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.

The purpose here is to study patterns of project collaboration found in one government supported programme for construction innovation. Preferred types of interaction were identified using data from two questionnaire surveys, one with experienced construction sector respondents and one aimed at construction researchers. All sixteen development projects within the Swedish Bygginnovationen programme were investigated, relying on documents and a survey of project managers. Important types of interaction, according to construction respondents, are informal contacts, joint research projects and staff mobility. For university respondents, informal contacts is also seen as the most important type of interaction, followed by MSc thesis work in firms and industrial PhD candidates. Grant applicants from manufacturing depended more on university laboratories and were less sensitive to firm/university distance. Laboratory use was also more frequent for projects relying on the field of materials engineering. In conclusion, there is a consensus about which types of collaboration are valuable. The broadness of participation in the programme, ranging over many industries, both as to origin of ideas and ultimate applications, reaches beyond narrow interpretations of the construction industry. Policy makers should recognize the innovation importance of university laboratory facilities and field testing, rather than seeing researchers as sources of ideas.

Bernt Johansson, born in Stockholm in 1942. earned his MSc in Civil Engineering from the Royal Institute of Technology in 1961. He worked as a consultant engineer and continued his studies and presented his PhD thesis in 1976 on the stability of box-girder beams. In 1985 he was recruited to Luleå University of Technology to start research on steel structures. He initiated work with thin-walled structures, high strength steel and composite structures collaborating with industry. He played a pivotal role in the development of Swedish and European design codes. He supervised many master’s, licentiate, and PhD students. He passed away in 2017

This paper comprises a study concerning the mechanical behavior of extra high strength steel. This is investigated by means of biaxial testing of flat cross-shaped specimens in the full σ1-σ2 plane, a concept developed earlier at Steel Structures, Luleå University of Technology. Furthermore, new specimen designs had to be developed to enable testing of a material with high yield strength and low ultimate over yield strength ratio, such as the extra high strength steel Weldox 1100. The tests are performed in two steps: one initial loading followed by unloading and a subsequent loading in a new direction. The test results, containing data from 15 biaxial tests, are characterized by a slightly anisotropic initial yield criterion where the proof stress in compression is consequently somewhat higher compared to the results in tension. In the subsequent loading the observed phenomena are a Bauschinger effect in the direction opposite the initial loading direction and that the transition from elastic to plastic state in subsequent loadings is gradual and direction-dependent.

The resistance of steel plate girders subjected to concentrated load can be described using a strength curve, which includes a gradual transition from yielding to buckling depending on the slenderness ratio of the web. The slenderness is a function of the ratio of the yield resistance to the critical buckling load. This paper describes a methodology for the determination of buckling coefficients for longitudinally stiffened plate girders subjected to partial edge loading or concentrated loads. After an extensive parametric analysis, the optimum parameters that govern the change from a global buckling mode to a more local buckling mode were found. As in similar buckling problems, the results show that the location and the relative flexural/torsional rigidity of the stiffener are relevant parameters that govern the final buckling shape. Finally an expression for the buckling coefficient used to determine the critical buckling load for longitudinally stiffened girder webs is presented.

This paper concerns the behaviour of bridge girder webs subjected to concentrated forces that are introduced in the web during launching, a load case usually referred to as patch loading. So far, this type of loading has, in engineering practice, been dealt with using formulas originating from investigations concerning the ultimate load carrying capacity. Numerous bridge launchings have, however, led to unwanted damages of the girder web, i.e. plastic deformations of such magnitudes that the webs had to be repaired. To avoid these damages it is necessary to have a design method, for launching situations, which focuses more on avoiding some irreversible behaviour than on the ultimate load carrying capacity. Such a design method has to be based on a deeper understanding of the behaviour of the girder. In Ref. [1] the first author discusses the fact that yielding of the flange occurs only after the web plate has been severely damaged. This paper describes the deformation behaviour of the web plate due to patch loading. For small loads the deformations will be similar to the first linear buckling mode. As the load increases a smaller buckle, in the opposite direction, will start to develop in the web plate close to the load. This behaviour, which may be named post-critical buckling, occurs also for girders of a perfectly elastic material. The investigations are based on laboratory tests and non-linear finite element analyses of three typical girders representing different slenderness categories.

The prediction of the resistance of plate edges to concentrated loads has been dealt with in numerous studies of a more or less empirical nature. The normal approach is to use two criteria for the resistance, one based on yielding and one based on instability. This study aims at a procedure that is harmonized with those normally used for describing other buckling problems. It has been carried out as part of the work with drafting Eurocode 3 Part 2 and the paper is intended as a background document for the suggested design rules.

This paper focus on three different applications of concentrated forces applied to the flanges of steel girders. Concentrated forces applied at one flange, opposite concentrated forces applied at two flanges and concentrated forces applied at an unstiffened girder end. The first application is recognized as patch loading, the second and third are herein referred to as opposite patch loading and end patch loading, respectively. Results from 43 tests with the high strength steel Weldox 700 are presented, covering all three load applications, with the majority of the tests performed as end patch loading. The tests have been added to test results published elsewhere and used for development of a unified design procedure that is harmonized with those normally used for describing other buckling problems

Different aspects concerning the resistance of steel girders subjected to concentrated forces have interested a large amount of researchers all over the world. The subject most dealt with among researchers is what is called "patch loading", a concentrated force applied at one flange. Generally, the resistance to concentrated forces is considered as being a problem of very complex nature. Therefore all studies aiming at predicting the ultimate resistance of steel girders to concentrated forces gives more or less empirical solutions. This thesis focus on three different applications of concentrated forces. Concentrated forces applied at one flange, opposite concentrated forces applied at two flanges and concentrated forces applied at an unstiffened girder end. The first application is recognized as patch loading, the second and third are herein defined as opposite patch loading and end patch loading, respectively. The report is divided in two parts, the main text and the appendices. The appendices are used to give results form tests performed herein and to present data for tests taken from the literature, but also to give results from a comparison with a design model suggested herein and the tests. The main text starts with an introduction giving the basis in the subject and a review of earlier work and ends up in a suggestion for a design model for the ultimate resistance for the three different applications of concentrated forces. The design model is developed with the purpose to be consistent for the three load applications, simple enough to be fit for use and also harmonized with those used for other buckling problems. The design model is based on a von Karman approach and includes three parts, an expression for the yield resistance, the elastic buckling load and a resistance function. The expression for the yield resistance is based on observations and conclusions from an experimental investigation, including a total of 48 tests on welded girders made from the high strength, quenched and tempered steel Weldox 700 and 12 tests on rolled beams. All three load applications were tested, with the majority of the tests performed as end patch load test. Approximate solutions for the elastic buckling load for patch loading, opposite patch loading and end patch loading are formulated on the basis of results from FEM. The buckling coefficients includes a contribution from the flange stiffness and the approximate solutions gives a reasonable accuracy compared to the result from FEM. The resistance function is empirically determined from about 250 patch load tests, since this is the only load application for which one can find tests on girders with slender webs in the literature. The resistance function is also proven suitable for opposite patch loading and end patch loading. Compared to results from a total of about 540 tests, the design model suggested herein gives a better accuracy in the prediction of the ultimate resistance for all three load applications than other leading design models from the literature. What can be considered as new and original in this thesis is that it gives a consistent model for prediction of the resistance of steel girders subjected to concentrated forces which is harmonized with the models for other instability problems a design model that extends the applicability to high strength, quenched and tempered steels additional solutions for the critical buckling loads for various boundary conditions

Syftet med denna studie har varit att genomföra en kartläggning och analys av relevanta studier och utredningar gjorda efter Korta Byggtider-programmet samt att föreslå åtgärder för att undvika negativa konsekvenser av korta byggtider på kort och lång sikt. Arbetet har utförts utgående från antagandet att pressade byggtider har negativa konsekvenser för arbetsmiljön på byggarbetsplatsen och för produktionskostnaderna. Baserat på de dokument och det material som har ingått i studien kan det dock inte påvisas att det finns grund för detta antagande. Vad som däremot kan konstateras är att ledarskapet och attityderna inom byggbranschen har mycket stor betydelse.

A model for the ultimate resistance of bridge girder webs to concentrated forces that are introduced in the web during launching is presented. The model is formulated on the basis of observations from tests with welded girders made from a high strength, quenched and tempered steel, as well as available 379 test results for different steel grades. The design model is compared with results from finite element calculations on large bridge girder cross sections and a discussion concerning the serviceability limit state. A simplified form of the design procedure is used in Eurocode 3 Part 1.5 and has also been proposed for use in Eurocode 9.

This paper presents the results from an experimental investigation including tests with welded girders and rolled beams subjected to three different cases of concentrated loads applied to the girder flanges. The welded girders were made from a high strength, quenched and tempered steel, while the rolled beams were of an ordinary steel grade. The results from the experimental investigation presented herein have been added to test results taken from the literature and used for a formulation of a design procedure for the resistance to concentrated loads. The suggested design procedure is unified for the three different load applications and also harmonized with the design procedures normally used for describing buckling problems in the steel codes. The design procedure is a further development of the design procedure for patch loading suggested in B. Johansson & O. Lagerqvist [J. Construct. Steel Res., 32 (1995) 69-105] and has in a simplfied form been suggested for use in Eurocode 3 Part 2 (Bridges), as well as in Eurocode 9.

This paper gives the results of an experimental investigation concerning the resistance of welded girders made of austenitic stainless steel subjected to concentrated forces applied at one flange. The results from three tests for each of the two load cases patch loading and end patch loading are presented, together with a comparison of the ultimate resistance from tests and the ultimate resistance according to Eurocode 3 Part 1.1, Ref. 1, and Eurocode 3 Part 1.5, Ref. 2, as well as a comparison of the load-deformation curves obtained in the tests and load-deformation curves obtained in earlier tests performed on girders made of high strength structural steel with identical geometries. It is shown that Eurocode 3 Part 1.5 gives a better prediction of the ultimate resistance than Eurocode 3 Part 1.1 and that the stainless steel girders have a weaker response to the applied load than the girders made of structural steel. Material: 304 steel.

An analytical method based on structural reliability has been developed with the objective to ensure a healthy indoor environment for people in residential buildings. The method has been applied to a model of the foundation of a house, which is principally a concrete slab on the ground, when the hazard to the indoor environment is radon. The reasons why radon is found indoors have been identified using fault tree analysis. Random variables in the model are defined such that resistance is the ability of people to withstand the radon concentration indoors without adverse health effects and the load effect is equal to the top event of the fault tree and is a function of the environmental load and the decisions made in the building process. A quantitative evaluation was made using both Monte Carlo simulation and First-order second-moment theory where the load effect is compared with the resistance defined as the threshold value for radon concentration indoors stated in the Swedish Building Regulations. The objective was to calculate the probability for exceeding the threshold value and to estimate analytically the safety index. Other interesting areas of application of the developed model could be for the environmental impact from moisture causing growth of micro-organisms and release of chemical emissions, or from soil contaminates like, for example, petroleum products.