Column Moment Demands from Orthogonal Beam Twisting

Abstract:

Beam column joint subassemblies in steel moment frames often have simply-supported gravity beams framing into the joint in the perpendicular direction. When these subassemblies undergo lateral displacement, moments enter the column from the beams. Some of these moments are directly applied from the in-plane beam and slab stresses as they contact the column, and additional moments occur as the slab causes the perpendicular simply supported beams to twist. In most design codes around the world, no explicit consideration of these moments is performed even though they may increase the likelihood of column yielding and a soft-storey mechanism. This paper quantifies the magnitude of these perpendicular beam twisting moments in typical subassemblies using inelastic finite element analysis. It is shown that for beam-column-joint-slab subassemblies where the primary and secondary beams are fully welded to the column, the addition of slab effects significantly increases the total stiffness and strength of the composite frame structure. In addition to this, it is also shown the twisting moment demand of the secondary beams increased the frames strength by approximately 2% for an imposed drift of 5% for the subassembly investigated when no gap was provided between slab and the column. It was also shown the twisting moment demand of the secondary beams increased the frames strength by approximately 10% for a maximum imposed drift of 5% for the subassembly investigated when a gap was provided between the slab and the column.

• Periodical: Key Engineering Materials (Volume 763)
• Pages: 259-269
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.763.259
• Online since: February 2018
• Authors: George Webb*, Kanyakon Kosinanonth, Tushar Chaudhari, Saeid Alizadeh, Gregory A. MacRae
• Keywords: Composite Slabs, Earthquake Engineering, Overstrength, Panel Zone, Steel Moment Frame

References

[1] Amadio, C., Akkad, N. and Fasan, M. (2015). Three-Dimensional Numerical Simulations of Steel Concrete Composite Beam-to-Column Welded and Bolted Joints. International Conference on Behavior of Steel Structures in Seismic Areas.

DOI: 10.1016/j.engstruct.2017.02.037

[2] Aschakulporn, P. and Chen J. (2015). Modelling of Steel Column and Concrete Slab Interactions.

[3] Chaudhari, T. D., MacRae, G. A., Bull, D. K., Chase, G., Hicks, S. and Clifton, C. G. (2015). Composite Slab Effects on Beam-Column Subassembly Seismic Performance, NZSEE Conference.

[4] Eurocode 8. (1998). Eurocode 8–Design of Structures for earthquake resistance–Part 1: General rules, seismic actions and rules for buildings. European Standard.

DOI: 10.3403/03244372

[5] Hobbs, M., MacRae, G. A., Bull, D. K., Gunasekaran, U., Leon, R. and Clifton, C. (2013). Slab Column Interaction – Significant or Not? Steel Innovations Conference.

[6] Pavlović, M., Marković, Z., Veljković, M. and Budevac, D. (2013). Bolted shear connectors vs. headed studs behaviour in push-out tests. Journal of Constructional Steel Research, 88, 134-149.

DOI: 10.1016/j.jcsr.2013.05.003

[7] SIMULIA. (2012). ABAQUS. Dassault Systèmes.

[8] Steel & Tube. (2014). Product Guide ComFlor 80.