Limitations of Sa(T1) as an intensity measure when assessing non-ductile infilled RC frame structures

O’Reilly, Gerard J.

doi:10.1007/s10518-021-01071-7

Cited by 42 publications

(12 citation statements)

References 59 publications

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“…This knowledge, combined with the increasing capacity of computers and collection of strong motion databases, have allowed to perform probabilistic calculations which had previously been unthinkable. In this way, statistical analyses of several spectrum-based IMs and EDPs (obtained through advanced nonlinear structural models) have been recently performed (Padgett et al 2008;Jalayer et al 2012;Ebrahimian et al 2015Ebrahimian et al , 2021Bojórquez et al 2017a,b;Pinzón et al 2020;Du and Padgett 2021;O'Reilly 2021).…”

Section: Introductionmentioning

confidence: 99%

New insights into the relationship between seismic intensity measures and nonlinear structural response

Alzate

Hurtado

Pujades

2021

Bull Earthquake Eng

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This paper focuses on the probabilistic analysis of Intensity Measures (IMs) and Engineering Demand Parameters (EDPs) in the context of earthquake-induced ground motions. Several statistical properties, which are desirable in IMs when they are used to predict EDPs, have been analysed. Specifically, efficiency, sufficiency and steadfastness have been quantified for a set of IMs with respect to two EDPs: the maximum inter-storey drift ratio, MIDR, and the maximum floor acceleration, MFA. Steadfastness is a new statistical property proposed in this article, which is related to the ability of IMs to forecast EDPs for large building suites. In other words, this means that efficiency does not significantly vary when different types of buildings are simultanously considered in the statistical analyses. This property allows reducing the number of calculations when performing seismic risk estimations at urban level since, for instance, a large variety of fragility curves, representing specific building typologies, can be grouped together within a more generic one. The main sources of uncertainty involved in the calculation of the seismic risk have been considered in the analysis. To do so, the nonlinear dynamic responses of probabilistic multi-degree-of-freedom building models, subjected to a large data set of ground motion records, have been calculated. These models have been generated to simulate the dynamic behavior of reinforced concrete buildings whose number of stories vary from 3 to 13. 18 spectrum-, energy- and direct-accelerogram-based IMs have been considered herein. Then, from clouds of IM-EDP points, efficiency, sufficiency and steadfastness have been quantified. For MIDR, results show that IMs based on spectral velocity are more efficient and steadfast than the ones based on spectral acceleration; spectral velocity averaged in a range of periods, AvSv, has shown to be the most efficient IM with an adequate level of steadfastness. For MFA, spectral acceleration-based-IMs are more efficient than velocity-based ones. A comparison is also presented on the use of linear vs quadratic regression models, and their implications on the derivation of fragility functions. Concerning sufficiency, most of the 18 IMs analysed do not have this property. Nonetheless, multi-regression models have been employed to address this lack of sufficiency allowing to obtain a so-called ‘ideal’ IM.

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Section: Introductionmentioning

confidence: 99%

New insights into the relationship between seismic intensity measures and nonlinear structural response

Alzate

Hurtado

Pujades

2021

Bull Earthquake Eng

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“…An analysis of two case-study buildings found that peak ground velocity (PGV) tended to be a reasonable predictor of structure displacement demands, which was also noted in past works like Ryan and Chopra. 37,38 Different combinations of IMs may be used to minimise dispersion in seismic response prediction, with studies [39][40][41][42][43][44] investigating optimal IMs for assessing existing buildings. For base-isolated structures, Sa(T iso ) will be employed herein due to its simplicity and physical meaning.…”

Section: Characterising Normalised Fpb Hysteretic Behaviourmentioning

confidence: 99%

Risk‐based seismic design of base‐isolated structures with single surface friction sliders

O’Reilly

Yagi

Suzuki

et al. 2022

Earthq Engng Struct Dyn

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Choosing friction pendulum isolators to avoid problems with device displacement capacity or boundary wall collision is a critical part of the seismic design of base isolation systems. This paper developed a probabilistic method to quantify the risk of failure in single friction pendulum bearing (FPB) devices. This was done by calibrating a demand-intensity model for FPBs from numerical analysis for several device property combinations. These properties encompassed the dynamic friction coefficient and effective radius of curvature-key parameters impacting these FPB devices' seismic response. Through this demand-intensity model, a closed-form and relatively simple approach to quantify the mean annual frequency of exceeding a given device displacement threshold, or risk of failure, was proposed. By applying this simplified method to several case study structures and comparing it with a more extensive assessment involving multiple stripe analysis (MSA) using hazard-consistent ground motions, the proposed simplified approach could provide very accurate estimates of displacement-based failure risk in FPB devices under the assumption of no non-linear behaviour in the superstructure. This proposed approach implies that structural engineers can now quickly assess the actual failure rates of different FPB device combinations used in practice to give a more uniform level of safety or reliability when designing and assessing FPB-isolated systems. It is also arguably much simpler, direct and accurate than currently available code-based approaches.

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“…In addition, an example application of the proposed procedure to a three‐storey three‐bay strong infilled RC frame with a column‐sway mechanism is provided in Appendix A. These frames have also been employed in other studies 7,13,25,26,59 . For this study, twelve planar frames featuring two different heights, two different widths and three different infill typologies were considered (Figure 9).…”

Section: Validation Of the Proposed Simplified Analysis Proceduresmentioning

confidence: 99%

“…These frames have also been employed in other studies. 7,13,25,26,59 For this study, twelve planar frames featuring two different heights, two different widths and three different infill typologies were considered (Figure 9). The definition of different typologies of infills was adapted from Hak et al 27 As modelling decisions, the frame section flexural response was modelled using the approach proposed by O'Reilly and Sullivan 38 for non-ductile RC frame structures in Italy.…”

Section: Case Study Structuresmentioning

confidence: 99%

Simplified modelling and pushover analysis of infilled frame structures accounting for strut flexibility

Akan

O’Reilly

Monteiro

2022

Earthq Engng Struct Dyn

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Seismic assessment of structures is often performed using their force–displacement capacity or pushover curve computed via non‐linear static analysis. However, these analyses' reliability depends on the numerical model's detail and its ability to capture salient failure mechanisms. Simplified analysis methods offer effective means of identifying structural deficiencies and provide analysts with a sound understanding of key structural characteristics, such as the strength hierarchy, status of the structural damage in terms of limit state exceedance or the progression of the inelastic mechanism, in addition to providing a method with which to check numerical analysis results. This work builds upon the existing literature for simplified analysis of moment frame structures and describes a simplified pushover‐based analysis procedure for infilled frame structures. Individual storey responses are obtained by combining the flexural resistance of the frame and accounting for the axial resistance of the infill (modelled as an equivalent axial strut) and the boundary frame members, assuming both systems work in parallel. Then, the displaced shape of the structure is iteratively calculated for a given base shear, which can be repeated until a pushover curve is obtained with relative ease. The proposed procedure is tested and evaluated versus other available methods by analysing several infilled reinforced concrete frames. It is shown that the method can perform simplified pushover analysis with a high degree of fidelity while improving over the other similar methods currently available.

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Limitations of Sa(T1) as an intensity measure when assessing non-ductile infilled RC frame structures

Cited by 42 publications

References 59 publications

New insights into the relationship between seismic intensity measures and nonlinear structural response

New insights into the relationship between seismic intensity measures and nonlinear structural response

Risk‐based seismic design of base‐isolated structures with single surface friction sliders

Simplified modelling and pushover analysis of infilled frame structures accounting for strut flexibility

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