9th fib PhD Symposium in Civil Engineering

At the 9th fib (International Concrete Federation) PhD Symposium in Civil Engineering, organized by the Karlsruhe Institute of Technology, I presented some of the experimental results of my research. Two years ago, I already participated in the 8th edition of this conference (in Copenhagen), and I enjoyed very much this conference which is aimed at concrete research. Very typical for these PhD symposia is that every speaker has 30 minutes: 20 minutes for the presentation and 10 minutes for questions. This scheme leaves much more room for discussion and interaction than your typical structural engineering conference.

The abstract of the paper is the following:
In slabs subjected to concentrated loads, the shear strength checks are conducted for two limit states: 1) shear over an effective width, and 2) punching shear on a perimeter around the point load. In cur-rent practice, the shear strength at the supports is determined with models that do not consider the transverse redistribution of load that occurs in slabs, which results in underpredictions for the actual slab shear capacity. Currently, an experimental program is being conducted at Delft University of Technology to determine the shear capacity of slabs under point loads near to the support. This paper presents the results of the tests conducted in continuous slabs and slab strips. In addition to studying the influence of the slab width, the specimens are tested with two types of reinforcement (ribbed and plain bars). The results of the experiments are compared to strength predictions from current design models. Also, recommendations for the support effective width and an enhancement factor for considering the effect of transverse load redistribution are given.

And here are the slides I used for the presentation:

Shear tests of reinforced concrete slabs and slab strips under concentrated loads from elantsoght.

IABMAS 2012

At the IABMAS (International Association for Bridge Maintenance and Safety) 2012 conference, I presented a case study we conducted some time ago for a local bridge owner.

The abstract of the paper is as follows:
A 50-year-old bridge showed large cracking in the approach bridge parts due to restraint of deformation and support settlement. After repair, it was uncertain at which crack width the traffic loads on the bridge should be further restricted. The shear capacity was calculated by counting on the aggregate interlock capacity of a supposedly fully cracked cross-section. An aggregate interlock relation between shear capacity and crack width based on an unreinforced section was used to find the crack width at which the shear capacity of the section with a through crack becomes smaller than the shear capacity of the section without a through crack. Limits for crack widths at which load restrictions should be imposed were found. The large structural capacity of the cracked concrete section shows that the residual bearing resistance based on the aggregate interlock capacity of reinforced concrete slab bridges with existing cracks is higher than expected.

And here are the slides of my presentation:

Residual capacity from aggregate interlock from elantsoght

How to stop making excuses

Image by Flickr user "I am marlon" and used under the Creative Commons license

There's always a reason why you are not starting to write that paper today, or why you are skipping the gym today. We are great at making up excuses for ourselves - which end up holding us back.

For writing, it has been a long time since I have put it off, as I feel the pressure of the paper and thesis deadlines, and because I enjoy writing. For sports, however, I always find an excuse why I cannot work out today: it is raining so I can't go for a run, I have too much work to do, I am tired...

However, I've started to challenge myself to determine when I am making up an excuse for myself, and not to fool myself anymore. Here's a few thoughts on how to stop making excuses.

1. Start small

My first triumph over my excuses-habit was when I ran just 2km in the rain. For once, the rain couldn't stop me, and I couldn't use it as an excuse. Similarly, if you want to get started on a paper on a given day, start small: just write the introduction, or just jot down a few ideas in your outline.

2. Plan realistically

Learn to manage your time, and know how much you can get done. There's no need to overload your planning with too many tasks. If exercising is your Achilles heel, then try to find 3 or 4 days a week in which you have time to exercise. If you want to write on your paper daily, make sure you can schedule at least 2 hours of uninterrupted time a day in your schedule.

3. Keep your momentum going

Once you've managed to overcome your excuses a few times, make sure you keep yourself going. It takes anywhere between 18 days and 254 days to create a new habit, so be prepared to do a little effort in the beginning. Just keep going strong, hold onto your goal for a while and take yourself seriously.

4. Listen to your thoughts

When  you come up with an excuse for yourself, stop a moment and think about it. Knowing that you are making up an excuse is one step. You can take a second step by reflecting on your goal and why you are making this excuse. Are you afraid to fail? What lies underneath the excuse? What are you -really- trying to tell yourself?

5. Track your progress 

As a big fan of stats, I love keeping track of my progress. I keep track of my writing through a word count spreadsheet, the stats at 750words.com and by neatly keeping an overview of my publications and presentations. For exercise, I've started to keep track of my activities in Nexercise, and for running only I am using Runkeeper.

6. Celebrate your successes

Don't forget to pat yourself in the back when you're making progress! You can reward yourself with something you really like: taking an evening off and watch a movie, buy something for yourself, go to the beach... It's always a good idea to stop, reflect and realize of your progress.

Spreiding puntlasten plaatviaducten

I'm proud to announce that we have an article published in the Dutch magazine "Cement", titled: "Spreiding puntlasten plaatviaducten." The printed version will be available on July 6, 2012.

Abstract:
In de afgelopen decennia zijn verkeerslasten en de verkeersintensiteit op de Nederlandse wegen en kunstwerken drastisch toegenomen. Veel van die kunstwerken zijn uitgevoerd als plaatviaducten
zonder schuifwapening. De vraag bestaat of het afschuifdraagvermogen van deze viaducten nog steeds voldoende is. Op basis van experimenteel en literatuuronderzoek is een nieuw lastspreidingsmodel ontwikkeld aan de TU Delft voor toepassing in de quick-scanmethode van Rijkswaterstaat.