Seismic assessment and loss estimation of existing school buildings in Italy

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Summary A principal aspect of seismic design is the verification of performance limit states, which help ensure satisfactory behaviour within a performance‐based earthquake engineering framework. However, it is increasingly acknowledged that while ensuring life safety is a suitable basic design requirement, more meaningful metrics of seismic performance exist. Expected annual loss (EAL) has gained attention in recent years but tends to be limited to seismic assessment. This article proposes a novel conceptual design framework that employs EAL as a design tool and requires very little building information at the design outset. This means that designers may commence from a definition of required EAL and arrive at a number of feasible structural solutions without the need for any detailed design calculations or numerical analysis. This works by transforming the building performance definition to a design solution space using a number of simplifying assumptions. A suitable structural response backbone is subsequently determined and used to identify feasible building typologies and associated structural geometries. The assumptions made to implement such a conceptual design framework are discussed and justified herein followed by a case study application. This proposed design framework is intended to form the first step in seismic design to identify suitable typologies and layouts before subsequent member detailing and design verification. This way, engineers, architects, and clients can make more informed decisions that target certain performance goals at the beginning of design before further refinement.

Section: Define Building Performance Objectivesmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Conceptual seismic design in performance‐based earthquake engineering

O’Reilly

Calvi

2018

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“…where F 1 (s lim ) and F 2 (s lim ) are the CDF values of the corresponding lognormal distributions, described in Equations 32 and 33 above, evaluated at s lim . It is also noted here that whilst the formulation described in Equation 34 has been derived for bilinear demand-intensity models, the same process could be followed for models with additional piecewise linear segments (eg, trilinear) by simply modifying the integration ranges and adding further terms outlined in Equation 31. It follows that should the coefficients of the two portions of the logspace fit be equal, the above expressions will reduce down to those initially proposed by Vamvatsikos 11 for a second-order hazard fit, and subsequently, should the k 2 term become zero to return to a linear hazard model fit, the above expressions will further reduce down to those initially outlined by Cornell et al 3 As such, these can be thought of as a further extension and development to the existing framework whereby nonlinear systems whose behaviour with respect to increasing intensity cannot be adequately modelled by a linear fit in logspace over the entire range of response can now be considered.…”

Section: Proposed Format For Bilinear Systemsmentioning

confidence: 99%

Probabilistic models for structures with bilinear demand‐intensity relationships

O’Reilly

Monteiro

2018

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Summary An extension to the existing SAC/FEMA expressions to estimate mean annual frequency of exceedance (MAFE) for a given limit state is described. In specific, this study pertains to structural systems whose demand versus seismic intensity relationship cannot be reasonably represented by a linear fit in logspace, but rather a bilinear fit over the entire range of structural response. Using a predefined limiting intensity, the median demand is separated into two distinct zones of response. These expressions are derived using a second‐order polynomial hazard model fit and can be considered a further extension of the closed‐form expressions available in the literature. The steps in the derivation are described along with an example application of the proposed expressions. Comparing different models shows that the MAFE can be significantly misrepresented when using a linear demand‐intensity model for systems whose behaviour deviates from this assumption in logspace. Similarly, a logarithmic function demand‐intensity fit is examined and seen not to be suitable in the specific situations focused on here. Furthermore, significant underestimation or overestimation is observed when using local fits in the vicinity of the behaviour transition point, which highlights the need for such a bilinear model when assessing the structural performance at the transition point's vicinity. Adopting a bilinear model is shown to better represent structural systems with complex response characteristics, also allowing the use of a single demand model for the entire range of response. This is at the same time still compatible with the existing framework for performance‐based seismic design and assessment.

“…Recent advancements in performance‐based earthquake engineering have pointed out the importance of the seismic design of nonstructural elements (NSEs) in buildings. Damage observed during the past earthquakes that have struck densely built regions, as well as recent loss estimation studies, indicate that NSEs significantly affect the immediate functionality and economic losses in typical buildings. For example, Miranda et al described the damage that occurred at the Santiago International Airport following the 2010 Chile earthquake.…”

Section: Introductionmentioning

confidence: 99%

“…The importance of NSEs is highlighted by the FEMA P‐58 seismic loss estimation methodology that explicitly considers the contributions of NSEs to the expected losses. A recent study dealing with the seismic loss assessment of school buildings in Italy reported that for reinforced and prestressed concrete school buildings, up to 80% of earthquake related losses might be associated to NSEs …”

Section: Introductionmentioning

confidence: 99%

Consistent floor response spectra for performance‐based seismic design of nonstructural elements

Merino

Perrone

Filiatrault

2019

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The achievement of adequate performance objectives for buildings under increasing seismic intensities is not only related to the performance of structural members but also to the behavior of nonstructural elements. The need to properly design nonstructural elements for earthquakes has been largely demonstrated in the last few years and has become an important objective within the earthquake engineering community. A crucial aspect in the proper design of nonstructural elements is the definition of the seismic demand in terms of both absolute acceleration and relative displacement floor response spectra. In the first part of this study, relative displacement and absolute acceleration floor response spectra were computed for four reinforced concrete moment-resisting archetype frames via dynamic time-history analyses and were compared with floor response spectra predicted by means of two recent simplified methodologies available in the literature. It was observed that one of the existing methodologies is generally unable to predict consistent absolute acceleration and relative displacement floor response spectra. An improved procedure is developed for estimating consistent floor response spectra for building structures subjected to low and medium-high seismic intensities. This new procedure improves the predictions of a relative displacement floor response spectrum by constraining its ordinates at long nonstructural periods to the expected peak absolute displacement of the floor. The resulting acceleration and relative displacement response spectra are then consistently related by the well-known pseudo-spectral relationship over the entire nonstructural period range. The effectiveness of the proposed methodology was appraised against floor response spectra computed from nonlinear time-history analyses. KEYWORDSfloor response spectra, nonstructural elements, nonstructural components, seismic demand | INTRODUCTIONRecent advancements in performance-based earthquake engineering have pointed out the importance of the seismic design of nonstructural elements (NSEs) in buildings. Damage observed during the past earthquakes that have struck densely built regions, 1-3 as well as recent loss estimation studies, 4,5 indicate that NSEs significantly affect the immediate functionality and economic losses in typical buildings. For example, Miranda et al 1 described the damage that occurred