Experimental Study on Shear Behavior of Prefabricated and Assembly Partially Encased Concrete Beam

The rise of logistics industry has given birth to the concept of logistics architecture, which is characterized by large load, large span and high floor height. For such buildings, the existing steel-concrete composite beams and steel reinforced concrete beams are not only expensive, but also resource consuming, which runs counter to the new green construction mode advocated in our country. In practical engineering applications, the owner urgently needs to reduce the project cost. Therefore it is particularly important to develop new horizontal components for such buildings. In order to solve the above problems, a prefabricated partially encased concrete beam(PPECB) by combining partially encased concrete beam(PECB) with unsupported construction method is proposed in this paper. In order to study the shear behavior of prefabricated partially encased concrete beams, eight partially prefabricated beams and one PEC beam(monolithic casting comparison specimen) were designed to study the shear behavior. The main purpose is to observe and record the whole test process, and obtain the shear failure characteristics, crack development, strain development law, and mid-span deflection curve of prefabricated partially encased concrete beams under vertical load. The shear failure mechanism of precast partially encased concrete beams is clarified. The influence of pouring method, steel web thickness, concrete strength, stirrup diameter, stirrup spacing and shear span ratio on the shear performance of precast partially encased concrete beams is discussed. The shear bearing capacity model of precast partially encased concrete beams is established, and the calculation method of shear bearing capacity of precast partially encased concrete beams is deduced. The test results show that the prefabricated partially encased concrete beam can basically maintain the overall working performance, which is more consistent with the shear performance of the cast-in-place partially encased concrete composite beam(PECB), and its shear bearing capacity is slightly lower than the cast-in-place partially encased concrete composite beam. In general, it is considered that the different pouring methods of pouring and prefabrication have little influence on the bearing capacity of specimens. The shear failure mode of prefabricated partially encased concrete beams is shear failure. The largest crack develops slowly before yielding and rapidly after yielding. The concrete strength, stirrup spacing and diameter have great influence on the crack development rate. With the increase of concrete strength grade, the shear capacity of prefabricated partially encased concrete beams increases. The shear capacity of prefabricated partially encased concrete beams increases with the increase of steel web thickness. Increasing the diameter of stirrups and decreasing the spacing of stirrups can improve the shear capacity of prefabricated partially encased concrete beams. When the shear span ratio is between 1.5 and 2.5, the shear capacity of prefabricated partially encased concrete beams decreases with the increase of shear span ratio. With reference to the existing specifications, the formula for calculating the shear capacity of prefabricated partially encased concrete beams is preliminarily given. Based on this theory, the calculated results are in good agreement with the test values, which can provide reference for practical engineering applications.