Research in the Structural Mechanics Section of the Department of Civil Engineering focuses on the static and dynamic analysis of structures. Five related research lines are developed: (1) vibrations in the built environment, (2) vibration based structural identification and evaluation , (3) building acoustics, (4) shape and topology optimization, and (5) computational structural engineering. Model development is supported by laboratory and in situ experiments. The Structural Mechanics Section has powerful computer hardware and software, and modern vibration measurement equipment.
Vibrations in the built environment. Vibrations originating from road and railway traffic, construction activities, machine foundations and earthquakes propagate through the soil and excite building foundations. Low frequent vibrations (1-80 Hz) may cause disturbance of sensitive equipment, annoyance to people, and structural damage. Ground-borne vibrations of walls and floors may also cause re-radiated noise between 16 and 250 Hz. Numerical models for the prediction of vibrations and ground-borne noise in buildings are developed and validated. Models are used to design vibration mitigation measures and to perform environmental impact studies. Accurate prediction of vibration requires detailed knowledge of material and geometrical properties, which are identified by means of in situ experiments and inverse modelling. Research focusses on quantification and reduction of model and parameter uncertainty; hybrid prediction models; dynamic soil characteristics; models for rail induced vibrations accounting for parametric excitation; design of vibration mitigation measures using topology optimization; efficient methodologies for large scale dynamic soil-structure interaction problems; vibration induced damage of unreinforced masonry buildings; seismic vulnerability analysis of buildings in low to moderate seismicity areas.
Vibration based structural identification and evaluation. Vibration monitoring of civil engineering structures (bridges, buildings, dams, wind turbines) gained a lot of interest, due to the relative ease of instrumentation and the development of new powerful dynamic system identification techniques to extract modal properties (eigenfrequencies, mode shapes, modal strains) from accelerations, displacements and/or strains. Operational modal analysis (using output-only data) opens the way for in situ model based diagnosis and structural health monitoring. Damage assessment can be based on observed changes of modal parameters extracted from vibration measurements. Research focusses on extension of the frequency domain by adding measured artificial forces; use of new sensor types (optical fiber strain sensors, 3D camera or laser based optical systems); determination of optimal sensor locations; automation of the modal parameter extraction process; inverse methods for model tuning, damage assessment and dynamic load identification; virtual sensing methods to estimate unmeasured response quantities from data provided by a limited number of sensors and a structural model; validation of complex interaction models (vehicle-bridge or human-structure interaction).
Building acoustics. Many people are affected by noise from traffic, industrial and construction activities or the neighbourhood, resulting in activity disturbance, social tensions and health problems such as sleep deprivation, damage to hearing and cardiovascular diseases. Research on building acoustics focuses on sound-structure interaction with the aim of improving the acoustic quality of buildings and the built environment. Numerical prediction models and experimental techniques are developed for gaining fundamental insights on sound transmission, sound radiation and sound absorption, and for analysing and improving the acoustic properties at the material, component, and building level. Special attention is paid to the many uncertainties that are encountered across the audio frequency range, as this is key for achieving robust solutions. Research objectives are efficient sound transmission modeling through complex building elements and systems; development of techniques for experimental identification of vibro-acoustic parameters; and quantification of prediction and identification uncertainties in order to achieve robust solutions.
Shape and topology optimization. Research on size, shape, and topology optimization is developed in collaboration with the Architectural Engineering group of the Department of Architecture. Integration of optimization in computer aided engineering enables design optimization, aimed at finding the best compromise between cost and performance. Research objectives are robust design optimization accounting for data and modelling uncertainties; and development of novel solutions for mitigation of vibration and noise in the built environment.
Computational structural engineering. This research line involves the theoretical and numerical modeling of innovative or complex materials and structural systems, with a focus on the failure behavior of civil engineering structures (buildings, bridges, off-shore structures, earth-retaining structures) under static, dynamic and environmental loading conditions. An accurate prediction of the non-linear structural response is achieved through the development of modern advanced numerical models, involving well considered constitutive models, spatial and temporal discretization, and accurate and robust solution schemes.Research objectives are development of robust integration techniques for the non-linear structural response; efficient analysis of the failure modes of structures and materials, including the development of parallel computational strategies for large scale problems; and development of computational techniques for long term cyclic loading with applications to the fatigue behavior of brittle building materials and soils.