Predicting Floor Response Spectra for Rc Frame Structures

Earthq Engng Struct Dyn

2015

Past earthquakes have shown the importance for critical facilities to remain functional during seismic events. In the performance assessment of these facilities, it is therefore essential to accurately evaluate the seismic demand of nonstructural components. Evaluation of these components is also important when estimation of nonstructural repair costs is a concern. In this paper, the use of a multivariate demand model for nonstructural components is proposed, in which demand is expressed in terms of both interstory drifts and floor acceleration spectra. A model is built using statistics of the demand vector derived from the results of a limited number of inelastic response history analyses of a structure. The model is then used to simulate any number of additional realizations of the demand vector required for an accurate estimation of the probability of functionality loss. A new proposal for a predictive equation to generate approximate realizations of floor response spectra is presented. A reinforced concrete frame is selected as an illustrative example to show the implementation of the probabilistic seismic demand model and to evaluate the proposed predictive equation for the floor response spectra. The results of the case study are used to demonstrate the importance of accounting for the correlation among the demand parameters when realizations of the seismic demand of nonstructural components are simulated. © 2016 John Wiley & Sons, Ltd

Section: Illustrative Examplementioning

confidence: 99%

Probabilistic seismic demand model for nonstructural components

Earthq Engng Struct Dyn

2015

“…In order to limit the number of parameters to be used for a probabilistic characterization of the FRS, the method proposed by [7] and later used in [8] is adopted. According to this method, at each floor level the spectrum is characterized by three ordinates only (named peak component acceleration demands): the ordinate corresponding to a component period value equal to 0 (i.e., the peak floor acceleration PFA), and the peak ordinates of the spectra calculated in the short-and in the fundamental-period region (FAS2 and FAS1, respectively).The boundaries of the two period regions are 0-0.5T 1 and 0.5T 1 -2.0T 1 , respectively, where T 1 denotes the fundamental period of the structure.…”

mentioning

confidence: 99%

Estimation of Floor Response Spectra Using the Uncoupled Modal Response History Analysis

2016

AMM

In performance-based earthquake engineering, probabilistic seismic demand models are usually developed by using methods which need a large number of nonlinear dynamic analyses to be run. In order to reduce the numerical effort, simplified methodologies of analysis have been proposed. Objective of the present study is to use the uncoupled modal response history analysis for the estimation of acceleration floor spectra, engineering demand parameters commonly used for measuring seismic demand in acceleration-sensitive non-structural elements. The procedure is evaluated for a 6-story reinforced concrete frame case study, designed to be representative of an existing structure lacking in specific capacity design rules.

“…Even if alternative intensity measures than the spectral acceleration were found to be good predictors for seismic demand on non-structural components (especially for the case of floor accelerations, as shown e.g. in [23,24,25]), S a is selected in this study because of its computability (i.e., availability of ground motion prediction equations, and correlation equations as well). The prediction equations of Boore and Atkinson [19] and Campbell Bozorgnia [19] are used to predict the S a (T i ) and AI values, respectively, while the equation of Baker and Jayaram [22] and that of Campbell and Bozorgnia [19] is used for the prediction of the S a (T i ) -S a (T j ) correlation and the S a (T i ) -AI correlation, respectively.…”

Section: Ground Motionsmentioning

confidence: 99%

Floor Acceleration Spectra Estimation in Reinforced Concrete Frames

Proceedings of the Fifteenth International Conference on Civil, Structural and Environmental Engineering Computing

Self Cite

Non-structural elements that are considered primarily sensitive to and subject to damage from inertial loading are classified as acceleration-sensitive elements. The response of acceleration-sensitive non-structural components in buildings is therefore directly affected by the floor acceleration demand that they experience during ground shaking. Reducing seismic damage to these elements is of primary importance not only for economic reasons, but also for maintaining the functionality of the building immediately after the earthquake. The purpose of this paper is to study the floor acceleration demand variation along the height of concrete frame buildings and how the sophistication of the structural modeling can be reduced in such estimation. In fact, development of probabilistic seismic demand models, that usually involve the use of methods such as the incremental dynamic analysis, the cloud analysis, and multiple stripe analysis requires a large number of non-linear analyses of the structure to be run. To reduce the numerical effort, a simplified methodology based on the modal pushover analysis procedure will be proposed and used for the characterization of floor spectra. To this purpose the seismic response of a selected case study, consisting in a six-storey three-bay frame of a reinforced concrete building, dimensioned to be representative of an existing structure designed according to a past seismic code (using the one in force in Italy between 1996 and 2008), will be analyzed. The estimates of peak absolute acceleration and response spectra at each floor level will be compared and contrasted.