Efficient production of high-rise buildings

Abstract: Production of one family houses has over time developed successfully in Sweden and producers have managed to reduce the production costs and industrialize the production process. The development has however not been that successful when it comes to high-rise buildings. There are many attempts made, but no one has really managed to create a product that can persuade the market. The systems used are not flexible and cannot cope very well with variations in the design. The aim of this work has been to develop and evaluate the idea of prefabricated high-rise buildings within the outlines of a scientific research. By understanding the problems that the building sector experiences today it will be possible to identify the solutions that are needed tomorrow. The main objective has been to develop new technologies and system concepts for buildings. Concepts that are highly flexible and respect the ambitions of the architect and technologies that will facilitate a more effective building process and address relevant key issues in building physics and building construction for cost reduction and a sustainable performance. Aside from the actual production cost it is also important to consider the lifecycle cost of the building. The production cost represents only a fraction of the total lifecycle cost of a building. A background research has been made to understand the building process and its problems, this information served for the formulation of a building concept. The work has been interdisciplinary and has not been limited to only one single point of view. Because of the nature of the method the work has resulted in new construction techniques. The initial idea of the prefabricated high-rise building has during the course of this work developed to a complete building concept. The Symphony Concept as it is called is about industrial prefabricated buildings that are assembled on site and is based on the idea of large and flat building elements with a very high degree of prefabrication. To evaluate the concept technology detailed researches have been made in different fields. The detailed researches made in this thesis regards the strength of sheet metal studs embedded in stiff insulation blocks, hazards connected with plastering on light weight constructions and fire protection of light weight constructions. The experiences from these researches are then applied in the building concept. Theory was put to practice with the construction of an experimental building called the Research Tower. The purpose of this pilot-project was primary to evaluate the construction technology and secondary to evaluate the properties of the building concept. To be able to find methods for production of sustainable, cost-effective and attractive high-rise buildings it is necessary to have a holistic view. A holistic concept that takes into consideration the whole building process will yield time- and cost-efficient production while it will also make it possible to achieve better quality. The detail researches shows that embedding of the sheet metal profiles in the rigid insulation blocks will increase the buckling load of the stud and that the thickness of the plastering layer and the material properties of its substrate will affect the strains in the plastering layer and the moisture stored in it. Regarding the fire protection it could be stated that the Symphony outer wall construction protected with a double layer of gypsum board can maintain segregation of the fire up to 60 min as long as the gypsum boards do not crumble. In the production of the pilot projected it could be stated that the fact that the whole building was designed by one homogenous team with information about all details, made it possible to foresee many problems. The production of elements even in the temporary experimental production facility proved to be fast and economic, even with untrained labour force and the elements could be prefabricated to a very high level with facades that are plastered before assembly.