Search

This paper presents an investigation of the collapse of a 325-year-old multi-tiered heritage temple during the 2015 Gorkha earthquake in Kathmandu, Nepal. The research comprises a reconnaissance survey followed by a geotechnical investigation and numerical back-analysis carried out to understand the potential causes of the collapse. The assessment of the structural configuration of the temple indicated seismic vulnerability in the design due to the presence of discontinuous columns over the height of the temple and age-weakened bonding in the masonry walls. The geotechnical investigation revealed the presence of competent soil strata at the location, assisting the survey which indicated no differential or excessive settlement in the foundation. A series of cyclic triaxial tests were conducted on samples recovered during the geotechnical investigation to determine dynamic behaviour of the soil. Further, dynamic analysis of the plinth of the temple under the recorded acceleration–time history indicated a maximum drift percentage of 1.4% and residual relative displacement of 32 mm suggesting the potential reason behind the collapse. The output of this research will support seismic rehabilitation of ancient structures within World Heritage sites across Nepal and effective action plans to safeguard them against future earthquake hazard.

Disasters affect millions of people annually, causing large numbers of fatalities, detrimental economic impact and the displacement of communities. Policy-makers, researchers and industry professionals are regularly faced with these consequences and therefore require tools to assess the potential impacts and provide sustainable solutions, often with only very limited information. This paper focuses on the themes of “disaster management”, “natural hazards” and “simulation”, aiming to identify current research trends using bibliometric analysis. This analysis technique combines quantitative and statistical methods to identify these trends, assess quality and measure development. The study has concluded that natural hazards (73%) are more predominant in research than man-made hazards (14%). Of the man-made hazards covered, terrorism is the most prevalent (83%). The most frequent disaster types are climate related, and in this study hydrological (20%), geophysical (20%), meteorological (15%) and climatological (5%) were the most frequently researched. Asia experiences the highest number of disaster events as a continent but in this study was only included in 11% of papers, with North America being the most recurrent (59%). There were some surprising omissions, such as Africa, which did not feature in a single paper. Despite the inclusion of key words “simulation” and “agent based” in the searches, the study did not demonstrate there is a large volume of research being carried out using numerical modelling techniques. Finally, research is appearing to take a reactive rather than proactive approach to disaster management planning, but the merit of this approach is questionable.

The 2020 Zagreb earthquake occurred on Sunday 22 March 2020. This earthquake was the first that happened during the lockdown imposed by governments to stop spreading the COVID-19. This fact makes the event interesting as a multi-hazard phenomenon. The lockdown made it not possible to deploy an earthquake reconnaissance mission. Therefore, it was necessary to undertake a remote mission supported by the monitoring and analysing social media (SM) platforms, such as Twitter and Instagram. This paper presents details and analysis of this monitoring and how it may help understand the impacts of an earthquake. In our work, we first identified the hashtags related to the event. Through the LastQuake app, we obtained the intensity reports from affected people and comments and pictures useful for damage assessment. The team obtained 59,246 tweets posted between the 20th March and the 30th April 2020 and 31,911 comments from LastQuake app users written on the day of the earthquake. Images from posts and comments were used for remote assessment of damage in buildings. Sentiment analysis (SA) was applied to tweets and comments related to the event to assess emergency management during the relief phase after the earthquake. Our work shows that only a limited number of pictures collected through social media were suitable for damage assessment of individual buildings. However, they were still useful as a proxy estimation of damages in some areas of Zagreb and surroundings. We also found SA supported by machine learning a valuable method to assess and identify critical aspects of the emergency and early recovery post-disaster phases. Applying SA we identified the most affected areas, the damages in the non-structural elements in hospitals, the support of collaborative networks for the evacuation of patients and the role of Ministers in the early recovery.

Synchrotron light sources are routinely used to perform imaging experiments. In this paper, we review the relevant computational stages, identify bottlenecks, and highlight future opportunities to streamline data acquisition for experimental microscopy workflows. We demonstrate our preliminary exploration with an end-to-end scientific workflow on Summit based on micro-computed tomography data. Computational elements include: 1) reconstruction of volumetric image data; 2) denoising with deep neural networks; and 3) non-local means based segmentation and quantitative analysis.

After the 2004 Boxing Day tsunami, much of the world's effort to defend against tsunami concentrated on tsunami warning and evacuation. The 2011 Great East Japan Earthquake and Tsunami led to direct and indirect losses as well as the deaths of many vulnerable members of Japan's coastal communities. This event has resulted in Japan rethinking and revising its design codes for sea defence structures. The new guidance emerging from this process is a valuable resource for other countries re-evaluating their own current mitigation strategies and this paper presents details of this process. The paper starts with the history of sea defence design standards in Japan and explains the process of revision of design guidelines since 2011. Examples of sea defences that failed and have since been rebuilt, observed during the two Earthquake Engineering Field Investigation Team (EEFIT) missions of 2011 and 2013, are also presented. The paper concludes with a discussion of international approaches and their application to nuclear power stations in Japan and the UK.

Cultural heritage structural documentation is of great importance in terms of historical preservation, tourism, educational and spiritual values. Cultural heritage across the world, and in Nepal in particular, is at risk from various natural hazards (e.g. earthquakes, flooding, rainfall etc), poor maintenance and preservation, and even human destruction. This paper evaluates the feasibility of low-cost photogrammetric modelling cultural heritage sites, and explores the practicality of using photogrammetry in Nepal. The full pipeline of 3D modelling for heritage documentation and conservation, including visualisation, reconstruction, and structure analysis, is proposed. In addition, crowdsourcing is discussed as a method of data collection of growing prominence.

Currently, there is a great deal of interest in assessing the resilience of infrastructure systems. Much of this interest stems from the realisation that these systems are not only critical to civil defence but also, given the correct set of circumstances, can fail catastrophically. Three case studies are presented that show how network theory, which has been successfully applied to other fields, can also be used to help understand potential vulnerabilities in infrastructure systems. Through these case studies it is shown that traditional network theory can be extended to analyse infrastructures that are large, spatially distributed systems, or that carry flows of resources or are interconnected with other infrastructure systems. These methods demonstrate how this approach can help infrastructure designers, owners and operators to make rapid assessments of vulnerabilities in their systems and to identify components that are more important to the functioning of the these networks. Furthermore, this approach provides a basis for identifying and prioritising appropriate measures to improve the reliability of infrastructure at the systems scale.

This paper applies graph theory metrics to network flow models, with the aim of assessing the possibility of using these metrics to identify vulnerable areas within infrastructure systems. To achieve this, a reduced complexity flow model that can be used to simulate flows in infrastructure networks is developed. The reason for developing this model is not to make the analysis easier, but to reduce the physical problem to its most basic level and therefore produce the most general flow model (i.e., applicable to the widest range of infrastructure networks). An initial assessment of the applicability of graph theory metrics to infrastructure networks is made by comparing the distribution of flows, calculated using this model, to the shortest average path length in three of the most recognized classes of network—scale-free networks, small-world networks, and random graph models—and it is demonstrated that for all three classes of network there is a strong correlation. This suggests that at least part...

Historical electrical disturbances highlight the impact of extreme weather on power system resilience. Even though the occurrence of such events is rare, the severity of their potential impact calls for (i) developing suitable resilience assessment techniques to capture their impacts and (ii) assessing relevant strategies to mitigate them. This paper aims to provide fundamentals insights on the modelling and quantification of power systems resilience. Specifically, a fragility model of individual components and then of the whole transmission system is built for mapping the real-time impact of severe weather, with focus on wind events, on their failure probabilities. A probabilistic multi-temporal and multi-regional resilience assessment methodology, based on optimal power flow and sequential Monte Carlo simulation, is then introduced, allowing the assessment of the spatiotemporal impact of a windstorm moving across a transmission network. Different risk-based resilience enhancement (or “adaptation”) measures are evaluated, which are driven by the resilience achievement worth (RAW) index of the individual transmission components. The methodology is demonstrated using a test version of the Great Britain’s system. As key outputs, the results demonstrate how, by using a mix of infrastructure and operational indices, it is possible to effectively quantify system resilience to extreme weather, identify and prioritize critical network sections, whose criticality depends on the weather intensity, and assess the technical benefits of different adaptation measures to enhance resilience.

The UK Earthquake Engineering Field Investigation Team (Eefit) was established as an independent society in 1982. Between 1984 and 2011, it carried out field missions to 29 earthquake zones, with reports on all of them freely available online. Over a hundred UK-based engineers have participated, split almost equally between industry and academia. There have been a number of significant benefits, including training through observations of the practical effects of ground shaking, fostering strong links between practising and academic participants, establishing international links and gathering data for research into a wide range of earthquake engineering topics. The paper outlines Eefit’s history and development, sets out its achievements and presents details of a recent 5-year government grant that will extend its effectiveness still further.

Extreme weather may have a significant influence on the resilience of transmission systems. However, modelling the impact of weather is very challenging due to its stochastic and unpredicted nature and behaviour. To cope with these challenges, this paper presents a Sequential Monte Carlo based time-series model for evaluating the effect of weather on power system components, with focus on the wind effect on transmission lines and towers, and in turn on the entire transmission power infrastructure. The concept of fragility curves is used, which express the failure probabilities of the components as a continuous function of the wind speed. The mapping of the wind profile on these fragility curves provides the weather-affected operational state of the transmission lines and towers at every simulation time step. The model is illustrated using a simplified 29-bus model of the transmission network of Great Britain (GB). The simulation results highlight and quantify how the GB test network becomes less resilient for extreme wind events, and the effectiveness of mitigation strategies such as network reinforcement or redundancy.

On December 26, 2004 a great earthquake (M-W 9.3) occurred off the western coast of Sumatra triggering a series of tsunami waves that propagated across the Indian Ocean causing damage and life loss in 12 countries. This paper summarizes the observations of lifeline performance, building damage and its distribution, and the social and economic impact of the tsunami made by the Earthquake Engineering Field Investigation Team (EEFIT) in Thailand and Sri Lanka. EEFIT operates under the umbrella of the UK's Institution of Structural Engineers. It is observed that good engineering practice can reduce economic losses, but additional measures are required to reduce risk to life.

This paper proposes a new moment resisting detail for use in earthquake resistant structures. The wedge detail tested in this project is a new design that builds upon the idea of inducing a plastic hinge away from the column face to dissipate the energy that would otherwise yield the connection. The plastic capacity of the beam is locally reduced by decreasing the depth of the web and reforming the flange to the new beam profile. This makes the section more plastic, so reducing the buckling problem suffered by other reduced section joints. Laboratory testing shows that the joint is capable of plastic rotations greater than 0.05 rad without any significant loss of energy dissipation capability, which is far in excess of the requirements for a joint given by the latest standards based on post-Northridge data.

Recently, it has come to light that footbridges may have problems with human induced vibrations if their lateral period of vibration is of the order of 1 s. This has been highlighted by the much-publicized case of the Millennium Footbridge in London. This paper describes a similar problem associated with the historic Cragside Bridge built circa 1875. This bridge is a wonderful historic bridge built in the grounds of Cragside Manor in Northumberland, United Kingdom by the famous Industrialist Lord Armstrong. An investigation of the bridge revealed that it suffered vibration problems resulting from insufficient lateral stiffness. When lightly loaded (approximately six people) the fundamental lateral natural frequency of vibration was 2.6 Hz. This mode was predominantly a lateral mode of vibration. A computer model of the bridge was developed and various loading scenarios were investigated. As the bridge is very lightweight, the computer model showed that the natural frequency could reduce to 1.12 Hz if the bridge was loaded to 4 kPa. Extra stiffening elements were added to the computer and, depending on the superimposed load, the frequency could be increased from 1.12 to 1.57 Hz (for a 4 kPa uniform live load) and increased to 3.67 Hz for an imposed load equivalent to approximately nine people. It is believed that this will help to remedy the problem, but further research is being conducted to reduce the problem further.

A materially non-linear plane-frame model is presented that is capable of analysing high-rise buildings subjected to earthquake forces. The model represents each storey of the building by an assembly of vertical and horizontal beam elements The model introduces yield hinges with ideal plastic properties in a regular plane frame. The displacements are described by the translation (sway) of each floor and the rotation of all beam-column intersections. The mass is only associated with the translations, and thus the analysis can be carried out as a static condensation of the rotations, combined with integration of the dynamic equations for the translations. The dynamic integration is here carried out by use of the Runge-Kutta scheme. This approach allows a building to be modelled by m(n+2) degrees of freedom (where m is the number of storeys and n is the number of bays). The rank of the condensed stiffness matrix is only m. Its construction, which requires the inversion of the rotational, rank m(n+1), stiffness matrix, is required only at time-steps where the pattern of yielding has altered from the previous time-step. This model is particularly attractive for non-linear response history analysis of high-rise buildings as it is efficient, allows each storey to have multiple redundancies, and each connection to be modelled with any suitable moment-rotation relationship. Three verification examples are presented and the results from static push-over analysis are compared with time-history results from the simplified model. The results verify that the model is capable of performing non-linear response history analysis on regular high rise buildings.

The increasing effects of climate change and extreme weather events on the operation of power systems highlight the need for developing effective techniques and models for evaluating the challenges that power systems may have to deal with in the future for maintaining high levels of resilience. Within this context, the aim of the `Resilient Electricity Networks for Great Britain (RESNET)' project is to develop and demonstrate a comprehensive approach to analyse the effects of climate-related changes on the resilience of the Great Britain's electricity system, and to develop tools for quantifying the value of adaptation measures that would enhance its resilience. This paper presents an overview of the key research activities and findings of RESNET project, specifically addressing possible climate change implications related to demand and supply scenarios, component ratings, and impact of extreme weather on system reliability. The final aim is to provide insights on various climate and weather-related challenges that the Great Britain's electricity system might face in the future.

Infrastructure systems are vitally important to our society as they deliver the goods and services that communities require to function. This reliance on infrastructure systems makes any disruption to their functioning liable to result in disproportionate consequences to communities. In this paper we investigate key parameters that exist in real world networks in an attempt to uncover the driving forces of network generation and evolution. We then present a network model that can reproduce networks with several non-trivial properties that are the key signature of real infrastructure networks. By changing the drivers that control evolution of our synthetic networks, the model can potentially help us to better predict what a future infrastructure network may look like, and how resilience it will be to future hazards.

Summary Background Hand eczema (HE) is a multifactorial disease, comprising different aetiological conditions and different morphologies. There are two aetiologically distinct groups of HE recognised: exogenous, such as contact dermatitis (allergic and/or irritant HE) and endogenous, such as the classic hyperkeratotic HE. Differences in the skin barrier properties of these two conditions could theoretically be expected. Aim To examine whether differences exist in the lipid profile and the susceptibility of the stratum corneum (SC) in patients with allergic/irritant HE and those with hyperkeratotic HE. Methods Using cyanoacrylate, SC samples were taken from 23 patients with allergic/irritant HE and 15 with hyperkeratotic HE for lipid analysis by high-performance thin-layer chromatography (HPTLC). Samples were also taken from adjacent, unaffected skin. Severity of HE was assessed by the Hand Eczema Severity Index (HECSI), and skin barrier susceptibility was assessed by measuring transepidermal water loss (TEWL) after a 24-hour patch test with sodium lauryl sulfate (SLS). Results No statistically significant difference was found between groups for the lipid analysis or for skin susceptibility to SLS. We found a significantly higher HECSI score for hyperkeratotic HE compared with irritant or allergic HE (P = 0.02). Conclusions There appears to be no difference in skin barrier between allergic/irritant HE (exogenous eczema) and hyperkeratotic HE (endogenous eczema) with regard to SC lipids or susceptibility to SLS.

A simplified procedure, which is a modification of the shear beam model, has been developed and applied to treat the seismic analysis of asymmetric buildings. This three dimensional procedure accounts for torsional coupling and the bending rotations at beam–column junctions and it can be used with a personal computer to give fast and reasonably accurate results, which compare well with those from comprehensive finite element analysis. This procedure will therefore be useful for preliminary seismic analysis and design of buildings.

Air traffic networks are essential to today’s global society. They are the fastest means of transporting physical goods and people and are a major contributor to the globalisation of the world’s economy. This increasing reliance requires these networks to have high resilience; however, previous events show that they can be susceptible to natural hazards. We assess two strategies to improve the resilience of air traffic networks and show an adaptive reconfiguration strategy is superior to a permanent re-routing solution. We find that, if traffic networks have fixed air routes, the geographical location of airports leaves them vulnerable to spatial hazard.