To investigate the mechanical properties of a dowel action under fatigue loads, nine reinforced concrete specimens were fabricated, and the monotonic and fatigue loadings were performed on these specimens, respectively. All of these specimens were divided into two series. Six specimens in SeriesⅠwith different bar diameters of 12, 20 and 25 mm were subjected to monotonic loads and were used to confirm the ultimate bearing capacity. The remaining three specimens in Series Ⅱ were subjected to fatigue loads and were designed to investigate the attenuation character of dowel action and the fatigue failure modes. The test results show that the accumulated fatigue damage due to fatigue loads can reduce the ultimate bearing capacity of specimens. With the increase in fatigue loads, the failure mode can transform to fatigue rupture of the dowel bar under the serviceability loading state,i. e. 55% of the monotonic capacity. The fatigue life is determined by the fatigue properties of steel and concrete.Based on the test data, the failure process of dowel action can be divided into two stages： the accumulation of fatigue damage and the fatigue rupture of dowel bar.
自密实混凝土（self-compacting concrete，SCC）的工作性能反映在其搅拌过程中，可以通过分析搅拌图像对工作性能的好坏进行初步的判断。该文利用双轴搅拌机搅拌了具备不同工作性能的8组SCC，并利用智能手机录制视频，采集了全部搅拌过程的图像信息。然后，从图像序列中选取感兴趣的图像和感兴趣的区域（region of interest，ROI），利用图像分析手段进行量化的比较。搅拌机指定叶片与转轴呈45。时的图像选为感兴趣的图像。ROI中的SCC轮廓线形状可以用作区分SCC的SF值的视觉特征。利用轮廓线上横坐标为300像素的点的纵坐标Y300，可以提炼轮廓线特征，并用于推算SCC的SF值。研究结果表明：Y300与SCC的SF值之间存在较好的相关关系，推算结果误差较小，可以用于开发基于双轴搅拌机的SCC工作性能实时检测系统。
