Analytical Modeling of Jointed Precast Concrete Beam-To-Column Connections with Different Damping Systems

K.M. Solberg, R.P. Dhakal and J.B. Mander

Department of Civil Engineering, University of Canterbury, Christchurch, New Zealand

J.G. Chase and G.W. Rodgers

Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand

Presented at New Zealand Society for Earthquake Engineering Annual Conference (NZSEE07), New Zealand, 2007.

Jointed precast concrete systems typically have low inherent damping and are thus particularly suitable for applying supplemental damping systems. Analytical modelling is utilised to characterise jointed beam-to-column rocking connections, using a rate-dependent tri-linear compound version of the well-known Menegotto-Pinto rule. The analytical model is verified against near full-scale experimental results. The beam-column connections are constructed utilising Damage Avoidance Design (DAD) principles with unbonded post-tensioned tendons. High force-to-volume extrusion-based energy dissipaters are externally fitted to provide supplemental energy dissipation and modify joint hysteretic performance. Multiple joint configurations are analysed, with supplemental damping systems modified to investigate the effect of damping forces on joint hysteresis. Particular attention is given to the re-centring limit. Good agreement between the analytical models and experimental results is demonstrated, with discussion of possible improvements. Overall, system damping behaviour is significantly improved by adding the extrusion based damping system.

Jointed precast concrete systems conforming to the Damage Avoidance Design (DAD) philosophy typically have low inherent damping and are particularly suited for supplemental damping systems. Recently, there has been considerable attention given to the use of yielding steel fuse-bars to provide hysteretic energy dissipation and modify the overall joint hysteresis (Li, 2006; Solberg 2007). Concomitantly, research into extrusion-based damping devices has resulted in the development of high force-to-volume lead extrusion dampers (Rodgers et al 2006a,b). These dampers provide force levels equivalent to, or much greater than, that provided by yielding steel fuse bars, and are sufficiently compact to allow placement directly into structural connections. This research outlines the experimental testing and analytical modeling of a prototype jointed precast beam-to-column subassemblage detailed according to the Damage Avoidance Design philosophy. As such systems perform in a bilinear elastic fashion without suffering damage, ideally supplemental damping should be added to improve energy dissipation. The present specimen was thus fitted with high force-to-volume lead extrusion dampers as a means of providing supplemental energy dissipation.

References

Rodgers, GW, Denmead, C, Leach, NC, Chase, JG. Mander, JB, (2006a) “Spectral evaluation of high forcevolume lead dampers for structural response reduction,” Proceedings New Zealand Society for Earthquake Engineering Annual Conference, Napier, New Zealand, March 10-12.

Rodgers, GW, Mander, JB, Chase, JG, Leach, NC, and Denmead, CS (2007). “Spectral Analysis and Design Approach for High Force-to-Volume Extrusion Damper-based Structural Energy Dissipation,” Earthquake Engineering & Structural Dynamics (EESD), In Press.

Rodgers, GW, Denmead, C, Leach, NC, Chase, JG. Mander, JB, (2006b) “Experimental development and analysis of a high force/volume extrusion damper,” Proceedings New Zealand Society for Earthquake Engineering Annual Conference, Napier, New Zealand, March 10-12.

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