This paper concerns the experimental and numerical verification of the effect of the cope profiles using evaluation approaches. Full-scale beam-to-column assemblies, which were designated to represent a connection of an I-section beam to RHS column member with through diaphragms, were tested under cyclic loads. Complete join penetration groove welds were used for the connection between the beam flange and diaphragm. The load was applied to the end of the beam end by a hydraulic ram dynamically. The prediction of brittle fracture with various sizes of ductile crack at the toe of beam copes. The applicability of Weibull stress approach and Toughness Scaling Model approach in predicting brittle fracture from crack tips was verified. Furthermore, the effect that the shape of weld access hole gives to ultimate strength of specimens was examined. Consequently, it was shown that the improved weld access hole had sufficient deformation capacity.
During the Kobe and Northridge earthquake, brittle fracture occurred frequently at the toes of beam cope in the beam-to-column connections. After the Kobe earthquakes, it had been developed beam-to-column connections without weld access hole using special backing bar. Architectural Institute of Japan (AIJ, 1998) recommended to use improved profiles of weld access holes, because, in the post-earthquake investigation, the connection without access hole showed much superior deformation capacity to that with weld access hole. No weld access hole procedure is suitable to Shop welding beam-to-column connection, while no weld access hole procedure is not able to use in the field welded beam-to-column connection, because the beam web interrupts the welding line. However, it might be occurred the brittle fracture at the toes of weld access hole with conventional detail, as shown in the report of large-scale investigations after the earthquake (AIJ Kinki, 1997).
The field-welded connections frequently require severe quality control and reinforcements by means to suppress the strain concentrations of toes of weld access holes. Several proposals have been made regarding reinforced connection details applicable to the special moment frame. The most popular details belong to the connections with horizontal haunches. However, when the haunches were contained in the beam-column connection, fabrication cost of each connections were much increase. Instead of using the haunches, the improvement of the detail of weld access hole, which shows large plastic deformation capacity as much as that of no access hole procedure, is necessary for the safety of welded connections.
