Tuesday, January 23, 2018

Pruebas de carga en puentes de hormigon armado: Experiencia de un programa de pruebas en Holanda

I recently gave a presentation titled "Pruebas de carga en puentes de hormigon armado: Experiencia de un programa de pruebas en Holanda" at the 1er Congreso Iberamericano de Ingenieria Civil. In this presentation, I gave an overview of the load testing work in the Netherlands. This was my first technical presentation in Spanish (so to reduce the amount of speaking that I had to do, I threw in a lot of videos...).

The conference paper has as English title "Proof load testing of reinforced concrete bridges: Experience from a program of testing in the Netherlands" with the following abstract:

For existing bridges with large uncertainties, analytical methods have limitations. Therefore, to reduce these uncertainties, field testing of a bridge can be used. A type of such a field test is a proof load test, in which a load equivalent to the factored live load is applied. If the bridge can carry this load without signs of distress, the proof load test is successful, and it has been shown experimentally that the bridge fulfils the code requirements. It should be understood that this method for assessment is different from the diagnostic load tests that are carried out in Ecuador prior to opening a bridge. The loads used for proof load tests are significantly larger. Therefore, it is important to instrument the bridge for a proof load test, and to evaluate during the test that the load does not result in permanent damage to the bridge. To research this topic, and to develop recommendations for proof load tests, a series of proof load tests and a collapse test were carried out in the Netherlands. Additional laboratory testing was carried out as well. Based on this information, recommendations for proof load tests of reinforced concrete slab bridges have been developed for the failure modes of flexure and shear. In the German and North American guidelines for load testing, load testing for shear is not permitted. However, many existing bridges do not fulfil the requirements for shear upon assessment according to the current live load models. Even though more experimental research is needed to develop proof load testing for shear in a guideline or code for the Netherlands, the currently available research results already lead to interesting conclusions with regard to the behaviour of bridges proof load tested in shear, and the required safety margin to avoid damage to the bridge.

The Spanish version of the abstract is as follows:

Para puentes existentes con largas incertitudes, métodos analíticos tienen limitaciones. Por esa razón, pruebas en el puente mismo pueden ser usados para reducir las incertitudes. Se puede utilizar pruebas de carga, en las cuales se aplica una carga equivalente a la carga viva con sus factores de carga correspondientes. Si el puente puede sostener esa carga sin aflicción, la prueba de carga es exitosa, y se ha demostrado de una manera experimental que el puente cumple con los requisitos de la norma en términos de capacidad. Se debe entender que ese método de pruebas de carga no es lo mismo que las pruebas diagnósticas que se usan en el Ecuador antes de abrir un puente al público. Las cargas involucradas en pruebas de carga son bastante largas. Por esa razón, es importante aplicar sensores en el puente, y evaluar si la prueba no aplica danos permanentes al puente. Para investigar ese tema, y para desarrollar recomendaciones para pruebas de carga, se hicieron una serie de pruebas de carga en Holanda, junto con una prueba de colapso, y pruebas en vigas en el laboratorio. Con esa información, se han desarrollado recomendaciones para pruebas de carga en puentes de hormigón armado tipo losa, para las modas de falla de flexión y cortante. En los códigos alemanes (DAfStB Richtlinie) y estadounidenses (ACI 437.2M-13 y el Manual for Bridge Evaluation) para cargas de prueba, no se permite probar estructuras que pueden fallar en cortante, pero muchos puentes existentes no cumplen con los requisitos para cortante cuando se los evalúa con las cargas vivas de hoy en día. Aunque todavía más datos experimentales son necesarios para permitir pruebas de carga para cortante en un código Holandés, la investigación presente ya resulta en observaciones importantes con respeto al comportamiento de elementos sometidos a cortante y el margen de seguridad que se necesita en una prueba de carga para evitar danos al puente.

You can find the slides of the presentation below:

Thursday, January 18, 2018

Assessment of slab bridges through proof loading in the Netherlands

I recently gave a presentation at the ACI Fall Convention in Anaheim, CA about our research on proof load testing of slab bridges. If all goes well, the paper will be published in an ACI SP. Below, you can find the slides of this presentation:

Tuesday, January 16, 2018

Pilot Proof-Load Test on Viaduct De Beek: Case Study

My colleagues and myself recently published a paper in the Journal of Bridge Engineering, titled "Pilot Proof-Load Test on Viaduct De Beek: Case Study". The paper reports on the proof load test on viaduct De Beek which our research group carried out in November 2015. I couldn't join my colleagues in the field at that time, but in the summer of 2016, I helped finalizing the analysis report of the test.

The abstract is as follows:

For existing bridges, proof-load testing can be a suitable assessment method. This paper addresses the evaluation of a posted reinforced concrete slab bridge over a highway through proof-load testing, detailing the preparation, execution, and analysis of the test. As the target proof-load and the required measurements for proof-load testing currently are not well-defined in the existing codes, this pilot case was used to develop and evaluate proposed recommendations for proof-load testing for a future guideline on proof-load testing for the Netherlands. Moreover, the pilot proof-load test is used to study the feasibility of proof-load testing for both shear and flexure.

You can download the paper here:

Thursday, January 11, 2018

Plastic model for asymmetrically loaded reinforced concrete slabs

My colleagues and I recently published a paper titled "Plastic model for asymmetrically loaded reinforced concrete slabs" in a Special Publication of the ACI, ACI-SP 321 "Recent Developments in Two-Way Slabs: Design, Analysis, Construction, and Evaluation". This SP is the result of a session held at the ACI Fall Convention in 2015.

You can purchase the SP through the ACI website.

The abstract of our paper is as follows:

Most methods for the design and analysis of reinforced concrete slabs for punching are based on experiments on slab-column connections, reflecting the situation in building slabs. Slab-column connections with unbalanced moments have also been studied in the past. Experiments indicate that the accuracy of models for asymmetrically loaded slabs is lower than for symmetrically loaded slabs. In this paper, the difference in accuracy between test predictions for symmetrically and asymmetrically loaded slabs is tackled. A plastic model, the Extended Strip Model, is proposed. The results of maximum loads according to this model are compared to experimental results of symmetrically and asymmetrically loaded slabs. The comparison between the proposed Extended Strip Model and the experimental results shows that the model has a consistent performance for both symmetrically and asymmetrically loaded slabs. Moreover, the model has as an advantage that it combines the failure modes of flexure, shear and punching. The proposed model can be used for the analysis of slabs. In particular, it can be used for the assessment of existing slab bridges subjected to concentrated live loads.

Tuesday, January 9, 2018

Ten best books I read in 2017

Just like every year, I present you with the 10 best books I read in the past year. I read a fair amount of pulp this year at the end of my pregnancy, as my brain couldn't make it through good fiction anymore, but I also read a few books I'd happily recommend you.

10. 80,000 Hours: Find a fulfilling career that does good - Benjamin Todd
An excellent, evidence-based book on choosing a career path that does good in this world.

9. What the most successful people do on the weekend - Laura Vanderkam
Part of a series of books. The other two are "what the most successful people do before breakfast" and what "what the most successful people do at work". Whereas the other two books are a rehash of typical time management tips, the topic of what to do on the weekend is fascinating and gave me some new insights.

8. The Yoga Sutras of Patanjali: The Book of the Spiritual Man - Charles Johnston
I listened to this, and while I found some parts inspiring, I certainly need more context and explanation to understand more of this work.

7. The autobiography of Benjamin Franklin
Another book I listened to, and it was quite enjoyable to listen to the advice and experiences of an icon in our history.

6. The end of average - Todd Rose
I also listened to this book - and I found elements of it interesting, and other elements were food for thought (but I did not agree with some of Rose's suggestions).

5. I know how she does it - Laura Vanderkam
I'm a fan of Vanderkam, and this book came just in time for me. I read it before returning to work after my maternity leave, and drew some inspiration from it.

4. The bone clocks - David Mitchell
I genuinely enjoy reading David Mitchell's books, and found this book another fascinating and enjoyable read.

3. Britt-Marie was Here - Fredrik Backman
I also enjoy reading Backman. This book was a heartwarming read.

2. Sprakeloos - Tom Lanoye
In Dutch - but something I would recommend all to read. A testimony to the life of Lanoye's mother. The link below takes you to the English translation of this work.

1. Uncle Tom's Cabin - Harriet Beecher Stowe
I listened to this book as well. A classic that I had not read in the past, and I understand why it is a classic.

Thursday, January 4, 2018

PhD Talk for AcademicTransfer: Locations for deep work

This post is part of the series PhD Talk for AcademicTransfer: posts written for the Dutch academic career network AcademicTransfer, your go-to resource for all research positions in the Netherlands.

These posts are sponsored by AcademicTransfer, and tailored to those of you interested in pursuing a research position in the Netherlands.

If these posts raise your interest in working as a researcher in the Netherlands, even better - and feel free to fire away any questions you might have on this topic!

We are the creatures of habit. Most days, we arrive around the same time at our office. Then, we perhaps get our coffee, check our email and see what we want to work on for the day. Or we check the news, start to read the comments, and before we realize, half an hour has gone. Or we start to reply emails, only to get lost in the rabbit hole of starting things without finishing them, or in email ping-pong.

If at the end of the day, when you leave your office, you have the feeling you have accomplished very little, you can try to switch up your routine. We've talked before about using pomodoros, planning, lists, and other tools to use your time wisely. Today, we will focus on how we associate a certain location to certain behavior.

Just like we associate our dining table with meals, we associate our office and our desk with our office-behavior. If you are struggling with bad habits and procrastination, try switching locations to induce deep work. Of course, if you have office hours or need to be available for your supervisors at certain times, don't simply disappear. You can change locations outside of the hours that you have meetings in your office, or communicate to others when you will be available.

Here are some strategies that you can use to break bad habits and focus on deep work:

1. Get a designated focus spot
If your office is large enough, or if you work from home, you can identify a "focus spot". A focus spot is a designated area for focused work. If you want to concentrate deeply on some work, take that work (and only that work) to your focus spot. You can for example take a notebook and print of a journal article. If you prefer a digital workflow, and can stay clear from the pull of the internet, then open the files you are going to use on your laptop. Set an intention to work for a certain amount of time, and stay during that time on task and in your focus spot.

2. Walk around
If sitting and reading makes you nod off, try standing or pacing around. If you are working on a computer, walking around is not very practical. If you are reading printed files on the other hand, walking around is possible. When walking around is not possible, try a standing desk to keep your body more alert. If you need to flesh out an important problem, take a notebook and go for a walk. Give your brain the space to process thoughts while you walk around. Leave your smartphone behind or on airplane mode to make sure you stay on task.

3. Go into nature or somewhere quiet
To refresh your brain and get a new perspective on things, go outside. Find a place in a park to read, a picnic table where you work for a while on your laptop, or a quiet nook on campus to hide away without disturbances. Take only what you need - either printed documents and a notebook, or your laptop (just make sure you only open the files you need and/or find a place without wifi so you avoid getting stuck into the internet).

4. Work from the library or coffee shop
If you want to switch locations to break bad habits, the most obvious choice would be to go to the library or a coffee shop. The quiet and studious atmosphere of a library can stimulate deep work for some, whereas the background noise in a coffee shop and the presence of other students will encourage others. You can make it a study date with friends or join a "shut up and write" group if you want accountability partners.

5. Associate activity with place
To make sure you stay on task, you can have a designated space per task. For those of us who work in the laboratory, the link between activity and place is already there: experiments are done in the laboratory. Similarly, you can decide to do all your reading in the library, all your writing on your focus spot, and your proofreading while walking around. Lighter work, such as administration, planning, and emails can be designated to a coffee shop. In between, you may be taking a walk in a park and use that time to clear your mind or think through a difficult research problem.

Tuesday, January 2, 2018

Ten best albums of 2017

As every year, I am presenting you with an overview of the ten best albums of the past year. This year, I only listened to albums and reviewed them until May. By June, during my time in Delft, I was so tired after work that I did not gather the strength and courage to write my reviews. After the baby was born, I didn't listen to any new album. With that in mind, here is my list for 2017:

10. King of Asgard - :Taudr:
Pagan metal with strong layering. You can find my review of this album on darkview.

9. Illimtable Dolor - Self-titled
Fine funeral doom. Read my review here.

8. Battle Beast - Bringer of Pain
Just good old heavy metal. You can find more on Darkview.

7. Psychedelic Witchcraft - Magick Rites and Spells
Seventies doom revival. Review on Darkview.

6. Magnet - Feel your fire
More seventies revival, but on the side of blues and rock and roll. You can read my full review on Darkview.

5. Immolation - Atonement
Raw energy. Dark death metal. For more, go to Darkview.

4. Jess and the Ancient Ones - The Horse and other weird tales
More psychedelic seventies stuff... I didn't review this album, but it happens to be an album that I listened to on Spotify.

3. Atlas Pain - What the oak left
Epic prog metal, and quite innovative at that. Review on Darkview.

2. Marche Funebre - Into the arms of darkness
Excellent doom/black from my homecountry Belgium. Head over to Darkview for my review.

1. Avatarium - Hurricanes and Halos
Best album of the year for a prog and 70s revival band. I never got around writing a review for this album as pregnancy made me too tired, but it is an excellent album.