Three specimens BBPC-3, BBPC-2 and

Three specimens BBPC-3, BBPC-2 and BBPC-4 with the same axial load ratio had different slenderness ratios, namely, 4.12, 7.06 and 10, respectively. As shown in Fig. 12, the final crack distribution height for the three specimens was 85, 133, and 200 cm, respectively, indicating that the specimens that exhibit a larger slenderness ratio have a higher crack distribution. However, the concrete crushing degree of BBPC-3 was obviously less than that of BBPC-2 and BBPC-4, which is attributed to the smaller slenderness ratio of BBPC-3 and the more concentrated deformation at the connection, resulting in a larger deformation of the reinforcement bars and a lesser degree of crushing of the concrete. This indicates that the reinforcement bars of BBPC-3 will yield, buckle or fracture earlier in the test, which was also verified by the failure mode and the smallest ultimate drift ratio of BBPC3 among the three specimens, BBPC-3, BBPC-2 and BBPC-4.