Experimental Study on Load Bearing Capacity of Prefabricated Partially Encased Composite Beams

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.

Automated summary

The study confirmed the influence of shear span ratio and damage form on the load bearing capacity of prefabricated partially encased composite beams. It proposed methods for calculating shear capacity and predicting bending capacity, as well as introduced reduction factors to consider asymmetric damage and weakened bending capacity of specimens without threaded rods. The calculated results matched well with experimental ones, providing a reliable reference for engineering design purposes.