A steel frame structure of a few storey building is considered in European project FRAMEUP. Each column of the building is constructed from steel profiles connected by column-to-column connection, called column splice. In FRAMEUP project new type of column splice connection is designed to facilitate assembly. This connection consists of a plate, called finger plate with characteristic shape of holes, called long open slotted holes. A column splice with long open holes is a type of friction connection, where finger plate transfer load between bottom of one column and top of a second part and preloaded bolts are used to clamp segments together. In this work, the behaviour of the connection is investigated. Moreover, general information about column splices, friction connection and loss of pretension are introduced in literature review. A recommendations, for the preloaded bolts are investigated in accordance with European standard EN 1993-1-8. An experimental static compression tests are performed in order to observe the real behaviour of the column splice with long open slotted holes. Several number of numerical tests are performed to predict behaviour of the connection by use of Abaqus software. The Numerical model is validated against experimental results. Further tests are performed in order to check an influence of other important factors on the behaviour of connection system. An influence of connection geometry i.e. filler plate thickness, characteristic of the surface and the material properties are analyzed. The variation of bolt forces as well as slip factor and reduction factor ks are investigated. Finally, experimental test and finite element method analysis are discussed and conclusion are given. / <p>Validerat; 20140913 (global_studentproject_submitter)</p>

No / Accepted for conference.

A 5. 0 em. diameter column was used for gas absorption. The column contained internal baffling and was operated in a countercurrent mode. Oxygen comprised the gaseous phase and tap water the liquid phase. The column was operated both with and without pulsations. The injection and exhaustion of compressed air to the system provided the pulsation mechanism. The mixing as well as the mass transfer characteristics were examined. A Set of experiments independent of the mass transfer work was carried out in order to study mixing in the column. A refluxing mechanism is uncovered in the mixing experiments. Values for the axial dispersion coefficient, volumetric mass transfer coefficient and reflux ratio are reported over the range of the operating parameters. / Thesis / Master of Engineering (MEngr)

This dissertation examines the Split Delivery Vehicle Routing Problem (SDVRP), a relaxed version of classical capacitated vehicle routing problem (CVRP) in which the demand of any client can be split among the vehicles that visit it. We study both scenarios of the SDVRP in this dissertation. For the SDVRP with a fixed number of the vehicles, we provide a Two-Stage algorithm. This approach is a cutting-plane based exact method called Two-Stage algorithm in which the SDVRP is decomposed into two stages of clustering and routing. At the first stage, an assignment problem is solved to obtain some clusters that cover all demand points and get the lower bound for the whole problem; at the second stage, the minimal travel distance of each cluster is calculated as a traditional Traveling Salesman Problem (TSP), and the upper bound is obtained. Adding the information obtained from the second stage as new cuts into the first stage, we solve the first one again. This procedure stops when there are no new cuts to be created from the second stage. Several valid inequalities have been developed for the first stage to increase the computational speed. A valid inequality is developed to completely solve the problem caused by the index of vehicles. Another strong valid inequality is created to provide a valid distance lower bound for each set of demand points. This algorithm can significantly outperform other exact approaches for the SDVRP in the literature. If the number of the vehicles in the SDVRP is a variable, we present a column generation based branch and price algorithm. First, a restricted master problem (RMP) is presented, which is composed of a finite set of feasible routes. Solving the linear relaxation of the RMP, values of dual variables are thus obtained and passed to the sub-problem, the pricing problem, to generate a new column to enter the base of the RMP and solve the new RMP again. This procedure repeats until the objective function value of the pricing problem is greater than or equal to zero (for minimum problem). In order to get the integer feasible (optimal) solution, a branch and bound algorithm is then performed. Since after branching, it is not guaranteed that the possible favorable column will appear in the master problem. Therefore, the column generation is performed again in each node after branching. The computational results indicate this approach is promising in solving the SDVRP in which the number of the vehicles is not fixed.

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The purpose of the thesis is to find out how to design column bases with conventional methods presented by European standards and codes, but above all from the Steel Construction Institute's handbook on structural joints and compare it with finite element analyses. However, today there are no good instructions for how column bases exposed to multiaxial bending should be designed, where assumptions based on structural mechanics also was compared with computer tools. The hand calculations are made in Excel and are something Northpower Stålhallar AB has requested, which will facilitate their work with design of column bases for VKR profiles placed at the middle, along one side, and at the corner of the plate. Several examples of column bases are touched upon in the work, with different load effects, as well as different dimensions of the column base, to assess how the result is affected. Examples of a dowel's bearing capacity are also treated. Finally, the calculations do not differ significantly from the results of the FE analysis at the smaller dimensions of the column foot, and that difference lies on the safe side with both uniaxial and multiaxial bending, as well as for transverse force capacity. The deviation for multiaxial bending was considerably larger, as the calculations were based on assumptions. The problem is that when bending in two directions, it is uncertain where the pressure resultant is located as the magnitude of the bending moment significantly affects the point of attack, while for uniaxial bending it can always be assumed that it is at the flanges.For the larger dimensions, however, it was the opposite, the FE analysis was on the safe side compared to the manual calculations. This makes the result extremely uncertain. The capacity differs at different dimensions of the column foot. The conclusion is that more calculations need to be made, as only a few were examined in this thesis, but based on these results, it is not appropriate to use manual calculations if it is this uncertain. When using a shear dowel, the tensile force on the anchor rods became significantly lower for the FE analysis, this is assumed to be due to the secondary force Nsec.Ed who can be added for design, which was neglected in the manual calculations. / Examensarbetets syfte är att ta reda på hur man dimensionerar pelarfötter med konventionella metoder som ingår i europeiska standarder och föreskrifter, men framför allt från Stålbyggnadsinstitutets detaljhandbok, och jämföra det med finita elementmetoden. Idag finns det dock inga anvisningar för hur pelarfötter utsatta för fleraxlig böjning skall dimensioneras, där antaganden också jämförs med datorverktyg. De analytiska beräkningarna är framställda i Excel och MathCad och är något Northpower Stålhallar AB har efterfrågat, som skall underlätta deras arbete med dimensionering av pelarfötter för VKR-pelarprofiler placerade vid mitten, långsidan och hörnet av fotplåten.Flera exempel på pelarfötter berörs i arbetet med olika lasteffekter, samt olika dimensioner på pelarfoten, för att bedöma hur resultatet påverkas. Ett exempel på en dymlings bärförmåga behandlas också. Slutligen är det tydligt att handberäkningarna inte differerar avsevärt från resultaten av FE-analysen vid den mindre dimensionen av pelarfoten, och den skillnaden ligger på den säkra sidan för handberäkningarna vid både enaxlig och fleraxlig böjning, samt för tvärkraftskapacitet. Avvikelsen för fleraxlig böjning var dock avsevärt större, då beräkningarna var baserade på antaganden. Problemet vid böjning i två riktningar är att det är osäkert vart tryckresultanten ligger då storleken av böjningarna påverkar angreppspunkten, medan för enaxlig böjning kan man alltid anta att resultanten är vid den tryckta flänsen.Med avseende på den större dimensionen var resultatet dock tvärtom, att FE-analysen låg på den säkra sidan gentemot handberäkningarna. Det här gör slutresultatet osäkert, då kapaciteten differerar vid olika dimensioner på pelarfoten. Slutsatsen är att det definitivt behöver göras fler beräkningar, då endast enstaka fall användes vid denna rapport, men utifrån resultatet från detta arbete är det inte lämpligt att använda handberäkningar ifall det är osäkert. Gällande dimensionering av en skjuvklack blev dragkraften på grundskruvarna betydligt lägre för FE-analysen, detta antas vara på grund av den sekundära kraften Nsec.Ed som kan användas vid dimensionering, vilket försummades vid handberäkningarna.

<p> The thesis summarizes the experimental and analytical results of studies on the behavior of two FRP-encased steel-concrete composite columns under axial loading. Composite columns have been conventionally constructed using steel and concrete. This study utilizes FRP in combination with steel and concrete to manufacture composite columns with enhanced behavior. The first type of column is a concrete-encased steel column wrapped with epoxy-saturated glass and carbon fiber reinforced polymer (GFRP and CFRP) sheets in the transverse direction. The second type of composite column utilizes a GFRP tube that surrounds a steel I section column, which is subsequently filled with concrete. </p> <p> To the best of the author's knowledge, columns comprising FRP, steel and concrete in the shape of the proposed composite systems has not been reported on in the literature. This study includes two major phases. In the first phase, behavior of stub columns is investigated where stability effects are ignored and failure is governed by the loss of cross-sectional strength. In the second phase, influence of stability on the behavior of the proposed composite columns is studied by testing specimens with various slenderness ratios. </p> <p> To investigate the cross-sectional strength, a total of nine short (500 mm in height) composite column specimens were constructed and tested under axial compression. Five specimens were wrapped with FRP sheets and the remaining four were constructed using a GFRP tube. Experimental results showed significant enhancement in the behavior of the composite columns which was achieved due to confinement and composite action between the constituent materials. The compressive strength of the confined concrete core in the composite specimens constructed using FRP sheets and GFRP tube increased by a factor of 2.4 and 1.8, respectively. An analytical model was developed to predict crosssectional behavior of the proposed composited column. </p> <p> With the primary objective of investigating the influence of slenderness on the behavior of the composite columns, ten additional column specimens, ranging between 1,000 mm and 3,000 mm in height, were tested. Five specimens were constructed using FRP sheets and five constructed using the GFRP tube technique. It was found that the compressive strength of the confined concrete core in the longest tubular composite specimen was reduced to approximately 60% of that of the corresponding short specimen. No confinement was achieved in the longest FRP wrapped composite column specimen. </p> <p> Three bare steel columns, ranging between 500 mm and 3,000 mm in height, were also tested to facilitate comparison with the composite columns in terms of increased axial capacity, as well as stiffness and energy dissipation characteristics of the columns. The compressive strength, elastic axial stiffness and ultimate axial strain of the bare steel columns increased by a factor of up to 10, 6 and 3, respectively, in the composite columns constructed utilizing the concrete-filled GFRP tube. These factors were reduced to 5 .2, 2.5 and 2.6, respectively, in the concrete-encased steel columns wrapped with FRP jackets. </p> <p> Finally, an analytical model was developed to establish the capacity curves for the proposed composite columns accounting for slenderness effects. A simple design equation to predict the compressive strength of the tubular composite columns was proposed based on the capacity curve generated from the analytical model. Compressive capacity of the composite columns predicted using the proposed design equation showed favorable agreement with the experimental results. </p> / Thesis / Doctor of Philosophy (PhD)

Reinforced concrete (RC) moment frames comprise a significant portion of the built environment in areas with seismic hazards. The beam-to-column joints of these frames are key components that have a significant impact on the structure's behavior. Modern detailing provides sufficient strength within these joints to transfer the forces between the beams and the columns during a seismic event, but existing structures built with poor detailing are still quite prevalent. Identifying the need and extent of retrofits to ensure public safety through nondestructive means is of primary importance. Existing models used to analyze the performance of RC beam-to-column joints have either been developed for modern, well-detailed joints or are simplified so that they do not capture a broad range of phenomena. The present study is aimed to extend a modeling technique based on the nonlinear truss analogy to the analysis of RC beam-to-column joints under cyclic loads. Steel and concrete elements were arranged into a lattice truss structure with zero-length bond-slip springs connecting them. A new steel model was implemented to more accurately capture the constitutive behavior of reinforcing bars. The joint modeling approach captured well the shear response of the joint. It also provided a good indication of the distribution of forces within the joint. The model was validated against three recently tested beam-column subassemblies. These tests represented the detailing practice of poorly-detailed RC moment frames. The analytical results were in good agreement with the experimental data in terms of initial stiffness, strength and damage pattern through the joint. / Master of Science