrete strength was C20. In each group, there were 3 reinforced concrete columns strengthened with prestressed CFRP sheets and 1 reinforced concrete column without being strengthened. The data such as ultimate bearing capacity and axial displacement were obtained from the static Load test. The analysis model was established by using finite element software ANSYS and the low strength concrete columns strengthened with prestressed CFRP sheets were studied. The results show that the prestressed CFRP sheets of the reinforced concrete columns which provide the hoop stress to concrete can obviously improve the ultimate bearing capacity of reinforced columns after longitudinal reinforcements yield. Moreover, the improvement is influenced by reinforcement ratio and prestress of CFRP sheets. When reinforcement ratio of thestrengthened column is lower, the improvement of reinforced concrete columns is higher with the increasing prestress of CFRP sheets. What＇s more, the columns strengthened with prestressed CFRP sheets can improve the ultimate compression strain of concrete, and increase axial deformation of the strengthened column~ using the prestressed CFRP strengthening technique can make that CFRP sheets participate in force earlier and make effectively use of high strength.