TY - THES A1 - Füllsack-Köditz, Raimo T1 - Verbundverhalten von GFK-Bewehrungsstäben und Rissentwicklung in GFK-stabbewehrten Betonbauteilen T1 - Bond characteristics of GFRP-rebars and cracking formation of GFRP reinforced concrete structures N2 - In der vorliegenden Arbeit werden im Rahmen von Ausziehversuchen die Verbundeigenschaften verschiedener Bewehrungsstäbe aus glasfaserverstärkten Kunststoffen (GFK) unter Berücksichti-gung signifikanter Einflussgrößen auf das Verbundverhalten wie Oberflächenprofilierung der Stäbe, Stabdurchmesser, Betonfestigkeit, Verbundlänge sowie Beanspruchungsart unter einheitlichen Versuchsrandbedingungen bestimmt. Es erfolgt eine Bewertung der Einflussgrößen, der Verbundeigenschaften und des Verbundversagens der untersuchten GFK-Bewehrungsstäbe. Basierend auf der Modellbildung zum Verbund zwischen GFK-Stäben und Beton wird die Bestimmung der Verankerungslänge aufgezeigt. Im Rahmen von Versuchen an GFK-stabbewehrten Dehnkörpern und Balken wird die Auswirkung der spezifischen mechanischen Eigenschaften der GFK-Stäbe auf die Rissentwicklung gegenüber stahlbewehrten Bauteilen untersucht. Insbesondere wird betrachtet, welchen Einfluss das Bewehrungsmaterial, der Bewehrungsgrad, die Betonfestigkeit sowie die Belastungsart auf die Mitwirkung des Betons auf Zug zwischen den Rissen sowie auf die Entwicklung des Rissbildes, der Rissbreiten und der Rissabstände haben. Auf Grundlage der experimentellen Untersuchungen wird die Übertragbarkeit der für Stahlbetonbauteile üblichen Ansätze zur Bestimmung der Rissbreite auf GFK-stabbewehrte Betonbauteile bewertet. N2 - The objective is to determine the bonding characteristics of different types of glass fiber reinforced plastic (GFRP) rebars using pull-out tests taking into consideration of significant influence parameters such as the type of bar surface deformation, bar diameter, concrete strength, bonding length and type of loading. The influence parameter will be appraised. The bonding characteristics an the bonding failure of the tested GFRP rebars will be classified. The determination of anchorage length for GFRP rebars will be shown based on bond models for GFRP rebars analogue to reinforcing steel. The scope of tests performed on GFRP reinforced beams and concrete tensile specimens will allow investigation into effects on the specific mechanical behaviours and the specific bonding characteristic of GFRP reinforcing bars on cracking formation. The effects of the physical behaviours of reinforcing material, percentage of reinforcement, concrete strength and type of loading on tension stiffening as well as crack pattern, crack widths and crack spacing will also be examined. Analysis of the results from these experiments will determine whether statements regarding crack width calculation are transferable between reinforced concrete structures and GFRP reinforced concrete structures. T3 - Schriftenreihe des Instituts für Konstruktiven Ingenieurbau - 1 KW - Verbundverhalten KW - Glasfaserverstärkter Kunststoff KW - Stahlbetonkonstruktion KW - Stahlbeton KW - Stahlbetonbau KW - GFK KW - Ausziehversuch KW - Rissentwicklung KW - Rissbreite KW - Verbund KW - GFRP KW - bond KW - cracking KW - concrete KW - pull-out Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20041206-2344 SN - 3-86068-240-7 ER - TY - JOUR A1 - Bargstädt, Hans-Joachim A1 - Blickling, Arno T1 - Determination of process durations on virtual construction sites N2 - The paper analyses the application of 3D gaming technologies in the simulation of processes associated with human resources and machinery on construction sites in order to determine process costs. It addresses the problem of detailing in process simulation. The authors outline special boundary conditions for the simulation of cost-relevant resource processes on virtual construction sites. The approach considers different needs for detailing in process simulation during the planning and building phase. For simulation of process costs on a construction site (contractors view) the level of detail has to be set to high. A prototype for determination of process durations (and hereby process costs) developed at the Bauhaus University Weimar is presented as a result of ongoing researches on detailing in process simulation. It shows the method of process cost determination on a high level of detail (game between excavator and truck) through interaction with the virtual environment of the site. KW - Prozesssimulation KW - Virtuelle Realität KW - Kalkulation KW - Kalkulationsverfahren KW - Computerspiel KW - Game Engine KW - QUEST3D KW - Prozesslogik KW - Baumaschinen KW - virtuelle Baustelle KW - game engine KW - virtual construction site Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20111215-6207 ER - TY - BOOK A1 - Alfen, Hans Wilhelm A1 - Schaedel, Volker T1 - Leitfaden "Beteiligung mittelständischer Bauunternehmen am Geschäftsfeld PPP" T1 - Guideline "Participation of medium-sized building companies at the business segment PPP" N2 - Die öffentliche Hand setzt zunehmend bei der Beschaffung von Bauwerken auf Alternativen, da aufgrund der negativen finanziellen Entwicklung der öffentlichen Haushalte die notwendigen Investitionsmaßnahmen nicht mehr oder nur eingeschränkt umgesetzt werden. Seit Anfang 2000 gehören auch die Modelle Public Private Partnerships (PPP - auch Öffentlich Private Partnerschaften genannt) zu diesen Alternativen. Dabei werden unter Berücksichtigung des Lebenszyklusansatzes alle Wertschöpfungsstufen von Bauwerken – Planen, Bauen, Finanzieren, Betreiben, ggf. Verwerten – integriert und als Gesamtleistung ausgeschrieben. Damit kann es möglich sein, Effizienzvorteile von bis zu 20% gegenüber der konventionellen Beschaffung zu erreichen. Bauunternehmen sind gefordert, sich dieser neuen Beschaffungsvariante anzupassen, wenn sie entsprechende Leistungen anbieten wollen. Sie übernehmen im Kerngeschäft die Errichtung und bauliche Erhaltung von Bauwerken. Auf Grund der Integration aller Wertschöpfungsstufen sind Bauunternehmen gefordert, ihre Leistungen mit den anderen am Lebenszyklus von Bauwerken beteiligten Partner zu koordinieren und in einen Gesamtzusammenhang zu stellen. Das Ziel des Leitfadens ist es, mittelständischen Bauunternehmen die Erarbeitung einer eigenen Strategie für das Geschäftsfeld PPP zu ermöglichen. Dabei gilt es, die besonderen Herausforderungen des Geschäftsfeldes ebenso wie die Besonderheiten mittelständischer Bauunternehmen zu berücksichtigen. Eine strategische Vorgehensweise bei der Erschließung des für Bauunternehmen neuen Geschäftsfeldes ist notwendig, da nicht nur die Vorlauf- und Angebotskosten bei PPP-Projekten um ein Vielfaches höher sind als bei konventionellen Bauprojekten, sondern auch die Herausforderungen und Risiken von PPP-Projekten sich deutlich von der bisherigen Tätigkeit unterscheiden. Eine Beteiligung am Geschäftsfeld ohne Strategie kann unter Umständen den Bestand des gesamten Bauunternehmens gefährden. Mit Hilfe des Leitfadens werden Handlungsempfehlungen dargestellt, die unternehmensspezifisch weiterentwickelt werden können. Die Anwendung des Leitfadens ermöglicht mittelständischen Bauunternehmen, die Stellung des Unternehmens im Bezug zum neuen Geschäftsfeld PPP zu identifizieren und daraus Rückschlüsse für eine Beteiligung am Geschäftsfeld PPP zu ziehen. N2 - Public authorities are more often to consider financing alternatives when acquiring buildings, facilities or structures. This is due to the decreasing money available in public budgets, which can result in a decrease or complete hold on implementing investment acitivities. Since the beginning of the year 2000 the Public Private Partnership (PPP) model has been considered to be such a financing alternative. When considering the life cycle approach, all value creation steps of structures – planning/design, construction, financing, operations, and if applicable final disposition, are being integrated and contracted out as one overall performance or service. With this approach it is possible to achieve 20% more efficiency compared to conventional acquisitions. Contracting businesses are being required to adopt this new alternative for acquisitions if they want to be able to offer adequate performance or services. Contracting businesses take the lead in the core business for construction and structural maintenance of buildings and structures. Due to the integration of all value creation steps, contracting businesses are required to coordinate and integrate their overall performance or services with all other partners who are involved in the life cycle of structures. The objective of this guideline is to allow medium-sized contractor businesses to develop their own strategy for the PPP business segment. Therefore it is essential to consider the special challenges of this new business segment as well as the characteristics of medium-sized contractor businesses. A strategic approach for the development of this new business segment is necessary because the proposal and bidding costs of PPP projects are much higher compared to conventional construction projects. In addition, challenges and risks of PPP projects differ considerably from previous practices. Participation without a strategy in this new business segment can, in certain circumstances, endanger the assets of the entire company. With the help of this guideline, applicable business activities can be derived and developed further for the company’s objectives. The implementation of this guideline allows medium-sized businesses to identify the position of the company related to the new PPP business segment and therfore draw conclusions for participation in the PPP business segment. T3 - Schriftenreihe der Professur Betriebswirtschaftslehre im Bauwesen - 5 KW - Public Private Partnership KW - Mittelstand KW - Baubetrieb KW - Unternehmensplanung KW - Strategische Geschäftseinheit Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20080709-13607 SN - 978-3-86068-344-6 ER - TY - THES A1 - Alalade, Muyiwa T1 - An Enhanced Full Waveform Inversion Method for the Structural Analysis of Dams N2 - Since the Industrial Revolution in the 1700s, the high emission of gaseous wastes into the atmosphere from the usage of fossil fuels has caused a general increase in temperatures globally. To combat the environmental imbalance, there is an increase in the demand for renewable energy sources. Dams play a major role in the generation of “green" energy. However, these structures require frequent and strict monitoring to ensure safe and efficient operation. To tackle the challenges faced in the application of convention dam monitoring techniques, this work proposes the inverse analysis of numerical models to identify damaged regions in the dam. Using a dynamic coupled hydro-mechanical Extended Finite Element Method (XFEM) model and a global optimization strategy, damage (crack) in the dam is identified. By employing seismic waves to probe the dam structure, a more detailed information on the distribution of heterogeneous materials and damaged regions are obtained by the application of the Full Waveform Inversion (FWI) method. The FWI is based on a local optimization strategy and thus it is highly dependent on the starting model. A variety of data acquisition setups are investigated, and an optimal setup is proposed. The effect of different starting models and noise in the measured data on the damage identification is considered. Combining the non-dependence of a starting model of the global optimization strategy based dynamic coupled hydro-mechanical XFEM method and the detailed output of the local optimization strategy based FWI method, an enhanced Full Waveform Inversion is proposed for the structural analysis of dams. T3 - ISM-Bericht // Institut für Strukturmechanik, Bauhaus-Universität Weimar - 2019,1 KW - Talsperre KW - Staumauer KW - Damage identification KW - Inverse analysis KW - Dams KW - Full waveform inversion KW - Wave propagation Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20190813-39566 ER - TY - THES A1 - Abu Bakar, Ilyani Akmar T1 - Computational Analysis of Woven Fabric Composites: Single- and Multi-Objective Optimizations and Sensitivity Analysis in Meso-scale Structures N2 - This study permits a reliability analysis to solve the mechanical behaviour issues existing in the current structural design of fabric structures. Purely predictive material models are highly desirable to facilitate an optimized design scheme and to significantly reduce time and cost at the design stage, such as experimental characterization. The present study examined the role of three major tasks; a) single-objective optimization, b) sensitivity analyses and c) multi-objective optimization on proposed weave structures for woven fabric composites. For single-objective optimization task, the first goal is to optimize the elastic properties of proposed complex weave structure under unit cells basis based on periodic boundary conditions. We predict the geometric characteristics towards skewness of woven fabric composites via Evolutionary Algorithm (EA) and a parametric study. We also demonstrate the effect of complex weave structures on the fray tendency in woven fabric composites via tightness evaluation. We utilize a procedure which does not require a numerical averaging process for evaluating the elastic properties of woven fabric composites. The fray tendency and skewness of woven fabrics depends upon the behaviour of the floats which is related to the factor of weave. Results of this study may suggest a broader view for further research into the effects of complex weave structures or may provide an alternative to the fray and skewness problems of current weave structure in woven fabric composites. A comprehensive study is developed on the complex weave structure model which adopts the dry woven fabric of the most potential pattern in singleobjective optimization incorporating the uncertainties parameters of woven fabric composites. The comprehensive study covers the regression-based and variance-based sensitivity analyses. The second task goal is to introduce the fabric uncertainties parameters and elaborate how they can be incorporated into finite element models on macroscopic material parameters such as elastic modulus and shear modulus of dry woven fabric subjected to uni-axial and biaxial deformations. Significant correlations in the study, would indicate the need for a thorough investigation of woven fabric composites under uncertainties parameters. The study describes here could serve as an alternative to identify effective material properties without prolonged time consumption and expensive experimental tests. The last part focuses on a hierarchical stochastic multi-scale optimization approach (fine-scale and coarse-scale optimizations) under geometrical uncertainties parameters for hybrid composites considering complex weave structure. The fine-scale optimization is to determine the best lamina pattern that maximizes its macroscopic elastic properties, conducted by EA under the following uncertain mesoscopic parameters: yarn spacing, yarn height, yarn width and misalignment of yarn angle. The coarse-scale optimization has been carried out to optimize the stacking sequences of symmetric hybrid laminated composite plate with uncertain mesoscopic parameters by employing the Ant Colony Algorithm (ACO). The objective functions of the coarse-scale optimization are to minimize the cost (C) and weight (W) of the hybrid laminated composite plate considering the fundamental frequency and the buckling load factor as the design constraints. Based on the uncertainty criteria of the design parameters, the appropriate variation required for the structural design standards can be evaluated using the reliability tool, and then an optimized design decision in consideration of cost can be subsequently determined. T3 - ISM-Bericht // Institut für Strukturmechanik, Bauhaus-Universität Weimar - 2020,1 KW - Verbundwerkstoff KW - Gewebeverbundwerkstoff KW - woven composites Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20200605-41762 SN - 1610-7381 ER -