56.03 Methoden im Bauingenieurwesen
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Der Einsatz von CAD-Applikationen hat die Planungsarbeit im Bauwesen entscheidend verändert. In der Entwurfsplanung sind die Änderungen bereits deutlich erkennbar. Seit der Anwendung von dreidimensionalen Planungswerkzeugen kann der Bauherr das Bauwerk in seiner virtuellen Gesamtheit am Computer betrachten und bewerten. Dies bietet viele Vorteile. So ist der Planer gezwungen alle wesentlichen Details a priori exakt zu planen, wodurch viele Fehler vermieden werden können. Dies bietet insbesondere für Planungen in Baubetrieben, z.B. im Rahmen der Arbeitsvorbereitung, neue Einsatzmöglichkeiten.
With the help of functional analytical methods complex analysis is a powerful tool in treating non-linear first-order partial differential equations in the plane. Some of the most important of these equations are the Beltrami equations. This is due to the fact that the theory of Beltrami systems is related to many problems of geometry and analysis, like non-linear subsonic two-dimensional hydrodynamics, problems of conformal and quasiconformal mappings of two-dimensional Riemannian manifolds, or complex analytic dynamics. The theory of Beltrami equations is strongly connected with the -operator. This singular integral operator is immediately recognized as two-dimensional Hilbert-transform, known also under the name of integral operator with Beurling kernel, acting as an isometry of L2(C) onto L2(C). In hypercomplex function theory the Beltrami equations have not yet this importance, but nevertheless, they are a basic condition for the transfer of complex methods and efforts for solving partial differential equations, especially of non-linear type, to the spatial case. Here we deal with hypercomplex Beltrami systems. For this we restrict ourselves to the quaternionic case, but without any loss of generality. We will show how a spatial generalization of the complex -operator can be used to solve systems of non-linear partial differential equations, in particular different types of spatial Beltrami systems. Also, the for practical purposes so important norm estimates will be derived. Some of our results are stronger as known results in the complex case, but they are applicable in the complex situation, too.
Problem of discretic programming in conditions of manycriterial is considered. Set of work, being subject to fulfilment, is available. Are certain also: set of the executors; set, machines; set of resources (materials, semifinished items and etc.) and other set. As a functional complex name set, which will be formed, when on one representative of each of the specified sets is nominated to one working place. The allowable decision of a examined problem represents set of not crossed complexes provided that, for each working place one functional complex is certain in the accuracy. The elementary case of a formulated above problem is known under the name >a problem about purposes< [1], when the complex is defined as a pair >an executor - working place<. In case of three-element complexes we come to a problem about three-combinations. In a general case the complex consists from m of elements and the problem of formation of m-element complexes is formulated on the m-colour column.
A technique for using object-oriented technologies to write structural analysis software has been developed. The structural design information of an individual building is stored in an object-oriented database. A global database provides general design values as material data and safety factors. A class library for load elements has been evolved to model the transfer of loads in a building. This class library is the basis for the development of further classes for other structural elements such as beams, columns or slabs. A software has been developed to monitor the forces transferred from one structural member to another in a building for load cases and combinations according to Eurocode 1. The results of the analysis are stored in the projects database from which a structural design report may be generated. The software was developed under Microsoft Visual C++. The Microsoft Foundation Class Library (MFC) was used to program the Graphical User Interface (GUI). Object Linking and Embedding (OLE) technology is useful to include any type of OLE server objects for example texts written with a word processor or CAD drawings in the structural design report. The Object-Oriented Database Management System (OODBMS) ObjectStore provides services to store the large amount of objects.
Gegenstand der Betrachtung ist ein spezielles Tourenproblem der Schüttgutoptimierung. Man stelle sich als Realitätsbezug ein Transportunternehmen vor, das eine Anzahl von gleichartigen Fahrzeugen in einem Fuhrpark stationiert hat. Vorgegebene Mengen von Schüttgut müssen von einer Kiesgrube zu mehreren Baustellen transportiert werden. Dabei sind Be- und Entladezeiten, unterschiedliche mittlere Geschwindigkeiten für Leer- bzw. Lastfahrten und Schichtzeiten zu berücksichtigen. Gesucht ist eine optimale Anzahl von einzusetzenden Fahrzeugen und die zugehörigen Tourenpläne mit dem Ziel der Minimierung der Transportkosten unter Beachtung der Lieferverträge. Die Lösung des Problems erfolgt in zwei Phasen. Zuerst wird die Frage geklärt, wieviele Fahrzeuge bei minimalem Kostenniveau einzusetzen und welche zu den Leerfahrten gehörigen Teilstrecken wie oft zu befahren sind. Anschließend wird mit heuristischen Verfahren versucht, die Menge der zu fahrenden Teilstrecken so auf die Fahrzeuge aufzuteilen, daß für jedes Fahrzeug eine zulässige Tour entsteht. Zur komplexen Lösung einer denkbaren Aufgabe liegt ein Programm in der Programmiersprache PASCAL vor. Die erzielten numerischen Resultate belegen, daß auch für Probleme größerer Dimension eine Optimallösung oder sehr gute Näherungen in vernünftiger Zeit gefunden werden.
In this study, we propose a nonlocal operator method (NOM) for the dynamic analysis of (thin) Kirchhoff plates. The nonlocal Hessian operator is derived based on a second-order Taylor series expansion. The NOM does not require any shape functions and associated derivatives as ’classical’ approaches such as FEM, drastically facilitating the implementation. Furthermore, NOM is higher order continuous, which is exploited for thin plate analysis that requires C1 continuity. The nonlocal dynamic governing formulation and operator energy functional for Kirchhoff plates are derived from a variational principle. The Verlet-velocity algorithm is used for the time discretization. After confirming the accuracy of the nonlocal Hessian operator, several numerical examples are simulated by the nonlocal dynamic Kirchhoff plate formulation.
Multimodel Numerical Analysis of the Elasto-Visco-Plastic Deformation of Materials and Constructions
(1997)
At the present time there is no a generally accepted theory of visco-plasticity which is applicable for a wide class of materials and arbitrary paths of loading. The multimodel approach, based on the creation of hierarchical sequence of the models, is the most rational. The developed library of elasto-visco-plastic models includes both simplest and sophistic models demanding numerous experimental data. A unified general form of constitutive equations for all used elasto-visco-plastic models are presented based upon the concept of tensorial internal state variables. It permits to use unified algorithm of boundary tasks solution for different variants of material models. The developed selection criteria system generates the necessary conditions and provides the choice of the simplest variant of theory sufficient for correct problem solution. Formulation of the selection criteria system is based on peculiarities of viscoplastic materials behavior for the wide range thermomechanical loading and numerous computational experiments with structures different complexity levels. A set of effective schemes of integration stress-strain relations and non-linear finite element system solution are discussed for the considered class of material models. Application possibility of different material models is studied both for material element and for complicated structures. Application of the multimodel approach in numerical computations has demonstrated possibility of reliable prediction of stress-strain response under wide variety of combined loading.
Die Kosten für die Unterhaltung von Bauwerken über den Lebenszyklus sind im Vergleich zu den Planungs- und Herstellungskosten erheblich größer. Insbesondere setzt eine Reduzierung des Instandhaltungsaufwandes als Teilprozeß der Bestandsverwaltung das rechtzeitige Erkennen von Bauschäden und das vorausschauende Ergreifen von Gegenmaßnahmen voraus. Das planmäßige Vorgehen beim Erkennen von Bauschäden, d.h. die regelmäßige Überwachung baulicher Anlagen, dient nicht nur dem sparsamen Umgang mit vorhandenen Mitteln, sondern verringert auch die Gefahr des plötzlichen Versagens von tragenden Bauteilen. Dadurch werden Gefahren für die Nutzer der Bauwerke frühzeitig abgewendet. Die Notwendigkeit der systematischen Instandhaltung mit modernen Methoden wird auch in den Schlußfolgerungen des dritten Bauschadensberichts des Bundesministeriums für Raumordnung, Bauwesen und Städtebau unterstrichen. Um den Zustand eines Bauteils festzustellen, werden ausreichende Informationen über Struktur, Material, Alter, Belastungen, Umweltbedingungen etc. benötigt. Zur Verarbeitung dieser Fülle von Informationen unterschiedlichen Typs (z.B. technische Dokumente, CAD-Zeichnungen, Photos etc.) bei der Überwachung und Dokumentation baulicher Anlagen ist eine geeignete DV-Unterstützung notwendig. Zur Verwaltung der komplexen Baustrukturinformationen werden objektorientierte Bauwerksmodelle benötigt. Zur bedarfsgerechten Aufbereitung der unterschiedlichen Informationsarten und -qualitäten ist zusätzlich eine multimediale Informationsverarbeitung sowohl intern als auch in der Benutzungsschnittstelle erforderlich. Im Beitrag werden die Grundlagen objektorientierter Methoden zur Bauwerksmodellierung sowie von Multimedia mit den Bereichen Text, Graphik (Vektor- und Pixelgraphik), Audio, Photo und Video einschließlich deren Verknüpfungsmöglichkeiten im Sinne von Hypermedia an Beispielen erläutert. Zusätzlich werden aktuelle Entwicklungstendenzen im Bereich der Telekommunikation mit den Möglichkeiten des Computernetzes INTERNET zur Bestandsverwaltung in verteilten Systemen aufgezeigt. Abschließend werden Anwendungen der objektorientierten und multimedialen Informationsverarbeitung in der täglichen Ingenieurpraxis am Beispiel des DV-Systems BestandManager zur Überwachung und Dokumentation baulicher Anlagen vorgestellt.
In the rpocess of project construction organization under conditions of limited resources the problem of investor arises, which in onecriteria setting is as follows N invsted projects reindexed i=1,2,...,n are considered, initial parameters of the problem are:- duraion of iproject construction, - expected profit per unit of time from i project after putting it info operation ,-the time fixed , after the expiry of it a fine is paid for each overdued unit of time units in number. The investor resources are limited, i.e., at every moment of time investor can provid delivering of necessary resources only for one project .Any admissible problem decision of investor represents one of n! permutation of of numbers 1,2,..,n. X={x}-is the set of all admissible solutions (SAS) of this problem . In works of different authors the quality of decision is evaluated either by objective function (OF) of the type MINSUM where,by the objective function of the of the type MINMAX
Die Zielstellung der ModalSplitBetrachtungen läuft darauf hinaus, Entscheidungs-kriterien zu erarbeiten, nach denen die einzelnen Personen ihre Verkehrsmittel auswählen. In dieser Veröffentlichung wurden alle drei Gruppen der Modelle (klassische, verhaltensorientierte und der Analyse) der Verkehrsaufteilung kurz charakterisiert. Dann wurden vier ausgewählte Modelle genauer beschrieben. Zum Schluß wird das Modell der Verkehrsmittelwahl dargestellt , das für die Untersuchung der Verkehrsaufteilung in Krakau verwendet wurde .
Modeling of Freeway Traffic
(2004)
An integrated modeling of freeway traffic is developed, whose implementation in an uniform computer –aided simulation model facilitate comparative evaluation and systematic coupling of several traffic simulations, traffic controls, traffic measurements and traffic scenarios. The integrated modeling of freeway traffic is a basic mapping of freeway networks, control methods, measurements and different simulations of traffic flow...
Model of stressed-strained State of Multilayer Masses with regard for Non-Ideal Contact of Layers
(1997)
Thus, mathematical model stressed- strained of a condition of layered masses is constructed. The model has high accuracy. It allows to simulate slippery contact of layers without friction. Thus not the order of permitting system of the equations is increased, and at its realization the method of fenite elements does not increase quantity of required degrees freedom. The differential operators included in system the equations are similar known in the classical theory of shells. It facilitates construction of a finite element. Presence in system of the differential equations of derivative of external forces allows to use her for the decision of contact problems with a stain of contact commensurable with thickness of a masses.
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 influence of vortex-induces vibrations on vertical tie rods has been proved as a determinant load factor in the lifetime-oriented dimensioning of arched steel bridges. Particularly, the welded connection plates between the suspenders and the arches often exhibit cracks induced primarily rods. In this context, the synchronization of the vortex-shedding to the rod motion in a critical wind velocity range, the so-called lock-in effect, is of essential interest.
A large-scale computer modeling and simulation method is presented for environmental flows in urban area. Several GIS and CAD data were used for the preparation of shape model and an automatic mesh generation method based on Delaunay method was developed. Parallel finite element method based on domain decomposition method was employed for the numerical simulation of natural phenomena. The present method was applied to the simulation of flood flow and wind flow in urban area. The present method is shown to be a useful planning and design tool for the natural disasters and the change of environments.
Effective knowledge management is increasingly considered as a cornerstone of sustainable business success. Knowledge management systems are strategically valuable for both ensuring consistency and continuous improvement of various aspects such as quality delivery, productivity and competitiveness. The small and medium enterprises (SMEs) in the construction industry are mostly operating under tighter timeframes, narrower profit margins and more constrained resources. Hence the recently commenced SMILE-SMC (Strategic Management with Information Leveraged Excellece for Small and Medium Contractors) project aims to support the information and knowledge management needs of the small and medium contractors in Hong Kong. This paper presents some snapshots on the SMILE-SMC project, and its conceptualized deliverables with some highlights of recent developments.
Today’s building industry not only demands more and more reduced construction time on building site, but also an advanced and mostly construction attendant design phase. Even though there is software available to support design processes in distributed environments, most applications only support simple document based exchange of information. In this paper a knowledge based system is presented to support cooperative, comprehensive design processes in distributed environments. The presented research project is financially supported by the German Research Community (DFG – Deutsche Forschungsgemeinschaft).
Essence of service unreliability on account of irregularity has been given. The reasons of occurance of overcrowded vehicles have been listed. The factor of service unreliability on account of irregularity has been determined. It is probability of the event, that the passenger finds departing vehicle fully filled, i.e. when all places seating and standing are occupied or condition of the travel, which would be not acceptable for passenger. Large dispersion of headways (i.e. irregularity) increases probability of such situations. To calculate the mentioned factor, the computer simulation was used. Both, passenger arrivals and vehicle operation have been modelled as stochastic interacted processes. Distributions of headways and passenger arrivals have been fixed by statistical methods. The >maximal capacity< of a vehicle has been determined. The set of parameters values for simulation runs has been given. The transformed results of computer simulation are series of nomographs for determination of a factor value. They were prepared for many types of trams and city buses, but only one nomograph has been presented. Difficulties in verification of model were discussed. Recommendations for rational utilisation level of public transport means capacity in the condition of randomness of passenger arrivals and disturbances in vehicle operation have been proposed. The other possibilities of service unreliability have been mentioned. General conclusions have been given
In our project, we develop new tools for the conceptual design phase. During conceptual design, the coarse functionality and organization of a building is more important than a detailed worked out construction. We identify two roles, first the knowledge engineer who is responsible for knowledge definition and maintenance; second the architect who elaborates the conceptual design. The tool for the knowledge engineer is based on graph technology, it is specified using PROGRES and the UPGRADE framework. The tools for the architect are integrated to the industrial CAD tool ArchiCAD. Consistency between knowledge and conceptual design is ensured by the constraint checker, another extension to ArchiCAD.
The processes in the life cycle of buildings are characterised by highly distinct teamwork. The integration of all the distributed working participants, by providing an environment, which especially supports the communication and collaboration between the actors, is a fundamental step to improve the efficiency of the involved processes and to reduce the total costs. In this article, a link based modelling approach and its “intelligent” link management is introduced (1). This approach realises an integration environment based on a special building model that acts as a decision support system. The link-based modelling is characterised by the definition and specialisation of links between partial models. These intelligent managed links enable a very flexible and task specific data access and exchange between all the different views and partial models of the participants.
Bauwerke werden heute mit umfassender Systematik Bauwerke werden heute mit umfassender Systematik die Brauchbarkeit der Bauwerke werden durch Normung und Prüfung intensiv beeinflußt. Der Computereinsatz ist in diesem Bereich allgemein üblich. Im Gegensatz zu Planungs- und Ausführungsphase eines Bauwerks ist die Betriebsphase wenig systematisiert. Dies ist überraschend, da die Betriebsphase über die Lebensdauer eines Bauwerks hinweg wesentlich größere Kosten verursacht, als der Rohbau und da der Nutzen des Bauwerks ja nicht in seiner Errichtung sondern in seinem Betrieb liegt. Die mangelnde Systematik der Bewirtschaftung ist beispielsweise daran ersichtlich, daß es im allgemeinen noch keine brauchbare Dokumentation der Gebäudebewirtschaftung, wenige Normen und wenig Software für diesen Aufgabenbereich gibt.
Unterschiedliche Sichten auf einen Anwendungsbereich drücken sich in unterschiedlich strukturierten Modellen aus. Diese Modelle enthalten im allgemeinen unterschiedliche Arten von Informationen über Objekte ihres Anwendungsbereiches. In diesem Beitrag soll ein Konzept zur Modellintegration beschrieben werden, das die Zusammenführung dieser Informationen gestattet. Im Gegensatz zu traditionellen Methoden des Datenaustauschs, bei dem Objekte des einen Modells in Objekte des anderen Modells konvertiert werden, beruht das Integrationskonzept auf dem Erkennen und dem Verbinden einander äquivalenter Objekte in den Modellen. Als Grundlage zur Beschreibung der Modellschemata wurde die in der ISO 10303-11 spezifizierte konzeptuelle Sprache EXPRESS benutzt. Der Objektzugriff wird durch ein Laufzeitsystem realisiert, das auf der Basis des Standard Data Acces Interface (SDAI ISO 10303-22) entwickelt wurde. Die Modellintegration umfaßt zwei Teilbereiche. Zum einen muß ein Abgleich der verschiedenen Schemata (Schema mapping) erfolgen. Zum anderen müssen Regeln zur Objektidentifikation (Object matching) beschrieben werden. Zur Angabe dieser Integrationsinformationen wurden Strukturen entwickelt. Die in diesen Strukturen abgelegten Beziehungen werden durch das Laufzeitsystem ausgewertet. Durch diese Vorgehensweise lassen sich zum einen alle verfügbaren Informationen über Objekte des Anwendungsbereiches zusammenführen, so daß sie im Gesamtkontext sichtbar werden und bearbeitet werden können. Zum anderen können Inkonsistenzen zwischen den Modellen erkannt und ausgewertet werden.
Buildings require both for construction and, due to their comparatively long life cycle for maintenance, significant raw material and energy resources. So far available knowledge about resource consumption during an entire life cycle of a building is still quite rare, because various criteria affect each other and/or overlay mutually. In this contribution a model based software concept is presented using an integrated approach for life cycle simulation and assessment of buildings. The essential point of the development consists of connecting an IFC compliant product model of a building via the Internet with data bases for the resource and energy requirement of building materials. Furthermore, numerical simulations allow calculating and minimizing the energy consumption, the resource requirement, the waste streams and also the noxious emissions. In the context of this paper we present the first release of software programs for architects and engineers, which help them to evaluate their design decisions objectively in early planning steps. Additionally the usage of the software is demonstrated by a test case study for a real world building. By applying this software in practice a substantial contribution for saving energy and natural resources can be provided in the sense of sustainable and ecological building design.
Informationstechnische Integration im Bauwesen durch Nutzung fachspezifischen Anwenderwissens
(1997)
Im vorliegenden Beitrag wird ein Integrationskonzept vorgestellt, bei dem das fachspezifische Wissen des Anwenders integraler Bestandteil des Konzeptes ist. Grundgedanke des Konzeptes ist es, die Informationen vorerst im Kontext der Anwendung, mit der sie erstellt wurden, zu belassen. Die Interpretation der Informationen erfolgt durch den Anwender, der diese Informationen zur Integration nutzen möchte. Er weiß, welche Daten er für seine Arbeiten benötigt, und er verfügt über das erforderliche fachspezifische Wissen, um die Informationen anderer Bearbeiter verstehen zu können. Damit ist es nicht erforderlich, die internen Datenstrukturen einer Software zu verstehen und in einem neutralen Format zu beschreiben. Die Integration erfolgt interaktiv am Bildschirm durch den Anwender. Das vorgestellt Konzept wird in den Kontext der in der Literatur beschriebenen Integrationskonzepte eingegliedert. Hierzu werden die Integrationskonzepte klassifiziert. Die Klassifikation erfolgt auf der Grundlage der Software-Architekturen. Das vorgestellte Integrationskonzept wird am Beispiel der Angebotsbearbeitung im Bauwesen konkretisiert.
We provide a critical overview of the current status of computational support for construction the management and building performance evaluation in North-America. This overview is based on the research conducted in relation to the design and construction of the Intelligent Workplace (IW), Carnegie Mellon University, Pittsburgh, Pennsylvania, USA. With regard to the commercial software products in the field of construction management the following limitations can be identified: Although project planning, cost estimating and construction simulation are supported, tasks like bidding as well as site and material management have not received the same level of attention. Few project management software packages are integrated in a total design support software system. Little analysis or evaluation options are provided to support managerial decision making. Various research groups address the construction planning and scheduling, construction contracting, site layout generation as well as the integration of these three topics. Currently problems such as efficient material management and calculation of environmental and energy responsive site management are insufficiently addressed within the ongoing research projects. In the domain of building performance simulation and decision support one can notice that, the development and application of computational tools is industry driven. As a result the concerns addressed by the tools are mainly issues pertaining to the selection and sizing of systems and components rather than an integrated performance evaluation. Consequently, these programs are rarely used by building designers, especially in the early design stages, where the predictive capabilities of simulation tools could be of significant value. Although many research institutions address the necessity for the integration of performance simulation within the overall design support environments most of the practically available performance simulation tools still remain mono-dimensional and isolated.
In this paper, we present an open-source code for the first-order and higher-order nonlocal operator method (NOM) including a detailed description of the implementation. The NOM is based on so-called support, dual-support, nonlocal operators, and an operate energy functional ensuring stability. The nonlocal operator is a generalization of the conventional differential operators. Combined with the method of weighed residuals and variational principles, NOM establishes the residual and tangent stiffness matrix of operate energy functional through some simple matrix without the need of shape functions as in other classical computational methods such as FEM. NOM only requires the definition of the energy drastically simplifying its implementation. The implementation in this paper is focused on linear elastic solids for sake of conciseness through the NOM can handle more complex nonlinear problems. The NOM can be very flexible and efficient to solve partial differential equations (PDEs), it’s also quite easy for readers to use the NOM and extend it to solve other complicated physical phenomena described by one or a set of PDEs. Finally, we present some classical benchmark problems including the classical cantilever beam and plate-with-a-hole problem, and we also make an extension of this method to solve complicated problems including phase-field fracture modeling and gradient elasticity material.
In this research project we intend to transfer the whole AEC-Bidding process to an agent-based virtual marketplace. Hereby, the existing legal regulations have to be considered. Important aspects in developing the virtual marketplace are to provide the possibility to realize an agentbased bidding consortium as well as to integrate subcontractors.
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.
The highway product model based on the length information of the centerline, and the application system is developed. This paper shows the schema and the modeling process of the product model, which includes geometric elements such as an alignment, lanes, sidewalks, shoulders and sprits, and accessories such as guard fences, plantings and signs. Furthermore, The Highway Sequence Editor (HSE) is developed as an application system to verify the model.
Priority-rule methods for approximately minimizing the duration of a project subject to minimal and maximal time lags between the activities of the project and limited availability of renewable resources are considered. Such a project can be modelled by a cyclic activity-on-node network. Two generation schemes for constructing feasible schedules are discussed: the serial and parallel schemes. Two different kinds of heuristic procedures are proposed. The sequential or direct method processes the activities or respectively nodes of the project network one after another without considering the strong components separately. The contraction method uses a bottom-up technique. First, a feasible subschedule is determined for each strong component. Second, each strong component is replaced by a single node and the resulting acyclic network is treated by the direct method. In conclusion, some results from an experimental performance analysis of the heuristics are given using a new network generator.
Der Effekt des praktischen Einsatzes von CAD-Systemen im Stahlbau erschöpft sich heute weitgehend in einer Verbesserung der Qualität der Planungsunterlagen und in der Verkürzung der Bearbeitungszeiten. Dabei ist bei schwierigen individuellen Konstruktionen die Einsparung an Arbeitszeit oft nicht sehr markant gegenüber einer traditionellen Arbeitsweise. Die dreidimensionale Erfassung, Speicherung und Verarbeitung von Konstruktionsdaten im Rechner verlangt neben größeren Rechenleistungen neue Verfahren für die Behandlung dieser Daten. Die Möglichkeiten der Automatisierung stahlbautypischer Produktionsvorgänge und einer variablen, computergestützten Planung erfordern wissenschaftlich-technische Betrachtungen des Gesamtproblems. Ausgehend von den Anforderungen des Stahlbaus wird ein neues dreidimensionales Volumenmodell für den rechnergestützten Entwurf und die Konstruktion erarbeitet. Es werden grundlegende Methoden zur Problembehandlung aufgezeigt. Die Methodik basiert im wesentlichen auf der Methode der Inzidenz-Matrizen, um die Beziehungen zwischen topologischen und geometrischen Informationen eines Körpers darzustellen. Die Ermittlung der lokalen Mannigfaltigkeiten wird mit dem Euler-Polyedersatz verglichen und an Beispielen demonstriert. Eine neue Methode zur Ermittlung der lokalen Mannigfaltigkeiten wird dargestellt. Stahlbauspezifische Konstruktionen werden erzeugt und ihre Gestalt nach Anforderungen verändert. Im besonderen werden stahlbauspezifische Ausklinkungen und Verschneidungen erarbeitet und an Beispielen präsentiert.
Many problems related to data integration in AEC can be better tackled by an approach that takes into account the heterogeneity of tasks, models and applications but does not require continuous consistency of the evolving design data, at each data management operation. Such an approach must incorporate adequate services that can facilitate reintegration of concurrently modified data at reasonably selected coordination points. In this paper we present a set of methods which, used in combination, can achieve that goal. After a description of the principal envisaged cooperative work scenario each of these methods is discussed in detail and current observations drawn from their software realisation are given. Whilst the suggested approach is valid for any EXPRESS-based data model, the practical focus of work has been on facilitating IFC-driven integration.
The idea of representing urban structure and various communication systems (water and energy supply, telephone and cable TV networks) as fractal objects is not absolutely new. However, known works, devoted to this problem use models and approaches from fractal physics. For example, to simulate urban growth Diffusion Limited Aggregation (DLA) model and Dielectric Breakdown (DB) model are used. This study introduces a different approach. Net structure of communication system is described by a graph of special type called regular G(l,r,n)-graph. Authors provide description of such graph, develop iterative process for its generation and prove its self-similarity, i.e. that every regular graph is a pre-fractal. After the infinite number of steps this process generates a fractal. The devised algorithm for generation and grathical representation of regular G(l,r,n)-graphs with different values of l,r and n has been programmed to receive computer simulations. For optimal graphic presentation of pre-fractals the Optimal Space Ordering method was suggested. It is based on the minimization of the >graph energy< value about vertices' coordinates. The effective procedure for optimization was developed that takes into account specific properties of graph energy as objective function For the fractal graph introduced the Hausdorff-Besikovich and similarity dimensions were calculated. It has been shown that >graph energy< is directly related to the graph's fractal properties. For G(3,3,n) and G(4,4,n) graphs fractal dimensions calculated by different methods are the same (D=1,5 and D=2 respectively), while topological dimension of both graphs is 1.
Objektorientierte Modellierungstechniken werden gegenwärtig vor allem Entwicklern von CAD-Systemen angeboten. Sie erzeugen über die Schritte OO-Modellanalyse und OO-Softwaredesign OO-Programme, die mit ihrer Compilation das durch den Softwareingenieur gefundene Modell festschreiben. Generell, aber insbesondere im Bauwerksdesign, ist dieses Vorgehen unbefriedigend, da hier eine Normung von Modellen nicht gelingt, der Entwurfsprozeß vergleichsweise lang ist und eine Kooperation von Ingenieurgewerken mit verschiedenen Modelldomänen die Regel sind. Darüber hinaus weisen die Modelle in frühen Phasen ein hohes Maß an Unschärfe und Abstraktion auf. CAD-Tools, die diese Phasen unterstützen, benötigen deshalb: statt eines genormten Produktmodells ein einheitliches, kognitiv begründetes Modellstrukturierungsparadigma, für das mit der Objektorientierung eine mögliche Ausprägung gegeben ist, ein explizites, verfügbares Domänenmodell zur fortwährenden Interpretation von Bauwerksmodellen, deskriptive Elemente, die die Interpretation von Objekten und Attributen erleichtern, ein Konzept zur Behandlung von Unschärfe und Abstraktion. Hieraus ergeben sich für die Entwicklung von CAD-Systemen folgende Forderungen : Explizite Verfügbarkeit von Klassenobjekten und deren Erzeugung und Veränderung zur Laufzeit, Vererbung auf Klassen- und Instanzniveau, Erweiterte Attributkonzepte (Facetten), Unterstützung der Aggregation als einer wesentlichen Modellstrukturierungsrelation, Verfügbarkeit von OO-Schnittstellen zum Aufbau von CAD-Systemen aus Tools einerseits, sowie zur Trennung von Modellverwaltung und Modellrepräsentation andererseits. Als ein herausragendes Merkmal des Objektorientierten Paradigmas wird die Anwendungsnähe genannt, da Erscheinungen der behandelten Domäne sich analog in Modellen und Programmen wiederfinden (sollen). Unter der Grundannahme, daß dieses Paradigma auch durch den Anwender zur Erstellung seiner Modellwelten verwendet wird, will FLEXOB eine homogene Umgebung schaffen, die die Modellwelt des Softwareingenieurs zu Analysezwecken dem Anwender zur Verfügung stellt und die die Erweiterung dieser Modellwelt auf deskriptivem Niveau ermöglicht. Das Tool FLEXOB und einige wesentliche Implementationsdetails werden im Beitrag vorgestellt. Es handelt sich bei diesem Tools um eine C++ Klassenbibliothek, die entweder als Objektmodul oder als Windows-DLL verwendet werden kann. Aspekte des Nutzungsregimes solch flexibler Modellverwaltungen werden im Beitrag ebenfalls angespochen.
The method of the finite elements is an adaptable numerical procedure for interpolation as well as for the numerical approximation of solutions of partial differential equations. The basis of these procedure is the formulation of suitable finite elements and element decompositions of the solution space. Classical finite elements are based on triangles or quadrangles in the two-dimensional space and tetrahedron or hexahedron in the threedimensional space. The use of arbitrary-dimensional convex and non-convex polyhedrons as the geometrical basis of finite elements increases the flexibility of generating finite element decompositions substantially and is sometimes the only way to get a clear decomposition...
Current building product models explicitly represent components, attributes of components, and relationships between components. These designer-focused product models, however, do not represent many of the design conditions that are important for construction, such as component similarity, uniformity, and penetrations. Current design and construction tools offer limited support for detecting these construction-specific design conditions. This paper describes the ontology we developed using the manufacturing concept of features to represent the design conditions that are important for construction. The feature ontology provides the blueprint for the additions and changes needed to transform a standard product model into a constructionspecific product model. The ontology formalizes three classes of features, defines the attributes and functions of each feature type, and represents the relationships between features explicitly. The descriptive semantics of the ontology allows practitioners to represent their varied preferences for naming features, specifying features that result from component intersections and the similarity of components, and grouping features that affect a specific construction domain. A software prototype that implements the ontology enables practitioners to transform designer-focused product models into feature-based product models that represent the construction perspective.
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.
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.
Integrated structural engineering system usually consists of large number of design objects that may be distributed across different platforms. These design objects need to communicate data and information among each other. For efficient communication among design objects a common communication protocol need to be defined. This paper presents the elements of a communication protocol that uses a mediator agent to facilitate communication among design objects. This protocol is termed the Mediative Communication Protocol (MCP). The protocol uses certain design communication performatives and the semantics of an Agent Communication language (ACL) mainly the Knowledge and Query Manipulation Language (KQML) to implement its steps. Details of a Mediator Agent, that will facilitate the communication among design objects, is presented. The Unified Modeling Language (UML) is used to present the Meditative protocol and show how the mediator agent can be use to execute the steps of the meditative communication protocol. An example from structural engineering application is presented to demonstrate and validate the protocol. It is concluded that the meditative protocol is a viable protocol to facilitate object-to-object communication and also has potential to facilitate communication among the different project participants at the higher level of integrated structural engineering systems.
Bei der Betrachtung von Stapelproblemen ergibt sich unter anderem folgendes Problem: Ein gegebener Stapel - bestehend aus den Elementen v i der Menge V - soll an anderer Stelle in einer vorgeschriebenen, veränderten Struktur wieder aufgebaut werden. Dazu stehen Hilfsstapelplätze zur Verfügung. Die Optimierung dieses Problems hinsichtlich der Anzahl der benötigten Hilfsstapelplätze ist NP-vollständig. Es werden Erfahrungen mit einem Branch-and-Bound Algorithmus zur Lösung des Problems vorgestellt sowie ein heuristischer Algorithmus diskutiert
There is an increasing need for 3D building extraction from aerial images for various applications such astown planning, environmental- and property-related studies. Aerial images usually reveal on one hand a certain amount of information not relevant for the given task of building extraction like vegetation, cars etc. On the other hand there is a loss of relevant information due to occlusions, low contrasts or disadvantageous perspectives. Therefore a promising concept for automated building reconstruction must incorporate a suffciantly complete model of the objects of interest. We propose a model-based approach to 3D building extraction from aerial images which reveals a tight coupling between a generic 3D object model and an explicit 2D image model. The generic object model employes domain specific volumetric primitives (i. e. building part models) and combination schemes. To cover the gap between 3D object models and 2D image data the image model is employed to predict the projective building appearences in aerial images. We present a strategy for a model-based building extraction based on the recognition-by-components principle and show first experimental results derived from international test sets
Die geometrische Modellierung hat in den Ingenieurwissenschaften eine große Bedeutung erlangt. Die Visualisierung von zwei- oder dreidimensionalen Problemstellungen ist aus heutigen Anwendungen nicht mehr wegzudenken. Zunehmend rücken Aufgabenstellungen aus dem Bereich der geometrischen Modellierung in den Vordergrund, die über die etablierten Dimensionen 1-3 hinausgehen und die nicht mehr rein geometrischer Natur sind. Hierzu zählen Aufgabenstellungen aus den Bereichen numerische Simulation, Parameteridentifikation und Strukturanalyse. Auf diese nicht-geometrischen Aufgabenstellungen sollen geometrische Verfahren, wie z.B. Triangulation, konvexe Hülle, geometrischer Schnitt und Interpolation angewendet werden. Hierzu werden diese Algorithmen, die alle auf der klassischen Geometrie des euklidischen Raumes beruhen, auf ihre Übertragbarkeit hin analysiert und überarbeitet. Am Beispiel einer Parameteridentifikation wird eine systematische Vorgehensweise vorgestellt, die es ermöglicht, trotz weniger Versuchsrechnungen den Bereich der in Frage kommenden Parameter umfassend zu beschreiben. Dies ermöglicht ein besseres Verständnis der Zusammenhänge der Parameter untereinander. Häufig existieren mehr als eine Parameterkombination, so daß diese eine Isolinie formen, die ihrerseits unendlich viele Lösungen des gestellten Problemes im Untersuchungsgebiet beschreibt.
The aim of this talk is to show that the methods used by Métivier and Lapidus to study the eigenvalue distribution of elliptic operators (e.g., of the Dirichlet Laplacian) can be adapted to the study of the similar problem for the Stokes operator. In this way we get asymptotic formulae for the eigenvalues of the latter operator even in the case when the underlying domain has an extremely irregular (fractal) boundary. In the case the boundary is not that irregular (e.g., when it is Lipschitz) the estimates we obtain are much better than the ones we can find in the current literature.
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.
In this paper, systematic analyses for the shoring systems installed to support the applied loads during construction are performed on the basis of the numerical approach. On the basis of a rigorous time-dependent analysis, structural behaviors of reinforced concrete (RC) frame structures according to the changes in design variables such as the types of shoring systems, shore stiffness and shore spacing are analyzed and discussed. The time-dependent deformations of concrete such as creep and shrinkage and construction sequences of frame structures are also taken into account to minimize the structural instability and to reach to an improved design of shoring system because these effects may increase the axial forces delivered to the shores. In advance, the influence of the column shortening effect, generally mentioned in a tall building structure, is analyzed. From many parametric studies, it has been finally concluded that the most effective shoring system in RC frame structures is 2S1R (two shores and one reshore) regardless of the changes in design variables.
The development of 3D technologies during the last decades in many different areas, leads us towards the complete 3D representation of planet earth on a high level of detail. On the lowest level we have geographical information systems (GIS) representing the outer layer of our planet as a 3D model. In the meantime these systems do not only give a geographical model but also present additional information like ownership, infrastructure and others that might be of interest for the construction business. In future these systems will serve as basis for virtual environments for planning and simulation of construction sites. In addition to this work is done on the integration of GIS systems with 3D city models in the area of urban planning and thus integration of different levels of detail. This article presents research work on the use of 3D models in construction on the next level of detail below the level of urban planning. The 3D city model is taken as basis for the 3D model of the construction site. In this virtual nD-world a contractor can organize and plan his resources, simulate different variants of construction processes and thus find out the most effective solution for the consideration of costs and time. On the basis of former researches the authors present a new approach for cost estimation and simulation using development technologies from game software.
Analytical models, describing oscillations of systems of interconnected solid and deformable bodies,making a complex movement in fields of inertia forces and gravitation forces, are resulted. Method of numerical investigation of dynamics of the specified systems, based on sharing of parameter prolongation method, Newton-Kantorovich algorithm, Flocke and Liapunov hteories, is developed. On the basis of constructed analytical models and numerical techniques a new, practically important problems of dynamics of systems, consisting of solid bodies, flexible rods, membranes and soft shells, which make a complex movement in fields of forces of inertia and gravity are solved. The received results are used during designing of responsible elements of structures, making a complex movement, which find application in construction and mechanical engineering.
This paper presents an innovative software platform OpenSTEP intended to build advanced distributed integrated systems and to conduct multidisciplinary collaborative projects in both academy and industry. The paper discusses an open system architecture, methodology, component library and CASE toolkit enabling the developers to build a wide range of interoperable applications and systems compliant with STEP and, particularly, with IFC becoming the increasingly important standard for information integration in architecture, engineering and construction.
This paper presents results of a study on distributed, or parallel, evolutionary computation in the topological design of steel structural systems in tall buildings. It describes results of extensive experimental research on various parallel evolutionary architectures applied to a complex structural design problem. The experiments were conducted using Inventor 2003, a networkbased evolutionary design support tool developed at George Mason University. First, a general introduction to evolutionary computation is provided with an emphasis on recent developments in parallel evolutionary architectures. Next, a discussion of conceptual design of steel structural systems in tall buildings is presented. Further, Inventor 2003 is briefly introduced as well as its design representation and evolutionary computation characteristics. Next, the results obtained from systematic design experiments conducted with Inventor 2003 are discussed. The objective of these experiments was to qualitatively and quantitatively investigate evolution of steel structural systems in tall buildings during a distributed evolutionary design process as well as to compare efficiency and effectiveness of various parallel evolutionary architectures with the traditional evolutionary design approaches. Two connectivity topologies (ring topology and fully-connected topology) have been investigated for four populations of structural designs evolving in parallel and using various migration strategies. Also, results of the initial sensitivity studies are reported in which two ways of initializing distributed evolutionary design processes were investigated, using either arbitrarily selected designs as initial parents or randomly generated ones. Finally, initial research conclusions are presented.
For many purposes geometric information about existing buildings is necessary, e.g. planing of conservation or reconstruction. Architectural photogrammetry is a technique to acquire 3D geometric data of buildings for a CAD model from images. In this paper the state of the art in architectural photogrammetry and some developments towards automation are described. The photogrammetric process consists of image acquisition, orientation and restitution. Special attention is put on digital methods, from digital image acquisition to restitution methods, supported by digital image processing. There are a few field of development towards automation, e.g. feature extraction, extraction of edges and lines and the detection of corresponding points. The acquired data may be used in a CAD environment or for visualization in Virtual Reality Models, using digital orthoimages for texture mapping.