scholarly journals Seismic Assessment via EC8 of Modern Heritage Structures

2016 ◽  
pp. 1002-1021
Author(s):  
Gerardo M. Verderame ◽  
Flavia De Luca ◽  
Gaetano Manfredi
Keyword(s):  
Reinforced Concrete ◽  
Nonlinear Models ◽  
Fragility Curves ◽  
Seismic Assessment ◽  
Eurocode 8 ◽  
Dynamic Identification ◽  
Limit States ◽  
Rc Building ◽  
Nonlinear Dynamic Analyses ◽  
Modal Dynamic Identification

Given the interest earned recently by modern heritage structures, seismic assessment criteria of Eurocode 8, for ordinary reinforced concrete structures, are applied to a modern heritage RC building. The case study, the Tower of the Nations in Naples, allows a discussion on knowledge approaches, analysis methodologies and modeling choices that can be considered. Modal dynamic identification, in situ inspections, and testing provided the necessary knowledge of the structure. Linear and nonlinear models of the structure are built up accounting for tuff infills' stiffness and strength contribution. Numerical modal properties are compared with those obtained through dynamic identification. Lumped plasticity model for reinforced concrete elements and equivalent strut macro models for tuff and concrete infills are employed for the nonlinear model of the structure. Seismic assessment through nonlinear dynamic analyses is carried out for two Limit States. Finally, fragility curves through cloud analysis are obtained for the different limit states considered.

scholarly journals Seismic Assessment via EC8 of Modern Heritage Structures

2015 ◽  
pp. 607-628
Author(s):  
Gerardo M. Verderame ◽  
Flavia De Luca ◽  
Gaetano Manfredi
Keyword(s):  
Reinforced Concrete ◽  
Nonlinear Models ◽  
Fragility Curves ◽  
Seismic Assessment ◽  
Eurocode 8 ◽  
Dynamic Identification ◽  
Limit States ◽  
Rc Building ◽  
Nonlinear Dynamic Analyses ◽  
Modal Dynamic Identification

Given the interest earned recently by modern heritage structures, seismic assessment criteria of Eurocode 8, for ordinary reinforced concrete structures, are applied to a modern heritage RC building. The case study, the Tower of the Nations in Naples, allows a discussion on knowledge approaches, analysis methodologies and modeling choices that can be considered. Modal dynamic identification, in situ inspections, and testing provided the necessary knowledge of the structure. Linear and nonlinear models of the structure are built up accounting for tuff infills' stiffness and strength contribution. Numerical modal properties are compared with those obtained through dynamic identification. Lumped plasticity model for reinforced concrete elements and equivalent strut macro models for tuff and concrete infills are employed for the nonlinear model of the structure. Seismic assessment through nonlinear dynamic analyses is carried out for two Limit States. Finally, fragility curves through cloud analysis are obtained for the different limit states considered.

scholarly journals Seismic Assessment of Arch Dams Using Fragility Curves

2015 ◽  
Vol 1 (2) ◽  
pp. 14-20 ◽  
Author(s):  
Vandad Kadkhodayan ◽  
S. Meisam Aghajanzadeh ◽  
Hasan Mirzabozorg
Keyword(s):  
Fragility Curves ◽  
Routine Data ◽  
Seismic Assessment ◽  
Arch Dam ◽  
The Other ◽  
Intensity Measure ◽  
Limit States ◽  
High Arch Dam ◽  
Arch Dams ◽  
Engineering Demand Parameter

In the present paper, the IDA approach is applied to analyzing a thin high arch dam. The parameters of Sa, PGA and PGV are used as intensity measure (IM) and the overstressed area (OSA) is utilized as engineering demand parameter (EDP) and then, three limit states are assigned to the considered structure using the IDA curves. Subsequently, fragility curves are calculated and it is showed that the PGA is a better parameter to be taken as IM. In addition, it is found that the utilizing the proposed methodology, quantifying the qualitative limit states is probable. At last, having the fragility curves and considering their slope in addition to the other routine data which can be extracted from these curves, one may be able to conclude that in what performance level the considered dam body seems to be weak and needs retrofitting works.

scholarly journals A reliability assessment of physical vulnerability of reinforced concrete walls loaded by snow avalanches

2013 ◽  
Vol 1 (3) ◽  
pp. 2589-2632
Author(s):  
P. Favier ◽  
D. Bertrand ◽  
N. Eckert ◽  
M. Naaim
Keyword(s):  
Reinforced Concrete ◽  
Fragility Curves ◽  
Human Beings ◽  
Snow Avalanches ◽  
Limit States ◽  
Engineering Structures ◽  
Rc Structures ◽  
Yield Line Theory ◽  
Non Gaussian ◽  
Structure Collapse

Abstract. Snow avalanches are a threat to many kinds of elements (human beings, communication axes, structures, etc.) in mountain regions. For risk evaluation, the vulnerability assessment of civil engineering structures such as buildings and dwellings exposed to avalanches still needs to be improved. This paper presents an approach to determine the fragility curves associated with Reinforced Concrete (RC) structures loaded by typical avalanche pressures and provides quantitative results for different geometrical configurations. First, several mechanical limit states of the RC wall are defined using classical engineering approaches (Eurocodes – EC2), and the pressure of structure collapse is calculated from the usual yield line theory. Next, the failure probability is evaluated as a function of avalanche loading using a Monte Carlo approach, and sensitivity studies (Sobol indexes) are conducted to estimate the respective weight of the RC wall model inputs. Finally, fragility curves and relevant indicators such a their mean and fragility range are proposed for the different structure boundary conditions tested. The influence of the input distributions on the fragility curves is investigated. This shows the wider fragility range and/or the slight shift in the median that has to be considered when the possible correlation/non-Gaussian nature of the input distributions is accounted for.

Effect of damage limit states on the seismic fragility of reinforced concrete frame-shear wall buildings

2021 ◽  
Vol 14 (9) ◽  
pp. 57-68
Author(s):  
Durga Mibang ◽  
Satyabrata Choudhury
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Analysis ◽  
Seismic Vulnerability ◽  
Design Method ◽  
Fragility Curves ◽  
Nonlinear Dynamic Analysis ◽  
Soil Condition ◽  
Shear Wall ◽  
Reinforced Concrete Frame ◽  
Limit States

Assessment of the seismic vulnerability of frame-shear wall buildings can be performed by non-linear dynamic analysis and it needs detailed analytical modeling, structural performance measures and various earthquake intensities. The codal based design method can hardly be used for designing buildings of pre-defined target objectives whereas the Unified performance-based design (UPBD) method can be designed for buildings of pre-defined target objectives. In the current study, the UPBD method for frame-shear wall buildings has been applied for different performance levels (PL) i.e. Immediate occupancy (IO), Life safety (LS) and Collapse prevention (CP) with 1%, 2% and 3% drift in both the directions of the buildings. The nonlinear dynamic analysis of the reinforced concrete (RC) frame-shear wall buildings is performed considering spectrum compatible ground motions (SCGM) as per EC-8 demand spectrum at 0.45g level and type B soil condition. Vulnerability assessment of the frame-shear wall buildings is conducted by generating fragility curves and the probability failure of structure is checked based on different configurations and damage limit states of the structure. Finally, the outcome of the work gives a proper idea of the nonlinear behavior of the dual system so that optimum design could be acquired for achieving higher safety aspects.

scholarly journals Fragility and robustness analysis of a multistorey RC building

2021 ◽  
Vol 73 (01) ◽  
pp. 27-44
Keyword(s):  
Fragility Curves ◽  
Nonlinear Dynamic Analysis ◽  
Robustness Analysis ◽  
Nonlinear Static Analysis ◽  
Limit States ◽  
Element Loss ◽  
Rc Building ◽  
Frame System ◽  
Nonlinear Static ◽  
Storey Building

The robustness of a reinforced concrete (RC) five-storey building (frame system stiffened by walls) is analysed in the paper. A high ductility class structure is designed in accordance with structural Eurocodes. The response of the structure to eight different scenarios of the ground floor vertical element loss is analysed. Nonlinear Static Analysis (NSA) and Nonlinear Dynamic Analysis (NDA) methods are used for the robustness analysis. Fragility curves of the building are derived from statistical analysis of these results. The values obtained through NSA and NDA, damage limit states of the system, and fragility curves, are compared. The influence of the position of the removed element on robustness of the structure is also analysed.

Fragility analysis of self-centering prestressed concrete bridge pier with external aluminum dissipators

2016 ◽  
Vol 20 (8) ◽  
pp. 1210-1222 ◽  
Author(s):  
Zhiliang Cao ◽  
Hao Wang ◽  
Tong Guo
Keyword(s):  
Reinforced Concrete ◽  
Prestressed Concrete ◽  
Fragility Curves ◽  
Limit State ◽  
Seismic Capacity ◽  
External Energy ◽  
Limit States ◽  
Performance Limit ◽  
Residual Drift ◽  
Capacity Evaluation

A novel self-centering prestressed concrete pier with external energy dissipators has been developed to realize seismic resilient performance and enhanced corrosion-resisting property. Self-centering capacity of the pier is provided by the unbonded post-tensioned tendons and damage is mostly concentrated on the replaceable dissipators. To investigate the seismic behavior of the proposed pier, a detailed analytical model considering interface opening and dissipator deformation was developed and verified through existing cyclic load tests. Based on the proposed model, a prototype reinforced concrete pier and a self-centering prestressed concrete pier with similar backbone curves are designed, and fragility analyses are conducted on the two piers through incremental dynamic analysis. One maximum drift-based performance limit state (i.e. collapse prevention) and two residual drift-based performance limit states (i.e. emergent usage and reconstruction) are defined for seismic capacity evaluation. Fragility curves indicate that the self-centering prestressed concrete pier has a slightly higher peak drift demand owing to its inferior dissipating capacity as compared with the reinforced concrete pier, while sustains a much lower residual drift demand due to its inherent self-centering characteristic.

Reliability Analysis of Seismic Isolation in Retrofitting of Simply Supported Bridges

2016 ◽  
Vol 847 ◽  
pp. 391-400
Author(s):  
Luigi Petti ◽  
Alessio Lodato ◽  
Angelo Mammone
Keyword(s):  
Seismic Isolation ◽  
Fragility Curves ◽  
Seismic Intensity ◽  
Finite Element Models ◽  
Design Strategies ◽  
Limit States ◽  
Damage Level ◽  
Simply Supported ◽  
Dynamic Analyses ◽  
Nonlinear Dynamic Analyses

The paper investigates the reliability of simply supported bridges, retrofitted or less with seismic isolation, by means of fragility curves, which represent the probability of reaching a certain damage level for an assigned seismic intensity. Taking advantage of the Multi Stripes methodology, several nonlinear dynamic analyses of a multi-span bridge representing the existing ones in Italy built in the 60 ' characterized by means of non linear finite element models in different design configurations of seismic retrofit have been carried out, in order to obtain the fragility functions.The obtained results allow to assess the isolation retrofit strategies effectiveness to mitigate the seismic risk of simply supported bridges, highlighting the influence of different design strategies on the probability of exceeding the limit states considered.

scholarly journals Effects of ground-motion sequences on fragility and vulnerability of case-study reinforced concrete frames

2020 ◽  
Author(s):  
Karim Aljawhari ◽  
Roberto Gentile ◽  
Fabio Freddi ◽  
Carmine Galasso
Keyword(s):  
Reinforced Concrete ◽  
Ground Motion ◽  
Seismic Performance ◽  
Numerical Models ◽  
Fragility Curves ◽  
Time History ◽  
Eurocode 8 ◽  
Positive Contribution ◽  
First Case

AbstractThis study investigates the effects of ground-motion sequences on fragility and vulnerability of reinforced concrete (RC) moment-resisting frames (MRFs). Two four-storey, four-bay RC MRFs are selected as case studies. These structures, which share the same geometry, are representative of distinct vulnerability classes in the Mediterranean region and are characterized by different material properties, cross-section dimensions, and detailing. The first case study is a ductile MRF designed according to Eurocode 8 (i.e., a special-code frame), while the second is a non-ductile MRF designed to sustain only gravity loads (i.e., a pre-code frame). The influence of masonry infills on their seismic performance is also investigated. Advanced numerical models are developed to perform cloud-based sequential nonlinear time history analyses using ground-motion sequences assembled by randomly pairing two real records via Latin hypercube sampling. Different structure-specific damage states are considered to derive fragility curves for the undamaged structures, when subjected to a single ground-motion record, and state-dependent fragility curves by considering the additional damage induced by a second ground-motion record within the sequence. Damage-to-loss models are then used to derive mean vulnerability relationships. Results of the analysis show the importance of considering the effect of damage accumulation in the pre-code frames. Moreover, the presence of infills shows an overall positive contribution to the seismic performance of both frame types. Vector-valued vulnerability relationships accounting for the damaging effect of two ground-motion records are finally presented in the form of mean vulnerability surfaces.

scholarly journals Assessment of an Existing RC Building before and after Strengthening Using Nonlinear Static Procedure and Incremental Dynamic Analysis

2010 ◽  
Vol 17 (4-5) ◽  
pp. 619-629 ◽  
Author(s):  
Amir A. Hedayat ◽  
Hakan Yalciner
Keyword(s):  
Structural Damage ◽  
Fragility Curves ◽  
Performance Level ◽  
Seismic Zone ◽  
Existing Buildings ◽  
Limit States ◽  
Rc Building ◽  
Nonlinear Static ◽  
Fema 356 ◽  
Strengthening Method

Inadequate attention during design and construction of some of reinforced concrete (RC) buildings in Cyprus has raised questions about the performance level of these existing buildings under future earthquakes. This study aimed to assess the seismic structural response of a four story existing RC building. For this purpose, first, the weak structural elements (e.g.\ the not safety column-beam joints and weak columns) were detected using linear static procedure (LSP) analyses on the basis of Turkish earthquake code. Then, two different strengthening methods were examined. In the first method which is common in Cyprus, the existing building was strengthened based on LSP, using column jacketing to satisfy seismic code requirements to remove the weak elements. The second strengthening method was carried out using nonlinear static procedures (NSP) to achieve the basic safety objective (BSO) performance level described in FEMA 356. For existing and both strengthened structures, pushover curves were obtained and following FEMA 356, performance points were calculated and compared. The seismic responses of existing and strengthened buildings were also assessed using incremental dynamic analyses (IDA). Nonlinear dynamic time history analyses have been performed by using SDOF models of these buildings under action of different scales of 20 ground motion records. Then IDA curves for each earthquake have been constructed. Limit – states at each performance level have been defined and summarizing the multi – record IDA curves, 16%, 50% and 84% fractile curves were obtained. Since selected structure represents common existing buildings in Cyprus, probabilistic structural damage estimation fragility curves were also obtained in terms of peak ground acceleration (PGA) for each considered performance level. Results showed that the strengthening method based on the NSP to satisfy the BSO requirements is much more effective than the one based on the LSP to improve the building performance and to reduce the probability of exceeding of limit states IO, LS and CP at any seismic zone.

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