The Experts below are selected from a list of 123 Experts worldwide ranked by ideXlab platform

M Holický - One of the best experts on this subject based on the ideXlab platform.

  • Specification of the Target Reliability Level
    2016 Second International Symposium on Stochastic Models in Reliability Engineering Life Science and Operations Management (SMRLO), 2016
    Co-Authors: M Holický
    Abstract:

    The target reliability levels recommended in national and international documents vary within a broad range, while the reference to relevant costs and failure consequences is mentioned only very vaguely. In some documents the target reliability index β is indicated for one or two reference periods (1 year and 50 years) without providing any link to the Design Working Life. This contribution attempts to clarify the relationship between the target reliability levels, construction costs, failure consequences, reference period, the Design Working Life and the discount rate. The theoretical study based on probabilistic optimization is supplemented by recommendations useful for code developers and practicing engineers. It appears that the optimal reliability level depends primarily on the construction costs, failure costs, and relative cost for improving structural safety, and less significantly on the discount rate and the time to failure.

  • Target Reliability Levels in Present Standards
    Transactions of the VŠB: Technical University of Ostrava Civil Engineering Series, 2014
    Co-Authors: M Holický, Jana Marková, Miroslav Sýkora
    Abstract:

    Abstract The target reliability levels recommended in national and international documents vary within a broad range, while the reference to relevant costs and failure consequences is mentioned only very vaguely. In some documents the target reliability index is indicated for one or two reference periods (1 year, 50 years or Life-time) without providing appropriate links to the Design Working Life. This contribution attempts to clarify the relationship between the target reliability levels, costs of safety measures, failure consequences, reference periods and the Design Working Life

  • Optimisation of the target reliability for temporary structures
    Civil Engineering and Environmental Systems, 2013
    Co-Authors: M Holický
    Abstract:

    The target reliability levels recommended in various national and international documents vary within a broad range, while the reference to the failure consequences and Design Working Life is made only very vaguely. In some cases, the target reliability indexes are indicated for one or two reference periods (for 1 year and 50 years); however, no explicit link to the Design Working Life, which is important particularly for temporary structures, is usually provided. This contribution attempts to clarify the relationship between the optimum target reliability of temporary structures, failure consequences, the Design Working Life and the discount rate. The theoretical study based on probabilistic optimisation is supplemented by recommendations useful for code-makers and required by practicing engineers. It appears that the optimum reliability indexes depend primarily on the ratio of the cost of structural failure to the cost per unit of the structural parameter and less significantly on the Design Working lif...

  • the target reliability and Design Working Life
    WIT Transactions on the Built Environment, 2011
    Co-Authors: M Holický
    Abstract:

    Design Working Life and target reliability levels recommended in various national and international documents are inconsistent. Indicative values of Design Working Life are within a range from 10 to 100 years for different types of structures, recommended target reliability indexes are usually given for one or two reference periods (1 year and 50 years), without an explicit link to the Design Working Life. The contribution attempts to clarify the relationship between the Design Working Life and the reliability index and to provide guidance for specification of the target reliability level for given consequences, Designs Working Life and discount rate. The theoretical study based on probabilistic optimization is supplemented by practical recommendations. It appears that the optimum reliability indexes depend primarily on the ratio of cost of structural failure (malfunctioning costs) and the cost per unit of structural parameter, less significantly on the Design Working Life and discount rate.

Quanwang Li - One of the best experts on this subject based on the ideXlab platform.

  • Hong Kong—Zhuhai—Macau sea link project, China
    Marine Concrete Structures, 2020
    Co-Authors: Kefei Li, Quanwang Li
    Abstract:

    The Hong Kong–Zhuhai–Macau (HZM) project links Zhuhai city and Macau city on the China mainland to the city of Hong Kong across the Ling'ding Ocean near the southeastern coast of China. The project consists of 26 km of sea bridges, two offshore artificial islands and an immersed tube tunnel of 6.8 km, with a Design Working Life of 120 years. This chapter introduces first the general layout and structural elements of the project, and then it focuses on the durability Design of the concrete structures for the 120-year Design Life, and the subsequent quality control in construction. On the basis of the collected data, a durability assessment is performed on the concrete elements for the achieved durability level. The strategy of Life-cycle management of concrete structures is elaborated through the inspection/monitoring scheme, the maintenance planning and the real-time durability assessment.

  • Durability for concrete structures in marine environments of HZM project: Design, assessment and beyond
    Cement and Concrete Research, 2020
    Co-Authors: Kefei Li, Dongdong Zhang, Quanwang Li
    Abstract:

    Abstract This paper reviews the fundamentals of the durability of structural concrete, and then applies the concepts to the durability Design, quality control, performance assessment and maintenance planning of concrete structures in Hong Kong-Zhuhai-Macau (HZM) sea link project with Design Working Life of 120 years. The durability Design adopts a multi-level philosophy for different durability risks and uses model-based approach to determine Design parameters. The long-term exposure data of 30 years were used to calibrate the chloride ingress model and quantify the modelling uncertainty. The durability quality control was realized through converting the Design values to laboratory characterization values, especially for the chloride diffusivity. With the data collected in construction phase, a full-probabilistic assessment is performed on the achieved performance against the chloride ingress, serving as basis for maintenance planning. The open issues related to the durability of concrete infrastructures with long service Life are elaborated in the end.

Kefei Li - One of the best experts on this subject based on the ideXlab platform.

  • Hong Kong—Zhuhai—Macau sea link project, China
    Marine Concrete Structures, 2020
    Co-Authors: Kefei Li, Quanwang Li
    Abstract:

    The Hong Kong–Zhuhai–Macau (HZM) project links Zhuhai city and Macau city on the China mainland to the city of Hong Kong across the Ling'ding Ocean near the southeastern coast of China. The project consists of 26 km of sea bridges, two offshore artificial islands and an immersed tube tunnel of 6.8 km, with a Design Working Life of 120 years. This chapter introduces first the general layout and structural elements of the project, and then it focuses on the durability Design of the concrete structures for the 120-year Design Life, and the subsequent quality control in construction. On the basis of the collected data, a durability assessment is performed on the concrete elements for the achieved durability level. The strategy of Life-cycle management of concrete structures is elaborated through the inspection/monitoring scheme, the maintenance planning and the real-time durability assessment.

  • Durability for concrete structures in marine environments of HZM project: Design, assessment and beyond
    Cement and Concrete Research, 2020
    Co-Authors: Kefei Li, Dongdong Zhang, Quanwang Li
    Abstract:

    Abstract This paper reviews the fundamentals of the durability of structural concrete, and then applies the concepts to the durability Design, quality control, performance assessment and maintenance planning of concrete structures in Hong Kong-Zhuhai-Macau (HZM) sea link project with Design Working Life of 120 years. The durability Design adopts a multi-level philosophy for different durability risks and uses model-based approach to determine Design parameters. The long-term exposure data of 30 years were used to calibrate the chloride ingress model and quantify the modelling uncertainty. The durability quality control was realized through converting the Design values to laboratory characterization values, especially for the chloride diffusivity. With the data collected in construction phase, a full-probabilistic assessment is performed on the achieved performance against the chloride ingress, serving as basis for maintenance planning. The open issues related to the durability of concrete infrastructures with long service Life are elaborated in the end.

A.c.w.m. Vrouwenvelder - One of the best experts on this subject based on the ideXlab platform.

  • Target reliability of new and existing structures: A general framework for code making
    2020
    Co-Authors: R.d.j.m. Steenbergen, Á. Rózsás, A.c.w.m. Vrouwenvelder
    Abstract:

    Target reliability levels, Design and remaining Working Lifes and reference periods recommended in various national and international codes and guidelines are sometimes inconsistent. Design Working Lifes for new structures are typically 50 to 100 years for different types of structures. For existing structures the remaining Working Life is often smaller than 50 years. Recommended target reliability indexes are usually given for one or two reference periods (one year and 50 years), without an explicit link to the Design Working Life. In this paper a general framework is given in order to make the reliability index independent of the Design Working Life and to provide guidance for specification of the target reliability level for different situations. The study is based on probabilistic economic optimization. Using this methodology, annual targets - in terms of failure rates - can be set for new structures, and (deteriorating) existing structures, given the marginal cost for reliability, failure consequences and the uncertainty in loading and resistance. © 2018 Delft University of Technology. All rights reserved.

  • Reliability based structural Design
    2013
    Co-Authors: A.c.w.m. Vrouwenvelder
    Abstract:

    According to ISO 2394, structures shall be Designed, constructed and maintained in such a way that they are suited for their use during the Design Working Life in an economic way. To fulfil this requirement one needs insight into the risk and reliability under expected and non-expected actions. A key role in this respect is played by the structural reliability analysis (SRA). In this paper the present state of the art will be summarised, including the simplifications to semi-probabilistic calculations as being used in daily practice. Although in principle the adopted Bayesian reliability approach should be able to take care of all uncertainties involved, present practice still uses other safety concepts like Robustness Design and Quality Assurance as tools for achieving the safety objectives of Design and assessment.

Michael Kasperski - One of the best experts on this subject based on the ideXlab platform.

  • Estimation of the Design Wind Speed
    Advanced Structural Wind Engineering, 2020
    Co-Authors: Michael Kasperski
    Abstract:

    The modern approach to the specification of the Design wind speed favours the explicit format which directly presents the Design value of the wind speed instead of hiding the value behind the product of the characteristic wind speed and a partial factor. This approach leads to better reliability consistency in case of highly variable geographic conditions and it avoids underestimations for systems with unfavourable non-linear characteristics. Some leading codes therefore have adopted this concept. This chapter presents tentative target values of the exceedance probability of the Design wind speed for the ultimate limit state with reference to the Design Working Life considering six importance classes for buildings and structures. Additionally, tentative target values are given for the serviceability limit state with reference to a single year. For the practical application, strategies are discussed in regard to the quality check of data, the sampling of the appropriate ensembles and the estimation of the Design value considering an appropriate confidence interval. Since statistical uncertainties remain large even for several decades of observations, a new approach is presented which leads to consistent values of the Design wind speed. Additionally, the complex topic of directionality is addressed on the example of storms induced by strong frontal depressions.

  • Specification of the Design wind load—A critical review of code concepts
    Journal of Wind Engineering and Industrial Aerodynamics, 2009
    Co-Authors: Michael Kasperski
    Abstract:

    Abstract In a simplified approach, the Design wind load can be specified based on an appropriate small target value of the exceedance probability. For the ultimate limit state, the reasonable reference period is the projected Design Working Life of the structure; for the serviceability limit state a suitable reference period is one year. Basically, at least the extreme wind speeds and the extremes of the aerodynamic coefficients have to be understood as random variables. Further random variables are the duration of a single storm and the relative intensity over the length of the storm. Neglecting these two parameters may lead to underestimations of the Design wind load. The Design values of the wind speeds are specified in codes with mainly two different concepts: either in terms of a product of the characteristic wind speed and a partial factor or directly as Design value. The variable wind speed is represented in codes by gust wind speeds, by 10-min mean wind speeds or by hourly mean wind speeds. For the Design value of the aerodynamic coefficient, mainly two concepts are used in codes: the mean value of the extremes or the 78%-fractile value, the latter known as ‘Cook–Mayne’ coefficient. The paper tries to sort out the differences between these approaches and tries to comment on one or the other shortcoming. Additionally, the complexity of the codification task is discussed when different wind climates have to be covered.