620 Ingenieurwissenschaften
Refine
Document Type
- Article (239)
- Doctoral Thesis (27)
- Conference Proceeding (9)
- Master's Thesis (4)
- Book (1)
- Habilitation (1)
- Report (1)
- Working Paper (1)
Institute
- Institut für Strukturmechanik (ISM) (215)
- Professur Stochastik und Optimierung (40)
- F. A. Finger-Institut für Baustoffkunde (FIB) (6)
- Professur Bauphysik (6)
- Graduiertenkolleg 1462 (5)
- In Zusammenarbeit mit der Bauhaus-Universität Weimar (4)
- Institut für Konstruktiven Ingenieurbau (IKI) (4)
- Materialforschungs- und -prüfanstalt an der Bauhaus-Universität (4)
- Professur Baubetrieb und Bauverfahren (4)
- Junior-Professur Komplexe Tragwerke (3)
Keywords
- Strukturmechanik (188)
- Angewandte Mathematik (184)
- Stochastik (41)
- Finite-Elemente-Methode (7)
- Beton (5)
- Modellierung (5)
- OA-Publikationsfonds2022 (5)
- Building Information Modeling (4)
- Bruchmechanik (3)
- Erdbeben (3)
- Ingenieurbau (3)
- OA-Publikationsfonds2020 (3)
- OA-Publikationsfonds2023 (3)
- Optimierung (3)
- Rissausbreitung (3)
- Sensitivitätsanalyse (3)
- Structural Engineering (3)
- damaged buildings (3)
- Alterung (2)
- Bruch (2)
- Bruchverhalten (2)
- Damm (2)
- Elastizität (2)
- Fehlerabschätzung (2)
- Ingenieurwissenschaften (2)
- Mathematische Modellierung (2)
- Mikrokapsel (2)
- OA-Publikationsfonds2021 (2)
- Papierware (2)
- Platte (2)
- Proceedings (2)
- Rice husk ash (2)
- Riss (2)
- Sandwichbauteil (2)
- Schaden (2)
- Simulation (2)
- Sommerkurs (2)
- Strömungsgeschwindigkeit (2)
- Tragendes Teil (2)
- Tragfähigkeit (2)
- Träger (2)
- Verkehr (2)
- Verkehrssicherheit (2)
- Wassergehalt (2)
- Wellpappe (2)
- Werkstoffkunde (2)
- Wärmeleitfähigkeit (2)
- crack (2)
- earthquake safety assessment (2)
- proceedings (2)
- rapid visual screening (2)
- soft computing techniques (2)
- summer school (2)
- vulnerability assessment (2)
- 3D reinforced concrete buildings (1)
- 56 (1)
- 5G (1)
- Abbiegespur (1)
- Adaptable design (1)
- Adaptive Pushover (1)
- Affecting factors; Measurement uncertainty; Materials testing; Quantitative comparison; Strain comparison; Tensile test (1)
- Alkali silica reaction (1)
- Alkali-Kieselsäure-Reaktion (1)
- Alkali-Kieselsäure-Reaktion; Fahrbahndecken; Flugbetriebsflächen; äußere Alkalizufuhr; Enteisungsmittel; Natriumchlorid; Alkaliacetate; Alkaliformiate; AKR-Performance-Prüfung; FIB-Klimawechsellagerung (1)
- Alterungsdihydrat (1)
- Anhydrit III (1)
- Architecture (1)
- Architektur (1)
- Aufstellstreifen (1)
- Ausfachung (1)
- Autoklav (1)
- Auxiliary lane; Conflict Indexes; Road safety; Traffic Conflict Technique; U-turn (1)
- BIM (1)
- BIM, BIM Adoption, BIM Advantages , Construction Industry, Pakistan (1)
- BIM; Building Information Modeling; site management; construction site. (1)
- Bauakustik (1)
- Bauindustrie (1)
- Bauphysik (1)
- Bauphysik und Sanierung (1)
- Bauschaden (1)
- Baustahl (1)
- Baustelle (1)
- Baustoff (1)
- Bautechnik (1)
- Bauteil (1)
- Bauwerk (1)
- Bauwesen (1)
- Bayes (1)
- Bayesian inference (1)
- Bayesian method (1)
- Beam-to-column connection; semi-rigid; flush end-plate connection; moment-rotation curve (1)
- Bedarfsermittlung (1)
- Belit (1)
- Benutzung (1)
- Berechnungsverfahren (1)
- Beschleunigungsstreifen (1)
- Biegezugbelastung (1)
- Bilddaten (1)
- Bindemittel (1)
- Biogasanlage (1)
- Biomechanics (1)
- Biomechanik (1)
- Boden-Bauwerk-Wechselwirkung (1)
- Bodenfeuchte (1)
- Bodenmechanik (1)
- Bolzen (1)
- Breitbandausbau (1)
- Brustkorb (1)
- Building safety assessment (1)
- Built environment (1)
- CO2 (1)
- Cable-stayed bridges; wind engineering; wind tunnel testing; construction (1)
- Calcinieren (1)
- Calciumsulfat (1)
- Capsular clustering; Design of microcapsules (1)
- Cohesive surface technique (1)
- Computational fracture modeling (1)
- Computermodellierung des Bruchverhaltens (1)
- Computersimulation (1)
- Concrete (1)
- Corrugated cardboard sandwich (1)
- Data exchange, Schema mapping, Quality assessment, Uncertainty, Coupling, BIM, Design patterns, Metamodel architecture (1)
- Database (1)
- Datenmodell (1)
- Deep Learning (1)
- Defekt (1)
- Denkmalpflege (1)
- Design Spectra (1)
- Dielektrische Spektroskopie (1)
- Dirac-Operator (1)
- Dissertation (1)
- Dreidimensionales Modell (1)
- Druckbelastung (1)
- Druckfestigkeit (1)
- Druckluft (1)
- Dual-support (1)
- Earthquake (1)
- Edelstahl (1)
- Elastizitätstheorie (1)
- Embankment, sensitivity analysis, parameter identification, Particle Swarm Optimization (1)
- Emission (1)
- Energiespeicherung (1)
- Energiewende (1)
- Entwurf von Mikrokapseln (1)
- Erasmus + (1)
- Erbeben (1)
- Erdbebensicherheit (1)
- Ergänzungsbaustoffe (1)
- Erweiterte Finite-Elemente-Methode (1)
- FEM (1)
- FM-Leistungserbringung (1)
- FTTx (1)
- Fachwerkbau (1)
- Facility Management (1)
- Facility-Management (1)
- Fahrleitung (1)
- Fahrleitungsmast (1)
- Faltung (1)
- Festphasen-Fermentation (1)
- Feststoff (1)
- Fire resistance; Parameter optimization; Sensitivity analysis; Thermal properties (1)
- Folded components (1)
- Food Waste Management (1)
- Fracture (1)
- Fracture Computational Model (1)
- Fracture mechanics (1)
- Frost (1)
- Frostangriff (1)
- Funktionentheorie (1)
- Förderungsprogramm (1)
- Gasleitung (1)
- Gebäude (1)
- Gebäudedaten-Modellierung (1)
- Geopolymer (1)
- Gesteinskörnung (1)
- Gesteinskörnungssubstitutionsmaterial (1)
- Gewinde (1)
- Gigabit (1)
- Gips (1)
- Glasfaser (1)
- Graphen (1)
- Graphene (1)
- Grundlage (1)
- Heilungseffekt (1)
- Highway (1)
- Hochfester Beton (1)
- Hochgeschwindigkeitsnetz (1)
- Hochwasser (1)
- Hochwasserschadensmodell (1)
- Holzkonstruktion (1)
- Homogeneity (1)
- Homogenität (1)
- Homogenization (1)
- Hydratation (1)
- Hydration and microstructure (1)
- Hydrothermalsynthese (1)
- Impedanzspektroskopie (1)
- Implicit (1)
- Incompressibility (1)
- Inertgas (1)
- Infiltration (1)
- Infrastruktur (1)
- Internal pozzolanic reactivity (1)
- Inverse Gaschromatographie (1)
- Kabelbrücke (1)
- Kapazität (1)
- Kapselclustern (1)
- Kaverne (1)
- Klimaänderung (1)
- Kohlenstoff (1)
- Kohäsionsflächenverfahren (1)
- Kommune (1)
- Konjugierte-Gradienten-Methode (1)
- Konstruktion (1)
- Konstruktiver Ingenieurbau (1)
- Kosten- und Leistungsentwicklung (1)
- Kosten-Nutzen-Analyse (1)
- Kostenoptimierung (1)
- Kristallitgröße (1)
- Körperschall (1)
- LED light source (1)
- Laser Welding; CO2; Diode; Distortion; Finite Element Analysis; Thermal Analysis; Mechanical Analysis; Numerical Model (1)
- Laserschweißen (1)
- Lastverformungsverhalten (1)
- Latin America (1)
- Lehm (1)
- Leichtbau (1)
- Lichtsignalanlage (1)
- Lichtsignalsteuerung (1)
- Luftverunreinigender Stoff (1)
- Luftzerlegung (1)
- MDLSM method (1)
- Machine Learning (1)
- Machine learning (1)
- Macro-mesoporous structure (1)
- Makroalgen (1)
- Marmara Region (1)
- Maschinelles Lernen (1)
- Maschinenbau (1)
- Material (1)
- Materialverhalten (1)
- Materialversagen (1)
- Mauerwerk (1)
- Mehrgitterverfahren (1)
- Mesoporous structure (1)
- Mexico (1)
- Mix design method (1)
- MoS2 (1)
- Molekülstruktur (1)
- Multi-criteria decision making (1)
- Multi-objective Evolutionary Optimization, Elitist Non- Dominated Sorting Evolution Strategy (ENSES), Sandwich Structure, Pareto-Optimal Solutions, Evolutionary Algorithm (1)
- Multiscale modeling (1)
- Muscle model (1)
- Muskel (1)
- Nanocomposite materials (1)
- Nanomechanik (1)
- Nanopore (1)
- Nanoporöser Stoff (1)
- Nanoverbundstruktur (1)
- Nanowissenschaften (1)
- Neuronales Netz (1)
- Nichtlineare Finite-Elemente-Methode (1)
- Nonlocal operator method (1)
- Nutzerorientierte Bausanierung (1)
- Operator energy functional (1)
- Organischer Abfall (1)
- Oxidkeramik (1)
- Pakistan (1)
- People Approach (1)
- Peridynamik (1)
- Phase-field modeling (1)
- Photobioreaktor (1)
- Planspiel (1)
- Planung (1)
- Polymer nanocomposites (1)
- Polymere (1)
- Polymermodified Cement Concrete (1)
- Polymermodifizierter Beton (1)
- Polymorphie (1)
- Post Occupancy Evaluation (1)
- Pozzolanic reactivity (1)
- Projektmanagement (1)
- Punktwolke (1)
- Qualitätsmanagement (1)
- Qualitätsstandard (1)
- Quartiersanalyse (1)
- RC Wall (1)
- RC frames (1)
- Randwertproblem (1)
- Raumklima (1)
- Reflektometrie (1)
- Regenwassermanagement (1)
- Relaxation (1)
- Rheological property (1)
- Richtlinien (1)
- Rietveld-Methode (1)
- Risiko (1)
- Risikoerfassung (1)
- Robustheit (1)
- Sauerstoff (1)
- Sauerstoffseparation (1)
- Schadenserkennung (1)
- Schadensprognose (1)
- Schubspannung (1)
- Schwellenwert (1)
- Schwingung (1)
- Schätztheorie (1)
- Seismic risk (1)
- Selbstheilendem Beton (1)
- Self-compacting high performance concrete (1)
- Self-healing concrete (1)
- Sensor (1)
- Sensortechnologien (1)
- Silica fume (1)
- SimCity (1)
- Simulationsmodell (1)
- Simulationsspiel (1)
- Simulationsszenario (1)
- Social context (1)
- Stahl (1)
- Stahlbau (1)
- Stahlbeton (1)
- Stahlbetonkonstruktion (1)
- Steifigkeit (1)
- Stickstoff (1)
- Stiffness matrix (1)
- Stochastic analysis (1)
- Stoffeigenschaft (1)
- Structural Health Monitoring (1)
- Strukturanalyse (1)
- Strukturschaden (1)
- Strömungsmechanik (1)
- Stütze (1)
- Suffosion (1)
- Supplementary cementitious materials (1)
- Sustainable construction technology (1)
- TPOGS (1)
- Taylor series expansion (1)
- Thermodynamische Eigenschaft (1)
- Thorax (1)
- Ton <Geologie> (1)
- Transformation (1)
- Transient and time domain; Dams; Infiltration; Soil moisture; calibration; levee model; soil moisture measurement; spatial time domain reflectometry (1)
- Ultra-high performance concrete. (1)
- Umfrage (1)
- Uncertainty analysis (1)
- Unsicherheit (1)
- Urban Environment (1)
- Variational principle (1)
- Verarbeitungseigenschaft (1)
- Verbundwerkstoff (1)
- Verkehrsinfrastruktur (1)
- Verkehrssignalanlage (1)
- Verwundbarkeit (1)
- Visualisierung (1)
- Vulnerability (1)
- Werkstoffprüfung (1)
- Windkanal (1)
- Wärmeübergang (1)
- XFEM (1)
- Zeitbereichsreflektometrie (1)
- Zement (1)
- Zufahrt (1)
- Zugbelastung (1)
- Zugversuch (1)
- adaptive pushover (1)
- aggregates (1)
- alkali-silica reaction; pavements; external alkalis; deicer; sodium chloride; alkali acetates; alkali formates; ASR performance test; cyclic climate storage (1)
- alpha-C2SH (1)
- alternative Bindemittel (1)
- artificial neural networks (1)
- bauphysikalische Methoden (1)
- beton (1)
- bogenförmig (1)
- bolt (1)
- building acoustics (1)
- capsular clustering (1)
- characteristic value (1)
- chloride binding (1)
- circumferential contact length (1)
- climate change (1)
- climate models (1)
- climatic loading (1)
- cohesive elements (1)
- computational modeling (1)
- congestion; signaled intersections; traffic capacity (1)
- conjugate gradient method (1)
- coupling (1)
- crack identification (1)
- crack propagation (1)
- crack sensor; fibre optic sensor; humidity sensor; SHM (1)
- cryogenic suction (1)
- defects (1)
- deformation behavior (1)
- destructive testin (1)
- digitale Organisation (1)
- discrete Dirac operator (1)
- discrete boundary value problems (1)
- discrete monogenic functions (1)
- earthquake (1)
- earthquake engineering (1)
- energetic approach (1)
- energy form (1)
- experimental validation (1)
- explicit time integration (1)
- external pozzolanic reactivity (1)
- extreme value analysis (1)
- finite element method (1)
- fisher-information matrix (1)
- flexural-torsional-buckling (1)
- foundations (1)
- fracture mechanics (1)
- functionally graded materials (1)
- gas pipes (1)
- grid-based (1)
- ground structure (1)
- heat transfer (1)
- high performance fine-grained concrete, rice husk ash, workability, compressive strength, splitting tensile strength, chloride penetration resistance (1)
- housing (1)
- hybride Werkstoffe (1)
- isogeometric methods (1)
- long-term examination (1)
- ländlicher Raum (1)
- macro algae (1)
- material aging (1)
- material failure (1)
- mathematical modelling (1)
- matrix-free (1)
- maximum stress (1)
- mean-squared error (1)
- microcapsule (1)
- micropolar elasticity (1)
- model comparison (1)
- molecular dynamics (1)
- multigrid method (1)
- multiscale (1)
- nanocomposite (1)
- nanosheets (1)
- non-destructive testing (1)
- nonlinear analysis (1)
- nonlocal theory (1)
- numerical modelling (1)
- occupant requirements (1)
- occupant satisfaction (1)
- openings (1)
- operator calculus (1)
- out-of-plane seismic load (1)
- peridynamics (1)
- photobioreactor (1)
- physics-informed activation function (1)
- polymorphe Unschärfemodellierung (1)
- quaternionic analysis (1)
- questionnaire (1)
- rapid classification (1)
- reinforced concrete wall (1)
- residential buildings (1)
- salt frost attack (1)
- seismic hazard analysis (1)
- seismic risk estimation (1)
- self healing concrete (1)
- self-healing concrete (1)
- site-specific spectrum (1)
- soil-structure interaction (1)
- sound pressure level prediction (1)
- stability (1)
- steel (1)
- stochastic (1)
- structural engineering (1)
- structural vulnerability (1)
- structure-borne sound (1)
- structure-borne sound sources (1)
- supervised learning (1)
- tapped blind holes (1)
- thermal conductivity (1)
- threat (1)
- three-dimensional truss structures (1)
- topology optimization (1)
- tower-like structures (1)
- ulva intestinalis (1)
- unreinforced masonry infill walls (1)
- variational principle (1)
- vibration-based damage identification (1)
- vibration-based methodology (1)
- water content measurement; TDR probe; clay-rock; dielectric spectroscopy; frequency domain finite element modeling (1)
- weak form (1)
- wind-induced vibration (1)
- zerstörungsfreie Prüfung (1)
- Überschwemmung (1)
- überschnittene Bohrpfahlwand (1)
- überstöchiometrisches Wasser (1)
Identification of modal parameters of a space frame structure is a complex assignment due to a large number of degrees of freedom, close natural frequencies, and different vibrating mechanisms. Research has been carried out on the modal identification of rather simple truss structures. So far, less attention has been given to complex three-dimensional truss structures. This work develops a vibration-based methodology for determining modal information of three-dimensional space truss structures. The method uses a relatively complex space truss structure for its verification. Numerical modelling of the system gives modal information about the expected vibration behaviour. The identification process involves closely spaced modes that are characterised by local and global vibration mechanisms. To distinguish between local and global vibrations of the system, modal strain energies are used as an indicator. The experimental validation, which incorporated a modal analysis employing the stochastic subspace identification method, has confirmed that considering relatively high model orders is required to identify specific mode shapes. Especially in the case of the determination of local deformation modes of space truss members, higher model orders have to be taken into account than in the modal identification of most other types of structures.
The design of engineering structures takes place today and in the past on the basis of static calculations. The consideration of uncertainties in the model quality becomes more and more important with the development of new construction methods and design requirements. In addition to the traditional forced-based approaches, experiences and observations about the deformation behavior of components and the overall structure under different exposure conditions allow the introduction of novel detection and evaluation criteria.
The proceedings at hand are the result from the Bauhaus Summer School Course: Forecast Engineering held at the Bauhaus-Universität Weimar, 2017. It summarizes the results of the conducted project work, provides the abstracts of the contributions by the participants, as well as impressions from the accompanying programme and organized cultural activities.
The special character of this course is in the combination of basic disciplines of structural engineering with applied research projects in the areas of steel and reinforced concrete structures, earthquake and wind engineering as well as informatics and linking them to mathematical methods and modern tools of visualization. Its innovative character results from the ambitious engineering tasks and advanced
modeling demands.
Institute of Structural Engineering, Institute of Structural Mechanics, as well as Institute for Computing, Mathematics and Physics in Civil Engineering at the faculty of civil engineering at the Bauhaus-Universität Weimar presented special topics of structural engineering to highlight the broad spectrum of civil engineering in the field of modeling and simulation.
The summer course sought to impart knowledge and to combine research with a practical context, through a challenging and demanding series of lectures, seminars and project work. Participating students were enabled to deal with advanced methods and its practical application.
The extraordinary format of the interdisciplinary summer school offers the opportunity to study advanced developments of numerical methods and sophisticated modelling techniques in different disciplines of civil engineering for foreign and domestic students, which go far beyond traditional graduate courses.
The proceedings at hand are the result from the Bauhaus Summer School course: Forecast Engineering held at the Bauhaus-Universität Weimar, 2018. It summarizes the results of the conducted project work, provides the abstracts/papers of the contributions by the participants, as well as impressions from the accompanying programme and organized cultural activities.
The characteristic values of climatic actions in current structural design codes are based on a specified probability of exceedance during the design working life of a structure. These values are traditionally determined from the past observation data under a stationary climate assumption. However, this assumption becomes invalid in the context of climate change, where the frequency and intensity of climatic extremes varies with respect to time. This paper presents a methodology to calculate the non-stationary characteristic values using state of the art climate model projections. The non-stationary characteristic values are calculated in compliance with the requirements of structural design codes by forming quasi-stationary windows of the entire bias-corrected climate model data. Three approaches for the calculation of non-stationary characteristic values considering the design working life of a structure are compared and their consequences on exceedance probability are discussed.
The fire resistance of concrete members is controlled by the temperature distribution of the considered cross section. The thermal analysis can be performed with the advanced temperature dependent physical properties provided by 5EN6 1992-1-2. But the recalculation of laboratory tests on columns from 5TU6 Braunschweig shows, that there are deviations between the calculated and measured temperatures. Therefore it can be assumed, that the mathematical formulation of these thermal properties could be improved. A sensitivity analysis is performed to identify the governing parameters of the temperature calculation and a nonlinear optimization method is used to enhance the formulation of the thermal properties. The proposed simplified properties are partly validated by the recalculation of measured temperatures of concrete columns. These first results show, that the scatter of the differences from the calculated to the measured temperatures can be reduced by the proposed simple model for the thermal analysis of concrete.
Different types of data provide different type of information. The present research analyzes the error on prediction obtained under different data type availability for calibration. The contribution of different measurement types to model calibration and prognosis are evaluated. A coupled 2D hydro-mechanical model of a water retaining dam is taken as an example. Here, the mean effective stress in the porous skeleton is reduced due to an increase in pore water pressure under drawdown conditions. Relevant model parameters are identified by scaled sensitivities. Then, Particle Swarm Optimization is applied to determine the optimal parameter values and finally, the error in prognosis is determined. We compare the predictions of the optimized models with results from a forward run of the reference model to obtain the actual prediction errors. The analyses presented here were performed calibrating the hydro-mechanical model to 31 data sets of 100 observations of varying data types. The prognosis results improve when using diversified information for calibration. However, when using several types of information, the number of observations has to be increased to be able to cover a representative part of the model domain. For an analysis with constant number of observations, a compromise between data type availability and domain coverage proves to be the best solution. Which type of calibration information contributes to the best prognoses could not be determined in advance. The error in model prognosis does not depend on the error in calibration, but on the parameter error, which unfortunately cannot be determined in inverse problems since we do not know its real value. The best prognoses were obtained independent of calibration fit. However, excellent calibration fits led to an increase in prognosis error variation. In the case of excellent fits; parameters' values came near the limits of reasonable physical values more often. To improve the prognoses reliability, the expected value of the parameters should be considered as prior information on the optimization algorithm.
As an optimization that starts from a randomly selected structure generally does not guarantee reasonable optimality, the use of a systemic approach, named the ground structure, is widely accepted in steel-made truss and frame structural design. However, in the case of reinforced concrete (RC) structural optimization, because of the orthogonal orientation of structural members, randomly chosen or architect-sketched framing is used. Such a one-time fixed layout trend, in addition to its lack of a systemic approach, does not necessarily guarantee optimality. In this study, an approach for generating a candidate ground structure to be used for cost or weight minimization of 3D RC building structures with included slabs is developed. A multiobjective function at the floor optimization stage and a single objective function at the frame optimization stage are considered. A particle swarm optimization (PSO) method is employed for selecting the optimal ground structure. This method enables generating a simple, yet potential, real-world representation of topologically preoptimized ground structure while both structural and main architectural requirements are considered. This is supported by a case study for different floor domain sizes.
Das Bauwesen hat sich in den letzten Jahren durch die Globalisierung des Marktes verbunden mit einer verstärkten Nutzung moderner Technologien stark gewandelt. Die Planung und die Durchführung von Bauvorhaben werden zunehmend komplexer und sind mit erhöhten Risiken verbunden. Geld- und Zeitressourcen werden bei einem immer härter werdenden Konkurrenzkampf knapper.
Das Projektmanagement stellt Lösungsansätze bereit, um Bauvorhaben auch unter erschwerten Bedingungen und erhöhten Risiken erfolgreich zum Abschluss zu bringen. Dabei hat ein systematisches Risikomanagement beginnend bei der Projektentwicklung bis zum Projektabschluss eine für den Projekterfolg entscheidende Bedeutung.
Ziel der Arbeit ist es, eine quantitative Risikoerfassung für Projektmanager als professionelle Bauherrenvertretung und die Simulation der Risikoauswirkungen auf den Verlauf eines Projektes während der Planungs- und Bauphase zu ermöglichen. Mit Hilfe eines abstrakten Modells soll eine differenzierte, praxisnahe Simulation durchführbar sein, die die verschiedenen Arten der Leistungs- und Kostenentstehung widerspiegelt. Parallel dazu soll die Beschreibung von Risiken so abstrahiert werden, dass beliebige Risiken quantitativ erfassbar und anschließend ihre Auswirkungen inklusive mögliche Gegenmaßnahmen in das Modell integrierbar sind.
Anhand zweier Beispiele werden die unterschiedlichen Einsatzmöglichkeiten der quantitativen Erfassung von Projektrisiken und der anschließenden Simulation ihrer Auswirkungen aufgezeigt. Bei dem ersten Beispiel, einem realen, bereits abgeschlossenen Schieneninfrastrukturprojekt, wird die Wirksamkeit einer vorbeugenden Maßnahme gegen ein Projektrisiko untersucht. Im zweiten Beispiel wird ein Planspielansatz zur praxisnahen Aus- und Weiterbildung von Projektmanagern entwickelt. Inhalt des Planspiels ist die Planung und Errichtung eines privatfinanzierten, öffentlichen Repräsentationsbaus mit teilweiser Fremdnutzung.
This study proposes an efficient Bayesian, frequency-based damage identification approach to identify damages in cantilever structures with an acceptable error rate, even at high noise levels. The catenary poles of electric high-speed train systems were selected as a realistic case study to cover the objectives of this study. Compared to other frequency-based damage detection approaches described in the literature, the proposed approach is efficiently able to detect damages in cantilever structures to higher levels of damage detection, namely identifying both the damage location and severity using a low-cost structural health monitoring (SHM) system with a limited number of sensors; for example, accelerometers. The integration of Bayesian inference, as a stochastic framework, in the proposed approach, makes it possible to utilize the benefit of data fusion in merging the informative data from multiple damage features, which increases the quality and accuracy of the results. The findings provide the decision-maker with the information required to manage the maintenance, repair, or replacement procedures.
The polymeric clay nanocomposites are a new class of materials of which recently have become the centre of attention due to their superior mechanical and physical properties. Several studies have been performed on the mechanical characterisation of these nanocomposites; however most of those studies have neglected the effect of the interfacial region between the clays and the matrix despite of its significant influence on the mechanical performance of the nanocomposites.
There are different analytical methods to calculate the overall elastic material properties of the composites. In this study we use the Mori-Tanaka method to determine the overall stiffness of the composites for simple inclusion geometries of cylinder and sphere. Furthermore, the effect of interphase layer on the overall properties of composites is calculated. Here, we intend to get ounds for the effective mechanical properties to compare with the analytical results. Hence, we use linear displacement boundary conditions (LD) and uniform traction boundary conditions (UT) accordingly. Finally, the analytical results are compared with numerical results and they are in a good agreement.
The next focus of this dissertation is a computational approach with a hierarchical multiscale method on the mesoscopic level. In other words, in this study we use the stochastic analysis and computational homogenization method to analyse the effect of thickness and stiffness of the interfacial region on the overall elastic properties of the clay/epoxy nanocomposites. The results show that the increase in interphase thickness, reduces the stiffness of the clay/epoxy naocomposites and this decrease becomes significant in higher clay contents. The results of the sensitivity analysis prove that the stiffness of the interphase layer has more significant effect on the final stiffness of nanocomposites. We also validate the results with the available experimental results from the literature which show good agreement.
The node moving and multistage node enrichment adaptive refinement procedures are extended in mixed discrete least squares meshless (MDLSM) method for efficient analysis of elasticity problems. In the formulation of MDLSM method, mixed formulation is accepted to avoid second-order differentiation of shape functions and to obtain displacements and stresses simultaneously. In the refinement procedures, a robust error estimator based on the value of the least square residuals functional of the governing differential equations and its boundaries at nodal points is used which is inherently available from the MDLSM formulation and can efficiently identify the zones with higher numerical errors. The results are compared with the refinement procedures in the irreducible formulation of discrete least squares meshless (DLSM) method and show the accuracy and efficiency of the proposed procedures. Also, the comparison of the error norms and convergence rate show the fidelity of the proposed adaptive refinement procedures in the MDLSM method.
Within the scope of literature, the influence of openings within the infill walls that are bounded by a reinforced concrete frame and excited by seismic drift forces in both in- and out-of-plane direction is still uncharted. Therefore, a 3D micromodel was developed and calibrated thereafter, to gain more insight in the topic. The micromodels were calibrated against their equivalent physical test specimens of in-plane, out-of-plane drift driven tests on frames with and without infill walls and openings, as well as out-of-plane bend test of masonry walls. Micromodels were rectified based on their behavior and damage states. As a result of the calibration process, it was found that micromodels were sensitive and insensitive to various parameters, regarding the model’s behavior and computational stability. It was found that, even within the same material model, some parameters had more effects when attributed to concrete rather than on masonry. Generally, the in-plane behavior of infilled frames was found to be largely governed by the interface material model. The out-of-plane masonry wall simulations were governed by the tensile strength of both the interface and masonry material model. Yet, the out-of-plane drift driven test was governed by the concrete material properties.
This work describes an algorithm and corresponding software for incorporating general nonlinear multiple-point equality constraints in a implicit sparse direct solver. It is shown that direct addressing of sparse matrices is possible in general circumstances, circumventing the traditional linear or binary search for introducing (generalized) constituents to a sparse matrix. Nested and arbitrarily interconnected multiple-point constraints are introduced by processing of multiplicative constituents with a built-in topological ordering of the resulting directed graph. A classification of discretization methods is performed and some re-classified problems are described and solved under this proposed perspective. The dependence relations between solution methods, algorithms and constituents becomes apparent. Fracture algorithms can be naturally casted in this framework. Solutions based on control equations are also directly incorporated as equality constraints. We show that arbitrary constituents can be used as long as the resulting directed graph is acyclic. It is also shown that graph partitions and orderings should be performed in the innermost part of the algorithm, a fact with some peculiar consequences. The core of our implicit code is described, specifically new algorithms for direct access of sparse matrices (by means of the clique structure) and general constituent processing. It is demonstrated that the graph structure of the second derivatives of the equality constraints are cliques (or pseudo-elements) and are naturally included as such. A complete algorithm is presented which allows a complete automation of equality constraints, avoiding the need of pre-sorting. Verification applications in four distinct areas are shown: single and multiple rigid body dynamics, solution control and computational fracture.
The present article aims to provide an overview of the consequences of dynamic soil-structure interaction (SSI) on building structures and the available modelling techniques to resolve SSI problems. The role of SSI has been traditionally considered beneficial to the response of structures. However, contemporary studies and evidence from past earthquakes showed detrimental effects of SSI in certain conditions. An overview of the related investigations and findings is presented and discussed in this article. Additionally, the main approaches to evaluate seismic soil-structure interaction problems with the commonly used modelling techniques and computational methods are highlighted. The strength, limitations, and application cases of each model are also discussed and compared. Moreover, the role of SSI in various design codes and global guidelines is summarized. Finally, the advancements and recent findings on the SSI effects on the seismic response of buildings with different structural systems and foundation types are presented. In addition, with the aim of helping new researchers to improve previous findings, the research gaps and future research tendencies in the SSI field are pointed out.
Building Information Modeling is a powerful tool for the design and for a consistent set of data in a virtual storage. For the application in the phases of realization and on site it needs further development. The paper describes main challenges and main features, which will help the development of software to better service the needs of construction site managers
Broadband electromagnetic frequency or time domain sensor techniques present high potential for quantitative water content monitoring in porous media. Prior to in situ application, the impact of the relationship between the broadband electromagnetic properties of the porous material (clay-rock) and the water content on the frequency or time domain sensor response is required. For this purpose, dielectric properties of intact clay rock samples experimental determined in the frequency range from 1 MHz to 10 GHz were used as input data in 3-D numerical frequency domain finite element field calculations to model the one port broadband frequency or time domain transfer function for a three rods based sensor embedded in the clay-rock. The sensor response in terms of the reflection factor was analyzed in time domain with classical travel time analysis in combination with an empirical model according to Topp equation, as well as the theoretical Lichtenecker and Rother model (LRM) to estimate the volumetric water content. The mixture equation considering the appropriate porosity of the investigated material provide a practical and efficient approach for water content estimation based on classical travel time analysis with the onset-method. The inflection method is not recommended for water content estimation in electrical dispersive and absorptive material. Moreover, the results clearly indicate that effects due to coupling of the sensor to the material cannot be neglected. Coupling problems caused by an air gap lead to dramatic effects on water content estimation, even for submillimeter gaps. Thus, the quantitative determination of the in situ water content requires careful sensor installation in order to reach a perfect probe clay rock coupling.
In the context of finite element model updating using output-only vibration test data, natural frequencies and mode shapes are used as validation criteria. Consequently, the correct pairing of experimentally obtained and numerically derived natural frequencies and mode shapes is important. In many cases, only limited spatial information is available and noise is present in the measurements. Therefore, the automatic selection of the most likely numerical mode shape corresponding to a particular experimentally identified mode shape can be a difficult task. The most common criterion for indicating corresponding mode shapes is the modal assurance criterion. Unfortunately, this criterion fails in certain cases and is not reliable for automatic approaches. In this paper, the purely mathematical modal assurance criterion will be enhanced by additional physical information from the numerical model in terms of modal strain energies. A numerical example and a benchmark study with experimental data are presented to show the advantages of the proposed energy-based criterion in comparison to the traditional modal assurance criterion.
In this work different fibre optic sensors for the structural health monitoring of civil engineering structures are reported. A fibre optic crack sensor and two different fibre optic moisture sensors have been designed to detect the moisture ingress in concrete based building structures. Moreover, the degeneration of the mechanical properties of optical glass fibre sensors and hence their long-term stability and reliability due to the mechanical and chemical impact of the concrete environment is discussed as well as the advantage of applying a fibre optic sensor system for the structural health monitoring of sewerage tunnels is demonstrated.
One major research focus in the Material Science and Engineering Community in the past decade has been to obtain a more fundamental understanding on the phenomenon 'material failure'. Such an understanding is critical for engineers and scientists developing new materials with higher strength and toughness, developing robust designs against failure, or for those concerned with an accurate estimate of a component's design life. Defects like cracks and dislocations evolve at
nano scales and influence the macroscopic properties such as strength, toughness and ductility of a material. In engineering applications, the global response of the system is often governed by the behaviour at the smaller length scales. Hence, the sub-scale behaviour must be computed accurately for good predictions of the full scale behaviour.
Molecular Dynamics (MD) simulations promise to reveal the fundamental mechanics of material failure by modeling the atom to atom interactions. Since the atomistic dimensions are of the order of Angstroms ( A), approximately 85 billion atoms are required to model a 1 micro- m^3 volume of Copper. Therefore, pure atomistic models are prohibitively expensive with everyday engineering computations involving macroscopic cracks and shear bands, which are much larger than the atomistic length and time scales. To reduce the computational effort, multiscale methods are required, which are able to couple a continuum description of the structure with an atomistic description. In such paradigms, cracks and dislocations are explicitly modeled at the atomistic scale, whilst a self-consistent continuum model elsewhere.
Many multiscale methods for fracture are developed for "fictitious" materials based on "simple" potentials such as the Lennard-Jones potential. Moreover, multiscale methods for evolving cracks are rare. Efficient methods to coarse grain the fine scale defects are missing. However, the existing multiscale methods for fracture do not adaptively adjust the fine scale domain as the crack propagates. Most methods, therefore only "enlarge" the fine scale domain and therefore drastically increase computational cost. Adaptive adjustment requires the fine scale domain to be refined and coarsened. One of the major difficulties in multiscale methods for fracture is to up-scale fracture related material information from the fine scale to the coarse scale, in particular for complex crack problems. Most of the existing approaches therefore were applied to examples with comparatively few macroscopic cracks.
Key contributions
The bridging scale method is enhanced using the phantom node method so that cracks can be modeled at the coarse scale. To ensure self-consistency in the bulk, a virtual atom cluster is devised providing the response of the intact material at the coarse scale. A molecular statics model is employed in the fine scale where crack propagation is modeled by naturally breaking the bonds. The fine scale and coarse scale models are coupled by enforcing the displacement boundary conditions on the ghost atoms. An energy criterion is used to detect the crack tip location. Adaptive refinement and coarsening schemes are developed and implemented during the crack propagation. The results were observed to be in excellent agreement with the pure atomistic simulations. The developed multiscale method is one of the first adaptive multiscale method for fracture.
A robust and simple three dimensional coarse graining technique to convert a given atomistic region into an equivalent coarse region, in the context of multiscale fracture has been developed. The developed method is the first of its kind. The developed coarse graining technique can be applied to identify and upscale the defects like: cracks, dislocations and shear bands. The current method has been applied to estimate the equivalent coarse scale models of several complex fracture patterns arrived from the pure atomistic simulations. The upscaled fracture pattern agree well with the actual fracture pattern. The error in the potential energy of the pure atomistic and the coarse grained model was observed to be acceptable.
A first novel meshless adaptive multiscale method for fracture has been developed. The phantom node method is replaced by a meshless differential reproducing kernel particle method. The differential reproducing kernel particle method is comparatively more expensive but allows for a more "natural" coupling between the two scales due to the meshless interpolation functions. The higher order continuity is also beneficial. The centro symmetry parameter is used to detect the crack tip location. The developed multiscale method is employed to study the complex crack propagation. Results based on the meshless adaptive multiscale method were observed to be in excellent agreement with the pure atomistic simulations.
The developed multiscale methods are applied to study the fracture in practical materials like Graphene and Graphene on Silicon surface. The bond stretching and the bond reorientation were observed to be the net mechanisms of the crack growth in Graphene. The influence of time step on the crack propagation was studied using two different time steps. Pure atomistic simulations of fracture in Graphene on Silicon surface are presented. Details of the three dimensional multiscale method to study the fracture in Graphene on Silicon surface are discussed.
This paper proposes an adaptive atomistic- continuum numerical method for quasi-static crack growth. The phantom node method is used to model the crack in the continuum region and a molecular statics model is used near the crack tip. To ensure self-consistency in the bulk, a virtual atom cluster is used to model the material of the coarse scale. The coupling between the coarse scale and fine scale is realized through ghost atoms. The ghost atom positions are interpolated from the coarse scale solution and enforced as boundary conditions on the fine scale. The fine scale region is adaptively enlarged as the crack propagates and the region behind the crack tip is adaptively coarsened. An energy criterion is used to detect the crack tip location. The triangular lattice in the fine scale region corresponds to the lattice structure of the (111) plane of an FCC crystal. The Lennard-Jones potential is used to model the atom–atom interactions. The method is implemented in two dimensions. The results are compared to pure atomistic simulations; they show excellent agreement.
Discrete function theory in higher-dimensional setting has been in active development since many years. However, available results focus on studying discrete setting for such canonical domains as half-space, while the case of bounded domains generally remained unconsidered. Therefore, this paper presents the extension of the higher-dimensional function theory to the case of arbitrary bounded domains in Rn. On this way, discrete Stokes’ formula, discrete Borel–Pompeiu formula, as well as discrete Hardy spaces for general bounded domains are constructed. Finally, several discrete Hilbert problems are considered.
A phantom-node method is developed for three-node shell elements to describe cracks. This method can treat arbitrary cracks independently of the mesh. The crack may cut elements completely or partially. Elements are overlapped on the position of the crack, and they are partially integrated to implement the discontinuous displacement across the crack. To consider the element containing a crack tip, a new kinematical relation between the overlapped elements is developed. There is no enrichment function for the discontinuous displacement field. Several numerical examples are presented to illustrate the proposed method.