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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the 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.
21

Footbridge Dynamics : Human-Structure Interaction

Zäll, Emma January 2018 (has links)
For aesthetic reasons and due to an increased demand for cost-effective and environmentally friendly civil engineering structures, there is a trend in designing light and slender structures. Consequently, many modern footbridges are susceptible to excessive vibrations caused by human-induced loads. To counteract this, today's design guidelines for footbridges generally require verification of the comfort criteria for footbridges with natural frequencies in the range of pedestrian step frequencies. To ensure that a certain acceleration limit is not exceeded, the guidelines provide simplified methodologies for vibration serviceability assessment. However, shortcomings of these methodologies have been identified. First, for certain footbridges, human-structure interaction (HSI) effects might have a significant impact on the dynamic response. One such effect is that the modal properties of the bridge change in the presence of a crowd; most importantly, the damping of the bridge is increased. If this effect is neglected, predicted acceleration levels might be overestimated. Second, as a running person induces a force of greater amplitude than a walking person, a single runner might cause a footbridge to vibrate excessively. Hence, the running load case is highly relevant. These two aspects have in common that they are disregarded in existing design guidelines. For the stated reasons, the demand for improvements of the guidelines is currently high and, prospectively, it might be necessary to require the consideration of both the HSI effect and running loads. Therefore, this licentiate thesis aims at deepening the understanding of these subjects, with the main focus being placed on the HSI effect and, more precisely, on how it can be accounted for in an efficient way. A numerical investigation of the HSI effect and its impact on the vertical acceleration response of a footbridge was performed. The results show that the HSI effect reduces the peak acceleration and that the greatest reduction is obtained for a crowd to bridge frequency ratio close to unity and a high crowd to bridge mass ratio. Furthermore, the performance of two simplified modelling approaches for consideration of the HSI effect was evaluated. Both simplified models can be easily implemented and proved the ability to predict the change in modal properties as well as the structural response of the bridge. Besides that, the computational cost was reduced, compared to more advanced models. Moreover, a case study comprising field tests and simulations was performed to investigate the effect of runners on footbridges. The acceleration limit given in the design guideline was exceeded for one single person running across the bridge while a group of seven people walking across the bridge did not cause exceedance of the limit. Hence, it was concluded that running loads require consideration in the design of a footbridge. / På grund av estetiska skäl och en ökad efterfrågan på kostnadseffektiva och miljövänliga konstruktioner är merparten av de gångbroar som konstrueras idag förhållandevis lätta och slanka. Med anledning av detta ökar risken för att stora svängningar uppstår på grund av dynamisk belastning från människor på bron. För att motverka att detta inträffar kräver dagens normer att komforten verifieras för gångbroar med egenfrekvenser inom området för människans stegfrekvens. Komforten verifieras genom att säkerställa att ett visst accelerationskriterium inte överskrids. För detta ändamål finns handböcker som tillhandahåller förenklade beräkningsmetoder för uppskattning av accelerationsnivåer. Brister i dessa beräkningsmetoder har emellertid identifierats. För det första kan olika typer av människa-bro-interaktion (HSI) ha en betydande inverkan på responsen hos vissa broar. Exempel på en HSI-effekt är att brons modala egenskaper förändras när människor befinner sig på bron; i huvudsak sker en ökning av brons dämpning. Om denna effekt inte tas i beaktande föreligger stor risk att överskatta förväntade accelerationsnivåer. För det andra är kraften från en löpare större än kraften från en gående person vilket gör att en ensam löpare på en gångbro kan ge upphov till accelerationsnivåer som överskrider gränsvärdena för komfort. Löpande personer är därför ett mycket relevant lastfall. Befintliga normer uttrycker inte explicit att någon av dessa aspekter bör tas i beaktande. Behovet av förbättrade riktlinjer för hur normerna bör tillämpas är därför mycket stort och i framtiden kan det bli nödvändigt att kräva att både HSI-effekter och löparlaster tas i beaktande. Därför syftar denna licentiatavhandling till att bidra till en fördjupad förståelse inom dessa två ämnen, med huvudfokus på ovan nämnda HSI-effekt i allmänhet och hur den kan beaktas på ett enkelt, noggrant och tidseffektivt sätt i synnerhet. En numerisk undersökning av HSI-effekten och dess inverkan på den vertikala responsen hos en gångbro genomfördes. Resultaten visar att HSI-effekten reducerar den maximala accelerationen och att störst reduktion erhålls då folksamlingen och bron har ungefär samma egenfrekvens och då folksamlingens massa är stor i förhållande till brons massa. Vidare utvärderades två förenklade metoder för beaktande av HSI-effekten vilka kan implementeras av konstruktörer med grundläggande kunskaper inom strukturdynamik. Det konstaterades att båda metoderna uppskattar HSI-effekten såväl som brons respons förhållandevis väl samtidigt som de reducerar beräkningstiden något jämfört med mer avancerade metoder. Effekten av löpare på gångbroar studerades genom en fallstudie med fältmätningar. Utifrån resultaten från dessa fältmätningar kunde det konstateras att accelerationsgränsen som anges i normerna överskreds när en ensam löpare sprang över bron men inte när en grupp på sju personer gick i takt över samma bro. Därför drogs slutsatsen att löparlaster bör tas i beaktande vid dimensionering av en gångbro. / <p>QC 20180320</p>
22

Brněnské brownfieldy u řeky Svitavy / Brno brownfields by the Svitava river

Žáková, Dagmar January 2018 (has links)
The theme of the diploma project is urban contemporary urban structure in the City of Brno. The main purpose of the selected brownfield is understanding the revitalisation of the city and gets the maximum benefit and to demonstrate the viability of the proposed development and its economic characteristics with the surrounding residential. Proposed is the public space, park and streets in this structure. The territory is located in the Brno-Husovice, near the river Svitava and surrounded by several decaying brownfield. My task was to find the right key to understand this whole area which includes the former object called motorárna - Zetor and find out the ideal solution for the future use of the complex and link it with existing structure to create functional urban organism. Currently, there is a chaotic and heterogeneous structure, which has a negative impact on the surrounding area, which is given by that the area and the surrounding buildings are isolated and hidden behind the unsightly walls. The territory is almost impenetrable, inside the area completely and the natural throughput to the river and partial recreation was supressed. With my project I was trying to create place, which will offer different city urban structure and activities for all day long. In such a place people will met and they will live, work and recreate there and use the river Svitava the right way.
23

Lávka pro pěší přes řeku Dyji v Břeclavi / Pedestrian Footbridge across the Dyje River in Břeclav

Pham, Hoang Anh January 2019 (has links)
This thesis deals with structural design of a steel frame footbridge with wheelchair access, which will lead pedestrian and cyclists‘ traffic over the river Thaya in Břeclav. The footbridge is a structure of one field, lightness of a bridge opening is 58,92 m and a span length is 60,25 m. A light width of an area between rails is 2,5 m. The footbridge is constructed of a truss beam cable – stayed bridge on an oblique pylon of 20,0 m length and a preloaded steel suspender. The thesis was processed according to valid standards ČSN EN.
24

Lávka pro pěší podporovaná kabely / Cable-supported pedestrian bridge

Knotek, Jan January 2019 (has links)
The subject of this diploma thesis is design a cable-supported pedestrian bridge. Three different variants of the solution were created for the design. For detailed processing, variant no.2 was chosen - a suspended bridge with a pylon in the middle of the span. The main task is the static design of the supporting structure. The model for the lengthways is created in ANSYS. The SCIA engineer was used to solve crosswise. The assessment and dimensioning was done according to the limit state principles and valid standards.
25

Lávka pro pěší přes rychlostní komunikaci / Footbridge across the expressway

Páleník, Petr January 2013 (has links)
The aim of this master thesis is a design of the pedestrian bridge across the highway. The bridge is formed by a slab structure of 6 spans with lenghts from 9 to 51 m. The main spans are suspended on a V shape pylon. The deck of the span across the highway is assambled of precast segments and composite deck slab. The deck is in the lenghtways kept in the parabolic arch. The model of the construction is made in software ANSYS, the solution was done non-linear. The design and assessment are according to the europien standard.
26

Návrh zavěšené lávky pro pěší / Design of cable-stayed pedestrian bridge

Uher, Lukáš January 2017 (has links)
This diploma thesis aims to design a structure of pedestrian bridge over the Svratka river. To make a preliminary study of possible bridging, three different outlines were drafted. The cable-stayed variant was selected for further analysis. Two towers, inclined in both their longitudinal and transverse direction, support a cast-in-place post-tensioned concrete deck through stay cables anchored in the tower and the deck. After determining the desired initial state, a finite element analysis was carried out using the Ansys software. The capacity of all main load-bearing elements was checked so it meets the ULS and SLS design criteria in accordance with EN 1992 codes.
27

Mostní konstrukce podporovaná kabely / Cable-supported bridge

Adler, Filip January 2017 (has links)
The subject of this master thesis is to design a pedestrian bridge supported by cables. There are three variants of studies created for this case and for most suitable one, all documentations were produced. The primary focus of this work is on static design solution with an output of several drawings. Static model for results from load cases included construction stages and was created in Midas Civil. Design and checks were performed by hand calculations, complemented by checks of several sections by IDEA StatiCa software. Analysis and calculations are compliant to up-to-date codes and respect the fundamentals of analysis due to limit states.
28

Lávka pro pěší přes řeku Nitru / Pedestrian bridge across the river Nitra

Tomečka, Petr January 2022 (has links)
The subject matter of this master thesis is to design pedestrian bridge across the river Nitra in a city Nitra. Out of three possible solutions arch bridge was considered to be the most optimal system for given situation and it was analysed in detail. The design and assessment of load-bearing structure was evaluated acording to valid standarts. The main goal was to comply with ultimate and serviceability limit state. Global calculation model was created in ANSYS Mechanical APDL 21 R2. Model of the slab of the deck in the cross direction was performer using SCIA Engineer 19.1. Load capacity of some cross sections was verified manually and some using computer software IDEA Statica 21.0. This thesis is extended with drawings of sequence of construction, detailed drawings of the bridge and visualizations.
29

Nosná ocelová konstrukce kryté lávky pro pěší mezi budovami výukového areálu / Load-carrying structure of the covered footbridge between buildings in schooling premises

Fiedlerová, Lucie January 2012 (has links)
The subject of this master’s thesis is to design the supporting steel structure covered pedestrian bridge between the learning area buildings A and D of the Faculty of Civil Engineering, street Veveří 95 in Brno. The construction is designed as a bridge rod spatial structure with two main girders. The girders are a combination Vierendeel girder and truss structure. The girders are connected at the level of the upper and lower band by a crosspiece. The horizontal stiffness of the upper and lower surface structure is ensured by bracing. The upper surface of the pedestrian bridge is horizontal in the longitudinal direction. The lower surface of the pedestrian bridge is curved in order to overcome the difference in height between buildings A and D. This solution is the result of comparison an evaluation of three alternative solutions.
30

Lávky pro pěší tvořené plochým obloukem / Pedestrian bridges formed by a flat arch

Jurík, Michal January 2012 (has links)
This doctoral thesis focuses on the research of the pedestrian bridges formed by the flat arch. To understand the basic static behaviour of the flat arch it was necessary to make a study of the development of the direct flat arch as footbridge with large span and the impact of stiffness on its camber. For the mathematical modeling FEM software ANSYS were used. The calculation has shown that a design of purely concrete flat arch would demand enormous bending stiffness, which can be achieved only through a massive cross-section. The findings gained in this chapter were further used to design a unique pedestrian bridge formed by the curved in plan flat arch, where to transfer of the large bending moments a steel pipe was designed. Several variants with different span and rise of the arch in plan were tested. From the tested variants was then selected footbridge with a span of 45 m and with the rise of the arch 10 m, which seemed to be the best solution according to the calculations and it was further analyzed in detail. The studied structure is formed by curved concrete slab that is stiffened through the steel brackets on the inner side of a steel tube with a graded thickness. The external cables that are situated in the handrail pipe balance the dead load torsional moment. Designed structure and the static analysis procedure were verified on a fully functional 1:6 scale model. The thesis describes the model analogy used for the design of the model, its structural design and its implementation. Load tests on the model confirmed correctness of the design of the proposed curved in plan pedestrian bridge, its high carrying capacity and the accuracy of the developed procedure of static analysis. Results and experiences acquired from the design and the realization of model are the basis for a practical realization of studied structures. The last part of the thesis deals with the possibility of replacement of the steel components with concrete in pedestrian bridges formed

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