Development of limit states for seismic fragility assessment of piloti-type structures verified with observed damage data

Shortly after the October 31, 2002, Molise, Italy, earthquake, a widespread fitness-for-service and building damage assessment was launched. In two months, more than 23,000 buildings were inspected using a standardized damage assessment form. As many as 100 inspection teams, consisting of public servants and volunteer professionals, totaled approximately 80,000 person-hours. Analysis of the collected building type and damage data shows high-vulnerability masonry buildings with significant preexisting damage. With the sole exception of San Giuliano, the modal values of the observed damage occurred for the negligible-to-slight damage levels D=0 or D=1, with only a few buildings showing higher damage levels. Nevertheless, due to their high vulnerability, about 40% of the inspected buildings were unusable, with important consequences for the number of people needing shelter. The survey made it possible to determine the usability of about 12,000 buildings and the repairs needed for about 1,000 buildings.

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Determination of limit-states for near-fault seismic fragility assessment of concrete gravity dams

Scientia Iranica ◽

10.24200/sci.2018.20701 ◽

2018 ◽

Vol 0 (0) ◽

pp. 0-0 ◽

Cited By ~ 2

Author(s):

Mohammad Ali Sotoudeh ◽

Mohsen Ghaemian ◽

Abdolreza Sarvghad Moghadam

Keyword(s):

Seismic Fragility ◽

Gravity Dams ◽

Limit States ◽

Near Fault ◽

Concrete Gravity Dams

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Seismic fragility assessment of ductile reinforced concrete building frames

International Journal of Disaster Resilience in the Built Environment ◽

10.1108/ijdrbe-06-2020-0059 ◽

2020 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Nibas Apu ◽

Ravi Sinha

Keyword(s):

Reinforced Concrete ◽

Building Codes ◽

Nonlinear Time History Analysis ◽

Seismic Fragility ◽

Fragility Functions ◽

Limit States ◽

Content Type ◽

Rc Frames ◽

Time Period ◽

Seismic Force

Purpose Increasing awareness of the society and complying with design requirements of building codes for seismic safety of structures and inhabitants during severe earthquakes are the primary purpose of seismic analysis. This study aims to present the variability in seismic fragility functions for frames of different heights for the most vulnerable condition of structure using nonlinear time history analysis. Design/methodology/approach A total of 4, 8 and 20 stories reinforced concrete (RC) moment-resisting two-dimensional frames are considered for this study. Ground motions (GM) are selected as per the conditional mean spectrum and these are conditioned on a target spectral acceleration at the concern time period. RC frames are designed and detailed as per Indian standards. A concentrated plasticity approach is adopted for non-linear analytical modeling of the RC frames. Deterministic capacity limit states in terms of maximum inter-story drift ratio are considered for different damage states. Fragility functions have been derived following a lognormal distribution from incremental dynamic analysis curves. Finally, the maximum likelihood estimation of the response is obtained for fitting curves with observed fragility. Findings The fragility functions of the three structures reflect that under critical or extreme conditions of GM the taller buildings have higher fragility than the shorter buildings for each level of limit states even though both are designed to meet their code-level design forces. Research limitations/implications The study is conducted on the extreme scenario of GM conditioned on the fundamental time period of each building, whereas comparison can be developed by selecting various methodologies of GM set. The probabilistic capacity model can be developed for future studies to check the fragility variation with deterministic and probabilistic capacity. Originality/value The investigation endeavors to present a comprehensive fragility assessment framework by analytical method. The outcome will be useful in the development of a disaster management strategy for new or old buildings and the response of seismic force with a variation of the building’s height. The findings will also be useful for updating the earthquake-resistant building codes for the new building construction in a similar context.

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Comparison of Two Mechanics-Based Methods for Simplified Structural Analysis in Vulnerability Assessment

Advances in Civil Engineering ◽

10.1155/2008/438379 ◽

2008 ◽

Vol 2008 ◽

pp. 1-19 ◽

Cited By ~ 6

Author(s):

H. Crowley ◽

B. Borzi ◽

R. Pinho ◽

M. Colombi ◽

M. Onida

Keyword(s):

Structural Analysis ◽

Vulnerability Assessment ◽

Ground Motions ◽

Structural Models ◽

Assessment Methods ◽

Static Response ◽

Nonlinear Analyses ◽

Damage Data ◽

Nonlinear Static ◽

Observed Damage

Analytical vulnerability assessment methods should ideally be validated or verified by comparing their damage predictions with actual observed damage data. However, there are a number of difficulties related to the comparison of analytical damage predictions with observed damage; for example, there are large uncertainties related to the prediction of the ground motions to which the damaged buildings have been subjected. Until such problems can be resolved, it is worthwhile considering the mechanics of simplified analytical vulnerability assessment methods and validating this part of the methodology through comparisons with detailed structural models. This paper looks at two mechanics-based vulnerability assessment methods (DBELA and SP-BELA) and compares the nonlinear static response predicted with these methods with finite elements-based nonlinear analyses of prototype buildings. A comparison of the predicted response of urban populations of buildings using the two methods is then carried out, and the influence of these differences on vulnerability curves is studied.

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Damage to buildings due to the 1989 Loma Prieta earthquake — a Canadian code perspective

Canadian Journal of Civil Engineering ◽

10.1139/l90-093 ◽

1990 ◽

Vol 17 (5) ◽

pp. 813-834 ◽

Cited By ~ 18

Author(s):

Denis Mitchell ◽

René Tinawi ◽

Richard G. Redwood

Keyword(s):

Seismic Design ◽

Soft Soil ◽

Steel Structures ◽

Building Structures ◽

Limit States ◽

Loma Prieta Earthquake ◽

Loma Prieta ◽

October 17 ◽

Design Earthquake ◽

Observed Damage

Damage to building structures during the October 17, 1989, Loma Prieta earthquake prompted site visits by the authors. This paper presents examples of damage to buildings constructed with reinforced concrete, steel, masonry, and timber. The observed damage is used to illustrate some of the seismic design clauses in the 1990 National Building Code of Canada, the 1984 Canadian Standards Association (CSA) Standard for the Design of Concrete Structures for Buildings, and the 1989 CSA Standard for the Limit States Design of Steel Structures. The important roles played by the presence of soft soil, poor structural layouts, inadequate detailing, the lack of reinforcement in masonry, as well as inadequate connections to foundations are highlighted. Examples of the performance of upgraded structures are also given, and the concern over the presence of existing hazardous buildings in significant seismic zones in Canada is emphasized. Key words: seismic design, earthquake, Loma Prieta, structures, codes, concrete, steel, masonry, timber, upgrading.

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Empirical Damage Relationships and Benefit-Cost Analysis for the Seismic Retrofit of URM Buildings

Earthquake Spectra ◽

10.1193/091816eqs153m ◽

2017 ◽

Vol 33 (3) ◽

pp. 1053-1074 ◽

Cited By ~ 2

Author(s):

Brandon Paxton ◽

Kenneth J. Elwood ◽

Jason M. Ingham

Keyword(s):

New Zealand ◽

Pacific Northwest ◽

Risk Mitigation ◽

Seismic Retrofit ◽

Construction Costs ◽

Benefit Cost Analysis ◽

Damage Data ◽

Strong Candidate ◽

Observed Damage ◽

Benefit Cost

Benefit-cost analyses for the seismic retrofit of unreinforced masonry (URM) buildings in downtown Victoria, British Columbia, Canada, were undertaken, considering the seismic hazard, building value, occupant/pedestrian exposure, a variety of strengthening measures, and local construction costs. The analyses are underpinned by building motion-damage relationships developed based on observed damage in past earthquakes in California and New Zealand. The considered upgrading measures ranged from parapet bracing to comprehensive seismic upgrades consistent with local practices. Parapet bracing and other partial retrofits were shown to have favorable benefit-cost ratios and thus be strong candidate measures for risk mitigation programs. Full upgrades were shown to have less favorable benefit-cost ratios. While applied to Victoria, the generality of the methodology and the use of observed damage data from California and New Zealand make the findings of this study particularly relevant for similar locations throughout the Pacific Northwest and abroad.

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Seismic Fragility of Suspended Ceiling Systems

Earthquake Spectra ◽

10.1193/1.2357626 ◽

2007 ◽

Vol 23 (1) ◽

pp. 21-40 ◽

Cited By ~ 51

Author(s):

Hiram Badillo-Almaraz ◽

Andrew S. Whittaker ◽

Andrei M. Reinhorn

Keyword(s):

Seismic Performance ◽

Dynamic Testing ◽

Fragility Curves ◽

Full Scale ◽

Seismic Fragility ◽

Limit States ◽

Performance Based Assessment ◽

Damage States

Full-scale dynamic testing of suspended ceiling systems was performed to obtain fragility data suitable for performance-based assessment and design. On the basis of the fragility data derived from testing, (1) the use of retainer clips improves the performance of ceiling systems in terms of loss of tiles, (2) including recycled cross tees in the suspension grid increases the vulnerability of the ceiling systems, (3) undersized (poorly fitting) tiles are substantially more vulnerable than properly fitted tiles, and (4) the use of compression posts improves the seismic performance of ceiling systems for the limit states of minor and moderate damage. Fragility curves are provided for four damage states.

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Evaluation of displacement-based vulnerability assessment methodology using observed damage data from Christchurch

Earthquake Engineering & Structural Dynamics ◽

10.1002/eqe.2450 ◽

2014 ◽

Vol 43 (15) ◽

pp. 2319-2339 ◽

Cited By ~ 4

Author(s):

S. R. Uma ◽

Rajesh P. Dhakal ◽

Mostafa Nayyerloo

Keyword(s):

Vulnerability Assessment ◽

Assessment Methodology ◽

Damage Data ◽

Displacement Based ◽

Observed Damage

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Seismic Fragility Analysis of Steel Liquid Storage Tanks Using Earthquake Ground Motions Recorded in Korea

Mathematical Problems in Engineering ◽

10.1155/2019/6190159 ◽

2019 ◽

Vol 2019 ◽

pp. 1-15

Author(s):

Sangmok Lee ◽

Byungmin Kim ◽

Young-Joo Lee

Keyword(s):

Ground Motions ◽

Fragility Analysis ◽

Seismic Fragility ◽

Elastic Buckling ◽

Fe Model ◽

Storage Tanks ◽

Limit States ◽

Liquid Storage ◽

Real Earthquake ◽

Earthquake Damages

Liquid-containing storage tanks are important structures in industrial complexes. Because earthquake damages to liquid storage tanks can cause structural collapse, fires, and hazardous material leaks, there have been continuous efforts to mitigate earthquake damages using seismic fragility analysis. In this regard, this study focuses on the seismic responses and fragility of liquid storage tanks. First, the characteristics of earthquake ground motions are a critical factor influencing the seismic fragility of structures; thus, this study employs real earthquake records observed in the target area, southeastern Korea, with the earthquake characteristics estimated based on the ratio of peak ground acceleration to peak ground velocity. When a liquid storage tank oscillates during an earthquake, additional forces can impact the tank wall owing to hydrodynamic pressures. Therefore, this study presents a sophisticated finite element (FE) model that reflects the hydrodynamic effect of an oscillating liquid. Another advantage of such an FE model is that detailed structural responses of the entire wall shells can be estimated; this is not possible in simplified lumped mass or surrogate models. Lastly, probabilistic seismic demand models are derived for three critical limit states: elastic buckling, elephant’s foot buckling, and steel yielding. Using the real earthquake ground motion records, constructed FE model, and limit states, a seismic fragility analysis is performed for a typical anchored steel liquid storage tank in Korea. In addition, for comparison purposes, a ring-stiffened model is investigated to derive a seismic fragility curve. The results of the seismic fragility assessment show that elastic buckling is the most vulnerable damage state. In contrast, elephant’s foot buckling and steel yielding indicate relatively severe damage levels. Furthermore, it is observed that ring stiffeners decrease the elastic buckling damage, although there is no practical effect on elephant’s foot buckling and steel yielding in all ground motion intensities.

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