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Ostermann A.,University of Innsbruck | Spielberger G.,University of Innsbruck | Tributsch A.,GuD CONSULT GmbH
Mathematical and Computer Modelling of Dynamical Systems | Year: 2016

In this paper, we discuss the application of autoregressive moving average (ARMA) processes in structural health monitoring. For this aim, we consider a linear system of differential equations driven by white noise, which could be seen as a continuous time model of an engineering structure under ambient excitation. A single component of the solution of such a system reflects the position or velocity of a fixed point of the observed structure. We first show that every such component behaves like an ARMA process. These considerations are illustrated by an example, where we show how the natural frequencies can be calculated from the process coefficients. However, the main focus of the paper lies in the detection of structural changes with ARMA processes. For this purpose, we propose a new distance measure that relies on the one-step prediction errors and some sampling strategies. Two case studies are included, which serve to demonstrate the performance of the proposed method. The first one is an off-duty steel truss railway bridge, followed by an in-depth study of an aluminium shear frame construction. In the latter case scenario, we show that the distance measure increases with increasing damage extent. © 2016 Informa UK Limited, trading as Taylor & Francis Group

Agency: European Commission | Branch: H2020 | Program: MSCA-ITN-ETN | Phase: MSCA-ITN-2015-ETN | Award Amount: 3.16M | Year: 2016

INFRASTAR aims to develop knowledge, expertise and skill for optimal and reliable management of structures. The generic methodology will be applied to bridges and wind turbines in relation to fatigue offering the opportunity to deal with complementary notions (such as old and new asset management, unique and similar structures, wind and traffic actions) while addressing 3 major challenges: 1/advanced modelling of concrete fatigue behaviour, 2/new non destructive testing methods for early aged damage detection and 3/probabilistic approach of structure reliability under fatigue. Benefit of cross-experience and inter-disciplinary synergies will create new knowledge. INFRASTAR proposes innovative solutions for civil infrastructure asset management so that young scientists will acquire a high employment profile in close dialogue between industry and academic partners. Modern engineering methods, including probabilistic approaches, risk and reliability assessment tools, will take into account the effective structural behaviour of existing bridges and wind turbines by exploiting monitored data. Existing methods and current state-of -the art is based on excessive conservatism which produces high costs and hinders sustainability. INFRASTAR will improve knowledge for optimising the design of new structures, for more realistic verification of structural safety and more accurate prediction of future lifetime of the existing structures. That is a challenge for a sustainable development because it reduces building material and energy consumption as well as CO2 production. Within the global framework of optimal infrastructure asset management, INFRASTAR will result in a multi-disciplinary body of knowledge covering generic problems from the design stage process of the new civil infrastructures up to recycling after dismantlement. This approach and the proposed methods and tools are new and will allow a step forward for innovative and effective process.

Henke S.,GuD CONSULT GmbH | Bienen B.,University of Western Australia
International Journal of Physical Modelling in Geotechnics | Year: 2013

Soil plugging in open-ended piles not only leads to an increase in compressive bearing capacity but also influences pile driving resistance. Numerous factors affect the tendency for soil plugging, for example pile geometry, penetration depth and installation method. In this study, the influence of the cross-sectional geometry of different open-ended piles (tubular, U- and sheet-piles) on the internal and external stress state at the pile toe is investigated. The underlying data were obtained from tests of pile installation (pile jacking) into dry silica sand conducted using a geotechnical beam centrifuge. During pile penetration the internal and external horizontal stresses at the pile toe were recorded to obtain the stress state inside the open-ended piles. The results are discussed with respect to the influence of the pile's geometrical properties (diameter of tubular piles, base width of U-piles and opening angle of sheet-piles) on the plugging tendency or the pile driving resistance. To conclude, a simple analytical approach based on equilibrium analyses is presented to predict the pile's bearing capacity.

Kirsch F.,GuD CONSULT GmbH | Klingmuller O.,GSP mbH
Geotechnical Special Publication | Year: 2012

While it is common practice to monitor pile installation for offshore platforms in the hydrocarbon industry, the installation of foundation structures for offshore wind turbines is a new challenge. Wind Turbines to be installed in the German sector of the North Sea are mostly built on pile foundations. Both monopile as well as multiple pile - mainly three pile (tripile) - solutions are designed. As these piles have to resist high lateral loading, they must be embedded in strong competent soil layers. Open-end steel piles of large diameters are generally used and installed by impact driving. In general, hard driving conditions exist. It will be shown that the monitoring of the driving process by the Pile Driving Analyzer is not only important for the assessment of hammer performance and stresses in the pile or axial soil resistance, but also for lateral resistance. The assessment of the cyclic stability of the foundation requires an accurate prediction of the static capacity, which can be realised by dynamic pile tests. A proposal is given for the derivation of approximate p-y-curves for lateral loading directly from the solutions of CAPWAP model parameters. © 2012 American Society of Civil Engineers.

The following paper introduces a newly developed design procedure to calculate the bearing capacity of cyclic axial loaded piles for both the ultimate limit state GZ 1B and the serviceability limit state GZ 2. The procedure incorporates the degradation of shaft friction due to compaction of the surrounding soil under cyclic shear as well as the resulting axial pile deformation due to cyclic compaction and accumulation of cyclic shear strain. Copyright © 2011 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.

In recent decades diaphragm wall technology has proven to be the best way to carry out deep watertight pits in urban areas. The observation of execution failures of recent years has lead to the realization that the joint represents the weakest point of a diaphragm wall. On the basis of execution failures possible damage and causes of damage are shown. An overview of common joint techniques results in a differentiated consideration of the possibilities of each joint system with its advantages and disadvantages. Codes and standards give no clear guidelines for choosing the right joint system and quality assurance during installation although quality assurance systems exist for the joints which will be presented individually and will then be compared. In the future, the firm, straight, and clean joint must be implemented before concreting the secondary element to minimize the risk of diaphragm wall pits. In future, not only the detection of possible defects during construction should be taken into consideration but a joint type should be developed, which eliminates causes of damage such as circulation concrete from the very beginning. Copyright © 2015 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.

Vrettos C.,University of Kaiserslautern | Borchert K.-M.,GuD CONSULT GmbH
Soils and Foundations | Year: 2011

The building complex of the Beisheim Center at the Potsdamer Platz in Berlin has recently been completed. Different building parts had to be founded partially on the existing tunnel structures and partially on a system of piled-raft and raft foundations. The combined foundation was designed so as to minimize sectional forces due to the different foundation stiffnesses that were the unknowns in the analysis. Based on pile load tests the nonlinear stiffness of piles has been determined. For the design, both foundation components have been first decoupled and analysed separately. Subsequently, the interaction effects have been estimated by a simplified procedure. The pile configuration has been optimized by considering its effects on the superstructure. The performance of the combined foundations has been checked by comparing computed deformations with actual measurements at relevant points. Parallel to this, the system has been analysed by a 3D finite element model. The concept and the key design items of the combined foundation are presented, and a comparison is made between the estimated deformations and the measurements. The methodology for the analysis of building response to train induced vibrations is outlined.

Various calculation methods were applied on the piled raft foundation of the high rise building "Skyper". The results are compared and discussed. Numerical methods as well as simplified methods based on the elas - tic half space theory lead in the actual case to reasonable results. With the derived subgrade reaction modulus and pile stiffness the raft reinforcement was computed. A recommendation for the application of numerical and simplified methods is given. © Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG.

GuD CONSULT GmbH | Date: 2012-07-06

A device and a method for surveying jet grouting piles in a subsoil, which is suitable for a drilling and grouting linkage assembly for creating a hole and a jet grouting pile in a region of the hole. A measurement device is integrated in the drilling and grouting linkage assembly and comprises a scanning element that is movable from a retracted position to an extended position. The scanning element is deflected inside the measurement device through a retraction and extension housing mounted on the measurement device. The scanning element comprises at least in segments a shape-memory alloy.

GuD CONSULT GmbH | Date: 2012-08-09

The present invention concerns a device for proving the quality of a jet grouting body. Such a jet grouting body is produced by means of a drilling and grouting linkage assembly. An extraction device according to the invention for extracting a suspension from such a jet grouting body comprises: a first segment with a cavity comprising a fluid, in particular a liquid, in which a first chamber is provided, the volume of which can be modified and which is connected with an opening for extracting a specimen, and a further segment which is intended to receive the fluid from the cavity. By receiving the fluid in the further segment, the volume of the first chamber can be enlarged; furthermore the extraction device can be integrated in a drilling and grouting linkage assembly.

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