To study the load bearing capacity of prefabricated partially encased composite (PEC) beams, 12 specimens were tested under cyclic loadings. According to the test results, when shear span ratio increases, the failure mode of the specimen changes from shear to bending, while the load bearing capacity of specimens decreases. Some specimens showed asymmetric damage of concrete on both sides of steel web, causing specimens’ bearing capacity to be controlled by bending and shearing as well as by torsion. The use of threaded rods has little effect on the ultimate load of prefabricated PEC beams, but has a great influence on the reduction rate of the load with the increase in shear span ratio. Using the superposition principle, a formula for calculating the shearing capacity of prefabricated PEC beams was proposed. Based on the plane section hypothesis, a method for predicting the bending capacity was also proposed. Two reduction factors were proposed to account for the negative effect of asymmetric damage on the bearing capacity and the weakened bending capacity of specimens without threaded rods. The calculated results match well with the experimental ones. Therefore, they can be used to predict the bending and shearing capacity of prefabricated PEC beams, while providing a reference for engineering design.

中文翻译：

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预制部分围护组合梁承载力试验研究

为了研究预制部分包裹复合材料 (PEC) 梁的承载能力，在循环载荷下测试了 12 个试样。试验结果表明，当剪跨比增大时，试件的破坏模式由剪切转变为弯曲，而试件的承载能力下降。有的试件显示出钢腹板两侧混凝土的不对称损伤，导致试件的承载力受弯剪和扭转控制。螺纹杆的使用对预制PEC梁的极限荷载影响不大，但随着剪跨比的增加，对荷载减小率的影响很大。利用叠加原理，提出了预制PEC梁抗剪承载力的计算公式。基于平面截面假设，还提出了一种预测弯曲能力的方法。提出了两个减少因素来解释不对称损伤对承载能力的负面影响以及无螺纹杆试样的弯曲能力减弱。计算结果与实验结果吻合较好。因此，它们可用于预测预制PEC梁的抗弯抗剪能力，同时为工程设计提供参考。