A new posttensioned T-stub connection (PTTC) for earthquake resistant steel moment resisting frames (MRFs) is introduced. The proposed connection consists of high strength posttensioned (PT) strands and bolted T-stubs. The post-tensioning strands run through the column and are anchored against the flange of the exterior column. The T-stubs, providing energy dissipation, are bolted to the flange of beam and column and no field welding is required. The strands compress the T-stub against the column flange to develop the resisting moment to service loads and to provide a restoring force that returns the structure to its initial position following an earthquake. An analytical model based on fiber elements is developed in OpenSees to model PTTCs. The analytical model can predict the expected behavior of the new proposed connection under cyclic loading. PTTC provides similar characteristic behavior of the posttensioned connections. Both theoretical behavior and design methods are proposed, and the design methods are verified based on parametric studies and comparison to analytical results. The parametric studies prove the desired self-centering behavior of PTTC and show that this connection can reduce or eliminate the plastic rotation by its self-centering behavior as well as providing required strength and stiffness under large earthquake rotations. 1. Introduction Post-tensioned energy dissipation (PTED) beam-to-column connections are newly proposed to be utilized as an alternative to welded connections in rigid moment frames (MRFs). They can provide required ductility and stable cyclic behavior under severe earthquakes. PTEDs main characteristics are the self-centering behavior and explicit energy dissipation capability. Self-centering addresses a rebounding capability that minimizes the residual deformations in the connection that finally results in minimal residual drift in the structure. Most of inelastic deformations and energy dissipation happens in energy dissipater (ED) devices, and the main structural elements such as beams and columns are supposed to remain elastic. EDs could be replaced in some cases after a major earthquake to make the structure ready for the next earthquake events. Ricles et al. [1, 2] developed a？？self-centering beam-to-column connection system in which the PT system is based on a series of high resistance steel strands running parallel to the beams whereas the ED system is composed of bolted steel top-and-seat angles. The dissipative mechanism is based on the formation of plastic hinges in each angle. The experimental results
References
[1]
J. M. Ricles, R. Sause, M. M. Garlock, and C. Zhao, “Posttensioned seismic-resistant connections for steel frames,” Journal of Structural Engineering, vol. 127, no. 2, pp. 113–121, 2001.
[2]
J. M. Ricles, R. Sause, S. W. Peng, and L. W. Lu, “Experimental evaluation of earthquake resistant posttensioned steel connections,” Journal of Structural Engineering, vol. 128, no. 7, pp. 850–859, 2002.
[3]
M. M. Garlock, J. M. Ricles, and R. Sause, “Experimental studies of full-scale posttensioned steel connections,” Journal of Structural Engineering, vol. 131, no. 3, pp. 438–448, 2005.
[4]
M. M. Garlock, R. Sause, and J. M. Ricles, “Behavior and design of posttensioned steel frame systems,” Journal of Structural Engineering, vol. 133, no. 3, pp. 389–399, 2007.
[5]
C. Christopoulos, A. Filiatrault, C. M. Uang, and B. Folz, “Posttensioned energy dissipating connections for moment-resisting steel frames,” Journal of Structural Engineering, vol. 128, no. 9, pp. 1111–1120, 2002.
[6]
C. C. Chou, J. H. Chen, Y. C. Chen, and K. C. Tsai, “Evaluating performance of post-tensioned steel connections with strands and reduced flange plates,” Earthquake Engineering and Structural Dynamics, vol. 35, no. 9, pp. 1167–1185, 2006.
[7]
C. C. Chou and C. C. Wu, “Performace evaluation of steel reduced flange plate moment connections,” Earthquake Engineering and Structural Dynamics, vol. 36, no. 14, pp. 2083–2097, 2007.
[8]
H. J. Kim and C. Christopoulos, “Seismic design procedure and seismic response of post-tensioned self-centering steel frames,” Earthquake Engineering and Structural Dynamics, vol. 38, no. 3, pp. 355–376, 2009.
[9]
C. C. Chou, Y. C. Wang, and J. H. Chen, “Seismic design and behavior of post-tensioned steel connections including effects of a composite slab,” Engineering Structures, vol. 30, no. 11, pp. 3014–3023, 2008.
[10]
C. C. Chou, K. C. Tsai, and W. C. Yang, “Self-centering steel connections with steel bars and a discontinuous composite slab,” Earthquake Engineering and Structural Dynamics, vol. 38, no. 4, pp. 403–422, 2009.
[11]
C. C. Chou and J. H. Chen, “Column restraint in post-tensioned self-centering moment frames,” Earthquake Engineering and Structural Dynamics, vol. 39, no. 7, pp. 751–774, 2010.
[12]
C. C. Chou and J. H. Chen, “Seismic design and shake table tests of a steel post-tensioned self-centering moment frame with a slab accommodating frame expansion,” Earthquake Engineering and Structural Dynamics, vol. 40, no. 11, pp. 1241–1261, 2011.
[13]
C. C. Chou and J. H. Chen, “Development of floor slab for steel post-tensioned self-centering moment frames,” Journal of Constructional Steel Research, vol. 67, no. 10, pp. 1621–1635, 2011.
[14]
C. C. Chou and J. H. Chen, “Analytical model validation and influence of column bases for seismic responses of steel post-tensioned self-centering MRF systems,” Engineering Structures, vol. 33, no. 9, pp. 2628–2643, 2011.
[15]
C. C. Chou and J. H. Chen, “Tests and analyses of a full-scale post-tensioned RCS frame subassembly,” Journal of Constructional Steel Research, vol. 66, no. 11, pp. 1354–1365, 2010.
[16]
D. Wang and A. Filiatrault, “Shake table testing of a self-centering post-tensioned steel frame,” in Proceedings of the 14th World Conference on Earthquake Engineering, Beijing, China, October 2008.
[17]
B. G. Morgen and Y. C. Kurama, “A friction damper for post-tensioned precast concrete moment frames,” PCI Journal, vol. 49, no. 4, pp. 112–133, 2004.
[18]
P. Rojas, J. M. Ricles, and R. Sause, “Seismic performance of post-tensioned steel moment resisting frames with friction devices,” Journal of Structural Engineering, vol. 131, no. 4, pp. 529–540, 2005.
[19]
M. Wolski, J. M. Ricles, and R. Sause, “Experimental study of a self-centering beam-column connection with bottom flange friction device,” Journal of Structural Engineering, vol. 135, no. 5, pp. 479–488, 2009.
[20]
K. C. Tsai, C. C. Chou, C. L. Lin, P. C. Chen, and S. J. Jhang, “Seismic self-centering steel beam-to-column moment connections using bolted friction devices,” Earthquake Engineering and Structural Dynamics, vol. 37, no. 4, pp. 627–645, 2008.
[21]
Y. C. Lin, J. M. Ricles, and R. Sause, “Earthquake simulations on a self-centering steel moment resisting frame with web friction devices,” in Proceedings of The 14th World Conference on Earthquake Engineering, Beijing, China, 2008.
[22]
A. Dimopoulos, T. Karavasilis, and G. Vasdravellis, “Seismic design, modeling and assessment of self-centering steel frames using post-tensioned connections with web hourglass shape pins,” Bulletin of Earthquake Engineering, vol. 11, no. 5, pp. 1797–1816, 2013.
[23]
“Part 1.8: design of joints, stage 49 drafts,” in Eurocode 3: Design of Steel Structures, European Committee for Standardization, Brussels, Belgium, 2003.
[24]
A. M. G. Coelho, L. S. Silva, and S. K. Bijlaard, Characterization of the Nonlinear Behavior of Single Bolted T-Stub Connections, Connections in Steel Structures V, Amsterdam, The Netherlands, 2004.
[25]
American Institute of Steel Construction, Seismic Provisions for Structural Steel Buildings, AISC, Chicago, Ill, USA, 2005.
[26]
F. McKenna, G. L. Fenves, and M. H. Scott, Open System for Earthquake Engineering Simulation, University of California, Berkeley, Calif, USA, 2000, http://opensees.berkeley.edu/.
[27]
H. Krawinkler, “Shear in beam-column joints in seismic design of steel frames,” Engineering Journal, vol. 15, no. 3, pp. 82–91, 1978.
[28]
Federal Emergency Management Agency (FEMA), Recommended Seismic Design Criteria for New Steel Moment Frame Buildings, FEMA-350, The SAC Joint Venture for FEMA, Washington, DC, USA, 2000.
