Damage‐based design with no repairs for multiple events and its sensitivity to seismicity model

Abstract

Conventional design methodology for the earthquake-resistant structures is based on the concept of ensuring 'no collapse' during the most severe earthquake event. This methodology does not envisage the possibility of continuous damage accumulation during several not-so-severe earthquake events, as may be the case in the areas of moderate to high seismicity, particularly when it is economically infeasible to carry out repairs after damaging events. As a result, the structure may collapse or may necessitate large scale repairs much before the design life of the structure is over. This study considers the use of design force ratio (DFR) spectrum for taking an informed decision on the extent to which yield strength levels should be raised to avoid such a scenario. DFR spectrum gives the ratios by which the yield strength levels of single-degree-of-freedom oscillators of different initial periods should be increased in order to limit the total damage caused by all earthquake events during the lifetime to a specified level. The DFR spectra are compared for three different seismicity models in case of elasto-plastic oscillators: one corresponding to the exponential distribution for return periods of large events and the other two corresponding to the lognormal and Weibull distributions. It is shown through numerical study for a hypothetical seismic region that the use of simple exponential model may be acceptable only for small values of the seismic gap length. For moderately large to large seismic gap lengths, it may be conservative to use the lognormal model, while the Weibull model may be assumed for very large seismic gap lengths.

Effect of cumulative seismic damage and corrosion on the life‐cycle cost of reinforced concrete bridges

“…The cyclic loading during each earthquake also results in the failure of the bond between steel and concrete, which results in a larger displacement at yield U y . Das et al [21] suggested that Equations (33) and (34) account for any change in the stiffness and displacement at yield due to an earthquake …”

“…The value of N corresponding to U max is obtained from cyclic demand spectrum [15] as (20) where V y is the lateral force at yield and the parameter is the ratio between the hysteretic energy and the seismic energy demand, E I , that can be written as (21) where is the ductility demand given by…”

The ductility-based strength reduction factor for the mainshock–aftershock sequence-type ground motions

“…Some researchers (Sunasaka et al 2002;Amadio et al 2003;Das et al 2007;Hatzigeorgiou and Beskos 2009;Hatzigeorgiou 2010a, b, c;Goda and Taylor 2012;Goda 2012;Di Sarno 2013;Zhai et al 2013aZhai et al , 2014 focused on the inelastic response spectra, such as inelastic displacement ratio, ductility demand, behavior factor and damage spectra for mainshock-aftershock sequence-type ground motions. In addition, several investigations (Fragiacomo et al 2004;Lee and Foutch 2004;Li and Ellingwood 2007;Hatzigeorgiou and Liolios 2010;Moustafa and Takewaki 2010;Ruiz-García and Negrete-Manriquez 2011;Ruiz-García 2012;Ruiz-García et al 2012Faisal et al 2013;Zhang et al 2013;Efraimiadou et al 2013;Han et al 2014) have been conducted to study the effects of aftershock on multiple-degree-of-freedom structures.…”

Response of Nonlinear SDOF Structures to Random Acceleration Sequences

“…The response of inelastic steel structures to simulated acceleration sequences was studied in [10,11]. Das and Gupta [12] used the spectrum of the force ratio in designing single-degree-offreedom (SDOF) structures to survive all possible earthquakes during their service life without undergoing repairs. Recently, recorded accelerograms were used to investigate the implication of repeated acceleration sequences on the inelastic displacement ratio and the ductility demand of SDOF and MDOF structures [13][14][15][16].…”