Assessment of hysteretic damping in reinforced concrete structures using local hinge characteristics
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Assessment of hysteretic damping in reinforced concrete structures using local hinge characteristics N. K. Shekhar1 · Y. M. Parulekar2,3 · T. Nagender2 · J. Chattopadhyay2,3 Received: 11 August 2020 / Accepted: 26 September 2020 © Springer Nature B.V. 2020
Abstract Performance-based seismic engineering is nowadays adopted for economical design of structures to resist earthquakes and it requires nonlinear static pushover analysis to be performed. In this approach, the energy dissipation due to nonlinear behavior of the structures is taken into account by obtaining the equivalent viscous damping and this damping is evaluated from the global pushover curve of the structures. However, the global structural damping is basically due to energy dissipation at local joints of the structures deforming beyond yield rotation. This paper presents the methodology of estimating equivalent damping from the local hinge characteristics of the structures at element level by carrying out Pushover analysis of three structures viz 3D six storeyed, 2D two storeyed and a simple column RC structure. This damping is assessed by considering cumulative hysteretic energy dissipated at all the plastic hinges developed in the structures and is compared with that calculated based on formulations given in codes such as FEMA-440 and ATC-40. Damping agrees well with that given in FEMA-440, estimated from global pushover curve of structures for ductility value greater than 3. Also, nonlinear time history analysis is performed for all the structures to validate the structural performance. Keywords Damping · Local nonlinearity · Hysteretic energy dissipation · Pushover analysis
1 Introduction In the past, strong earthquakes have caused significant damage to many structures and consequently incurred losses to human, infrastructure and economy. As a result of these, researchers have focused on evolving a performance-based design methodology (Kowalsky et al. 1995) for more reliable and predictable performance of structures during a seismic event. These researchers, codes and guides have described that performance-based seismic * Y. M. Parulekar [email protected] 1
Bhabha Atomic Research Centre, Mysore 571130, India
2
Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai 400085, India
3
Homi Bhabha National Institute, Mumbai 400094, India
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Vol.:(0123456789)
Bulletin of Earthquake Engineering
analysis can be achieved not only through nonlinear static analysis (Freeman 1998), but also with different approaches with different level of accuracy and computational efforts. However, nonlinear static problem makes the analysis much simpler. In this method, the capacity curve of structure and site-specific earthquake demand curve is needed to be drawn on a common scale known as acceleration-displacement response spectrum (ADRS) format, subsequently, the intersection of these two curves give us the performance point (Priestley and Kowalsky 2000). The demand curves are different for different values of damping percentage and there is
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