Tsunami are propagating waves characterized by long wavelengths and large amplitudes close to the shore. They may also have a profile characterised by a large trough preceding the positive wave. These waves are destructive, causing severe damage to structures and human casualties when they reach coastal areas (e.g., Indian Ocean, 2004; Japan, 2011). Runup is a local characteristic of a wave flow inland and this measure, easily identifiable in the field, is extensively used as an indicator of tsunami inundation and impact on the coast. In this paper, an innovative large scale experimental programme is applied to develop runup equations for long propagating waves. A pneumatic generator with a controlled valve system, capable of exchanging large volumes of water with the propagation flume is used. This novel generation system allows waves to be generated that have much larger wavelengths than those experimentally reproduced to date. Moreover, it enables leading depressed waves to be stably generated and analysed for the first time. To analyse the influence of wavelength and wave shape on runup, the experimental data was partitioned into groups classified by wave period T/Tb (where Tb is the travel time of a linear wave along the length of the beach) and wave shape (elevated or N-waves). In this paper, elevated waves refer to waves of translation having a single positive elevation above mean water level, and N-waves refer to waves of translation comprising both a negative elevation (below mean water level) and a positive elevation. Dimensional analysis (using experimentally determined wavelength, potential energy and wave amplitudes) was applied to identify correlated measures. A statistical analysis was used to determine a power law relationship between runup and measures of the waveform, and to test the significance of the power law hypothesis. The experimental results show how both the wavelength and wave shape influence the runup distance. For TTb<1, the runup is seen to scale as R∼a, while for TTb>1, it scales as R∼a.
Empirical fragility curves, constructed from databases of thousands of building-damage observations, are commonly used for earthquake risk assessments, particularly in Europe and Japan, where building stocks are often difficult to model analytically (e.g. old masonry structures or timber dwellings). Curves from different studies, however, display considerable differences, which lead to high uncertainty in the assessed seismic risk. One potential reason for this dispersion is the almost universal neglect of the spatial variability in ground motions and the epistemic uncertainty in ground-motion prediction. In this paper, databases of building damage are simulated using ground-motion fields that take account of spatial variability and a known fragility curve. These databases are then inverted, applying a standard approach for the derivation of empirical fragility curves, and the difference with the known curve is studied. A parametric analysis is conducted to investigate the impact of various assumptions on the results. By this approach, it is concluded that ground-motion variability leads to flatter fragility curves and that the epistemic uncertainty in the ground-motion prediction equation used can have a dramatic impact on the derived curves. Without dense ground-motion recording networks in the epicentral area empirical curves will remain highly uncertain. Moreover, the use of aggregated damage observations appears to substantially increase uncertainty in the empirical fragility assessment. In contrast, the use of limited randomly-chosen un-aggregated samples in the affected area can result in good predictions of fragility.
The importance of functioning education infrastructure for the post-disaster recovery of communities is becoming well-acknowledged. Yet, recent natural-hazard events worldwide have highlighted that school communities still face many post-disaster recovery-impeding challenges. A significant investment in resilience enhancement through appropriate disaster preparedness and post-disaster recovery management is needed to tackle such global challenges. This paper summarises a series of stakeholder engagements (through interviews and focus group discussions) aimed at developing evidence-based recommendations to foster a more rapid post-disaster recovery in schools in disaster-prone marginalised communities. The case-study community is in Central Sulawesi, Indonesia – a region still recovering from the 2018 Central Sulawesi earthquake, tsunami, and liquefaction which caused damage to over 1200 schools. The considered stakeholders have significant experience in post-disaster recovery management in Central Sulawesi. This paper identifies early-response funding mechanisms, true collaborations between stakeholders, and improved capacity for self-organisation as critical elements for an inclusive, sustainable, safer and more resilient education system. Although the discussion in this paper focuses on Central Sulawesi, the project's outcomes are scalable to other regions in Indonesia, South-East Asia, and other disaster-prone developing nations.
The majority of existing reinforced concrete (RC) buildings were built prior to the introduction of seismic codes. As observed in various recent earthquakes, due to their lack of structural capacity and ductility such structures are very vulnerable and have suffered considerable damage. The number of cyclic tests that have been carried out to investigate the behaviour of RC components with detailing typical of these buildings is very limited. Such tests are very relevant for seismic vulnerability assessment purposes. In this paper, a low-cycle fatigue testing campaign on RC columns and connections specifically devised to investigate various physical parameters that affect damage development, is presented. The campaign consists of 19 columns and 7 beam-column connections. Some of the preliminary results and observations are presented and discussed.
Recent tsunami events have stimulated research activity into tsunami fragility functions which have been largely based
on empirical data. However, empirical fragility functions are biased because the influence of earthquake and tsunami
damage are difficult to separate. We develop a new theoretical framework to assess the structural performance of a
building due to tsunami inundation by drawing on recent experimental and theoretical progress at UCL on building.
Different nonlinear static analyses, i.e. constant-height pushover (CHPO) and variable-height pushover (VHPO), are
compared with nonlinear dynamic analysis in assessing the fragility curves of a case study structure for a set of realistic
tsunami wave traces. The results of VHPO provide a good prediction of collapse fragility curves obtained from the
dynamic analysis under a wide range of tsunami time-histories. On the other hand, CHPO provides a larger, i.e. about
10% in median value, fragility in case global failure is considered 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.
Developmental Language Disorder (DLD) is frequent in childhood and may have long-term sequelae. By employing an evidence-based approach, this scoping review aims at identifying (a) early predictors of DLD; (b) the optimal age range for the use of screening and diagnostic tools; (c) effective diagnostic tools in preschool children.
Horizontal seismic demand is represented in seismic design codes by a single elastic response spectrum. Using a single spectrum conceals the difference between ground motions that are highly polarised and those for which the demand does not depend significantly on the orientation. In this study, two suites of ground motion were developed using the program RspMatchBi, with each suite characterised by different orientation dependence and seismic demand. Reinforced concrete space frames with various arrangements in plan were modelled in OpenSees. Non-linear time history analysis was carried out with the suites of records applied to the models at 9 degree increments, through 360 degrees of non-redundant orientations. An iteration process was implemented to determine the scaling factor for each ground motion at which storey drift exceeded a design level of 2.5% in 50% of applied orientations. Various performance criteria were also taken into account to investigate the changes in orientation dependence of seismic structural response. Results suggest that azimuthdependent structures are more vulnerable to orientation-dependent seismic demand, and that the investigation of directionality for seismic design needs further consideration in terms of performance criteria and structural periods at each principle axis.
Tsunami damage, fragility and vulnerability functions are statistical models which provide an estimate of expected damage or losses due to tsunami. They allow for quantification of risk, and so are a vital component of catastrophe models used for human and financial loss estimation, and for land-use and emergency planning. This paper collates and reviews the currently available tsunami fragility functions in order to highlight the current limitations, outline significant advances in this field, make recommendations for model derivation, and propose key areas for further research. Existing functions are first presented, and then key issues are identified in the current literature for each of the model components: building damage data (the response variable of the statistical model), tsunami intensity data (the explanatory variable), and the statistical model which links the two. Finally, recommendations are made regarding areas for future research and current best practices in deriving tsunami fragility functions (section 6). The information presented in this paper may be used to assess the quality of current estimations (both based on the quality of the data, and the quality of the models and methods adopted), and to adopt best practice when developing new fragility functions.
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