Thursday, January 24, 2019

Two papers from IABMAS 2018

My colleagues and I have published two papers in IABMAS 2018. I was supposed to travel to Melbourne to present these papers, but it was very shortly after my return from my annual research stay in Delft, and my baby girl did not take well to my absence and return, so I was adviced to invest time in restoring our bond. I was warned against not traveling after such a short time again, as it may leave her confused. So I canceled the conference (only second time ever I had to cancel a conference, and I did feel bad about it, but I also felt bad about my baby not being well because of my long absence...).

The two papers we published were part of a Special Session that we organized at the conference (it's a pity I couldn't travel and chair the session I spent so much time preparing on, but such is life...).

The first paper is "Monitoring crack width and strain during proof load testing" and the abstract is:
In a proof load test, the applied load is representative of the factored live load, to demonstrate experimentally that the bridge fulfils the code requirements. Signs of distress must be caught with the instrumentation by defining stop criteria. In the literature, several stop criteria for flexure are available. The German guidelines describe, amongst others, a limiting crack width and strain. However, the background of these limiting values is not clear. Therefore, a theoretical approach based on flexural theory is followed. The theoretically derived values are then compared to experimental results obtained from beam experiments. The result of this research work is a limiting value of crack widths and strains that can be used during proof load testing of concrete bridges. The arbitrary stop criteria that were used in the past can now be replaced by stop criteria that are based on the theory of concrete beams in flexure.

The second paper is "Twenty years monitoring of a high strength concrete cantilever bridge" and the abstract is:
In 1997 the Second Stichtse Bridge, a high strength concrete box girder bridge was built in the Netherlands using the balanced cantilever method. At that time, the long-term behaviour of this material (with a cube compressive strength of 75 MPa) was not known. Therefore, it was proposed to monitor the material behaviour and the deflections of the bridge for ten years, and a few properties have been monitored for twenty years. To evaluate the concrete material properties over time, concrete cubes were cast with the segments, and stored inside the bridge at the section locations. These samples have been tested periodically. Also shrinkage measurements were carried out on a concrete sample stored inside the bridge. The deflections of the bridge superstructure have been measured periodically along both edges of the bridge. Based on the available data, it is found that the concrete compressive and splitting tensile strength, as well as the shrinkage deformations, remain constant. The deflections are stabilizing as well.

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