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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
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Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Showing 61 to 62 of 62 (0.039 seconds)| 61 |
Maximering av spännvidd vid ändfack för betongbjälklag i bostäder / Maximizing span at tip compartment for concrete floors in homesKouriya, Julia, Yacob, Zina January 2014 (has links)
Dagens samhälle har fått en explosiv utveckling som förverkligar mycket som för bara några år sedan var inte mer än fantasier. Dagens utvecklingsförsprång ställer oss, byggnadskonstruktörer, inför rejäla utmaningar. Den globala folktillväxten ökar väsentligt vilket leder till tätbefolkade städer. Detta utvecklar ett stort utrymmesbehov hos många av oss. Allt detta resulterar i att efterfrågan på stora och öppna planlösningar ökar markant. En av dagens tendenser är att beställare och arkitekter har en benägenhet att tänja på gränserna på maximala spännvidder mellan bärande betongväggar, för bjälklagstjockleken 250 mm. Detta är ett tillfredsställande mått för att klara ljudklass B. Dessutom är det opraktiskt att variera bjälklagstjocklekar inom ett projekt, därför vill man ha uniformitet med samma tjocklek över projektet. För att vi ska kunna förverkliga vårt uppdrag har vi varit tvungna att genomgå en lång beräknings- och undersökningsprocess. I våra beräkningar har vi lagt fokus på två upplagsfall. Det första upplagsfallet ”fri-inspänd” och det andra fallet ”inspänd-yttre gavelvägg”. Första fallet har varit det värsta fallet i och med att vi bara har ett stöd som måste bära hela betongbjälklaget, vilket har varit en stor utmaning. Andra fallet var dock betydligt enklare på grund av de två stöden som utgjorde en stor del av ”arbetet” och lyfter upp bjälklaget, hela tyngden vilade inte på armeringen som i föregående fall. Inte bara spännvidden skall klaras utan även angiven sprickvidd på 0,3 mm. Examensarbetet består av förklarande fakta som är strikt relaterad till efterföljande beräkningar. Alla beräkningar har utförts för hand, utan programstöd. / Today's society has received a degenerate development embodying much that just a few years ago was no more than fantasies. This development sets us, structural engineers, facing real challenges. The global population growth increases significantly leading to densely populated cities. This develops a large space need for many of us. All this results in the increasing demand for large and open floor plans significantly. One of the current trends is that the clients and architects have a tendency to push the limits on maximum spans between bearing concrete walls, slabs for thickness 250 mm. This is a satisfactory measure of the concrete content to manage audio class B. Moreover, it is impractical to vary the slab thickness within a project, so he wants to have uniformity with the same thickness over the project. For us to be able to realize these long spans between bearing walls, we have been forced to undergo a long calculation and examination process. To begin with, we have studied the company's requirements and preferences, based on that, we started joists analysis. In our calculations, we have laid emphasis on two cases. The first circulation fall "free - clamped" and the second, "clamped- outer end wall." The first case has been the worst case, in that we only have one support that must bear the entire concrete slab, which has been a major challenge. Second case was considerably easier due to the two supports which made a large part of "work" and lifts the slab, the full weight rested not on the reinforcement as in the previous case. Not just the span must be met, but also given crack width of 0.3 mm. The thesis consists of explanatory facts that are strictly related to the subsequent calculations. All calculations have been performed by hand, without program support.
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Rehabilitation of Exterior RC Beam-Column Joints using Web-Bonded FRP SheetsMahini, Seyed Saeid Unknown Date (has links)
In a Reinforced Concrete (RC) building subjected to lateral loads such as earthquake and wind pressure, the beam to column joints constitute one of the critical regions, especially the exterior ones, and they must be designed and detailed to dissipate large amounts of energy without a significant loss of, strength, stiffness and ductility. This would be achieved when the beam-column joints are designed in such a way that the plastic hinges form at a distance away from the column face and the joint region remain elastic. In existing frames, an easy and practical way to implement this behaviour following the accepted design philosophy of the strong-column weak-beam concept is the use a Fibre Reinforced Plastic (FRP) retrofitting system. In the case of damaged buildings, this can be achieved through a FRP repairing system. In the experimental part of this study, seven scaled down exterior subassemblies were tested under monotonic or cyclic loads. All specimens were designed following the strong-column weak-beam principal. The three categories selected for this investigation included the FRP-repaired and FRP-retrofitted specimens under monotonic loads and FRP-retrofitted specimen under cyclic loads. All repairing/retrofitting was performed using a new technique called a web-bonded FRP system, which was developed for the first time in the current study. On the basis of test results, it was concluded that the FRP repairing/retrofitting system can restore/upgrade the integrity of the joint, keeping/upgrading its strength, stiffness and ductility, and shifting the plastic hinges from the column face toward the beam in such a way that the joint remains elastic. In the analytical part of this study, a closed-form solution was developed in order to predict the physical behaviour of the repaired/retrofitted specimens. Firstly, an analytical model was developed to calculate the ultimate moment capacity of the web-bonded FRP sections considering two failure modes, FRP rupture and tension failure, followed by an extended formulation for estimating the beam-tip displacement. Based on the analytical model and the extended formulation, failure mechanisms of the test specimens were implemented into a computer program to facilitate the calculations. All seven subassemblies were analysed using this program, and the results were found to be in good agreement with those obtained from experimental study. Design curves were also developed to be used by practicing engineers. In the numerical part of this study, all specimens were analysed by a nonlinear finite element method using ANSYS software. Numerical analysis was performed for three purposes: to calculate the first yield load of the specimens in order to manage the tests; to investigate the ability of the web-bonded FRP system to relocate the plastic hinge from the column face toward the beam; and to calibrate and confirm the results obtained from the experiments. It was concluded that numerical analysis using ANSYS could be considered as a practical tool in the design of the web-bonded FRP beam-column joints.
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