Proof load testing of reinforced concrete slab bridges in the Netherlands

I recently presented a paper at the annual meeting of TRB, the Transportation Research Board. The abstract of the paper is as follows:

The bridges built during the development of the Dutch road network after the Second World War are reaching their originally devised service life. A large subset of the Dutch bridge stock consists of reinforced concrete slab bridges. This bridge type often rates insufficient according to the recently introduced Eurocodes. Therefore, more suitable methods are developed to assess reinforced concrete slab bridges to help transportation officials make informed decisions about the safety and remaining life of the existing bridges.
If information about a bridge is lacking, if the reduction in structural capacity caused by material degradation is unknown, or if an assessment shows insufficient capacity but additional capacity can be expected, a bridge might be suitable for a field test. A proof load test demonstrates that a given bridge can carry a certain load level. In the Netherlands, a number of existing reinforced concrete slab bridges have been proof loaded, and one bridge has been tested to collapse. Bridges with and without material damage were tested. These bridges were heavily instrumented, in order to closely monitor the behavior of the bridge. Critical positions for bending moment and shear were studied.
Based on the proof load tests that were carried out over the past years, a set of recommendations for the systematic preparation, execution, and analysis of proof load test results is compiled. These recommendations will ultimately form the basis of the guideline for proof load testing for the Netherlands, which is currently under development.

You can find the slides here:

Proof load testing of Reinforced Concrete Slab Bridges in the Netherlands from Eva Lantsoght

Effective Width in Shear of Reinforced Concrete Solid Slab Bridges under Wheel Loads

Just like last year, I've given a presentation at the Annual Meeting of the Transportation Research Board. Last year, I wrote as well about navigating TRB for the first time, and how I enjoyed using the conference app.


Like last year, my presentation was in the section about Concrete Bridges. Here is the abstract of the corresponding paper, that is published in the Annual Compendium of Papers:

For the assessment of reinforced concrete slab bridges in the Netherlands, the shear stress resulting from the dead loads and live loads is determined in a spreadsheet or from a finite element model. In a spreadsheet-based approach, an assumption for the distribution of the loads from the wheel prints is necessary. When finite element methods are used, it is necessary to determine over which length (a multiple of the effective depth) the peak shear stress can be distributed for comparison to the design shear capacity.
To recommend a load-spreading method, experiments were executed on slab strips of increasing widths. The shear capacity did not increase with the increasing width upon passing a threshold. This threshold is compared to different load spreading methods, indicating that a distribution from the far side of the wheel print is to be preferred. This recommendation is also supported by the results of a statistical analysis and the stress distribution in nonlinear finite element models.
To find the distribution width in a finite element method, a numerical model is compared to an experiment on a slab subjected to a concentrated load in which the support consists of a line of 7 bearings equipped with load cells measuring the reaction forces. These measurements were compared to the stress profile at the support from the model, showing that the peak can be distributed over 4 times the effective depth.
These recommendations for the effective width and distribution width are research-based tools that replace the previously used rules of thumb resulting from engineering judgement.

Effective Width in Shear of Reinforced Concrete Solid Slab Bridges under Wheel Loads from Eva Lantsoght

First Time at the TRB Annual Meeting

Last January, I attended the Annual Meeting of the Transportation Research Board in Washington DC.

The Annual Meeting, nicknamed the Superbowl of Transportation, attracts between (estimated) 11000 and 20000 participants, of which 5000 international participants. The Annual Compendium of Papers holds about 2500 papers. Between 20% and 30% of these papers make it into the Transportation Research Record Journal, a journal that has seen its impact factor rise steadily over the past year: from 0,093 in 2003 to 0,482 in 2010 (click here for the full analysis).

TRB is by far the largest conference I ever attended. At first, I was absolutely overwhelmed, and therefore I decided to share my lessons learned with you:

1. Get the app

If you have a smartphone or tablet, make sure to get the app. In a next post I'll go at length into the excellent app and use of social media by TRB, but as for now it is most important to know that the app will hold your schedule, and will show you where to go.

2. Travel early

I arrived on Saturday evening, with the conference starting on Sunday morning (even though the schedule at a glance does not really show that you should expect to dive in at 8 am on Sunday:

As a result, I missed out on Transportation Camp on Saturday, and didn't really get to opportunity to get the jetlag out of the way.
If possible, I'd also recommend finding the time to explore the hotels and surroundings some time before the conference, to avoid loosing too much time trying to find your way around.

3. Prepare your schedule

If you use the app, prepare your schedule in the app (the online scheduling option won't sync to the app). Otherwise, use the online version and print it out or send it to your Outlook or Google Calendar.
With so many sessions, workshops and committee meetings to attend, you can't just decide on the go where to go. Also, keep in mind that the distance between rooms can be large, so you can't plan to hop from one session to the other.
Keep some time available to have a look at the exhibition hall as well.

4. Book early

I had to wait for my paper acceptance to request travel budget, but if you can, register early and book your hotel room early!
If you're late, you end up in one of the overflow hotels. Some of these hotels are just next to the three conference hotels, but for other hotels (like the Mayflower, where I stayed) you need to take the shuttle or the metro, and the commute becomes long (especially during rush hour).

5. Use the metro, not the shuttle

One morning, I left at 7:12 with the shuttle, only to make it at 8am to the conference hotels. The metro might be crowded, and have tracks that are closed, at least it is not influenced by rush hour traffic.

6. Define your committee(s) of interest

In the schedule, you can see which committees organize the sessions. If you are interested in the research supervised by one of the committees, it'd be wise to search by the committee number in the schedule.

7. Eat at odd times or locations

Trying to get food at lunch time or dinner time in one of the restaurants around the conference hotels is a challenge. Therefore, go a little earlier or later, or take the metro to a different location.

Have you attended TRB? What would you advise first time attendees? What would you have done differently?

TRB Annual Meeting - Social Media and an App, done Right

The Annual Meeting of the Transportation Research Board is the first conference I attended that really created a buzz online.

Attendees shared technical information, thoughts and discussion from the sessions, used Twitter to get into a dialogue, and to create a community (connecting, sharing tips of where to eat, and how to get around).

The result: a mass of tweets:

3,968 tweets using #TRBAM Sun. Jan. 13-Thursday, Jan. 17, 2013. In 2012, we had 2,830 during the same #TRBAM timeframe cc: @my1sttrb
— TRB (@TRBofNA) January 23, 2013

I'll leave the analysis of why TRB managed to get this discussion going to the experts, but here are a few thoughts from my side:

• In every mail, on every opening screen, the @TRBofNA handle and the #TRBAM hashtag showed up.
• First time attendees were sent for help to the glorious @My1stTRB
• With over 10000 attendees, there must be a decent number of people that are into using Twitter for professional purposes. Percentage-wise this group might be the same as in other conferences that I attended, but the net number will be larger, which gets the discussion going.
• TRB is particularly welcoming to young members (up to 35 years). Being oriented towards younger people includes reaching out their means of communication too.
• @TRBofNA consistently tweets high-quality content, and has a large following.

Besides the great use of social media (especially Twitter), TRB also provided an app for its attendees. In my opinion, every conference should take this step. Here's what I liked so much about the app:

• you have your schedule in your pocket at all times
• you can read the abstract of the presentation, without having to carry the conference proceedings along
• you can quickly see where the room of the meeting or session will be
• you can type notes into the app

The TRB app is developed by Conference Compass, which turns out to be a company from Delft (a nice surprise, that is).

Transportation Research Board (TRB) Annual Meeting: Presentation and Paper

At the 92nd Annual Meeting of the Transportation Research Board, I've presented in the session of "Topics in Concrete Bridges".

You can find the slides of my presentation here:

Assessment of the Shear Capacity of Existing Reinforced Concrete Solid Slab Bridges from elantsoght

The paper, published in the Annual Compendium of Papers, can be accessed online.

As always, if this topic is of your interest, give me a shout-out and let's exchange ideas!