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The aim of this paper is to present so-called discrete-continual boundary element method (DCBEM) of structural analysis. Its field of application comprises buildings constructions, structures and also parts and components for the residential, commercial and un-inhabitant structures with invariability of physical and geometrical parameters in some dimensions. We should mention here in particular such objects as beams, thin-walled bars, strip foundations, plates, shells, deep beams, high-rise buildings, extensional buildings, pipelines, rails, dams and others. DCBEM comes under group of semianalytical methods. Semianalytical formulations are contemporary mathematical models which currently becoming available for realization due to substantial speed-up of computer productivity. DCBEM is based on the theory of the pseudodifferential boundary equations. Corresponding pseudodifferential operators are discretely approximated using Fourier analysis or wavelet analysis. The main DCBEM advantages against the other methods of the numerical analysis is a double reduction in dimension of the problem (discrete numerical division applied not to the full region of the interest but only to the boundary of the region cross section, as a matter of fact one is solving an one-dimensional problem with the finite step on the boundary area of the region), one has opportunities to carrying out very detailed analysis of the specific chosen zones, simplified initial data preparation, simplistic and adaptive algorithms. There are two methods to define and conduct DCBEM analysis developed – indirect (IDCBEM) and direct (DDCBEM), thus indirect like in boundary element method (BEM) applied and used little bit more than direct.

The execution of project activities generally requires the use of (renewable) resources like machines, equipment or manpower. The resource allocation problem consists in assigning time intervals to the execution of the project activities while taking into account temporal constraints between activities emanating from technological or organizational requirements and costs incurred by the resource allocation. If the total procurement cost of the different renewable resources has to be minimized we speak of a resource investment problem. If the cost depends on the smoothness of the resource utilization over time the underlying problem is called a resource levelling problem. In this paper we consider a new tree-based enumeration method for solving resource investment and resource levelling problems exploiting some fundamental properties of spanning trees. The enumeration scheme is embedded in a branch-and-bound procedure using a workload-based lower bound and a depth first search. Preliminary computational results show that the proposed procedure is promising for instances with up to 30 activities.

We present an algebraically extended 2D image representation in this paper. In order to obtain more degrees of freedom, a 2D image is embedded into a certain geometric algebra. Combining methods of differential geometry, tensor algebra, monogenic signal and quadrature filter, the novel 2D image representation can be derived as the monogenic extension of a curvature tensor. The 2D spherical harmonics are employed as basis functions to construct the algebraically extended 2D image representation. From this representation, the monogenic signal and the monogenic curvature signal for modeling intrinsically one and two dimensional (i1D/i2D) structures are obtained as special cases. Local features of amplitude, phase and orientation can be extracted at the same time in this unique framework. Compared with the related work, our approach has the advantage of simultaneous estimation of local phase and orientation. The main contribution is the rotationally invariant phase estimation, which enables phase-based processing in many computer vision tasks.

Analysis of the reinforced concrete chimney geometry changes and their influence on the stresses in the chimney mantle was made. All the changes were introduced to a model chimney and compared. Relations between the stresses in the mantle of the chimney and the deformations determined by the change of the chimney's vertical axis geometry were investigated. The vertical axis of chimney was described by linear function (corresponding to the real rotation of the chimney together with the foundation), and by parabolic function (corresponding to the real dislocation of the chimney under the influence of the horizontal forces - wind). The positive stress pattern in the concrete as well as the negative stress pattern in the reinforcing steel have been presented. The two cases were compared. Analysis of the stress changes in the chimney mantle depending on the modification in the thickness of the mantle (the thickness of the chimney mantle was altered in the linear or the abrupt way) was carried out. The relation between the stresses and the chimney's diameter change from the bottom to the top of the chimney was investigated. All the analyses were conducted by means of a specially developed computer program created in Mathematica environment. The program makes it also possible to control calculations and to visualize the results of the calculations at every stage of the calculation process.

Subject of the paper is the realisation of a model based efficiency control system for PV generators using a simulation model. A standard 2-diodes model of PV generator is base of the ColSim model, which is implemented in ANSI C code for flexible code exporting. The algorithm is based on discretisized U-I characteristics, which allows the calculation of string topologies witch parallel and serial PV cells and modules. Shadowing effects can be modelled down to cell configuration using polar horizon definitions. The simulation model was ported to a real time environment, to calculate the efficiency of a PV system. Embedded System technology allows the networked operation and the integration of standard I/O devices. Futher work focus on the adaption of shadowing routine, which will be adapted to get the environment conditions from the real operation.

Die meisten Insolvenzen in Deutschland kommen aus der Bauindustrie. Die Gründe hierfür sind vielschichtig, jedoch kann mittels eines modern ausgerichteten M-I-S und Baustellen-Controllings frühzeitig erkannt werden, wie sich die Baustellenergebnisse entwickeln. Hierzu ist es notwendig, dass die Arbeitskalkulation ständig auf dem Laufenden gehalten wird. Nur wenn dies geschieht, sind monatliche Soll-/ Ist-Vergleiche und eine Betrachtung der cost-to-complete möglich und sinnvoll. Eine monatlich rollierende Prognose des Baustellenergebnisses zum Bauende ermöglicht, dass gravierende Veränderungen des Ergebnisses umgehend aufgedeckt werden. Nur in Kenntnis dieser Entwicklungen kann das Management frühzeitig (im Sinne eines Frühwarnsystems) agieren und Steuerungsmaßnahmen ergreifen. Die Ergebnisprognose zum Bauende ist allein als Steuerungsinstrument nicht ausreichend. Die Finanzsituation der Baustelle muß auch regelmäßig geprüft werden, d.h. der Leistungsstand mit der Rechnungsstellung an den Bauherren abgeglichen sowie die unbezahlten Rechnungen des Bauherren überprüft werden. Das beste Prognoseergebnis ist wertlos, wenn der Bauherr seine bezogenen Leistungen nicht vergütet. Die wirtschaftlichen Daten stehen den Verantwortlichen online im Baustellen-Informations-System (B-I-S) zur Verfügung. Ein Ampelsystem verdeutlicht die wirtschaftliche Lage der Baustelle.

For the dynamic behavior of lightweight structures like thin shells and membranes exposed to fluid flow the interaction between the two fields is often essential. Computational fluid-structure interaction provides a tool to predict this interaction and complement or eventually replace expensive experiments. Partitioned analyses techniques enjoy great popularity for the numerical simulation of these interactions. This is due to their computational superiority over simultaneous, i.e. fully coupled monolithic approaches, as they allow the independent use of suitable discretization methods and modular analysis software. We use, for the fluid, GLS stabilized finite elements on a moving domain based on the incompressible instationary Navier-Stokes equations, where the formulation guarantees geometric conservation on the deforming domain. The structure is discretized by nonlinear, three-dimensional shell elements.
Commonly used sequential staggered coupling schemes may exhibit instabilities due to the so-called artificial added mass effect. As best remedy to this problem subiterations should be invoked to guarantee kinematic and dynamic continuity across the fluid-structure interface. Since iterative coupling algorithms are computationally very costly, their convergence rate is very decisive for their usability. To ensure and accelerate the convergence of this iteration the updates of the interface position are relaxed. The time dependent, 'optimal' relaxation parameter is determined automatically without any user-input via exploiting a gradient method or applying an Aitken iteration scheme.

The reduction of oscillation amplitudes of structural elements is necessary not only for maintenance of their durability and longevity but also for elimination of a harmful effect of oscillations on people and technology operations. The dampers are widely applied for this purpose. One of the most widespread models of structural friction forces having piecewise linear relation to displacement was analysed. T The author suggests the application of phase trajectories mapping in plane "acceleration – displacement". Unlike the trajectories mapping in a plane "velocity – displacement", they don't require large number of geometrical constructions for identification of the characteristics of dynamic systems. It promotes improving the accuracy. The analytical assumptions had been verified by numerical modeling. The results show good enough coincide between numerical and analytical estimation of dissipative characteristic.

The paper contains a description of dynamic effects in the silo wall during the outflow of a stored material. The work allows for determining the danger of construction damage due to resonant vibrations and is of practical importance by determining the influence of cyclic pressures and vibro–creeping during prolonged use of a silo. The paper was devised as a result of tests on silo walls in semi-technical scale. The model is generally applicable and allows for identification of parameters in real- size silos as well.

The paper proposes a new method for general 3D measurement and 3D point reconstruction. Looking at its features, the method explicitly aims at practical applications. These features especially cover low technical expenses and minimal user interaction, a clear problem separation into steps that are solved by simple mathematical methods (direct, stable and optimal with respect to least error squares), and scalability. The method expects the internal and radial distortion parameters of the used camera(s) as inputs, and a plane quadrangle with known geometry within the scene. At first, for each single picture the 3D position of the reference quadrangle (with respect to each camera coordinate frame) is calculated. These 3D reconstructions of the reference quadrangle are then used to yield the relative external parameters of each camera regarding the first one. With known external parameters, triangulation is finally possible. The differences from other known procedures are outlined, paying attention to the stable mathematical methods (no usage of nonlinear optimization) and the low user interaction with good results at the same time.

In this paper proposed the application of two-parameters damage model, based on non-linear finite element approach, to the analysis of masonry panels. Masonry is treated as a homogenized material, for which the material characteristics can be defined by using homogenization technique. The masonry panels subjected to shear loading are studied by using the proposed procedure within the framework of three-dimensional analyses. The nonlinear behaviour of masonry can be modelled using concepts of damage theory. In this case an adequate damage function is defined for taking into account different response of masonry under tension and compression states. Cracking can, therefore, be interpreted as a local damage effect, defined by the evolution of known material parameters and by one or several functions which control the onset and evolution of damage. The model takes into account all the important aspects which should be considered in the nonlinear analysis of masonry structures such as the effect of stiffness degradation due to mechanical effects and the problem of objectivity of the results with respect to the finite element mesh. Finally the proposed damage model is validated with a comparison with experimental results available in the literature.

This paper presents results of applying Fuzzy Inference System for estimation of the number of potential Park and Ride users. Usually it is difficult to evaluate the number of users because it depends on human factor and data in the considered system are uncertain. In such situation the traditional mathematical approaches can not take into consideration rough data. Therefore a fuzzy approach can be applied in this case. A fuzzy methodology is treated as a proper way to describe choice of mode of transport, and especially that uncertainty accompanied of choosing process has rather fuzzy character. The proposed approach is based on the Mamdani Fuzzy Inference System and for calculation there is used Matlab software with Fuzzy Logic Toolbox. Mamdani model requires, as an input data, knowledge of the shape of membership function. These functions can be calibrated taking into consideration results of questionnaires conducted among users of Park and Ride system. Due to lack of representative sample of users, one has decided to use results of experts' questionnaires as a input data for calibration the shape of membership functions. Describing factor will be generalized cost of the trip for different modes of transport. Proposed approach consists of two main stages: modeling of share of public/private transport trips and Multimodal model estimating number of Park and Ride users. Verification of presented methodology is treated as an indirect proof. Proposed approach can be applied for estimation of bi-modal split. Then the results are compared with traditional approaches based on logit functions. Comparable results of proposed fuzzy approach with traditional logit models can be treated as a confirmation of chosen methodology.

Optimum technological solutions must take into account the entire life cycle of structures including design procedures as well as quality assurance, inspection, maintenance, and repair strategies. Unfortunately, current design standards do not provide a satisfactory basis to ensure expected structural lifetimes. The latter may vary from only a few years for temporary structures to over a century for bridges, water dams or nuclear repositories. Consistent scientific concepts are urgently required to cover this wide spectrum of lifetimes in structural design and maintenance. This was a motivation for a group of scientists at the Ruhr-University Bochum (RUB) to start a special research program supported by the German Research Foundation (DFG) within the Cooperative Research Center SFB 398 since 1996. Institutes of the University Wuppertal and of the University Essen-Duisburg joined the research group. The goal of the Center is to study sources of damage and deterioration in materials and structures, to develop consistent models and simulation methods, to predict structural lifetimes and finally to integrate this predictions into new lifetime-oriented design strategies.
Research activities in our center are organised in three Project Groups as follows:
- Modelling of lifetime effects
- Methods for lifetime-oriented structural analyses
- Future lifespan-oriented design strategies.

The concept is presented of the sensitivity analysis of the limit state of the structure with respect to selected basic variables. The sensitivity is presented in the form of the probability distribution of the limit state of the structure. The analysis is performed by the problem-oriented Monte Carlo simulation procedure. The procedure is based on the problem's definition of the elementary event, as a structural limit state. Thus the sample space consists of limit states of the structure. Defined on the sample space the one-dimensional random multiplier is introduced. This multiplier refers to the dominant basic variable (group of variables) of the problem. Numerical procedure results in the set of random numbers. Normalized relative histogram of this set is an estimator of the PDF of the limit state of the structure. Estimators of reliability, or the probability of failure are statistical characteristics of this histogram. The procedure is illustrated by the example of sensitivity analysis of the serviceability limit state of monumental structure. It is the colonnade of Licheń Basilica, situated in central Poland. Limit state of the structure is examined with reference to the upper deck horizontal deflection. Wind actions are taken as dominant variables. An assumption is made that the wind load intensities acting on the lower and on the upper storey of the colonnade, respectively, are identically distributed, but correlated random variables. Three correlation variants of these variables are considered. Relevant limit state histograms are analysed thereafter. The paper ends with the conclusions referring to the method and some general remarks on the fully probabilistic design.

VARIATION OF ROTATIONAL RESTRAINT IN GRID DECK CONNECTION DUE TO CORROSION DAMAGE AND STRENGTHENING
(2006)

The approach to assessment of rotational restraint of stringer-to-crossbeam connection in a deck of 100-year old steel truss bridge is presented. Sensitivity of rotational restraint coefficient of the connection to corrosion damage and strengthening is analyzed. Two criteria of the assessment of the rotational restraint coefficient are applied: static and kinematic one. The former is based on bending moment distribution in the considered member, the latter one – on the member rotation at the given joint. 2D-element model of finite element method is described: webs and flanges are modeled with shell elements, while rivets in the connection – with system of beam and spring elements. The method of rivet modeling is verified by T-stub connection test results published in literature. FEM analyses proved that recorded extent of corrosion damage does not alter the initial rotational restraint of stringer-to-crossbeam connection. Strengthening of stringer midspan influences midspan bending moment and stringer end rotation in a different way. Usually restoring member load bearing capacity means strengthening its critical regions (where the highest stress levels occur). This alters flexural stiffness distribution over member length and influences rotational restraint at its connection to other members. The impact depends on criterion chosen for rotational restraint coefficient assessment.

Car following models are used to describe the behavior of a number of cars on the road dependent on the distance to the car in front. We introduce a system of ordinary differential equations and perform a theoretical and numerical analysis in order to find solutions that reflect various traffic situations. We present three different variations of the model motivated by reality.

Die Kommunale Wohnungsgesellschaft mbH Erfurt(KoWo) ist mit ihren rund 20.000 Wohnungen in der Landeshauptstadt das größte Wohnungsunternehmen in Thüringen. Der Immobilienbestand ist heterogen in seinem technischen Zustand und im Bezug auf die unterschiedlichen Lagen der Objekte. Bedingt durch Leerstände und unterschiedliche Modernisierungsmaßnahmen und -stände unterscheidet sich die Wirtschaftlichkeit verschiedener Objekte deutlich. Ohne eine einheitliche Einwertung des Immobilienbestandes im Bezug auf die Objektattraktivität, die Standortqualität und die Objektwirtschaftlichkeit fällt eine langfristige strategische Entwicklung des Immobilienportfolios schwer. Über die Schritte der technischen Bestandserfassung, die Einwertung über ein Scorintmodell, die Abbildung in einem Portfoliomodell mit zugehöriger Normstrategie bis hin zur Weiterverarbeitung der Daten in der 20-jährigen Instandsetzungsplanung wird praxisnah aufgezeigt, wie die Vorgehensweise bei der Einwertung des Immobilienportfolios ist.

Im Bereich der Altbausanierung und der Bestandserfassung im Bauwesen ist es häufig notwendig, bestehende Pläne hinsichtlich des Bauwerkszustandes zu aktualisieren oder, wenn diese Pläne nicht (mehr) zugänglich sind, gänzlich neue Planunterlagen des Ist-Zustandes zu erstellen. Ein komfortabler Weg, diese Bauwerksdaten zu erheben, eröffnet die Technologie der Laservermessung. Der vorliegende Artikel stellt in diesem Zusammenhang Ansätze zur Teilautomatisierung der Generierung eines dreidimensionalen Computermodells eines Bauwerkes vor. Als Ergebnis wird ein Volumenmodell bereitgestellt, in dem zunächst die geometrischen und topologischen Informationen über Flächen, Kanten und Punkte im Sinne eines B-rep Modells beschrieben sind. Die Objekte dieses Volumenmodells werden mit Verfahren aus dem Bereich der künstlichen Intelligenz analysiert und in Bauteilklassen systematisch kategorisiert. Die Kenntnis der Bauteilsemantik erlaubt es somit, aus den Daten ein Bauwerks-Produktmodell abzuleiten und dieses einzelnen Fachplanern – etwa zur Erstellung eines Energiepasses – zugänglich zu machen. Der Aufsatz zeigt den erfolgreichen Einsatz virtueller neuronaler Netze im Bereich der Bestandserfassung anhand eines komplexen Beispiels.