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.

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.

scholarly journals Fragility Assessment of a Container Crane under Seismic Excitation Considering Uplift and Derailment Behavior

2019 ◽  
Vol 9 (21) ◽  
pp. 4660
Author(s):  
Quang Huy Tran ◽  
Jungwon Huh ◽  
Nhu Son Doan ◽  
Van Ha Mac ◽  
Jin-Hee Ahn
Keyword(s):  
Structural Damage ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Three Dimensional ◽  
Time History ◽  
Element Model ◽  
Seismic Excitation ◽  
Damage State ◽  
Limit States ◽  
Container Crane

While the container crane is an important part of daily port operations, it has received little attention in comparison with other infrastructures such as buildings and bridges. Crane collapses owing to earthquakes affect the operation of the port and indirectly impact the economy. This study proposes fragility analyses for various damage levels of a container crane, thus enabling the port owner and partners to better understand the seismic vulnerability presented by container cranes. A large number of nonlinear time-history analyses were applied for a three-dimensional (3D) finite element model to quantify the vulnerability of a Korean case-study container crane considering the uplift and derailment behavior. The uncertainty of the demand and capacity of the crane structures were also considered through random variables, i.e., the elastic modulus of members, ground motion profile, and intensity. The results analyzed in the case of the Korean container crane indicated the probability of exceeding the first uplift with or without derailment before the crane reached the structure’s limit states. This implies that under low seismic excitation, the crane may be derailed without any structural damage. However, when the crane reaches the minor damage state, this condition is always coupled with a certain probability of uplift with or without derailment. Furthermore, this study proposes fragility curves developed for different structural periods to enable port stakeholders to assess the risk of their container crane.

scholarly journals Fragility Assessment of Container Crane under Seismic Excitation Considering Uplift and Derailment Behavior

2019 ◽  
Author(s):  
Quang Huy Tran ◽  
Jungwon Huh ◽  
Nhu Son Doan ◽  
Van Ha Mac ◽  
Jin-Hee Ahn
Keyword(s):  
Structural Damage ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Three Dimensional ◽  
Time History ◽  
Element Model ◽  
Seismic Excitation ◽  
Damage State ◽  
Limit States ◽  
Container Crane

While the container crane is an important part of daily port operations, it has received little attention compared with other infrastructures, such as buildings and bridges. Crane collapse due to earthquake affects the operation of the port, and indirectly impacts the economy. This study proposes fragility analyses for various damage levels of the container crane that allow the port owner and partners to better understand the seismic vulnerability presented by container cranes. A large quantity of nonlinear time history analyses was applied for a three-dimensional (3D) finite element model to quantify the vulnerability of the container crane in considering the uplift and derailment behavior. The uncertainty of demand and capacity of the crane structures were also considered through random variables, i.e. elastic modulus of members, ground motion profile, and intensity. The results analyzed in the case of a Korean container crane showed that the probability of exceeding the first uplift with or without derailment is shown before the crane reaches the structure’s limit states. This means that under low seismic excitation, the crane might be derailed without any structural damage. But when the crane reaches the minor damage state, it is always coupled with a certain probability of uplift with or without derailment. This study also proposes the fragility curves developed for different structural periods to enable port stakeholders to assess the risk of their container crane.

scholarly journals Seismic Fragility Curves for RC Flat Slab Buildings with and Without Infill

2019 ◽  
Vol 9 (2) ◽  
pp. 3541-3547
Keyword(s):  
Ground Motion ◽  
Structural Damage ◽  
Fragility Curves ◽  
Commercial Buildings ◽  
Seismic Zone ◽  
Rapid Urbanization ◽  
Load Effect ◽  
Flat Slab ◽  
Capacity Curves ◽  
Building Models

Rapid urbanization leads to more demand for construction of commercial buildings in Indian cities. The ease construction and more space demand of buildings are constrained in conventional buildings. To overcome constrained, the flat slab buildings evolved and practiced recent time in urban cities. It is becoming more popular for multistoried commercial buildings but experiences larger displacements under lateral load effect caused by earthquakes. These buildings need urgent to assess the vulnerability of buildings. In this fragility analysis is carried out, and it is useful for the evaluation of the probability of structural damage due to earthquakes as a function of ground motion indices. This paper is an attempt made to develop the fragility curves for seven-storey RC commercial buildings and a comparison made between the bare frame, flat slab, flat slab with drop, flat slab with drop and perimeter beam buildings without and with exterior infill walls. The building models are analyzed using ETABS software and designed as per IS 456. In this, infills are considered along the perimeter of the plan of the building and no infill in ground storey. The infill wall is modelled as equivalent diagonal strut model. The Auto hinges are assigned for both beam and column members. Pushover analysis has been performed on the building models using ETABS software. Yield and ultimate spectral displacement and spectral acceleration are obtained from capacity curves. For the development of fragility curves, HAZUS methodology has been used. Fragility curves are developed for all the eight building models and compared the probability of damage of structures for bare frames and open ground storey buildings. In this assumed, the expected intensity ground motion is considered as seismic zone PGA values. It is observed that in considered flat slab models, flat slab with drop and perimeter beam building is showing minimum probability of damage results in both with and without infill for given intensities.

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.

Seismic Performance Evaluation of Liquid Storage Tanks Using Nonlinear Static Procedures

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Konstantinos Bakalis ◽  
Athanasia K. Kazantzi ◽  
Dimitrios Vamvatsikos ◽  
Michalis Fragiadakis
Keyword(s):  
Seismic Performance ◽  
Failure Modes ◽  
Fragility Curves ◽  
Nonlinear Static Analysis ◽  
Elastic Response ◽  
Storage Tanks ◽  
Limit States ◽  
Modes Of Failure ◽  
Liquid Storage ◽  
Nonlinear Static

A simplified approach is presented for the seismic performance assessment of liquid storage tanks. The proposed methodology relies on a nonlinear static analysis, in conjunction with suitable “strength ratio-ductility-period” relationships, to derive the associated structural demand for the desired range of seismic intensities. In the absence of available relationships that are deemed fit to represent the nonlinear-elastic response of liquid storage tanks, several incremental dynamic analyses are performed for variable post-yield hardening ratios and periods in order to form a set of data that enables the fitting of the response. Following the identification of common modes of failure such as elephant's foot buckling (EFB), base plate plastic rotation, and sloshing wave damage, the aforementioned relationships are employed to derive the 16%, 50%, and 84% percentiles for each of the respective response parameters. Fragility curves are extracted for the considered failure modes, taking special care to appropriately quantify both the median and the dispersion of capacity and demand. A comparison with the corresponding results of incremental dynamic analysis (IDA) reveals that the pushover approach offers a reasonable agreement for the majority of failure modes and limit states considered.

scholarly journals Fragility and Vulnerability Analysis of an RC Building with the Application of Nonlinear Analysis

Buildings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 390
Author(s):  
Radomir Folić ◽  
Miloš Čokić
Keyword(s):  
Comparative Analysis ◽  
Structural Damage ◽  
Fragility Curves ◽  
Response Spectrum ◽  
Damage Index ◽  
Fragility Analysis ◽  
Elastic Response ◽  
Damage State ◽  
Damage States ◽  
Rc Building

In this paper, the seismic response of a five-story reinforced concrete (RC) frame system building is analysed through fragility analysis. The structure is designed in accordance with structural Eurocodes EN1990, EN1991, EN1992 and EN1998, as a high-ductility (DCH) system. For the analysis of the response of a structural system to earthquake actions, the methods of nonlinear static (NSA) and nonlinear dynamic analyses (NDA) are applied and, based on the obtained results, fragility curves are constructed using statistical methods. A relationship between the intensity measure (IM) and engineering demand parameters (EDPs) is needed in order to estimate a fragility curve. Fragility functions represent a possibility for different states of damage to occur in a certain structural systems at the observed value of the specified IM. Ten accelerograms, used in NDA, are selected and scaled, according to EN1998 provisions, for the chosen elastic response spectrum and referent PGA. Obtained results are used for the statistical analysis and construction of fragility curves. Structural damage state threshold parameters are determined based on the Park and Ang modified damage index methodology and provisions given in FEMA, HAZUS, VISION 2000 and EN codes. Comparative analysis of the structural damage probability for the analysed RC building, calculated using different methodologies to determine damage states, is applied. The fragility analysis results showed the difference between the probabilities of the damage states to occur when different calculation methods are used. This reflects on the assessment of vulnerability curves as well. The obtained results, calculated using different methods, are analysed using comparative analysis.

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