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The 26 December 2004 Indian Ocean tsunami caused damage to many buildings and killed a lot of people in several countries that border on the Indian Ocean including Thailand. To understand the behaviour of reinforced-concrete buildings under tsunami loads, a generic one-storey building has been developed from the average values of the structural ind...
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... This approach needs to fix a measure of the uncertainties involved, which converge to a unique number that synthetically encloses the uncertainties associated with demand and the uncertainties connected to structural capacity. Analytical fragility curves have been proposed as a prediction tool for different types of constructions [17][18][19]26]. Recently, Ferrotto and Cavaleri [27] proposed an approach for masonry buildings in the Mediterranean area. ...
Tsunami vulnerability of coastal buildings has gained more and more interest in recent years, in the consciousness of what losses may be caused. The improvement of the available approaches for the quantitative estimation of the probability of building damage and for defining possible strategies for risk mitigation is an actual goal. In this framework, several authors have provided empirical fragility curves based on field surveys after tsunamis. Nevertheless, a predictive approach based on analytical fragility curves, which can be extended to many classes of buildings, is essential for the scopes of civil protection and risk mitigation. In this paper, an approach for the construction of fragility curves, proposed for masonry structures under tsunami waves, is discussed and refined in the part regarding the assignment of the uncertainties. Further, an assessment of the reliability of the lognormal fragility distribution is carried out based on a Monte Carlo simulation applied to 4 classes of buildings. Here, it is shown that Monte Carlo analysis allows a direct evaluation of the uncertainties without the need to resort to ambiguous regression analyses and rules of combination of the uncertainties of demand and capacity based on the regression analysis results or other uncertainty estimation approaches.
... Different authors (e.g. [8][9][10][11][12][13][14][15][16][17][18]) have faced the problem of obtaining a fragility curve for different classes of constructions. However, no analytical fragility functions for masonry buildings seem that have been proposed until now. ...
... Conversely, analytical fragility curves have been proposed mainly for reinforced concrete and steel moment resisting frame structures [5,6,19,38,27,34]. To the best knowledge of the authors, no analytical fragility functions for masonry buildings have been proposed until now. ...
... There are several studies that propose approaches to generate fragility curves [5,19,38,27,34,15]. Each study follows a specific procedure depending on the type of loads considered, the intensity measure assumed to derive fragility, the type of structure considered. ...
Evaluation of tsunami vulnerability of coastal buildings is gaining high interest in recent years in the areas with high tsunami hazard. Fragility evaluation is a fundamental step to obtain a quantitative estimation of the probability of building damage and in order to define possible strategies for risk mitigation. Several empirical fragility curves are available for masonry structures. However, an empirical fragility curve is generally based on field surveys after tsunami events, not always available. Conversely, analytical fragility curves are based on prediction approaches. In this paper, a proposal for the evaluation of analytical fragility curves for masonry structures typical of the Mediterranean coasts based on simplified structural analyses and damage indexes is presented. The proposal considers the uncertainties in both the structural demand and capacity probabilistically.
Several Monte Carlo simulations on some masonry structure types have been carried out to evaluate the fragility related to each fixed damage state assuming the inundation depth as intensity measure. Finally, the validity of the results is discussed by comparisons with empirical fragility curves available in the literature.
... Many difficulties arise to define generalized analysis strategies for each structural type (reinforced concrete, steel, masonry, and timber structures). Differently from the case of seismic analysis of structures, for which several modeling strategies have been widely assessed, the assessment of buildings under tsunami load is extremely different [4][5]. The substantial difference between tsunami and seismic loads is that the latter is directly connected to mass and stiffness characteristics of the structure. ...
... Such curves are expressed assuming different damage states for the structures of the site, the type of structures (depending of the type of the materials used), the number of floors etc. (response variables). Then, the fragility curves are linked with the explanatory variables such as the inundation depth, the tsunami force, etc. [5,[7][8][9]. Other strategies involve the definition of analytical fragility curves based on the analytical evaluation of capacity [10][11]. ...
Tsunamis are among the most dangerous natural disasters for coastal areas experiencing tsunami hazard. One of the major concerns in the assessment of strategies for the risk mitigation is to estimate vulnerability of structures and infrastructures. However, reliable approaches for the evaluation of the structural capacity under tsunami loads are nowadays not always available for all the types of structures, especially masonry. On this aim, the paper deals with the modeling issues of 3D masonry structures subjected to tsunami loads and the effect on the structural behavior of different modeling approaches. First, a brief state of the art on the available studies is presented regarding the evaluation of tsunami forces on buildings and the studies carried out on the determination of structural capacity.
Then, an advanced structural analysis software based on the Finite Element Method (FEM) is used to analyze the influence of parameters such as load type, masonry type and interaction properties type. Finally, an application on a typical two-storey masonry structure subjected to tsunami load according to the actual codes is presented and discussed, providing recommendations on the assumptions to be made for the definition of a reliable numerical model.
The findings of the numerical simulations revealed that the structural response is strongly influenced by the modeling approach defined for the masonry walls in terms of interaction properties and the type of connection between orthogonal walls. Moreover, it was observed that, as for the case of seismic analysis, when local behavior governs the failure, lower structural capacity is obtained, while in the case of global behavior governing the failure, higher structural performances are provided.
... In the model, the water hydrodynamic distribution pressures acting on buildings due to tsunamis were accounted for as equivalent uniform lateral loads applied on the structural elements for each flow depth (Medina et al. 2019). Hence, each flow depth had a corresponding specific building response due to the related failure mechanisms of the structure (Foytong et al. 2015). ...
A fragility function shows the building damage likelihood based on a demand parameter such as the tsunami flow depth. While empirical fragility functions have been developed by using postdisaster damage survey data, regions with no recent tsunami damage cannot develop these estimations. Alternatively, analytical fragility functions could be developed to fill this gap. Along the Colombian Pacific coast, several tsunami events have occurred; however, the aftermath resulting from the structure physical damage was not recorded. Fortunately, other regions of the have collected tsunami damage information, which has been analyzed and represented in terms of empirical fragility functions. This paper provides a comparative study of empirical and analytical tsunami fragility functions. It is focused on the analytical fragility functions developed for typical structures in Tumaco, Colombia and on empirical fragility curves taken from damage survey data of recent tsunami events. The differences in the assessments of the damage produced by the two methods in the case of a two-story reinforced concrete building in Tumaco is discussed herein. As a result of the comparison, it was shown that the structures in Tumaco have higher collapse probabilities at lower flow depths than structures in other places along the Pacific and Indian Oceans.
... For each flow depth, a particular load distribution was applied on the structure elements. Therefore, each flow depth has a specific building structural response due to the failure performance of the structure under different actions [28]. The water distribution pressures on the structures due to tsunamis were considered here as uniform according to the results obtained from large-scale wave tests on walls [29]. ...
... In addition, this guideline recommends some load combinations, in which lateral forces are represented by hydrodynamic forces in combination with impulsive forces and debris forces. By contrast, other researchers have suggested that only hydrodynamic and buoyancy forces could be considered approaching the pressure distribution, because they are responsible for the main pressures that could cause building damage [55,54,28]. Although the debris impact could be crucial in building damage, due to its probability of occurrence and the modeling issues, some authors have neglected it to assess building vulnerability [9,26]. ...
... In tsunami vulnerability assessments, there is not a standard methodology that allows researchers to obtain fragility curves from numerical or theoretical methods. Although some investigations have been carried out in order to get the structural response of a particular building, the theoretical damage assessment of these structures under tsunami loads is still a new field of knowledge within the risk analysis [77,78,16,8,9,79,28]. ...
From the last large seismic movements generated in the Pacific Ocean, it has been demonstrated that tsunamis have a high potential of destruction of buildings on the coasts. In that sense, although along the Pacific Colombian coast several earthquakes that have generated tsunami were reported during the last century, there are no local data to quantify the physical damage that future events could produce on nearby cities. For the purpose of establishing tools to increase the risk management capabilities along the Colombian-Ecuadorian Pacific Coast, this paper summarizes a research aimed to describe a new integrated methodology to obtain fragility curves for local buildings at risk of a tsunami. This task was accomplished using computational non-linear structural analysis, combined with a Monte Carlo statistical algorithm to obtain numerical probabilistic fragility curves. The structural capacity of buildings was obtained from nonlinear structural simulations using the finite element method, to calculate later the damage of each building. Two different damage models to estimate the probability of damage were tested in order to evaluate the one that better represents the structural behavior of buildings, in which the tsunami was considered in the structural model as forces scattered to different heights, thus representing different flow depths. As a result, a methodology was developed to calculate theoretical probabilistic fragility curves for the typical structures found in the Colombian Pacific coast, although this methodology could be expanded to any structural system located in any region around the world. As an illustrative example, the methodology proposed in this research was applied to a typical reinforced concrete building, obtained from a previous work in which all the Tumaco city buildings were characterized according to their structural features.
... Macabuag et al. [31] proposed a method for deriving analytical tsunami fragility functions for an RC frame structure using iterative structural analyses and design standard tsunami loadings and also proposed the material strain be used as engineering demand parameter. Foytong et al. [32] investigated numerically the response of a RC building under increasing tsunami loading, considering shear and flexural failure in the collapse state. Nanayakkara and Dias [33] developed a probabilistic model using Monte Carlo simulations to produce fragility functions for masonry and RC structures, considering only the complete collapse state, as it was the easiest to define. ...
... [23,24,27]) and results from other numerical studies (i.e. [32]). ...
... The numerical tsunami fragility curves for the RC MRF 2-storey building are finally compared with the results of a relevant numerical study conducted by Foytong et al. [32]. The median values of inundation depth proposed in our study are close to the key-point results (where the behaviour of the structure changes) derived by Foytong et al. [32], also enhancing the reliability of the proposed curves. ...
Harbours are crucial assets for the sustainment and development of human activities. The recent devastating tsunami events as well as the increasing number of people, structures and economic activities being exposed to tsunami hazards revealed the need for the estimation of the effects of tsunami wave on seaport structures. However, only a limited number of tools to estimate the potential impacts of tsunami are available until now. This study aims at developing analytical tsunami fragility functions for some representative typologies of seaport structures in Greece. In particular, low-code moment resisting frame (MRF) and dual reinforced concrete (RC) buildings of various heights, and a typical warehouse are considered in the analysis. A numerical investigation is performed considering different combinations of tsunami loads based on FEMA P646 (2008) recommendations for gradually increasing tsunami inundation depths and for the various structure typologies. To minimize the uncertainties related to the definition of damage limit states, tsunami nonlinear static analyses are performed and appropriate tsunami capacity curves are derived for the considered structures. Structural limit states are defined on tsunami capacity curves in terms of threshold values of material strain. For the complete
damage state, shear failure is also considered, since the collapse of structures may be caused by the occurrence of either a flexural or shear failure in structural components. Fragility curves are numerically calculated for the different damage states using nonlinear regression analysis. They could be used within a probabilistic risk assessment framework to assess the vulnerability of low-code RC buildings and typical warehouses exposed to tsunami hazard along European-Mediterranean and other regions of similar facilities worldwide.
... Therefore, only preliminary comparisons can be made. The numerical tsunami fragility curves for the 2-storey RC MRF building subjected to tsunami forces were finally compared with the results of a relevant numerical study conducted by Foytong et al. (2015). They analyzed a generic one-storey building to capture responses under tsunami forces. ...
While lessons learnt from recent devastating tsunami events revealed the need for the estimation of the effects of tsunami wave on coastal structures, only a limited number of tools to estimate the potential impacts of tsunami are available until now. This study aims at developing an efficient analytical methodology for assessing the vulnerability of typical seaside low-code reinforced concrete buildings subjected to tsunami. Tsunami loading is taken into account based on FEMA (2008) recommendations for gradually increasing tsunami inundation depths. Tsunami nonlinear static analyses are performed and appropriate tsunami capacity curves are derived. Appropriate structure-specific limit states are defined on the tsunami capacity curves in terms of threshold values of material strain. For the complete damage state, shear failure is also considered, since the collapse of structures may be caused by the occurrence of either a flexural or shear failure in structural components. The proposed methodology results to the development of log-normally distributed fragility curves for different structural damage states, as a function of the inundation depth, considering different sources of uncertainty. It is shown that the height of the structure represents a key factor affecting the vulnerability assessment. The proposed methodology and the derived fragility curves could be used within a quantitative risk assessment framework to assess the structural damages of typical low-code RC buildings in South Europe subjected to tsunami loading.
... For each earthquake wave in this table, peak ground acceleration was normalized and set to 0.05g in x and y directions, and to 0.033g in z direction. Foytong et al. [28] compared the results from previous studies and found the value of 2.0 to be conservatively large. They recommended that the appropriate value for coefficient C should range from 0.7 to 2.0. ...
Nuclear power plants under expansion and under construction in China are mostly located in coastal areas, which means they are at risk of suffering strong earthquakes and subsequent tsunamis. This paper presents a safety analysis for a new reinforced concrete containment vessel in such events. A finite element method based model was built, verified and first used to understand the seismic performance of the containment vessel under earthquakes with increased intensities. Then, the model was used to assess the safety performance of the containment vessel subject to an earthquake with peak ground acceleration (PGA) of 0.56g and subsequent tsunamis with increased inundation depths, similar to the 2011 Great East earthquake and tsunami in Japan. Results indicated that the containment vessel reached Limit State I (concrete cracking) and Limit State II (concrete crushing) when the PGAs were in a range of 0.8g–1.1g and 1.2g–1.7g, respectively. The containment vessel reached Limit State I with a tsunami inundation depth of 10 m after suffering an earthquake with a PGA of 0.56g. A site-specific hazard assessment was conducted to consider the likelihood of tsunami sources.
... It should be highlighted that the existing literature typically considers CHPO to investigate the structural performance [36] and that VHPO and TH are applied for the first time in this study. Future activities will focus on the identification of a pushover procedure which combines the two pushover methods presented herein in order to capture the post-peak behaviour and to adopt a realistic load pattern evolution. ...
Current guidelines for design and assessment of buildings under tsunami actions do not explicitly state how to apply tsunami loads to buildings and which analysis methods to use in order to assess the structural response to the tsunami loads. In this paper, a reinforced concrete (RC) moment-resisting frame, which is designed as a tsunami evacuation building, is selected as a case study and subjected to simulated 2011 Tohoku tsunami waves. To assess tsunami impact on the model building, different nonlinear static analyses, i.e. constant-height pushover (CHPO) and variable-height pushover (VHPO), are compared with nonlinear dynamic analysis. The results of VHPO provide a good prediction of engineering demand parameters and collapse fragility curves obtained from the dynamic analysis under a wide range of tsunami loading. On the other hand, CHPO tends to overestimate interstorey drift ratio (IDR) and underestimate column shear by about 5–20%. It provides a larger fragility, i.e. about 10% in median value, for global failure and a smaller fragility for local shear failure. On the basis of these results, it is recommended that VHPO be used in future fragility analysis of buildings subjected to tsunami. However, pushover methods might not be adequate in cases where the tsunami inundation force time-histories are characterised by a “double-peak”, which subjects the structure to a two-cycle load. Finally, it is found that tsunami peak force is better correlated to IDR than flow velocity and inundation depth for the considered structure. This suggests that the peak force would be a more efficient intensity measure than the other two in the development of tsunami fragility curves.
