My thesis in 3 Posters- Part II: Application of time series methods on long-term structural monitoring data for fatigue analysis

The second part of "My thesis in 3 Posters" is related to my studies during my secondment in Lausanne, Switzerland.  

During this period, I joined the Structural Maintenance and Safety Laboratory (MCS) of Civil Engineering depertment at EPFL.  My work in this lab was devoted to take advantage of valuable long-term monitoring data that is recorded by this lab for about two years. I have employed Time Series methods such as ARIMA to prepare a new load model for fatigue analysis while there is seasonality effect. This new model can deal with missing data, it can capture seasonality effect, and it can be used to generate fatigue loading for further analysis. 

A short abstract in addition to my poster is provided below. 

ABSTRACT: 

Structural health monitoring (SHM) can be employed to reduce uncertainties in different aspects of structural analysis such as: load modeling, crack development, corrosion rates, etc. Fatigue is one of the main degradation processes of structures that causes failure before the end of their design life. Fatigue loading is among those variables that have a great influence on uncertainty in fatigue damage assessment.

Conventional load models such as Rain-flow counting and Markov chains work under stationarity assumption, and they are unable to deal with the seasonality effect in fatigue loading. Time series methods, such as ARIMA (Auto-Regressive Integrated Moving Average), are able to deal with this effect in the data; hence, they can be helpful for fatigue load modelling. The goal of this study is to implement seasonal ARIMA to prepare a load model for long-term fatigue loading that can capture more details of the loading scenario regarding the seasonal effects in traffic loading.

Conference papers: 

▪ "Application of Time Series Methods on Long-Term Structural Monitoring Data for Fatigue Analysis", SMAR2019, 5th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures, 27 – 29 August 2019 in Potsdam, Germany. 

**Please open the following link to be able to see the poster

https://drive.google.com/file/d/1k5exXroDYMPCeGPqsnpGoVoPlALkcMut/view?usp=sharing

Participating the SMAR 2019 with ESR4: Imane Bayan and ESR5: Bartek Sawicki

My thesis in 3 Posters- Part I: AK-SYS-T: A new approach to address time-dependent reliability using Kriging meta-modelling

Time has passed very fast and INFRASTAR is becoming THREE years old. it means it is time for all PhDs within INFRASTAR to boost their energies and finalise their results and get ready to defend their theses. As ESR number 10 of this program I am not an exception form this fact and I am getting ready to finish my PhD. During this period I have achieved invaluable experiences by working on different topics with skilled researchers and competent research centres. 

As a result, I believe I have done a very good PhD during this period and I am going to introduce the main parts of my work in posters in three different posts. 

This post is the first part of this chain and it is related to the first phase of my work in which we have developed a new time-dependent reliability method that is called AK-SYS-T. A short abstract on this work as well as some outcomes are presented afterwards.

Abstract: 

The objective of this study is to investigate system reliability methods for time-variant reliability analysis. The main challenge in time-variant reliability analysis is dealing with low probabilities of failure while computationally expensive performance functions are involved. Time-variant problems are often simplified by discretizing time intervals. This enables one to transform the initial problem to a system problem. System reliability methods can therefore be used to address time-variant reliability problems. AK-SYS is an efficient system reliability method which can be applied when costly-to-evaluate performance functions are considered. Application of this method for time-variant reliability problems is introduced in this study that is supported with two academic examples from literature.

Outcomes: 

Journal papers: 

▪ AK-SYS-T: A new time-dependent reliability method based on Kriging meta-modelling, Reliability Engineering and Systems Safety (Under review)

Conference papers: 

▪ Time variant reliability analysis based on Ak-SYS, ICASP13, 26-30 May 2019, Seoul, South Korea 

▪ Application of AK-SYS method for time-dependent reliability analysis, CFM2019, 26-30 August       2019, Brest, France
Poster session: 
 ▪ MATHIAS October 2019 by Total R&D

**Please open the following link to be able to see the poster

https://drive.google.com/file/d/1mfGJpQ7URy2cUsNfn8NdC2aKYQaf7p9M/view?usp=sharing

Presenting this poster in MATHIAS 2019 by Total R&D