Regular closed-polygon sections (RCPS) are a cost-efficient alternative to circular hollow sections,widely used for telecommunication towers, lighting and overhead electrical lines, having a potentialas wind towers. Current regulations cover only mild steels and provide limited knowledge on thefailure mechanisms or the influence of initial imperfections. This paper summarises the findings ofan RFCS funded study (RFSR-CT- 2015-00021) on short polygonal members investigating whetherplate or shell-theory would be best fit for a certain RCPS. The study was performed throughextended numerical and laboratory tests. A formula is proposed describing the limit for the failuremode shift of an RCPS, assisting the design by designating the appropriate Eurocode to beconsidered.

Having in mind the topic of industrialised construction and the benefits of modular construction, sandwich panels are investigated to be utilised as load-bearing wall elements. To assess its full potential, the present paper tackles the linear elastic buckling response of axially loaded angle sandwich panels, by means of numerical and analytical calculations, as the upper bound of its load bearing capacity. The failures modes are obtained and framed for concentrically loaded angle panels with fixed and pin-ended supports. A parametric study of the angle panel comprising a series of finite element models is undertaken where responses are compared with analytical calculations based on the theory of sandwich panels. Boundaries for local and global buckling are identified and framed.

This paper introduces a novel joint based on a friction connection designed for column-splices. The jointwas developed within the scope of modular construction to improve the fast assembly of prefabricatedframes and to accommodate eventual misalignments. Gaps at the connection are considered on the jointhorizontal and vertical axis to accommodate misalignments whether they are rotations and/ordisplacements and so to allow for the easy fit of the columns. The efficiency of the joint resistance basedon different connection gaps subjected to uniform compression is assessed.

Sweden has a strong demand on the construction of student accommodations and consequently significant efforts have been taken to increase and streamline construction methods. In addition, the fluctuation on the number of students admitted at each year, in each university, lead to periods of house shortage or, in opposition to that, to eventual surplus on the housing market. For these reasons urges finding a fast execution process in construction to fulfil the market needs, together with a housing mechanism of control which balances the students’ needs with the housing availability. In this sense, the Frameup system arises as a solution to solve both problems by combining a modular construction with an innovative execution process.

The FRAMEUP buildings uses a steel frame in combination with prefabricated 3D modules - fully equipped and suitable for student accommodations – which are assembled by starting from the roof to the 1^st floor. The existence of the lifting system permits the erection of the building, promoting each time the building is lifted, a clearance of one-floor-height, at ground level, for the assembly of a new floor. The procedure is repeated several times, according to the number of floors, until the 1^st floor of the building, the last floor of the execution sequence, is assembled.

Alongside with its advantage on the fast execution, the Frameup system allows to efficiently increase or decrease the number of the floors and consequently its exchangeability with other buildings of same nature. Thus, assuming a net of FRAMEUP buildings at each university, its exchangeability system would create the necessary conditions so that the number of floors at each campus would follow the fluctuations of the students’ population among the different universities on different periods of time, so to suppress the needs for housing or to avoid the surplus on construction.

Sweden has a strong demand on the construction of student accommodations and therefore significant efforts have been taken towards an affordable and easy solution of the problem. A concept combining these requirements may be based on the use of structural steel frames in combination with prefabricated 3D modules fully equipped and suitable for student accommodations. Therefore, the need to investigate and develop a system suitable for an effective assembly of student residences is considered in this paper, as part of an international project, Optimization of the frames for effective assembling - FRAMEUP. The Fig. 1 reveals an overview of the system within the execution process.The Frameup system introduces a new approach in terms of execution technique which consists of the execution of a building starting from the roof to the 1st floor. The existence of a lifting system constituted of a horizontal rigid frame - grid - in combination with lifting towers - pylons - permits the erection of the building, promoting each time the building is lifted, a clearance of one-floor-height plus tolerances at the ground level. This creates room enough for the assembly of the lower floor from below the previously assembled floor. The procedure is repeated several times according to the number of floors until the 1st floor of the building, the last floor of the execution sequence, is assembled. Moreover the Frameup system introduces an innovation, the Frameup conveyor system, which streamlines the assembly process so to move/slide the elements, as they come, directly from the lorry to their final position in the building.The development of the Frameup system benefits from a stepwise detailed 3D modeling and structural analysis and design tools. However, when it comes to attest the reliability and efficiency of the system, a full scale feasibility test is essential and it is performed on the majority of the sequences of construction.

The methodology developed under the project FRAMEUP includes the construction of residential buildings from the top to the base, whose compartments are prefabricated modules. The construction begins with the execution of the roof, on the ground level, which is later on lifted, allowing from beneath the construction of the lower floors, while it protects them from the weather. The construction ends with the execution of the ground floor. It is adopted a framed structure with tubular sections for which the beam-to-column connections are developed and the columns-splices designed to facilitate and the use of this constructive methodology.

The novel joint presented in this paper is a friction connection used for column-splice connections of modular buildings as part of the innovative construction method introduced in the research project Optimization of frames for effective assembling - FRAMEUP. This type of joint provides a quick assembly and can deal with misalignments by introducing a connection gap. A filler and finger plate are welded to the upper part of the column to this end.The gap between finger plates and lower column faces is closed during tightening of the bolts and, thus, establishes a slip-resistant connection. The efficiency of the joint resistance based on different connection gaps subjected to uniform compression is assessed.The column-splice is composed of four slip-resistant connections, one at each side of the tube. Each finger plate consists of three long slotted holes and is welded to the upper column face. Long slotted holes are used to accommodate vertical misalignments and, therefore, allow fitting the bolts which are pre-installed in the lower column. Filler plates with different thicknesses (4, 6 and 8 mm) welded between the finger plate and upper column face are used to create a connection gap which allows balancing horizontal misalignments. The lower column faces consist of each nine holes with no clearance in order to pre-fit the bolts in a workshop. Thus, the assembling process on the construction site can be speeded up as once the lowercolumns are in place all bolts can be tightened immediately.

In the majority of university cities in Sweden, a strong demand for student accommodations has initiated various development and research projects focusing on costs reduction and fast execution. The present thesis brings up a solution based on the development of a feasible assembly concept and process, for a Modular Building erection, where prefabricated 3D Modules are assembled into a sway steel frame. The concept has been initiated within FRAMEUP project: Optimization of Frames for Effective Assembling (RFCS contract RFS-PR-10121). One of the main project objectives was to investigate and develop a competitive structural system suitable for fast in-situ execution and dismounting. Thus, in order to streamline the construction process, the use of optimized prefabricated frames and room 3D modules has become a very attractive alternative. The building is designed considering a six-story building, as it has been seen as the suitable choice of industrial partners in the project on market demands for the optimal payoff time. The use of Intensive Use of Steel together with Modular Construction enhances the conditions for industrialization of the construction process towards the cost reduction.The development of the whole concept is described and followed up by a 4D construction sequence. The concept is based on the original structural system for which calculations, drawings and feasibility test at full scale are made to prove the credibility of the system. The 3D Modules are designed by Norrbotten based SME, which has influenced the global concept design. In addition, development of a novel joint, by means of laboratory tests and finite element models, is shown in the thesis. It is believed that its use in the frame, for the column splice connection, may be advantageous for the execution process. The issue of execution tolerances has been addressed by advanced FEA, which has been validated by experiments.

I majoriteten av svenska universitetsstäder har stark efterfrågan på studentbostäder initierat flera utvecklings- och forskningsprojekt med fokus på kostnadsbesparingar och snabbt uppförande. Föreliggande uppsats behandlar en lösning baserad på utveckling av ett koncept med prefabricerade byggnadsmoduler vilka monteras i ett ramverk av stål. Konceptet har initierats inom FRAMEUP-projektet Optimization of Frames for Effective Assembling (RFCS contract RFS-PR-10121). En av de främsta målsättningarna var att utveckla ett konkurrenskraftigt konstruktivt system som är lämpligt för såväl snabb montering som snabb nedmontering på plats. I syfte att effektivisera konstruktionsfasen är användning av optimerade prefabricerade ramar och rumsmoduler att attraktivt alternativ. Byggnaden är dimensionerad för sex våningar eftersom det har ansetts som ett optimum ur ett återbetalningsperspektiv av medverkande industriella partners. Användningen av koncepten Intensive Use of Steel och Modular Construction förbättrar möjligheterna till industrialisering av konstruktionsprocessen vilket möjliggör kostnadsbesparingar.Utvecklingen av hela konceptet är beskriven och följs upp med en 4D konstruktionssekvens. Konceptet är baserat på det ursprungliga konstruktiva systemet för vilket beräkningar, ritningar och genomförbarhetsprov i fullskala är utförda. Modulerna är konstruerade av SME i Norrbotten vilket har påverkat det övergripande konstruktionskonceptet. Därutöver redovisar uppsatsen utvecklingen av en ny typ av förband vilket undersöks med provning och FE-beräkningar. Det är tänkbart att användande av detta förband i ramverkets pelarskarvar kan leda till ett optimerat uppförande. Frågan om utförandetoleranser har adresserats med avancerade FE-beräkningar vilka har validerats med provningar.