Instability of beams with reduced beam section moment connections emphasizing the effect of column panel zone ductility

Abstract Column panel zone (PZ) ductility significantly affects the failure mode of beams with reduced beam section (RBS) moment connections. Even though good hysteretic behaviour is expected in connections with strong PZs, their flexural strength considerably deteriorates due to beam instability. In contrast, weak PZs are prone to high shear deformation, resulting in brittle fracture of connections. This study aims to question the provisions specified in the codes for the design of PZs. To this end, a numerical analysis was conducted on a series of subassemblies with various PZ properties. Use of lower deep sections is another major concern. It is indicated in this study that partial shear yielding in PZs can improve the hysteretic response of specimens by avoiding premature instability in beams. The results show that the PZ ultimate shear strength commonly prescribed in the design codes does not extend to an adequate safety margin. Furthermore, a new parameter is expressed for controlling an RBS beam as regards instability. This parameter is able to appropriately model the behaviour of RBS beams. The results are generally in good agreement with the existing experimental data.

[1]  Stephen A. Mahin,et al.  Lessons from damage to steel buildings during the Northridge earthquake , 1998 .

[2]  Duane K. Miller.  LESSONS LEARNED FROM THE NORTHRIDGE EARTHQUAKE , 1998 .

[3]  Nicholas S. Trahair,et al.  The behaviour and design of steel structures , 1977 .

[4]  Nicholas S. Trahair,et al.  Inelastic Lateral Buckling of Determinate Beams , 1976 .

[5]  Michael D. Engelhardt,et al.  CYCLIC - LOADING PERFORMANCE OF WELDED FLANGE - BOLTED WEB CONNECTIONS , 1993 .

[6]  Andrew J. Zekany,et al.  Experimental Investigation of Dogbone Moment Connections , 1998 .

[7]  Wai-Fah Chen,et al.  Joint Flexibility in Steel Frames , 1985 .

[8]  Chia-Ming Uang,et al.  Cyclic Response and Design Recommendations of Reduced Beam Section Moment Connections with Deep Columns , 2002 .

[9]  Sashi K. Kunnath,et al.  Inelastic Behavior and Design of Steel Panel Zones , 2000 .

[10]  J. Hancock,et al.  On the mechanisms of ductile failure in high-strength steels subjected to multi-axial stress-states , 1976 .

[11]  H Krawinkler,et al.  Shear in Beam-Column Joints in Seismic Design of Steel Frames , 1978, Engineering Journal.

[12]  Alan R. Kemp.  Inelastic Local and Lateral Buckling in Design Codes , 1996 .

[13]  Chia-Ming Uang,et al.  Cyclic Stability Criteria for Steel Moment Connections with Reduced Beam Section , 2001 .

[14]  Michael D. Engelhardt,et al.  Experimental Evaluation of Cyclically Loaded Reduced Beam Section Moment Connections , 2002 .

[15]  Egor P. Popov,et al.  Panel zone flexibility in seismic moment joints , 1987 .