Experimental research on local compression bearing capacity of concrete considering the influence of ducts and core area

In order to make sound understanding of the influence of some key factors to local compressive bearing capacity of concrete, such as ducts, concrete core area within the range of inner surface of indirect reinforcements, and the ratio of calculated bottom area for local compression to local compression area of concrete, axial local compression experiments on 12 plain concrete specimens, 9 concrete specimens with the mesh indirect reinforcement, and 9 concrete specimens with the spiral indirect reinforcement were completed. Experimental data included as strain distribution of the indirect reinforcement, features of the wedges and their failure modes. Experimental results show that the enhancement coefficient of concrete strength for local compression decreases due to ducts, particularly when the diameter of the ducts increases. If the type, diameter, number, and spacing of mesh indirect reinforcement are identical, or if the type, diameter, and spacing of spiral indirect reinforcement are same, the local compressive bearing capacity of concrete increases linearly with the increase of concrete core area. Based on experimental results, calculation formulas for local compressive bearing capacity of concrete considering the influence of diameter of ducts and concrete core area are established.