Post-disaster Condition

At the end of this step, the team should be able to do the following:
a) Identify damage modes/levels, and the spatial distribution of damage in the affected area
b) Quantify the losses and service disruption in the affected area
c) Identify the pre- and post-disaster performance of building types
d) Identify invention options to recover and improve performance of building types

Local partners and technical expertise

The table below presents a list of suggested local partners and technical expertise required to contribute to or lead the activities of this step.

Module 5.1. Analysis objective

In this module, task teams will discuss and define the scope and objectives of the risk assessment to inform the planning phase.

Activity 5.1.1 Define objective of analysis                                             

Under this activity the scope and specific objectives of the risk assessment of the existing school facilities are discussed. With support from local experts, task teams are to define the objectives, resolution, and methodology of the risk assessment required to inform further steps in the RSRS. The risk assessment ranges from a low-resolution assessment (for example, at the national level) to a high-resolution assessment (for example, at the portfolio level with information per building). The resolution relates to the level of granularity at which risk will be quantified, which is governed by the resolution and quality of the available data on hazard, vulnerability, and exposure. This discussion will drive the decision as to whether fatalities, economic losses, and expected downtime, given few or several hazard events, will be quantified. It is important to ensure the study will be not only technically consistent but also feasible with the available resources and within the specified time frame.

Guidance:

Do not overestimate the power of numbers or underestimate the value of analytics. As mentioned earlier, the RSRS advocates for the use of quantitative risk assessment^[1]. While qualitative risk assessments contribute to raising awareness, quantitative assessments are instrumental to defining priorities, designing solutions, and monitoring progress on school safety and resilience. Yet the misinterpretation of results and unreliable data can jeopardize the potential benefits of quantitative work. Although absolute values of risk or vulnerability may prove meaningless in some cases, logical analysis—or analytics—may prove fundamental to the design of intervention strategies, as it allows for the comparison of relative values within a territory or across different building types. Different disaster risk analysis methods can be used to derive the data needed to assess risk (see box 1)^[2]. 

In post-disaster conditions, the damage and vulnerability assessment may take precedence over the risk assessment. The vulnerability of affected school buildings changes as a result of the impact of a hazard event and, later on, of the reconstruction interventions. Damage and vulnerability assessments are needed to understand those changes and inform the definition of reconstruction interventions. If possible to conduct one, a scenario risk analysis is useful to reproduce analytically the impact of a disaster and calibrate the fragility and vulnerability curves of index buildings. In the long run, infrastructure managers will need to recalculate risk every time a disaster occurs. While a disaster modifies risk, it does not eliminate it, and reconstructed (new and repaired) school facilities will inevitably be exposed to hazard events in the future.

Module 5.2. Assessment of risk to school facilities

Through the activities in this module, task teams, with support from specialists, will ascertain the likelihood and expected magnitude of damage, losses, and disruptions in the school infrastructure networks from future hazard events.

Activity 5.2.1 Undertake hazard analysis             

This activity aims to define the intensities, frequencies, and spatial distribution of selected hazard events with different probabilities of occurrence. The results of this hazard analysis will be used for the risk assessment^[3]. The activity builds on existing hazard data sets and maps^[4]. As it should be conducted by experts, the role of the task teams will be to facilitate access to the existing information and technical discussions with relevant agencies. 

Guidance:

The existing hazard information (preliminarily screened in activity 1.4.1) should be reviewed to ensure quality and completeness. The different sources of information (see box 2) should be cross-checked, updated, and integrated to eliminate any discrepancies and/or fill in missing information in the existing hazard data sets and maps. 

Then a decision should be made whether a hazard analysis will be conducted for the existing geological and climate-related phenomena in the area.  

The hazard data sets and maps to be used under this activity should come from sources recognized by the government. In the hazard/risk information field, the reliability of the results is a sensitive issue, as it drives decisions from the government and perception from communities. Unfortunately, no “official” hazard maps are available in many developing countries. In addition, a wide range of methodologies and approaches exist for hazard analysis. In any case, task teams should ensure relevant government agencies participate in the discussion of the data and methodology to be used and, if possible, in the hazard analysis. In this way, the results of the study will be endorsed by those agencies.

Task teams should be aware that hazard data sets and maps need to be updated after a disaster. In post-disaster conditions, experts should collect new data about the disaster event, such as information on event intensities and geolocation, new fault data, site effects, new attenuation relations, or new geodetic data, and integrate all the information into the existing hazard model. This activity is not related to the education sector, however, and its implementation is not within the scope of the RSRS. If needed, task teams should seek support from specialized government agencies.

Activity 5.2.2. Establish the exposure model         

This activity focuses on the creation of an exposure model of the school facilities and their occupants. From the baseline results (activity 1.2.4), school buildings in the exposure model are linked to index buildings with known fragility and vulnerability curves. Other building attributes, such as replacement value, location, capacity, and needs for functional improvements, among others, are also included in the model. Occupancy rates are adopted to simulate the use of the facilities by students and teachers at different times of day. 

Guidance:

As in the hazard analysis, this activity is to be conducted by specialists. It is important, however, that task teams understand the concept of an exposure model and how it fits into the risk model.

The fragility and vulnerability assessment of the selected index buildings is a critical and nontrivial task. As the risk model is very sensitive to changes in vulnerability parameters, it is essential to ensure the derivation and assignment of vulnerability curves are grounded in both advanced analytical methods and expertise from senior local and (if possible) international experts. This is further discussed in the next activity.   

Task teams should work with infrastructure managers to establish realistic unitary replacement costs. The value of the elements at risk is needed to estimate economic losses. Replacement cost is usually used as the value for infrastructure assets in the exposure model. Replacement costs may vary by regions, urban versus rural areas, or even the education levels the facilities serve. Also important to note is that the replacement cost is higher than the actual cost of the existing school building, since the condition of a new building will be an improvement over the old one, and its lifespan will be longer.

The exposure model of affected school facilities in post-disaster conditions can either be identical to that in pre-disaster conditions, or it can integrate the characteristics of the reconstructed school building(s). The exposure model in the former is used to reproduce the impact of the specific hazard event associated with the disaster, while that in the latter case will support the risk assessment of the fully recovered school portfolio.

Activity 5.2.3. Assess the fragility and vulnerability of index buildings

The purpose of this activity is to construct the fragility and vulnerability functions of each index building. This is one of the most critical tasks specialists must provide for risk assessment, as these functions drive the quantification of expected damage and losses to the exposed elements from the impact of hazard events. Their development requires specialized knowledge and extensive experience. 

Through either empirical or analytical methods, structural engineers have studied the failure modes of a wide range of structures and developed their fragility and vulnerability functions. This information, fortunately, is progressively made available in specialized papers, providing local specialists with a reference on which to build. By no means, however, is the use of these functions a straightforward process. Local specialists will, in any case, need to go through a “tuning-up” process, based on the particularities of the index buildings.

Guidance:

The role of the task teams in this highly specialized activity is mainly to ensure the participation of senior specialists from technical government agencies, universities, or even the private sector and facilitate their access to international literature or (if feasible) international experts. In our experience, this activity presents one of the biggest challenges in terms of the use of quantitative methods for risk assessment. The lack of local expertise and constraints on access to global knowledge make the activity too complex in most of developing countries. At the same time, a growing number of research groups are interested in this work, and advanced structural analysis methods are now available that improve the reliability of these functions. This situation was the reason for the development of the Global Library of School Infrastructure (GLOSI).

GLOSI was developed under the GPSS with the purpose of making available experience with and results of fragility and vulnerability functions in several index buildings from different countries. In this way, local experts can obtain access through a common language to a catalog of index buildings with specific information about the methodology and results of these assessments. GLOSI saves users from having to conduct their own analyses from scratch and with no international reference.

Fragility and vulnerability curves are also useful to quantify the benefits of retrofitting interventions. Retrofitting solutions are better designed when critical problems affecting the building structure have been revealed by the vulnerability analysis. Factors that contribute to the vulnerability of the building include, but are not limited to, fragilities in the main structural system, irregularities in plan or elevation, large openings, soft stories, short columns, large unstable wall panels, weak foundations, and heavy roofs.

The forensic assessment of the causes of failure in affected school buildings in post-disaster condition offers an opportunity to improve intervention measures for reconstruction. Task teams should seek advice from local senior engineers and facilitate their contributions to the reconstruction plan. The teams can collect and analyze new data on the structural performance of and potential damage to different structural typologies, and the discovery of new failure modes may contribute to updating knowledge on index building performance and retrofitting designs. Previous quantification of damage levels and associated losses may be replaced with new data, leading to the improvement of existing vulnerability functions. 

Activity 5.2.4. Quantify risk in terms of expected losses and service disruption

The aim in this activity is to quantify the probability of fatalities, economic losses, and downtime as a result of given hazard events. By integrating results from hazard, exposure, and vulnerability components, the magnitude and probability of adverse consequences (risk) from hazard events of different magnitudes can be estimated. At the end of this activity, task teams will learn not only about the magnitude and probability of potential consequences but also how they change across the country, regions, or municipalities and among different school facilities. Most important, decision makers will have science-based figures about risk for schoolchildren, teachers, and school communities. 

Guidance:

Rather than absolute values of risk, we look at relative values by which the risk conditions can be compared within the school infrastructure portfolio. Several sources of uncertainty are involved throughout the risk assessment, and it is important that experts make them explicit in their presentation of the results. Task teams should understand the meaning of risk values, associated uncertainties, and applications for risk reduction purposes. The following concepts will be helpful: 

• Unlike in insurance applications, where risk values are used to estimate the cost paid for an insurance policy, relative risk values are used for risk reduction purposes to compare risk conditions among school facilities. In other words, for the selection and prioritization of interventions, what is needed is a risk metric that is applied consistently through the whole portfolio, even if it differs somehow from absolute risk values. This is what we mean by relative risk values. 
• Risk and uncertainty cannot be separated. Analytically, uncertainty is addressed through a probabilistic approach. For decision-making purposes, risk values should be taken as reference to inform decision options. In practical terms, this means we should act to reduce risk in schools, no matter if our best risk estimate might differ from the actual consequences once the hazard event occurs. 
• Safety benefits can be estimated in terms of change (reduction) of the relative risk, given the implementation of an intervention in a specific index building (such as structural retrofitting). 

The resulting risk figures are instrumental for the focusing and prioritization of interventions. A key task with regard to the intervention and implementation strategy in the next steps is to define where interventions should be focused and prioritization criteria. Risk assessment results can be used to establish quantitative indicators of, among others, the safety benefits and cost efficiency of the interventions. By combining these indicators, the outcomes of the investment are optimized and priorities for implementation defined.

A challenge, moving forward, is to quantify the expected downtime in a network of school facilities, given different hazard events. In the same way risk assessment results inform risk reduction interventions, a downtime assessment could inform measures to increase sector resilience and reduce indirect adverse consequences for children. Conceptually, the time frame for the recovery of an affected network of school infrastructure will be a function of four main components: the level of damage to school facilities, their location and accessibility, the redundancy of the system to redistribute students in the aftermath of the disaster, and the sector’s implementation capacity.       

Communication of risk information might become challenging if not managed properly.  Task teams should be aware that the access to the results of risk assessment in school infrastructure must be restricted until the plan is finalized and a communication strategy is defined by infrastructure managers. In this sense, it is also very important for task teams, with support from the risk modelers, to explain thoroughly to relevant agencies the outputs of this study.

Module 5.3. Analysis of intervention options for school buildings

Activities under this module focus on understanding the current performance of the existing school buildings and intervention options to improve it.

Activity 5.3.1. Evaluate current performance of index buildings                                                 

This activity focuses on identifying the current performance of index buildings based on the results of the vulnerability analysis and risk assessment. The current structural performance of an index building is a measure of its as-is potential structural response to specific hazard events.  Performance is evaluated against acceptance criteria prescribed in building regulations, guidelines, handbooks, and other technical documents, and an index building complying with the criteria is deemed to meet the specified performance level (see box 3). Performance refers not only to the building structure but also to nonstructural components, such as partitions, parapets, pediments, furniture, and equipment that can harm children, teachers, and staff if they fall. Moreover, nonstructural components that provide utility services are essential to the continuity of school operations in the aftermath of a disaster.

Guidance:

Task teams should now understand the goal of a structural retrofitting intervention is to improve the performance level of the school building. Note “performance level” is a different way to describe and communicate risk. Unlike risk quantitative metrics, which are complex and difficult for nonexperts to understand, the use of performance levels has, in our experience, proved effective for engineering purposes, as well as for communication to stakeholders and communities. Even though it is not yet used widely in developing countries, we advocate for this approach. It will help in filling the regulation gaps for retrofitting design that, unfortunately, are very common in these countries. Moreover, moving the attention of decision makers and school communities from risk to performance level is a strategic step toward a consensus in a society about safety or acceptable risk for schoolchildren.

This concept and approach are fully applicable in post-disaster condition. Although their implementation goes beyond the RSRS and the education sector, task teams can promote and facilitate action from relevant agencies toward the definition of performance level targets for reconstruction interventions.

Activity 5.3.2 Identify interventions to improve performance of index buildings                                                 

The aim of the final activity in this step is to identify the need for interventions to improve the performance of index buildings. This activity should be conducted by local senior structural engineers with support (if needed) from international experts. Interventions relate to modifications made to structural and nonstructural components that enhance the performance of an index building. These modifications are known as “retrofitting.” The change in performance can be simulated by using the mathematical models and calculation methods applied in activity 5.3.1. As a result of this activity, the team is to specify the needs for intervention across the group of index buildings to improve their performance to target levels.  

Guidance:

Note that the higher the performance level objective, the higher the cost of and the longer the time frame for the retrofitting work. The intervention measures, their cost, and their implementation time frame vary widely from one index building to another. Moreover, for the same index building, many retrofitting techniques may apply with different cost and implementation requirements. Cost-benefit analysis is useful to select among retrofitting options. Overall, task teams should request from the engineering team a comprehensive analysis of the intervention options and associated benefit-to-cost ratios. When the cost of retrofitting interventions and functional improvements is higher than a specified percentage (ranging from 40–60 percent) of the building’s replacement value, the solution is considered not to be cost-efficient, and the intervention option shifts to the replacement of the existing building.      

At this point the team should focus only on defining the need for intervention and the analysis of retrofitting options for index buildings. These inputs will be integrated into the design of the intervention strategy in step 6, where the decision for the intervention is made through a logic-tree method that addresses considerations beyond engineering criteria. In summary, this activity should make clear for each index building whether retrofitting intervention or replacement is recommended from the structural point of view. 

In post-disaster conditions, intervention work must not only be undertaken to repair damage to school buildings but also to improve their performance in the face of future hazard events. Different situations may occur for similar index buildings, depending on the intensity of the seismic demand experienced by the buildings during an earthquake—light to heavy damage, or even partial or total collapse. Even if a building sustains only light damage, this does not mean its performance is acceptable, as it may experience higher seismic demand in future events.

Output

The completion of activities under each module will result in one or more output(s). 

^[1]_{Analysis methods for the resilient assessment of school infrastructure have had limited development so far. The Global Program for Safer Schools is developing methodologies in partnership with universities.}

^[2]_{Analysis methods for the resilient assessment of school infrastructure have had limited development so far. The Global Program for Safer Schools is developing methodologies in partnership with universities.}

^[3]_{A risk assessment integrates three components: hazard, exposure, and vulnerability.}

^[4]_{A hazard analysis from scratch is a big endeavor that goes beyond the RSRS.}

^[5]_{FEMA 310: Federal Emergency Management Agency. "Handbook for the seismic evaluation of buildings—A Prestandard." FEMA (1998). https://www.fema.gov/media-library/assets/documents/2007.}

^[6]_{The term “lines of intervention” varies from one country to another. Task teams should inquire about the formal definition in the country of operation.}