Ongoing research projects
Ongoing research projects in iMMC (January 2020)
This a short description of research projects which are presently under progress in iMMC.
Hereunder, you may select one research direction or choose to apply another filter:
List of ongoing projects in the division: GCE
|Simulating flow in Tonle Sap, Cambodia|
Researcher: Anh Hoang Le
Supervisor(s): Sandra Soares Frazao
- Simulating flow and sediment transport in the Lower Mekong River;
- Simulating flow in Tonle Sap, Cambodia by SLIM;
- Study on floc characteristics in Luang Prabang, Laos and Mekong Delta
|Preforming of composite thermoset prepreg fabrics.m|
Researcher: Catherine Doneux
Supervisor(s): Thomas Pardoen
Graduated as Civil Engineer at University of Liege in 1992,C. Doneux began her career with a first experience on the assessment of an existing prestressed railway bridge. Thanks to several FNRS grants, she obtained a PhD degree in the domain of steel-concrete composite structures under seismic action in 2002 and was involved in several researches on paraseismic design at ULg until 2005. After some career break, she joined UCL in December 2008 to take part to the development of new composite activities related to various applied research projects in collaboration with the industry (aeronautics). Her main fields of expertise are the mechanical characterization of composite materials by mechanical testing, the quality control of the standardised tests and the development of new tests. She has also some experience in fatigue testing, damage characterization and fracture mechanics. She is currently working on the preforming of composite thermoset prepreg fabrics.
Researcher: Henri de Chaunac de Lanzac de Montlogis
Supervisor(s): Alain Holeyman
The context the Fondytest spin-off is the construction business, and in particular the foundations of new construction works. The objective of the spin-off is to offer quality assurance of newly built foundations thanks to a innovative dynamic load test device developed at UCL.
|Numerical and experimental investigation of monopile driving resistance in carbonate rocks|
Researcher: Mustafa Jafari
Supervisor(s): Alain Holeyman, Pierre Latteur
|Optimization of tensegrity bridges based on morphological indicators|
Researcher: Jonas Feron
Supervisor(s): Pierre Latteur
Tensegrity structures are composed of struts and tendons in such way that the compression is “floating” inside a net of tension in a stable self-equilibrated state. Although tensegrity forms have inspired artists and architects for many years, there exist very few real construction projects across the world. The main reasons are, among others, the complex construction processes and the lack of design guidelines. This research, performed in collaboration with the company BESIX, aims at proving the feasibility of a first pure tensegrity bridge around the world.
When the structure is externally loaded, large displacements occur and require non-linear calculation before reaching an equilibrium. Indeed, in tensegrity structures more than in conventional ones, form and forces are intrinsically correlated. This phenomenon is due to their intern mechanism, unless appropriate pre-stressing is applied. An allowable stiffness can be possible, but at a certain material cost, which in turn justifies the relevance of the optimization of the weight.
While designing a tensegrity structure, optimization and form finding are often great challenges. Indeed, the large amount of parameters (span, height, shape, cross sections, materials, loads, pre-stress, etc) makes the search for the structure with the best performances cumbersome. A solution to this problem is to reduce the number of degrees of freedom to consider, by grouping them into dimensionless numbers, the morphological indicators.
In 2014, R.E. Skelton et al were pioneers in using a similar approach for optimizing planar tensegrity bridges uniformly loaded. In 2017, P. Latteur et al adapted the morphological indicators methodology, used so far to optimize mainly trusses and arches, to 3D non-linear and pre-stressed lattice structures such as tensegrity structures. In 2019, J. Feron et al used this methodology to investigate the performances of different 3D forms of uniformly loaded tensegrity footbridges.
This research focus on the required checks to ensure the practicality, the constructability and the economical and structural efficiency of a pure tensegrity footbridge thanks to non linear finite element analysis, experimental validation, parametric design, prestress optimization and dynamic behavior assessment
|Evaluation of alternative damping approaches for nonlinear time history analysis, and their influence on the development of fragility curves used in seismic risk, for low-to-moderate seismicity regions.|
Researcher: Jose Baena Urrea
Supervisor(s): Joao Saraiva Esteves Pacheco De Almeida
One of the major sources of uncertainty in dynamic non-linear time history analysis (THA) of structures is modelling of damping as this parameter is not easy to measure and continues largely misunderstood. Damping simulates energy dissipation on structural and nonstructural elements that is not explicitly modelled. Although it is known to be frequency-independent and amplitude-dependent, these features are not typically considered by practicing engineers. The classical and most used model is Rayleigh damping, developed in the XIX century as a mathematic convenient representation of friction effects in acoustic waves transmission.
During the last decades, engineers have accepted this model in linear THA because the damping forces are relatively small compared with the other resisting forces in the structures and due to efficiency, simplicity and low computational cost. Contrary to this, when nonlinear THA are performed, several numerical pathologies appear such as spurious damping forces in the massless degrees of freedom and other issues resulting from stiffness decay during the analysis. Over the years researchers have developed damping models to overcome these challenges, but the scientific community still did not reach a generalised agreement. The most suitable model will depend, to a certain degree, on the specific structural problem. Unfortunately, one major concern with damping modelling is that the structural response can change drastically depending on the model used.
Nonlinear THA are commonly used to define fragility functions, which are statistical curves of performance relating demands (accelerations and displacements, typically) versus probability of exceedance of reaching a specific level of damage. They are used in the context of seismic risk analyses and will depend on the damping model employed.
This research focus on evaluating current models and proposing an alternative approach better matching experimental evidence of the response at the element level. Subsequently, the influence of these damping models on the development of fragility curves will be assessed. Finally, their impact on the final outcome of seismic risk assessment for low-to-moderate seismicity regions, such as Belgium, will be computed and interpreted.