Application of FMEA method for assessment of reliability of structures

In the last years several methods have been proposed, aimed to explore the theme of degradation and reliability of building components, with the main purpose of preventing performance deficits in general, and especially from sudden and unforeseen faults. This topic is an element of strong competitiveness in the world of professionals and business, and fits with the trend clearly demonstrated by the regulatory framework, particularly in the field of structures. One of the methods that can be used to assess the suitability of a component to its performance specifications, and which belongs to the field of Risk Management, is FMEA, (Failure Modes and Effects Analysis). This methodology analyzes a project from the point of view of its reliability before it is carried out and realized.To allow this verification the components are firstly verified in the form of drawings, technical specifications, flow-charts, information, standards, etc. that are all the elements that make up the documentation of the work to be performed and the knowledge that is available on the subject. There have been many applications of FMEA on building components, and it is of particular interest - considering the recrudescence of seismic events of the last decade, but also the emergence of structural defects, even of a certain gravity – for the use in the field of structures. This is of a considerable relevance in a period when there are issues about the possibility of adaptation of the real estate to earthquakes, but it also raises the argument of the modalities and the criteria leading the inevitable reconstruction of what no longer exists. In this article an example of application to a reinforced concrete structure is shown, from which it is possible to notice the most critical items and the modalities for preventing negative events

Paper Session II-C - Reliability of Structures for the Moon

The subject of risk and reliability for lunar structures is introduced and critical issues are introduced. Our purpose is to suggest an approach to the complicated lunar structure reliability question, the difficulty being that the estimation of reliability of unique structural types on a planetary body on which no construction has occurred has little precedence

The Model for Assessment the Reliability of Structures in Virtualized Data Centers

In this paper has been proposed model of communication system with dynamic network topology in which the process of changing the topology graph over time is to create or break connections between components within a single physical server or between pairs of components that are located on different machines. An essential criterion is the availability of system performance connectivity graph at the time of transition from one state to another topological and fixed number of nodes. Analysis showed that virtual topological structure of such a cloud network will depend on the probability of failure in the middle of the road segment. The probability of blocking close to zero when the number of available channels is 20-30% of the total subscribers

Probabilistic Analysis of Tunnel Liners

The use of probabilistic methods to analyse reliability of structures is being applied to a variety of engineering problems due to the possibility of establishing the failure probability on rational grounds. In this paper we present the application of classical reliability theory to analyse the safety of underground tunnels

A formula of evaluating structural safety based on fuzzy set theory

This article presents an approach to assess safety levels of structures. A new formula for determining the fuzzy reliability of structures is proposed for the case where the set of loading effect and set of structural durability are general fuzzy sets. Illustration example concerning the bending strength evaluation of a simple-beam structure, is presented with the choice of triangular fuzzy sets for loading effect and structural durability

Seismic reliability of structures equipped with LIR-DCFP bearings in terms of superstructure ductility and isolator displacement

This research deals with the seismic reliability of non-linear base-isolated structures equipped with Lateral Impact Resilient Double Concave Friction Pendulum (LIR-DCFP) devices. Specifically, exceeding probabilities within the reference lifetime are assessed with respect to both superstructure ductility and isolator displacement demand. The innovative LIR-DCFP bearing has an improved inner slider with an internal gap and is capable to reduce adverse effects of the lateral impact between the inner slider and the restraining rims. The dynamic behavior of the superstructure is represented by a simplified one-degree-of-freedom model describing its lateral response. The isolation system is characterized by a model based on rigid body dynamics also including the lateral impact behavior. A wide parametric analysis is developed for several system properties considering the friction coefficients as relevant random variables. Different sets of natural seismic records able to match conditional spectra for a site in Riverside (California) were selected to consider the aleatory uncertainties of the seismic input. Incremental dynamic analyses were performed to determine the statistics of significant engineering demand parameters and compute probabilities exceeding specific limit states to define fragility curves. Finally, employing seismic hazard curves, the seismic reliability of isolated structures was evaluated. For increasing values of the internal gap, structures equipped with LIR-DCFP devices exhibit better seismic performance with respect to classical DCFP bearings with same size, especially, if the superstructure is designed to behave essentially elastic when the lateral capacity of the isolation level is not reached, or the hardening post-yield stiffness of the superstructure is relatively high. Reductions up to 20% in the exceeding probabilities within 50 years related to the ductility demand are achievable using the suggested LIR-DCFP isolator

The world OA iniciative for scientific communication in civil engineering and institutional repository as its answer – the case study of Slovenia. Poster presentation at 79th IFLA Congress.

Scientific communication in technics consists primarily of articles in peer-reviewed scholarly journals. In our research of 2026 articles, published in JCR journals in the field of civil engineering in 2007, we found out that 21% of them are published as open accessed articles, most of them as articles archived in institutional repositories. They reached 29% of all citations in the analysed period. In accordance with these findings, in 2011 the repository at the University of Ljubljana, Faculty of Civil and Geodetic Engineering was built in open source tool ePrints. 1400 theses as well as 200 research articles have been archived in it till January 2013. The library was one of the most important stakeholders in its building as it is still today. Each of the repository unit is linked into Slovenian bibliographical information system COBISS and its cataloguing part COBIB as well as the part of high valuated research works of Slovenian researchers SICRIS. The statistics (150.000 visits from all over the world in one year) is a motivation for us to develop it further. In the near future the connection to the Slovenian Digital Library (dLib.si) shall be established, which will ensure the preservation of metadata

Probabilistic strength retention factors for steel and concrete and effect on structural reliability of columns in fire

Evaluating reliability of structures requires consideration of the uncertainties in demand and capacity. While material strengths exhibit a significant scatter at high temperature, no probabilistic model is available to quantify these uncertainties. To fill this gap, this work has compiled a database of test data on strength retention factors for steel and concrete, formulated a set of temperature-dependent probabilistic models based on these data, and applied the models in FE analyses of columns in fire. The proposed material models yield an average response similar to well-established deterministic models (Eurocode), but allow an explicit evaluation of the variability in structural fire response due to experimentally observed variability in material strength

Efficient adaptive importance sampling for time-dependent reliability analysis of structures

Various methods have been used by researchers to evaluate the time-dependent reliability of structures. Among them, the stochastic-process-based method is theoretically the most rigorous but also computationally the most expensive. To enable the wide application of the stochastic-process-based method in the time-dependent reliability analysis of complex problems, an efficient importance sampling method is presented. This new method, extended from an existing method for time-independent reliability analysis, offers an efficient solution for time-dependent problems of structural systems with multiple important regions. Furthermore, to enhance the efficiency and robustness of the proposed method, a number of numerical measures are proposed. The capability and efficiency of the proposed method are demonstrated through two numerical examples

ENVIRONMENTAL LOAD FACTORS AND SYSTEM STRENGTH EVALUATION OF JACKET PLATFORMS IN OFFSHORE MALAYSIA

API (WSD) and ISO 19902 (LRFD) codes are being used nowadays for design of Jacket platforms all over the world. ISO LRFD code is a probabilistic code which takes into account the uncertainties of material and loads and thus enables an economical design. This advantage is not available for API WSD code. The sustainable development of physical structures depend not only on reliability of structures but also on cost saving. Thus it is high time for Malaysia to adopt ISO code with local environmental load factors. ISO load factors are based on calibration of the Gulf of Mexico and North Sea environment. In this study, three offshore regions of Malaysia have been taken separately