Performance Assessment of Masonry School Buildings to Seismic and Flood Hazards Using Bayesian Networks

Performance assessment of schools is an integral part of disaster risk reduction of communities from natural hazards such as earthquakes and floods. In regions of high exposure, these hazards may often act concurrently, whereby yearly flood events weaken masonry school buildings, rendering them more vulnerable to frequent earthquake shaking. This recurring damage, combined with other functional losses, ultimately result in disruption to education delivery, affecting vulnerable schoolchildren. This project examines behaviour of school buildings to seismic and flood loading, and associated disruption to education from a structural and functional perspective. The study is based on a case study of school buildings in Guwahati, India, where the majority of the buildings can be classified into confined masonry (CM) typology. This project presents three stages of analyses to study the performance of these CM school buildings and the system of schools, as summarised in the following. The first stage of the study involves refinement of the World Bank’s Global Library of School Infrastructure taxonomy to widen its scope and to fit the CM school typology. This leads to the identification of index buildings, which are single-story buildings with flexible diaphragms differing mainly in the level of seismic design. In the second stage, a novel numerical modelling platform based on Applied Element Method is used to analyse the index buildings for simplified lateral loads from both the aforementioned hazards. Seismic loading is applied in the form of ground acceleration, while flood loading is applied as hydrostatic pressure. Sequential scenarios are simulated by subjecting the building to varying flood depths followed by lateral ground acceleration, after accounting for the material degradation due to past flooding. Analytical fragility curves are derived for each case of analysis to quantify their physical performance, using a non-linear static procedure (N2 method) and least square error regression. The third stage of the study employs a Bayesian network (BN) based methodology to model the education disruption at the school system level, from exposure of schools to flood and seismic hazards. The methodology integrates the qualitative and quantitative nature of system variables, such as the physical fragility of school buildings (derived in the second stage), accessibility loss, change of use as shelters and socio-economic condition of the users-community. The performance of the education system impacted by the sequential hazards is quantified through the probability of the various states of disruption duration. The BN also explores the effectiveness of non-structural mitigating measures, such as the transfer of students between schools in the system. The framework proves to be a useful tool to assist decision-making, with regard to disaster preparedness and recovery, hence, contributing to the development of resilient education systems

Hybrid reconnaissance mission to the 30 October 2020 Aegean sea earthquake and tsunami (Izmir, Turkey & Samos, Greece): description of data collection methods and damage

On 30 October 2020, an earthquake of Mw 6.9 hit the Aegean coasts of Turkey and Greece. The epicentre was some 14 km northeast of Avlakia on Samos Island, and 25 km southwest of Seferihisar, Turkey, triggering also a tsunami. The event has been followed by >4,000 aftershocks up to Mw 5.2 The Earthquake Engineering Field Investigation Team (EEFIT) has immediately gathered a team to conduct a hybrid reconnaissance study,bringing together remote and field investigation techniques. The mission took place between 16 November and 17 December, inclusive of three sets of field study carried out by the field crews for building damage assessment in the affected areas in Turkey and Greece under the coordination of the remote team. The mission also aimed to assess the viability of alternative data sources for an appraisal of the future viability of hybrid missions. This paper summarises the mission setup and findings, and discusses the benefits of and difficulties encountered during this hybrid reconnaissance activity

Seismic Performance Assessment of Low-Rise Unreinforced and Confined Brick Masonry School Buildings Using the Applied Element Method

Masonry buildings are generally vulnerable to seismic action, as evidenced extensively in past earthquakes. In order to improve their seismic performance, several modifications have been introduced, such as reinforcing or confining the masonry. This paper presents a seismic analysis and fragility assessment procedure for non-engineered masonry building typologies, employing the applied element method (AEM). Compared to buildings with stiff diaphragms, the conventional pushover-based procedure is challenging for the seismic assessment of masonry buildings with flexible diaphragms, due to the lack of a global box-like behaviour. This study first presents a novel and validated method for nonlinear pushover analysis, independent of the type of diaphragm action on the building, by applying incremental ground acceleration and by considering suitable engineering demand parameters for the assessment of lateral capacity. Based on the failure mechanisms, a seismic performance assessment and fragility evaluation approach is then proposed, for reliable accounting of both the in-plane and out-of-plane failure modes. Finally, the proposed methodology is applied to a number of unreinforced and confined masonry school buildings with different seismic detailing levels, as often found in the Himalayan belt and beyond

Traditional Structures in Turkey and Greece in 30 October 2020 Aegean Sea Earthquake: Field Observations and Empirical Fragility Assessment

On 30th October 2020, an earthquake of magnitude 6.9 hit the Aegean coasts of Turkey and Greece. The epicentre was some 14 km northeast of Avlakia settlement on Samos Island, and 25 km southwest of Turkish town Seferihisar, Izmir. The destruction the earthquake caused concentrated mainly on the mid-rise RC buildings in certain districts of Izmir city. Among the diverse building typologies affected by the event are the traditional/vernacular hybrid timber-masonry and masonry buildings that are common to Turkey and Greece. This paper summarises and discusses the damage levels and mechanisms observed in these types of buildings, based on an extensive field and remote reconnaissance survey in the affected areas in both countries conducted by the Earthquake Engineering Field Investigation Team (EEFIT) of the United Kingdom Institute of Structural Engineers (IStructE). The observed damage is then discussed in light of the level of maintenance and occupancy status. The collected data are also used to empirically construct fragility curves, to assess whether a small sample can be used to describe the overall performance of the buildings in the area and how these compare to the outcomes of previous studies on comparable building stocks.</jats:p

Hybrid Reconnaissance Mission to the 30 October 2020 Aegean Sea Earthquake and Tsunami (Izmir, Turkey & Samos, Greece): Description of Data Collection Methods and Damage

On 30 October 2020, an earthquake of Mw 6.9 hit the Aegean coasts of Turkey and Greece. The epicentre was some 14 km northeast of Avlakia on Samos Island, and 25 km southwest of Seferihisar, Turkey, triggering also a tsunami. The event has been followed by &amp;gt;4,000 aftershocks up to Mw 5.2 The Earthquake Engineering Field Investigation Team (EEFIT) has immediately gathered a team to conduct a hybrid reconnaissance study, bringing together remote and field investigation techniques. The mission took place between 16 November and 17 December, inclusive of three sets of field study carried out by the field crews for building damage assessment in the affected areas in Turkey and Greece under the coordination of the remote team. The mission also aimed to assess the viability of alternative data sources for an appraisal of the future viability of hybrid missions. This paper summarises the mission setup and findings, and discusses the benefits of and difficulties encountered during this hybrid reconnaissance activity.</jats:p

Hybrid Reconnaissance Mission to the 30 October 2020 Aegean Sea Earthquake and Tsunami (Izmir, Turkey &amp; Samos, Greece): Description of Data Collection Methods and Damage

On 30 October 2020, an earthquake of Mw 6.9 hit the Aegean coasts of Turkey and Greece. The epicentre was some 14 km northeast of Avlakia on Samos Island, and 25 km southwest of Seferihisar, Turkey, triggering also a tsunami. The event has been followed by &amp;gt;4,000 aftershocks up to Mw 5.2 The Earthquake Engineering Field Investigation Team (EEFIT) has immediately gathered a team to conduct a hybrid reconnaissance study, bringing together remote and field investigation techniques. The mission took place between 16 November and 17 December, inclusive of three sets of field study carried out by the field crews for building damage assessment in the affected areas in Turkey and Greece under the coordination of the remote team. The mission also aimed to assess the viability of alternative data sources for an appraisal of the future viability of hybrid missions. This paper summarises the mission setup and findings, and discusses the benefits of and difficulties encountered during this hybrid reconnaissance activity.</jats:p