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The vibrations of axially loaded composite beams with partial interaction are considered. The equations of motion and the pertaining boundary conditions are derived from Hamilton's principle. Mainly free — but also forced — vibrations are considered. The natural frequencies are calculated as a function of the axial force and the stiffness of the interaction between the layers. The analytical result obtained for the eigenfrequencies of the simply supported beam is taken as a starting point for an approximation of the eigenfrequencies of beams subject to other boundary conditions. The proposed approximation — which has no numerical fitting parameters — is shown to be in good agreement with the exact solutions, especially for the case of a beam clamped at both ends.

In this study, an alternative and general approach is advanced to evaluate the air leakage area and air infiltration rate in building envelope components such as exterior/internal walls and floors. In this method, the leakage area is determined with the help of acoustical and physical methods by measuring the sound reduction index of the building. The air flow rate through air leaks is determined with the help of leakage area and pressure difference over the floor/wall. The heat losses and convective moisture rate through leaks in the building are subsequently evaluated with the help of the calculated air infiltration rate.

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In this paper, the footfall-induced vibrations in typical timber and lightweight composite floors in residential buildings are investigated. The two-floor structures have approximately comparable distributed mass and that the transverse flexural stiffnesses of the two structures are not substantially different. An analysis is carried out to assess the floor acceptability of the two structures, based upon derived expressions as well as some design codes and guidelines such as the Eurocode. For the analysis, two cases are considered for each floor structure: a composite action and noncomposite action. It has been shown that use of composite action, under certain conditions, has more advantages than its noncomposite counterpart with respect to the floor acceptability for general residential applications. Moreover, the limitations of the different criteria of the codes, guidelines for assessing floor vibrations in timber and lightweight floor structures, and possible improvements of these criteria are discussed in this paper.

To meet the goals of the directive 2010/31/EU on the energy performance of buildings, the building sector in Europe now faces a transition towards more energy efficient buildings. Research and development of new energy solutions and technology will be necessary for the transition and the importance of analyzing building energy performance increases. This paper aims to review and evaluate different methods that are commonly used to analyze energy performance in residential buildings in Nordic countries, primarily in Sweden, Norway and Finland. A short international review of regulations is also included. The goal is to find commonly used methods and possibilities for the future. The introduced methods are summarized, categorized and compared based on their advantages and disadvantages. Although the three Nordic countries have similar climate conditions and building traditions, the review shows relatively large variations in the definitions of energy performance for residential buildings, as well as variations in how measurements and calculations are used in the methods for energy performance analysis. In the conducted review, methods, or parts of methods, are also found to be used. The methods used to analyze energy performance are found to be more similar than the concepts of energy performance itself in the three countries. These aspects may be considered in further work to develop an international policy practice for energy performance of residential buildings in cold climate.

Vi beskriver en nyligen införd modell för arbetsintegrerat lärande (AIL) eller co-op (co-operative education) på högskoleingenjörsprogrammen i maskinteknik respektive elektro- och datorteknik. Modellen innebär att genom samverkan med företag i närregionen erbjuda och garantera ett antal programstudenter feriearbeten under två perioder, samt examensarbeten. I modellen ingår också företagsanknutna projektarbeten och en studieresa. Upplägget förväntas bidra till positiva effekter för samtliga parter, för utbildningsprogrammen, för samarbetsföretagen samt för studenterna. Vi förklarar även hur arbetsintegrerat lärande stöds av vedertagna lärandeteorier.

I denna artikel introduceras en modell för lärande där peer - lärande och formativ bedömning är integrerade med en traditionell föreläsningsform. I detta sammanhang genomfördes en fältstudie för att testa användbarheten av modellen för en byggingenjörskurs. Resultaten visar att modellen har gett lovande resultat med hänsyn till uppfyllandet av de förväntade studieresultaten. Artikeln diskuterar också några praktiska och teoretiska aspekter samt vilka hänsynstagande till kursens innehåll och uppläggning som skulle kunna påverka vid fullgörandet av modellen.

The authors investigate the human induced vibrations in typical composite timber floors inresidential buildings. Assessment methods given in different design codes and guidelines,such as the Eurocode, are discussed. A case study analysis based on the differentmethodologies is carried out to assess the acceptability of a specific timber floor. Twoextreme cases are considered: full and non-composite action. It is shown that compositeaction improves the floor acceptability for general residential applications. The limitations ofthe different criteria given in the codes and guidelines for assessing floor vibrations in timberfloor structures are discussed and, also, the possible improvement of these criteria.

The aim of this paper is to study the dynamics of partially interacting composite beams subjectedto axial loads, a situation occurring in e.g. beam-columns. The eigenfrequencies arederived for the simply supported composite beam subjected to an axial force. Measurements ofthe fundamental frequencies of a simply supported composite beam consisting of three layersare carried out considering different values of the applied axial force. The agreement betweenthe theoretical and experimental results is discussed. It is also shown that the application ofthe axial force introduces frictional moments at the boundaries, which make the experimentalboundary conditions deviate somewhat from those of an ideal simply supported beam.

In this work, a combined variational calculus and experimental approach are used to characterize the structural vibration behaviour of layered composite beams. Experimental dynamic tests are carried out on a composite simply supported beam with varied interaction strength between the layers. From the results, the influence of connections on the flexural natural frequencies, flexural deformation and damping is investigated. A good agreement between the derived theoretical equations and experimental results is obtained.