Experimental investigation of blind-bolted joints to concrete filled steel columns

Eight concrete filled steel column-steel beam end plate joints connected with blind bolts were tested under axial tension and combined bending-shear static loading. The influence of the binding bars on the integrity of the panel zone of the joints was investigated, and the performance of the blind-bolted joints was discussed. The test results show that the blind bolts have good mechanical properties, and reliable working performance. The binding bars can effectively reduce the tube deformation of square concrete-filled steel tubes and improve the integrity of the joint panel zone. In contrast, binding bars are not so effective in enhancing the performance of joints with circular columns since the circular steel tubes are not susceptible to local buckling. Compared with binding bars, passing-through bolts are more effective in improving the joint performance. Under the combined action of bending and shear, the blind-bolted joints show good deformation capacity. The research results have provided a good basis for the future development of finite element models.