Ph.d.-forsvar ved Mads Jacob Baandrup

Mads Jacob Braandrup forsvarer sin ph.d.-afhandling "Innovative design of steel girders in cable-supported bridges"

Forsvaret finder sted tirsdag, d. 26.maj 2020, klokken 13.00.

Forsvaret vil foregå online via dette link.

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Kort resumé: 

The main design principles for girders in cable-supported bridges have remained largely unchanged for the past 50 years and have reached a point where the potential for further development is limited. The design concept is subject to substantial fatigue issues, and in future super-long bridges with spans beyond 3 km, the girder self-weight becomes a critical design factor preventing even longer bridge spans. To accommodate the challenges of decreasing self-weight and reducing fatigue issues, it is anticipated that radical design changes will be required in girders.

In this thesis, entitled "Innovative design of steel girders in cable-supported bridges", three different methods of structural optimization are applied in search of innovative girder concepts. The main focus is on reducing self-weight and on identifying more efficient load-carrying principles and, thus, more material-efficient structures.

Initially, parametric optimization is applied to pursue any possible weight savings in the conventional girder design. Here, the main findings are possible weight savings in the range of 6%-14%, however confirming that the conventional design concept is limited in further development, without altering the structural concept.

Next, topology optimization of continuum structures is applied in search of innovative girder designs. Based on the main structural features of the optimized designs, a simple interpreted design is established with an initial weight saving of 13%. After a subsequent parametric optimization to identify the full potential, a total weight saving in excess of 28% is gained while maintaining constructability.

Finally, large-scale truss optimization is applied with constraints on stresses and stability. A significant weight saving of 45% is achieved with a truss girder considerably different compared to the conventional design. The higher weight savings gained with the truss girder, compared to the interpreted design, are though achieved at the expense of increasing structural complexity.

The newly identified design principles and possible weight savings emphasize the potential of using significantly different girder concepts and may close the gap toward super-long cable-supported bridges and reduce material quantities.


tir 26 maj 20
13:00 - 15:00


7 JUNI 2020