CFRP布对先张法预应力Bulb-T梁抗弯性能影响研究

Research on the influence of CFRP fabric on the bending performance of pre-tensioned prestressed Bulb-T beams

为研究碳纤维增强复合材料(CFRP)布对先张法预应力Bulb-T梁抗弯性能的影响,采用有限元软件ABAQUS建立了三维实体模型,并进行了四点弯曲试验数值模拟,分析了在不同CFRP布加固方式下Bulb-T梁损伤过程及受力性能。结果表明:先张法预应力Bulb-T梁模拟值与试验结果误差较小,建立的模型可以较准确地模拟足尺预应力钢混梁的破坏形态、预拱度、荷载-位移曲线;CFRP加固能够显著提升梁体的抗弯刚度及开裂荷载,延缓开裂时间、抑制裂缝的扩展,其中,下翼缘板底部粘贴CFRP布可在失效前对跨中裂缝密集区起到有效控制,弯剪区包裹加固减小了梁体加载点及垫块之间“八”字形裂缝的展开;下翼缘板底部粘贴CFRP布对抗弯承载力的提升效果更加显著,且极限承载力和刚度随着加固层数的增加而增大。

In order to study the effect of carbon fiber reinforced composite(CFRP)fabric on the bending performance of pre-tensioned prestressed Bulb-T beams,the finite element software ABAQUS was used to establish a three-dimensional solid model for numerical simulation of four-point bending test,and to analyze the differences of damage process and force performance under different CFRP cloth reinforcement methods.The results show that the simulated values of pre-tensioned prestressed Bulb-T girders established by the pre-tensioning method have the same little deviation as those of the test results,which can accurately simulate the damage morphology,pre-arching,and load-displacement curves of the foot-size prestressed steel-hybrid girders.The CFRP reinforcement can significantly improve the flexural stiffness and cracking load of the girders,delay the cracking time,and inhibit the expansion of the cracks,in which the CFRP fabric pasted on the bottom of the lower flange can be applied to the intensive cracked areas in the middle of the spans before the failure of the CFRP fabric.The CFRP fabric pasted at the bottom of the lower flange plate can effectively control the intensive cracking area in the span before failure,and the wrapping reinforcement in the bending shear area reduces the unfolding of the figure-eight cracks between the beam loading point and the pads.The CFRP fabric pasted at the bottom of the lower flange plate enhances the bending capacity significantly,and the ultimate capacity and stiffness increase with the increase of the number of layers of reinforcement.