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SLaMA Solver Frame: facilitating earthquake risk reduction with a computer app

r.gentile@ucl.ac.uk18 January 2022

Earthquake-induced direct and indirect losses tend to be high in highly populated earthquake-prone areas, especially in countries where most of the existing buildings and infrastructure are designed or built according to pre-seismic codes (if any). Therefore, there is a dire need to develop holistic strategies for mitigating and managing seismic risk. On the one hand, this involves risk understanding and quantification (e.g., risk/loss assessment methodologies). On the other hand, there is a crucial need to develop and implement strategies and techniques for repairing and retrofitting existing structures, which should be structurally effective, easy to apply, cost-effective, possibly reversible, and respectful of the architectural, heritage and cultural conservation requirements.

Both in the “diagnosis” and the “prognosis” phases, procedures to assess the structural performance under earthquake loads are paramount. Among many possibilities within the literature, choosing an appropriate assessment procedure depends on a simplicity vs accuracy trade-off governed by technical, economical, and time constraints. Moreover, various stakeholders have different needs on this matter: private owners likely need a detailed assessment focused on individual buildings or small portfolios, while government agencies or (re)insurance companies might look at large portfolios tolerating a lower refinement level and accepting higher uncertainties.

It is fundamental to select a procedure that can highlight the structural weaknesses of the considered structural system, so that it is possible to design retrofit solutions to specifically fix those. One procedure complying with this requirement, while being easy to apply, is SLaMA – Simple Lateral Mechanism Analysis.

Although SLaMA is normally applied using spreadsheets, it allows for defining the nonlinear force-displacement capacity and the sequence of local and global mechanisms of a building. It was introduced for the 1st time in the 2006 version of the New Zealand Society of Earthquake Engineering, NZSEE, Guidelines for the “Assessment and Improvement of the Performance of buildings in earthquakes” (NZSEE 2006), and revamped in the 2017 version (NZSEE 2017), after a substantial amount of research (Gentile 2017, Pampanin 2017; Del Vecchio et al. 2018; Gentile et al. 2019;  Gentile et al. 2019a; 2019b; 2019c; Bianchi et al. 2019). SLaMA is essentially mandatory in New Zealand, since it is required as an essential step before any other seismic numerical analysis is carried out. Its scope, however, is geographically much larger: more than 15 world-class companies (in New Zealand, Italy, Netherlands, UK) are using this method.

“SLaMA Solver Frame” is a free Windows/MacOS app created to enable engineers applying SLaMA using a graphical user interface, and without the need to create ad hoc spreadsheets. This app refers to reinforced concrete frame buildings, which constitute a substantial portion of the building stock in many countries around the world.

As shown in the tutorial video below, SLaMA Solver Frame is completely standalone (i.e., it does not require any other software to be run). It provides a “type and check” environment, in which every time the user inputs a parameter, the app automatically updates specific plots, therefore allowing for continuous cross checks and minimising input error. For each beam and column, SLaMA solver Frame provides their expected failure mode (flexure, bar buckling, shear, lap splice). For each beam column joint sub-assembly within the frame, the app determines its hierarchy of strength, indicating the member-level mechanism that causes its failure. Finally, by composing the results of each sub-assembly, SLaMA solver Frame provides an estimation of the plastic mechanism and the non-linear force-displacement curve.


SLaMA Solver Frame can be downloaded for free (for Windows and MacOS) at https://www.robertogentile.org/en/slamaf/. If you find any bugs, or you have any suggestions/comments, please feel free to report them dropping an email to robstructuralapps@gmail.com.


Disclaimer for SLaMA Solver Frame

SLaMA Solver Frame is provided by Dr Roberto Gentile under the Creative Commons “Attribution-No Derivatives 4.0 International” License. The purpose of SLaMA solver Frame is to cross-check by hand or spreadsheet calculations. This software is supplied “AS IS” without any warranties and support. The Author assumes no responsibility or liability for the use of the software. The Author reserves the right to make changes in the software without notification. The Author also make no representation or warranty that such application will be suitable for the use selected by the user without further calculations and/or checks.

 


Roberto Gentile is a Lecturer in Crisis and Catastrophe Modelling at IRDR.


References

Bianchi, Ciurlanti, and Pampanin. (2019). A SLaMA-Based Analytical Procedure for the Cost/Performance-Based Evaluation of Buildings. In COMPDYN 2019 – 7th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering. Crete Island, Greece.

Del Vecchio, Gentile, Di Ludovico, Uva, and Pampanin. (2018). Implementation and Validation of the Simple Lateral Mechanism Analysis (SLaMA) for the Seismic Performance Assessment of a Damaged Case Study Building [Open Access]. Journal of Earthquake Engineering 24 (11): 1771–1802. https://doi.org/10.1080/13632469.2018.1483278.

Gentile (2017). Extension, refinement and validation of the Simple Lateral Mechanism Analysis (SLaMA) for the seismic assessment of RC structures. PhD thesis. Polytechnic university of Bari, Italy.

Gentile, Pampanin, Raffaele, and Uva. (2019). Analytical Seismic Assessment of RC Dual Wall/Frame Systems Using SLaMA: Proposal and Validation [Open Access]. Engineering Structures 188: 493–505. https://doi.org/10.1016/j.engstruct.2019.03.029.

Gentile, Pampanin, Raffaele, and Uva. (2019). Non-Linear Analysis of RC Masonry-Infilled Frames Using the SLaMA Method: Part 1—Mechanical Interpretation of the Infill/Frame Interaction and Formulation of the Procedure [Open Access]. Bulletin of Earthquake Engineering 17 (6): 3283–3304. https://doi.org/10.1007/s10518-019-00580-w.

Gentile, Pampanin, Raffaele, and Uva. (2019). Non-Linear Analysis of RC Masonry-Infilled Frames Using the SLaMA Method: Part 2—Parametric Analysis and Validation of the Procedure [Open Access]. Bulletin of Earthquake Engineering 17 (6): 3305–26. https://doi.org/10.1007/s10518-019-00584-6.

Gentile, Del Vecchio, Pampanin, Raffaele, and Uva. (2019). Refinement and Validation of the Simple Lateral Mechanism Analysis (SLaMA) Procedure for RC Frames [Open Access]. Journal of Earthquake Engineering. https://doi.org/10.1080/13632469.2018.1560377.

New Zealand Society for Earthquake Engineering (NZSEE). (2006). Assessment and improvement of the structural performance of buildings in earthquakes. Wellington, New Zealand.

New Zealand Society for Earthquake Engineering (NZSEE). (2017). The Seismic Assessment of Existing Buildings – Technical Guidelines for Engineering Assessments. Wellington, New Zealand.

Pampanin. (2017). Towards the Practical Implementation of Performance-Based Assessment and Retrofit Strategies for RC Buildings: Challenges and Solutions. In SMAR2017- Fourth Conference on Smart Monitoring, Assessment and Rehabilitation of Structures. 13-15 March 2017. Zurich, Switzerland.

 

UCL IRDR 11th Annual Conference: Why Warnings Matter, and the UCL Warning Research Centre Launch, Part One

Joshua Anthony3 November 2021

Following a challenging year of managing natural hazards, including COVID-19, this one-day online event provided thought-provoking talks, interactive discussions and online networking opportunities on why warnings matter. In addition, the UCL Warning Research Centre as part of the Department of Science and Technology Studies was launched. The event explored the role, design, use, and evaluation of warnings for different hazards from different stakeholder perspectives to examine how effective people-centered warning systems can be developed and help to be prepared for both the expected and unexpected. The event was hosted by the Institute for Risk and Disaster Reduction and the Warning Research Centre.

On the 23rd of June, the UCL Institute for Risk and Disaster Reduction welcomed researchers, students, practitioners, policymakers, the media and the general public to a day of thought-provoking discussions on why warnings matter, and how we can do better at warnings both prior and during crises for all hazard types. Our in-house and guest experts presented a global perspective on the latest research and analysis through talks, interactive discussions and in conversation. We explored multi-dimensional aspects of warnings, considering their physical, social, economic, environmental, institutional, political, cultural and gendered dimensions, and the challenges involved in making warnings successful to mitigate against losses.

This blog is part one of a series presenting the key findings from the conference proceedings. The rapporteurs whose notes form this material are Calum MacKay and Simone Phillips who are both from the University of Glasgow on the MSc Earth Futures Programme.


Part One.

Panel Discussion 1: Warning Systems ‒ Exceptional versus expected events


 

The presenters for this session were Dr. Mickey Glantz, University of Colorado, Dr. Daniel Straub, Technical University of Munich, and Rebekah Yore, UCL. The session was moderated by Dr. Joanna Faure Walker, UCL.

Summaries of each presenters’ arguments are as follows:

Mickey Glantz

Not everyone considers a warning a warning. There are 5 key factors to warning hesitancy: complacency, convenience, confidence, low levels of trust, calculation of individual engagement. We don’t research the risks, collective responsibility is lacking as people focus on themselves. Emotional responses are common, not rational. There are also two types of people in hazard scenarios: risk averse people and risk takers.

Early warning systems are a chain. To make them more effective the lead time needs more attention. We need to create more lead time in order to get the warning to people earlier and through the system quicker.

Forecast hesitancy also plays a key role in effective early warning systems. We discount previous disasters we don’t learn from them, therefore we reinstate old vulnerabilities.

Readiness is also missing, society doesn’t have resources for long term preparedness.

Daniel Straub

Calculating the effectiveness of warning systems. If people think it’s a false alarm they won’t comply. This then creates a child who cries wolf scenario for future hazard warnings. We must find the right balance between detection rate and false alarm rate.

It is challenging and near impossible to quantify effectiveness but can still help the study of warning systems.

Rebekah Yore

It is important to identify the vulnerable population when deploying early warning systems. Failure in one element of the warning system can cause failure for the entire system.

Her research focuses on 3 case studies, all islands that are used to hazards: Japan 2011- Tsunami, Philippines 2013- typhoon and Dominica 2017- Hurricane. In all case studies not one warning system reached everyone, therefore these places need multiple types of warning. Some of the issues with the current warning systems were that interestingly modern smartphone warnings did not reach people. There was also mixed messaging from different agencies and government sources leading to room for interpretation from locals. Furthermore, issues such as poverty were not taken into account.

Finally, it must be noted that Individual and group risk perceptions are always changing and are dynamic.

This discussion was then followed by an address to questions from the audience, which are summarised thus:

How do we deal with both false alarms but also misinformation particularly in the context of social media or governments giving misinformation? How can we include groups who are not familiar with local warning systems like tourists or newcomers?

Mickey Glantz

Tourists have never seen a false alarm so unlikely to be affected in the same way in a real event by locals who have faced false alarms. Use of drills is helpful because one of the issues that comes up in the social sciences is that we all recognise that warnings need to be built into our everyday lives. We need to practice them as a way of living rather than just facing them when a hazard approaches. What has become practice then takes over and people are able to respond really quite calmly and really quite cohesively as Mickey thinks drills are a really good mechanism for embedding some key practices that help to familiarise through everyday life with some lifesaving rules.

What can we do to protect assets and livelihoods in the context of warnings?

Rebekah Yore

It is something that requires more research. Preparation mechanisms such as micro insurance for example are very important. So it may be that a mechanism that allows people to put things out and places structures in place before it occurs can help to protect some of those assets and livelihoods. Whether this means the ability to be able to pack things up and leave a location, or ability to be able to move, or an ability to be able to put certain protective measures in place. Maybe not save everything but save something or save enough.

Mickey Glantz

We don’t understand probabilities. We don’t understand nature. Many people don’t really understand the risks in their area. These perceptions become reality, if our perceptions are wrong the actions we take based on them have real consequences. So we tend to look at disasters as in many cases one and done.  But that’s not reality.

In one sentence what change do you think needs to occur to help with warning for exceptional events in an environment that does have expected events?

Daniel Straub

Understanding things through quantification is also to make use of all the data that we can now collect. The social sciences have a better understanding and also have models of factors that make a difference, and it would be useful for social science to do more with quantification in their research.

Rebekah Yore

Addressing structural inequality and addressing why people are disadvantaged and why other people aren’t. I think let’s just put our money where our mouth is; preparation is key.

Mickey Glantz

We have to put more emphasis on readiness and preparedness. People can get ready more easily than they can get prepared because they don’t have the resources. So, warnings are very important to them, I feel we have to push readiness as tactical responses to warnings and threats, as well as long term preparedness which seems to fall to governments and larger organisations. Readiness is for me and preparedness is for the community to deal with.

Next up in this blog series will be notes on “Warnings and the launch of the Warning Research Centre”, keynote speech from Assistant Secretary-General and Special Representative of the Secretary-General for Disaster Risk Reduction in the United Nations Office for Disaster Risk Reduction, Mami Mizutori.


Watch the full conference on youtube here!

Conference URL:

https://www.ucl.ac.uk/risk-disaster-reduction/events/2021/jun/ucl-irdr-11th-annual-conference-why-warnings-matter-and-ucl-warning-research-centre

Conference Rapporteurs: Simone Phillips and Calum Mackay

Conference Convener: Dr. Carina Fearnley


Please email us for any further information at IRDR-comms@ucl.ac.uk

Or check out our website: https://www.ucl.ac.uk/risk-disaster-reduction/

Institute for Risk and Disaster Reduction (IRDR), University College London (UCL)

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