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Structural Safety (structural + safety)

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Engineering87%

Selected Abstracts

Seismic collapse risk of precast industrial buildings with strong connections

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 8 2010
Miha Kramar
Abstract A systematic seismic risk study has been performed on some typical precast industrial buildings that consists of assemblages of cantilever columns with high shear-span ratios connected to an essentially rigid roof system with strong pinned connections. These buildings were designed according to the requirements of Eurocode 8. The numerical models and procedures were modified in order to address the particular characteristics of the analyzed system. They were also verified by pseudo-dynamic and cyclic tests of full-scale large buildings. The intensity measure (IM)-based solution strategy described in the PEER methodology was used to estimate the seismic collapse risk in terms of peak ground acceleration capacity and the probability of exceeding the global collapse limit state. The effect of the uncertainty in the model parameters on the dispersion of collapse capacity was investigated in depth. Reasonable seismic safety (as proposed by the Joint Committee on Structural Safety) was demonstrated for all the regular single-storey precast industrial buildings addressed in this study. However, if the flexural strength required by EC8 was exactly matched, and the additional strength, which results from minimum longitudinal reinforcement, was disregarded as well as large dispersion in records was considered, the seismic risk might in some cases exceed the acceptable limits. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Structural seismic response analysis based on multiscale approach of computing fault,structure system

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 4 2009
T. Ichimura
Abstract Structural safety for earthquake waves emitted from a nearby fault is a major concern. For a large complex structure, it might be desired to estimate its seismic response by analyzing a fault,structure system: a full three-dimensional model in which a source fault and a target structure are modeled so that fault processes, wave propagation and amplification processes, and resulting dynamic responses of the structure can be computed numerically. To analyze this fault,structure system, this paper proposes an efficient approach based on multiscale analysis, i.e. waves emitted from the source fault are computed in the entire system in the geological length-scale; then they are refined in a small part of the system that includes the structure, and the seismic response of the structure is accurately computed in the engineering length-scale. Using a long highway tunnel as an example, this paper examines the validity of the proposed approach. The usefulness and applicability of the proposed approach to estimate the structural seismic responses are discussed. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Structural safety: a fascinating subject

BETON- UND STAHLBETONBAU, Issue S1 2008
Luc Taerwe
No abstract is available for this article. [source]

Response of SDOF system to non-stationary earthquake excitation

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 15 2004
R. S. Jangid
Abstract Earthquake excitation is often modelled by non-stationary random process (i.e. uniformly modulated broad-band excitation) for analysis of structural safety subjected to seismic hazards. In this paper, the non-stationary response of a single-degree-of-freedom (SDOF) system to non-stationary earthquake motion is investigated for different shapes of modulating functions. The evolutionary power-spectral density function (PSDF) of the displacement of the SDOF system is obtained using the time-varying frequency response function and the PSDF of the earthquake excitation. The close form expressions for time-varying frequency response function are derived for different shapes of the modulating functions. In order to study the effects of the shape of the modulating function, a comparison of the non-stationary earthquake response of the SDOF system is also made for different modulating functions having the same energy content. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Effects of non-proportional loading paths on the orientation of fatigue crack path

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 5 2005
L. REIS
ABSTRACT Fatigue crack path prediction and crack arrest are very important for structural safety. In real engineering structures, there are many factors influencing the fatigue crack paths, such as the material type (microstructure), structural geometry and loading path, etc. In this paper, both experimental and numerical methods are applied to study the effects of loading path on crack orientations. Experiments were conducted on a biaxial testing machine, using specimens made of two steels: 42CrMo4 and CK45 (equivalent to AISI 1045), with six different biaxial loading paths. Fractographical analyses of the plane of the stage I crack propagation were carried out and the crack orientations were measured using optical microscopy. The multiaxial fatigue models, such as the critical plane models and also the energy-based critical plane models, were applied for predicting the orientation of the critical plane. Comparisons of the predicted orientation of the damage plane with the experimental observations show that the shear-based multiaxial fatigue models provide good predictions for stage I crack growth for the ductile materials studied in this paper. [source]

Zur Berechnung der klimatisch bedingten Temperaturbeanspruchungen von Außenwandbekleidungen

BAUPHYSIK, Issue 2 2008
Nabil A. Fouad Univ.-Prof.
Außenwandkonstruktionen werden durch die ständig veränderlichen klimatischen Randbedingungen maßgeblich thermischbeansprucht. Durch diese instationären nichtlinearen Temperaturbeanspruchungen können Schäden bis hin zu Standsicherheitsproblemen entstehen. In diesem Beitrag wird anhand eines Beispiels einer Außenwandkonstruktion beschrieben, welche physikalischen Grundlagen und Annahmen für eine instationäre Temperaturfeldberechnung anzusetzen sind und wie eine praxisnahe Berechnung durchgeführt werden kann. Calculation of climatic induced temperature loading of external wall claddings. Exterior wall panels are being mainly thermally loaded due to the changing climatic boundary conditions. This nonlinear transient temperature loading could cause damages for example of the wall cladding and in severe cases even lead to problems conside ring the structural safety of the whole construction. In this paper all the physical basics and assumptions which have to be done for the calculation of the transient temperature fields are introduced and an example of a practical calculation on an exterior wall cladding is shown and discussed. [source]

Sonderlösungen bei der Tragwerksplanung auf der Grundlage der neuen Normen , Klimatische Einwirkungen

BAUTECHNIK, Issue 3 2005
Hans-Jürgen Niemann Prof. em.
Der folgende Beitrag befaßt sich mit den klimatischen Einwirkungen auf weit gespannte Dächer. Im Zentrum stehen die Windlasten. Die Angaben der Norm lassen sich durch Sonderuntersuchungen zuschärfen, soweit die Regelungen das nahe legen und der zusätzliche Aufwand gerechtfertigt ist. Das gilt sowohl für das Windklima am Bauwerksstandort als auch für die aerodynamischen Beiwerte, für die im allgemeinen Windkanalversuche die Grundlage bilden. In einer neuen Norm, der DIN 1055 Teil 100: "Grundlagen der Tragwerksplanung, Sicherheitskonzept und Bemessungsregeln", werden erstmalig die Anforderungen an die Tragsicherheit und Gebrauchstauglichkeit einer Konstruktion formuliert und festgelegt. Sie definiert die Lastannahmen als Teil des Sicherheitskonzepts, legt die Anforderungen an das Lastniveau fest und bestimmt so die Spielräume für eine Zuschärfung der Lastannahmen durch Sonderuntersuchungen für ein bestimmtes Bauprojekt. Hinzu kommen einzelne Öffnungsklauseln, die in den Normen für Wind- und Schneelasten vorgesehen sind. Der Beitrag stellt die Rahmenbedingungen für eine Optimierung der Lastannahmen dar. Special solutions in structural design on the basis of the new design codes , climatic actions. The following contribution deals with climatic actions on large lightweight roofs of stadia. The focus is on the wind loads. In some cases, it becomes necessary or advantageous to provide more precise design wind loads compared to the code provisions. This applies to the local wind climate as well as to the aerodynamic coefficients. The framework for such investigations is established by the requirements set by the code DIN 1055-100: Basis of design, with regard to structural safety and reliability, and by those basic stipulations in the wind loading code which may not be altered. The author presents and discusses the framework for optimised design wind loads. [source]

Verstärken von Stahlbetonstützen mit textilbewehrtem Beton

BETON- UND STAHLBETONBAU, Issue 10 2009
Regine Ortlepp Dr.-Ing.
Versuche; Bewehrung Abstract Der Aufsatz beschreibt die Ergebnisse experimenteller Untersuchungen zur Wirkung einer Textilbetonverstärkung an 2 m langen Stützen mit und ohne innen liegender Stahlbewehrung. Die Verstärkung mit textilbewehrtem Beton wurde auf zwei verschiedene Weisen ausgeführt, sowohl als vollständige Umwicklung über die gesamte Länge der Stützen als auch als teilweise Verstärkung über eine Länge von 30 cm in den Lasteinleitungsbereichen. Die einzelnen Anteile am Tragverhalten der verstärkten Stützen wurden untersucht. Ein einfaches Berechnungsmodell wird angegeben. Strengthening of Columns using Textile Reinforced Concrete (TRC) In the context of rehabilitation and repair works or in the course of usage changes of existing buildings the planning engineer frequently is confronted with the task of strengthening the loadbearing structure. This can become necessary, for example, if live loads are increased because of changes of use or if the structural safety of a building must be restored after a fire or earthquake. Particularly columns represent important components and elements of the static system for many buildings, whose main task is bearing normal forces. The results of experimental tests on the effect of a strengthening from textile reinforced concrete at 2 m long columns, both with and without internal steel reinforcement, are described in this article. The strengthening with textile reinforced concrete was made both wrapping round completely along the full height of the columns and partly wrapping round the columns along 300 mm in the load introduction ranges. Related to the unstrengthened reference columns ultimate load increasings by up to 85% could thereby be achieved. The individual components of the load bearing properties are analysed. A simple calculation model is indicated. [source]