Gentle Driving of Piles (GDP) at a sandy site combining axial and torsional vibrations: Part I - installation tests

Gentle Driving of Piles (GDP) is a new technology for the vibratory installation of tubular (mono)piles. Its founding principle is that both efficient installation and low noise emission can be achieved by applying to the pile a combination of axial and torsional vibrations. Preliminary development and demonstration of the proposed technology...

Dynamic Pile Response During Vibratory Driving and Modal-Based Strain Field Mapping

For offshore wind turbines (OWTs), the monopile comprises the most common type of foundation and vibratory driving is one of the main techniques for monopile installation (and decommissioning). In practice, prior to pile installation, a pile driving analysis is performed to select the appropriate installation device and the relevant settings....

Energy flux analysis for quantification of vibratory pile driving efficiency

In this paper, the energy flux in a pile modeled as an elastic shell, is studied theoretically and experimentally. Based on this analysis, a new procedure is proposed to quantify the pile installation efficiency. This procedure is of importance for vibratory installation of the foundations of offshore wind turbines and it is believed to be...

Static and dynamic testing of delamination in hybrid SHCC/concrete beams

The focus of this study is to characterize delamination using static and dynamic tests and to assess the interface failure mechanism of an innovative hybrid concrete beam, made out of conventional concrete and a special class of fibre reinforced material, known as Strain Hardening Cementitious Composite (SHCC). Three SHCC beams were subject to...

Observation and interpretation of closely spaced fundamental modes of a high-rise building

In this paper the dynamic behaviour of a high-rise building with complex structural system is studied. In some cases, to optimize the building design, the horizontal stability of the building is accomplished by the contribution of several structural components. This is the case of the JuBi tower, the building studied in this paper. The...

Experimental identification of the dynamic behaviour of pile-soil system installed by means of three different pile-driving techniques

A novel pile-driving technique, named Gentle Driving of Piles (GDP), that combines axial low-frequency and torsional high-frequency vibrations has been developed and tested recently. During the experimental campaign, several piles were installed onshore, making use of the GDP shaker. Besides those, a number of additional piles were installed...

Energy flux method for identification of damping in high-rise buildings subject to wind

Buildings are becoming taller, lighter, slenderer. These changing characteristics make tall buildings more sensitive to environmental loads, including wind gusts. A building is considered "tall" when its height and slenderness influence the design. Given the demand of improving building performance, the serviceability limit state (SLS) has...

On the importance of soil damping for tall buildings loaded by wind

In this paper, the overall damping as function of the velocity of vibration of two tall structures subjected to wind is studied. The overall damping ratio is studied by means of two simple, but representative and complementary models and it is compared with that identified in two buildings in The Netherlands. In the models, the soil-structure...

Evaluation of the applicability of an energy method to calculate the damping in a lab-scale structure

The aim of this paper is to identify the local energy dissipation in a lab-scale structure by means of the energy flow analysis. In most of the existing approaches the damping is identified either in terms of the modal damping factors or at the material scale. In this paper, an alternative method to these global and material-based approaches...

Results of the AVATAR project for the validation of 2D aerodynamic models with experimental data of the DU95W180 airfoil with unsteady flap

The FP7 AdVanced Aerodynamic Tools for lArge Rotors - Avatar project aims to develop and validate advanced aerodynamic models, to be used in integral design codes for the next generation of large scale wind turbines (10-20MW). One of the approaches towards reaching rotors for 10-20MW size is the application of flow control devices, such as...

IEA wind annex XX: HAWT aerodynamic and models from wind tunnel measurements - final report