超高性能混凝土加固钢筋混凝土梁抗剪性能

为研究超高性能混凝土加固钢筋混凝土梁的抗剪性能，采用不同厚度的超高性能混凝土对梁侧面进行加固，并对其进行单点静载试验。观察梁的破坏过程和破坏模式，并根据梁的荷载-应变曲线，分析超高性能混凝土加固层对钢筋混凝土梁承载力和刚度的影响；同时，采用数字图像相关方法对试验梁的裂纹发展进行了对比分析。结果表明：与未加固梁相比，加固梁的破坏形态由脆性剪切破坏转变为延性弯剪及弯曲破坏；随着加固层厚度的增加，加固梁开裂荷载、峰值荷载和变形能力明显提高；通过数字图像相关方法，可以直接从试验梁表面获取细微变形和应变分布情况，并进一步预测试验梁表面微裂缝位置及破坏形式。最后，建立了超高性能混凝土加固钢筋混凝土梁的抗剪承载力计算公式，并与试验结果进行了对比，结果吻合较好。

Investigation of Shear Behavior of Reinforced Concrete Beams Strengthened by Ultra-high performance Concrete

In order to investigate the shear behavior of reinforced concrete (RC) beams strengthened by ultra-high performance concrete (UHPC), experimental investigations were conducted based on the studies of RC beams strengthened with different thicknesses of UHPC layers. The failure process and mode of the beams were observed during the test. The influence of UHPC on the bearing capacity and stiffness of RC beams was analyzed by analyzing the load-strain curve of test beams. In addition, contrastive analyses were carried out by using digital image correlation (DIC) method simulation to investigate the development of cracks. The results showed that the failure modes of strengthened beams changed from brittle shear failure to ductile flexural shear and flexural failure. The ductility and energy dissipation capacity of strengthened beams were improved. The cracking load, peak load and deformation capacity of the strengthened beams increased obviously with the increase in the thickness of UHPC layer. Through the DIC method, the micro deformation and strain distribution on the surface of the test beams can be obtained, and the formation of cracks and failure modes can be further predicted. Finally, a calculation method to predict the shear capacity of RC beams strengthened by UHPC is established and validated by the test results. The calculation results were in good agreement with the test results.