Generating damping modification factors after artificial inputs in scenarios of local records scarcity

Abstract

150 to 250 words)The damping modification factors are utilized to alter the design spectral ordinates for constructions whose damping differs significantly from 5%, this being the level that is routinely considered by most codes. Such factors are habitually evaluated after suites of historical inputs representing the local seismicity. However, such records may not be readily available, due either to moderate seismicity or to limited seismological network; in such cases, representative artificial accelerograms might be used instead. This paper proposes a methodology for establishing damping modification factors after artificial inputs generated to match the 5% design spectra; this approach can be used for countries, regions or cities. The proposed methodology is based on performing dynamic analyses on underdamped and overdamped SDOF linear systems by using the aforementioned selected accelerograms. Although previous studies have highlighted the differences among factors generated after natural and artificial inputs, it has been observed that such discrepancies are mainly due to the longest significant (Trifunac) duration of the artificial accelerograms. Therefore, the artificial inputs are generated as their duration fits those of the available local strong motion records. An application to Colombia is presented; the results are compared with those for some available Colombian records. The sensitivity of the calculated factors to the soil type, period and seismic zone is investigated; matching expressions are provided. Such expressions are compared with the prescriptions of major design codes and with other studies. The suitability of the proposed formulation is further verified in an example on an isolated hospital building.

Damping modification factors for the design of seismic isolation systems in Peru

“…Saez’s equation was derived from linear dynamic analyses on SDOF systems considering 130 acceleration records of ground motion in three types of soil. Piscal and López-Almansa (2018) proposed a methodology for establishing DMFs from a set of artificial seismic records. The artificial inputs were generated as their duration fits those of the available Colombian strong-motion records.…”

“…The artificial inputs were generated as their duration fits those of the available Colombian strong-motion records. The sensitivity of the calculated factors to the soil type, period, and Colombian seismic zone was investigated and matching expressions period-dependent was provided (Piscal et al, 2018). Recent studies (Greco et al, 2018a, 2018b, 2019) have used a stochastic approach with non-stationary input to study the effect of soil type and strong-motion duration on DMFs for high-damping response spectral.…”

“…The DMFs calculated with Equation 17 ( DMF peruvian ) were compared with DMFs calculated with the period-dependent expressions proposed by Lin and Chang (2004), Hatzigeorgiou (2010), Arakawa and Kobayashi (2012), Saez et al, (2012), NCh2745-2013 (2013), Daneshvar et al (2016), and Piscal and López-Almansa (2018). The comparison was made by calculating the sum of RMSE ξ in a range of vibration periods from 1.50 to 4.0 s, through Equation 20:…”

“…An interesting study by Saez et al (2012) discussed the results obtained from 130 ground motions measured in three types of soils from Chile and showed significant discrepancies with the results of other seismic codes worldwide (Saez et al, 2012). Moreover, Piscal and López-Almansa (2018) proposed a methodology for establishing DMFs expressions after generating artificial accelerograms fitted to the 5% damped design spectra of Colombian code. The derived expressions were compared with other major seismic regulations, being concluded that lie within their range and noticeably such codes show important scattering.…”

“…The derived expressions were compared with other major seismic regulations, being concluded that lie within their range and noticeably such codes show important scattering. (Piscal and López-Almansa, 2018).…”