BESIX Nederland is participating in the HIVIBE consortium, a research initiative to better understand and predict the vibration behaviour of high-rise buildings in the Netherlands. Predicting this more accurately than today will contribute to prevent structural problems, to improve user comfort, and to avoid being too conservative in the design and using an unnecessary amount of material.
The research programme is currently underway and entering its empirical phase, with measurements on eight skyscrapers in the Netherlands. Of these, three were built by BESIX Nederland: New Orleans (Rotterdam), Terraced Tower (Rotterdam) and Grotius (The Hague).
“The vibration behaviour of high-rise buildings is very difficult to predict accurately with current calculation methods. The influence of the subsoil in the Dutch delta plays an important role in this respect”, says Frederic Stroobandt, Senior Project Manager at BESIX Engineering. The Dutch delta is the western part of the country where 60% of the Dutch population lives and which is to a large extent below sea level.
Furthermore, in the Netherlands as in other countries around the world, the trend is to build taller and thinner buildings, while using other materials such timber or new concretes, especially for sustainability purposes. “Building taller, lighter and thinner makes buildings more sensitive to wind, which causes vibrations that can have consequences for structural safety and user comfort”, adds Frederic Stroobandt.
The HIVIBE consortium launched a large-scale research, which is being carried out in two phases. The first phase, which ended in 2021, served as a preliminary investigation to determine which properties should be measured and which techniques were available to do so. In addition, the partners identified the buildings and criteria to be used.
In the second phase, starting in 2021 and ending in 2024, eight buildings have been selected on which monitoring systems are being set up and implemented.
Measuring systems will be installed to measure several characteristics of the building over a long period of time. The measurement system consists of several elements. Anemometers are installed on the masts of the buildings to record the wind speed. Accelerometers and inclination sensors at two different heights determine the vibrations and quasi-static behaviour in the main support directions of the building. Finally, multiple deformation sensors on the main structure at ground level measure the dynamic deformation and determine the load on the foundation.
Parallel to the measurements on the selected buildings, one of HIVIBE's members, the Netherlands Organisation for Applied Scientific Research (TNO), is participating in the updating of the Eurocode EN 1991-1-4, which comprises the European standards describing the principles and requirements for the calculation of wind loads. The purpose of this update is to provide a way of better predicting peak-wind accelerations. And all the partners in the HIVIBE initiative will also contribute! First, each company involved will create a spreadsheet according to the new Eurocode calculation methods. These spreadsheets will be compared and discussed in order to converge and create a common spreadsheet, which in turn will be compared with the measurements carried out under the HIVIBE initiative. The conclusions of this work will finally be used to finalise the new version of the Eurocode EN 1991-1-4.
The HIVIBE consortium includes, in addition to BESIX NL, the companies BAM, Zonneveld, Fugro, IMd, Aronsohn, Structure Portante Grimaud, Peutz, SCIA, SKW and TNO. And the name HIVIBE perfectly sums up the project: "HIghrise VIBrations in delta cities Explored"!