• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 6
  • 5
  • 3
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 20
  • 20
  • 12
  • 7
  • 5
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 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.
1

A life-cycle assessment of concrete in Hong Kong : the consumption and disposal of concrete materials and the environmental criteria and factors regarding its production, use and disposal /

Bezy, Susana Elizabeth. January 1995 (has links)
Thesis (M. Sc.)--University of Hong Kong, 1995. / Includes bibliographical references.
2

Stomstabilisering hos prefabricerade betongkonstruktioner i 3D-beräkningsprogram

Rydberg, Carolin, Reiderstedt, Kasper January 2016 (has links)
This thesis has been executed in cooperation with Abetong which is a leading company in the prefabrication of concrete structures. For a prefabricated concrete building the design engineer must take into consideration the connections between the concrete elements in order to make sure that the building will possess a sufficient structural stability. Therefore the structural engineer might have to re-calculate the original structure that often has been designed as an on site-built building. The purpose of this thesis is to examine the forces between elements related to different models to see if the structural engineer has to make a re-design. To get results for this study we have used FEM-design 3D Structure. The results of forces from the program were compared with Abetongs standard forces of point connections and recess lists and showed that the structural engineer can use the original calculation up to around five stories when a prefabricated shall be erected.
3

Development of a CFRP system to provide continuity in existing reinforced concrete buildings vulnerable to progressive collapse

Orton, Sarah Lynn, January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.
4

Construções habitacionais de concreto moldado no local / Cast in place concrete residential construction

Pinto, Antonio Carlos Alvarenga 05 April 2006 (has links)
Orientador: Vinicius Fernando Arcaro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil / Made available in DSpace on 2018-08-09T14:58:15Z (GMT). No. of bitstreams: 1 Pinto_AntonioCarlosAlvarenga_M.pdf: 2870920 bytes, checksum: cffdfb27613fef6b77831bd28b0b89f3 (MD5) Previous issue date: 2006 / Resumo: Descreve-se, em forma cronológica, as etapas de planejamento, projeto e construção de um empreendimento habitacional com 351 unidades, localizado na cidade de Campinas, SP. São apresentados, também, comentários, críticas e sugestões para aperfeiçoamento dos processos construtivos adotados. Apresenta-se, ainda, a análise estrutural e dimensionamento (verificação) dos elementos estruturais de concreto armado de uma residência em dois pavimentos construída com a tecnologia objeto de estudo desse trabalho / Abstract: In a chronological order, the planning, the project and the construction steps of a residential enterprise, containing 351 units, in the city of Campinas, São Paulo, Brazil, are described. Comments, critical analyzes and suggestions are presented for the improvement of the construction process as well. Also, the paper details the structural analysis and dimensions of the structural elements of a two floor reinforced concrete residential building built under the technology proposed here / Mestrado / Estruturas / Mestre em Engenharia Civil
5

Robustness of reinforced concrete framed building at elevated temperatures

Lee, Seungjea January 2016 (has links)
This thesis presents the results of a research programme to investigate the behaviour and robustness of reinforced concrete (RC) frames in fire. The research was carried out through numerical simulations using the commercial finite element analysis package TNO DIANA. The main focus of the project is the large deflection behaviour of restrained reinforced concrete beams, in particular the development of catenary action, because this behaviour is the most important factor that influences the frame response under accidental loading. This research includes four main parts as follows: (1) validation of the simulation model; (2) behaviour of axially and rotationally restrained RC beams at elevated temperatures; (3) derivation of an analytical method to estimate the key quantities of restrained RC beam behaviour at elevated temperatures; (4) response and robustness of RC frame structures with different extents of damage at elevated temperatures. The analytical method has been developed to estimate the following three quantities: when the axial compression force in the restrained beam reaches the maximum; when the RC beams reach bending limits (axial force = 0) and when the beams finally fail. To estimate the time to failure, which is initiated by the fracture of reinforcement steel at the catenary action stage, a regression equation is proposed to calculate the maximum deflections of RC beams, based on an analysis of the reinforcement steel strain distributions at failure for a large number of parametric study results. A comparison between the analytical and simulation results indicates that the analytical method gives reasonably good approximations to the numerical simulation results. Based on the frame simulation results, it has been found that if a member is completely removed from the structure, the structure is unlikely to be able to develop an alternative load carrying mechanism to ensure robustness of the structure. This problem is particularly severe when a corner column is removed. However, it is possible for frames with partially damaged columns to achieve the required robustness in fire, provided the columns still have sufficient resistance to allow the beams to develop some catenary action. This may be possible if the columns are designed as simply supported columns, but have some reserves of strength in the frame due to continuity. Merely increasing the reinforcement steel area or ductility (which is difficult to do) would not be sufficient. However, increasing the cover thickness of the reinforcement steel to slow down the temperature increase is necessary.
6

Seismic Retrofitting Of Reinforced Concrete Buildings Using Steel Braces With Shear Link

Durucan, Cengizhan 01 September 2009 (has links) (PDF)
The catastrophic damage to the infrastructure due to the most recent major earthquakes around the world demonstrated the seismic vulnerability of many existing reinforced concrete buildings. Accordingly, this thesis is focused on a proposed seismic retrofitting system (PSRS) configured to upgrade the performance of seismically vulnerable reinforced concrete buildings. The proposed system is composed of a rigid steel frame with chevron braces and a conventional energy dissipating shear link. The retrofitting system is installed within the bays of a reinforced concrete building frame. A retrofitting design procedure using the proposed seismic retrofitting system is also developed as part of this study. The developed design methodology is based on performance-based design procedure. The retrofitting design procedure is configured to provide a uniform dissipation of earthquake input energy along the height of the reinforced concrete building. The PSRS and a conventional retrofitting system using squat infill shear panels are applied to an existing school and an office building. Nonlinear time history analyses of the buildings in the original and retrofitted conditions are conducted to assess the efficiency of the PSRS. The analyses results revealed that the PSRS can efficiently alleviate the detrimental effects of earthquakes on the buildings. The building retrofitted with PSRS has a more stable lateral force-deformation behavior with enhanced energy dissipation capability than that of the one retrofitted with squat infill shear panels. For small intensity ground motions, the maximum inter-story drift of the building retrofitted with the PSRS is comparable to that of the one retrofitted with squat infill shear panels. But for moderate to high intensity ground motions, the maximum inter-story drift of the building retrofitted with the PSRS is considerably smaller than that of the one retrofitted with squat infill shear panels.
7

Approche performantielle des bétons : vers une meilleure caractérisation des indicateurs de durabilité / Approach of performance based durability : towards a better characterization of sustainability indicators

Allahyari, Ilgar 20 May 2016 (has links)
La fabrication du ciment, par sa phase de clinkérisation, est très énergivore et émet une quantité importante de gaz à effet de serre dans l'atmosphère. En effet, la production d'une tonne de clinker génère environ une tonne de CO2. Afin de réduire ces émissions, une des alternatives est l'utilisation des additions minérales dans la confection des bétons en remplacement partiel du ciment. Cette substitution apparait comme une des solutions les plus efficaces permettant à la fois de diminuer l'énergie consommée et de réduire le dégagement de CO2 dans l'atmosphère. Cette étude s'inscrit dans un projet plus global de développement des bétons de bâtiment à matrices binaires (ciment + additions) s'appuyant sur des critères de propriétés de transfert. En effet, afin de répondre à certaines exigences de durabilité, une campagne expérimentale a été menée sur des bétons confectionnés selon la norme européenne NF EN 206 qui autorise deux méthodes de formulation : * l'approche dite prescriptive, qui porte sur des obligations de moyens, * l'approche dite performantielle, qui consiste à fixer des exigences en terme de performances basées sur des indicateurs généraux ou spécifiques de durabilité. Ce travail de recherche a donc consisté à comparer les propriétés physico-chimiques de bétons à forte teneur en addition minérale (filler calcaire, cendre volante, laitier de haut fourneau et métakaolin), dérogeant à l'approche prescriptive avec celles des bétons de référence répondant à cette même norme. Cette comparaison s'est effectuée au travers d'indicateurs de durabilité généraux (porosité accessible à l'eau, perméabilité à l'oxygène, coefficient de migration des ions chlorure et teneur en Ca(OH)2) et d'indicateurs spécifiques : la résistance à la carbonatation naturelle et accélérée. D'un point de vue méthodologique, les travaux réalisés dans le cadre de cette recherche ont montré l'intérêt de l'approche performantielle pour la formulation des bétons. Mais, à l'heure actuelle, les outils disponibles, c'est à dire les indicateurs généraux et spécifiques, ne sont pas suffisants pour répondre à l'ensemble des bétons couvrant ce texte normatif. A l'échelle du matériau (béton pour une application en bâtiment), les campagnes expérimentales menées ont montré que dans la majorité des cas, les bétons à forte teneur en addition minérale (dérogeant aux spécifications) présentent des comportements proches de ceux observés sur les bétons de référence (répondant à l'approche prescriptive). / The manufacturing of cement, by its clinkering process, is very energy-consuming and emits an important quantity of greenhouse gases in the atmosphere (1 ton of clinker produced 1 ton of CO2 released into the atmosphere). To maximize this latter from an environmental point of view, it is necessary to reduce the cement content. This can be done by replacing part of the cement with mineral additives during the manufacturing phase. This substitution seems one of the most effective solutions allowing, at the same time, to decrease the energy consumed and to reduce the release of CO2 into the atmosphere. This study is part of a more comprehensive development project of concrete building binary matrices (cement + mineral additives) based on transfer properties criteria. Indeed, in order to answer certain sustainability requirements, an experimental campaign was conducted on concrete, made according to the new European standard (EN 206) that allows two methods of formulation: * a traditional prescriptive approach, based on limiting values for the composition (minimum binder content, maximum water to binder ratio, compressive strength class...) of concrete exposed to some aggressive environmental conditions, * an innovative method based on a performance approach for concrete properties. The present work aims at studying the physico-chemical properties of cementitious materials with high substitution rates of cement by mineral additions (limestone filler, fly ash, slag, metakaolin) derogating from the prescriptive approach with reference to concrete corresponding to the same standard. This comparison was made with general durability indicators (water porosity, oxygen permeability, chloride migration coefficient and portlandite content) and specific durability indicators: carbonation in natural and accelerated conditions. From a methodological point of view, the research carried out in the framework of this project has shown the interest of the performance-based approach with regards to the concrete formulation. But at the moment, the available tools, namely the general and specific indicators, are not sufficient to respond to all these types of concrete. However, considering the performance, economic and environmental criteria, laboratory results showed that concrete made according to a performance-based approach had a performance close to reference concrete and the standard prescription could still be reassessed.
8

Stavební průzkum a diagnostika konstrukce / Survey and Diagnostics of Building Construction

Moravská, Veronika January 2016 (has links)
This thesis deal with survey and diagnostics of industrial building in Chropyne. The theoretical presents to the general issue of building technical surveys, diagnostics reinforced concrete structures and describes methods for diagnosis of reinforced concrete structures. Practical part deals with building survey and diagnostics of the object including static assessment.
9

Seismic evaluation and retrofitting of an existing building in Athens using pushover analysis

Lazaris, Angelos January 2019 (has links)
Earthquakes are one of the biggest problems in civil engineering all over the world. Due to earthquakes, great disasters in cities with collapsed structures and human losses have been caused. More specific, old buildings that have been built based on old regulations and design building codes do not fulfil anymore the new criteria of seismic designing.In this study, an old building has been evaluated for the seismic load in order to decide if there is a need for strengthening it using retrofitting methods. The seismic evaluation is based on Eurocode 8 and after the application of retrofitting techniques the building fulfilled its seismic design criteria. The existing building is a four-storey, concrete structure that has been built in 1970 and is located in Athens (the capital city of Greece). The seismic evaluation is conducted by using the software Seismostruct.Two analyses are performed in order to evaluate the seismic behavior of the building. First, an eigenvalue analysis is conducted before and after retrofitting. By using this analysis the torsional sensitivity of the building has been checked. Then, using pushover analysis, the comparison of the target displacement (expected displacement of the building for the design seismic action) for each limit state and the displacement of the building when the first member of the building reached the corresponding limit state, is presented. Target displacement must not be greater than this displacement in order to ensure the safety of the building. If the comparison shows that target displacement is greater, the weak links in the facility should be identified and the proper retrofitting method should be applied for the improvement of the seismic behavior of the building. Pushover analysis is conducted before and after the application of retrofitting methods.After performing the eigenvalue and pushover analysis of the existing building it was found that the building was torsional sensitive and shear failures occurred in many beams of the structure. Regarding the bending failures, the target displacement was not greater than the displacement of the building when the first member of the building reached any of the corresponding limit states. Therefore the building was safe against bending failures. With the application of X-shaped steel braces in selected frames, the building had higher stiffness and it was not torsional sensitive but shear failures occurred again in many beams. Furthermore, compressive failures occurred in columns that were connected with the steel braces. Finally, with the application of fibre reinforced plastic jacketing in the members that failed in the previous pushover analysis there were no shear or compressive failures. Finally the structure was safe against seismic actions.The application of retrofitting methods improved the seismic behavior of the building and the structure fulfilled the updated regulations of Eurocode 8 regarding seismic design. This project thesis may give rise to further studies and researches concerning seismic retrofitting and seismic damage prevention.
10

Statická analýza bytového domu / Static analysis of residential building

Hanzlík, Petr January 2014 (has links)
The discussion of the master’s thesis is static analysis of residental building. The thesis details the original solution from assesment and a new design variant solution. The work is focused on static solution of monolithic concrete plate with ribs and is devoted to limit states assessment of the plate with ribs. The thesis includes a time analysis structure and prestressed ribs in the new variant.

Page generated in 0.0476 seconds