Structural engineering of tall residential tower

'Ensuring sufficient stability'

Engineering firm IOB was asked by developer De Maese Woningen for the structural engineering of the seventy-meter high residential tower 70LUX in Zoetermeer. From the preliminary design to the final design, technical design and design ready for execution. IOB also provided part of the construction supervision.

Initially, structural engineer and consultant André Lankhof of IOB worked on the design for a completely monolithic construction, which did include the possibility for prefabricated execution. Says Lankhof, "In consultation with main contractor STATON Bouw, this was later definitively changed to a partially precast construction. We then converted the design to the precast system and worked this out further with the precast supplier."

The engineering firm was involved in the project as early as the sketch phase for structural advice. In the DO phase, modeler Gert Verhage joined in to consult with the client, architect, and installation consultant in order to fit the installations into the design without compromising the strength of the structure. Verhage: "In this project that process took a little longer, partly because the DO had to include a variant with an extra parking layer. As a result, the whole picture no longer matched and things had to be adjusted. In the end, that variant did not go ahead. The municipality also set requirements for the parking facilities/parking balance in the area, which had to be taken into account."

On this project in particular, the foundation proved to be a puzzle, partly because of the existing foundation piles left in the ground. "The bottom four layers were poured on site. Because on top of that came a seventy-meter high tower, it was important to ensure high stability in this. There were also some challenges in the many connections at different levels. In the end, it came together well."

Different disciplines

In addition to structural consultancy and engineering, IOB also offers structural and installation engineering consultancy and engineering, fire safety and construction cost consultancy, among other services. The firm is active in the industrial and energy sector, existing real estate and housing projects, such as 70LUX and recently the Rotterdam residential tower STACK. Clients include companies, property developers, contractors, corporations and municipalities. Lankhof: "The advantage for our clients is that we have different disciplines in-house. This not only enables us to provide integrated multidisciplinary advice and engineering, but in projects we can also look at a discipline that we do not have commissioned for that project. If, for example, in a project that we are working on structurally, it turns out that holes have to be drilled in a load-bearing concrete structure, it is nice that the structural engineer can ask his colleague structural engineer to take a look."