De Trefkoel

The construction of “De Trefkoel” was divided into two phases. The first phase, a residential building with care homes, was finalised in 2014. The second phase was a new design program for a combination of student homes, youth homes and business space. This new program is accommodated in three parts of the complex, the two lower building blocks and one large residential tower. The original design of the concrete walls and floors on the ground floor was converted into a structure of colomns with light separation walls. To ensure the stability of the low-rise building seismic walls were placed. This way, a so called 'soft storey' was created which reduces the stiffness of the structure. For the tower, the number of stability walls were reduced. This has a positive influence on the stiffness of the building and reduces the horizontal base shear force. The elevator shaft is designed with a specifically chosen steel structure that has no influence on the stiffness of the construction. The ground floor is a reinforced concrete floor. This floor is used to spread the horizontal forces, coming from the top floors, evenly into the pile foundation. There was a demand for a crawling space under the floor, which led to a double ground floor, and one of them is functioning as a seismic element. The foundation was increased in size and heavily reinforced. The foundation piles were altered into a different type that could have more reinforcement. Finally the building was horizontally dilated per floor. The stone facade has also been dilated per floor and provided with a double diagonal anchor. The anchors have sufficient capacity to take on the horizontal forces from an earthquake.