Structural Robustness

В статье рассматривается подход к проектированию систем управления с повышенным потенциалом робастной устойчивости на основе использования четырехпараметрических структурно-устойчивых отображений в качестве управляющих воздействий для систем с одним выходом. Приведено математическое описание систем подобного типа, пример системы управления и результаты моделирования.

a We introduce a new type of hybrid material: nanostructured elastomer covered by a hard photoactive metal-oxide thin film resembling exoskeleton of insects. It has extreme water repellency and fast self-recovery after damage. A new fabrication method for replicating high aspect ratio, hierarchical re-entrant aluminum structures into polydimethylsiloxane (PDMS) is presented. The method is based on a protective titania layer deposited by atomic layer deposition (ALD) on the aluminum template. The ALD titania transfers to elastomeric scaffold via sacrificial release etching. The sacrificial release method allows for high aspect ratio, even 100 µm deep and successful release of overhanging structures, unlike conventional peeling. The ALD titania conformally covers the 3D multihierarchical structures of template and protects the polymer during the release etch. Afterwards it prevents high aspect ratio nanostructures from elasticity based collapse. The resulting nanostructured hybrid PDMS/titania replicas display robust superhydrophobicity without any further fluoro-coating or modification. Mechanical and thermal robustness results from thick nanostructured elastomeric layer which is conformally covered by ceramic titania instead of monolayer hydrophobic coating. We have demonstrated the durability of these replicas against mechanical abrasion, knife scratches, rubbing, bending, peel tape test, high temperature annealing, UV exposure, water jet impingement and long term underwater storage. Though the material loses its superhydrophobicity in oxygen plasma exposure, a fast recovery from superhydrophilic to superhydrophobic can be achieved after in 20 min UV irradiation. UV-assisted recovery is correlated to the high photoactivity of ALD titania film. This novel hybrid material will be applicable to the large area superhydrophobic surfaces in practical outdoor applications.

The race towards new building heights confronts numerous challenges. The main challenge that
controls the design of a tall slender structure is the building drift. Another challenge confronting
the designer is probably the robustness required to avoid progressive collapse due to localized
failures in case of a column loss. The study investigates how to improve the building performance
to overcome these challenges.
One of the most efficient and economical structural systems used to incapacitate these challenges
is the use of belt trusses to provide a significant drift control through the tying of the peripheral
columns enhancing in the process the building resistance to progressive collapse by means of
holding the damaged elements' initial failure and redistributing the load supported by the failed
elements. The optimum locations of the belt trusses still remain a crucial and also a pending
question.
The study provides an answer to this question by demonstrating the results of a 25 storey steel
building as a design example with belt trusses placed in different locations. The results indicate
that both the drift and progressive collapse will be obviously enhanced merely by determining the
optimum locations of belt trusses.

Average case complexity, in order to be a useful and reliable measure, has to be robust. The probability distribution, generally uniform, over which expectation is taken should be realistic over the problem domain. But algorithm books do not certify that the uniform inputs are always realistic. Do the results hold even for non uniform inputs? In this context we observe that Binary Tree sort is more robust than the fast and popular Quick sort in the average case.

Many of modern life activities involve the risk of fire, explosions, and impacts. In addition, natural extreme events are becoming more and more common. us, robustness, the ability to avoid disproportionate collapse due to an initial damage, and resilience, the ability to adapt to and recover from the effects of changing external conditions, represent two important characteristics of current structures and infrastructures. eir definitions are reviewed in this paper with the aim of sorting and describing the different approaches proposed in the literature and in the international standards. A simple example is also analysed in order to compare different methods.

Extreme loads can have devastating effects on civilian structures since these buildings are not designed to have to withstand extreme events. Typical buildings and other critical infrastructure are particularly prone to external man-made attacks. This study focuses on probabilistic analyses, and investigates the probability of failure of a precast concrete wall subjected to blast loads. The wall under investigation is a non-load bearing precast concrete panel used as exterior cladding for buildings. From the blast design point of view, these walls must protect people and equipment from external detonations. The aim of the paper is to compute both the fragility curves of typical precast concrete cladding subjected to blast loads, and the failure probability of the cladding, considering a detonation of a vehicle borne improvised explosive device (VBIED). To this aim non-linear dynamic analyses are carried out by the widely adopted equivalent non-linear SDOF method for the precast concrete panel. The fragility curves and the failure probability of the precast concrete cladding wall are computed using Monte Carlo simulations.

The International Journal of Software Engineering & Applications (IJSEA) is a bi-monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of the Software Engineering & Applications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on understanding Modern software engineering concepts & establishing new collaborations in these areas.

Abstract The main objective of the present paper is to suggest guidelines for the improvement of how robustness is treated in future generations of the Eurocodes, namely concerning the design philosophy and the design requirements. It is now widely recognised that robustness has a governing role in attaining sustainable and resilient infrastructures. Without surprise, robustness was identified by the European Commission as one of the key additions to the existing Eurocodes under the presently ongoing revisions. This should be seen as a stimulus to develop updated (or new), rational, accurate, and practical design methodologies and requirements for robustness, extending and enhancing current coverage of robustness in the Eurocodes. This paper starts by reviewing how robustness is treated in the Eurocodes, pin-pointing the limitations of the existing design framework. Subsequently, a performance-based design framework for robustness is proposed that allows designers to determine if a given structure is sufficiently robust. Different levels of sophistication are proposed to cater for different levels of classes of structures. Therefore, the suggested approach enables the best available knowledge and the latest technologies to be applied in a way that is acceptable for practitioners, promoting competitiveness, cost-effectiveness and sustainability in design and innovation.

The growing need for assuring efficient and sustainable investments in civil engineering structures has determined a renovated interest in the rational design of such structures from designers, clients and authorities. As a result, risk-informed decision-making methodologies are increasingly being used as a direct decision tool or as an upper-level layer from which performance-based approaches are then calibrated against. One of the most important and challenging aspects of today's structural design is to adequately handle the system-level effects, the known unknowns and the unknown unknowns. These aspects revolve around assessing and evaluating relevant damage scenarios, namely those involving unacceptable/intolerable damage levels. Hence, the importance of risk analysis of disproportionate collapse, and along with it of robustness. However, the way robustness has been used in modern design codes varies substantially, from simple provisions of prescriptive rules to complex risk...

The growing need for assuring efficient and sustainable investments in civil engineering structures has determined a renovated interest in the rational design of such structures from designers, clients and authorities. As a result, risk-informed decision-making methodologies are increasingly being used as a direct decision tool or as an upper-level layer from which performance-based approaches are then calibrated against. One of the most important and challenging aspects of today’s structural design is to adequately handle the system-level effects, the known unknowns and the unknown unknowns. These aspects revolve around assessing and evaluating relevant damage scenarios, namely those involving unacceptable/intolerable damage levels. Hence, the importance of risk analysis of disproportionate collapse, and along with it of robustness. However, the way robustness has been used in modern design codes varies substantially, from simple provisions of prescriptive rules to complex risk analysis of the disproportionate collapse. As a result, implementing design for robustness is still very much a grey area and more so when it comes to defining means to quantify robustness. This paper revisits the most common robustness frameworks, highlighting their merits and limitations, and identifies one among them which is very promising as a way forward to solve the still open challenges.

The main objective of the present paper is to suggest guidelines for the improvement of how robustness is treated in future generations of the Eurocodes, namely concerning the design philosophy and the design requirements.
It is now widely recognised that robustness has a governing role in attaining sustainable and resilient infrastructures. Without surprise, robustness was identified by the European Commission as one of the key additions to the existing Eurocodes under the presently ongoing revisions. This should be seen as a stimulus to develop updated (or new), rational, accurate, and practical design methodologies and requirements for robustness, extending and enhancing current coverage of robustness in the Eurocodes.
This paper starts by reviewing how robustness is treated in the Eurocodes, pin-pointing the limitations of the existing design framework. Subsequently, a performance-based design framework for robustness is proposed that allows designers to determine if a given structure is sufficiently robust. Different levels of sophistication are proposed to cater for different levels of classes of structures. Therefore, the suggested approach enables the best available knowledge and the latest technologies to be applied in a way that is acceptable for practitioners, promoting competitiveness, cost-effectiveness and sustainability in design and innovation.

When a continuous concrete slab is excessively loaded or a certain support is lost due to an accidental event, membrane action can be activated in order to generate an alternative load transfer to the remaining supports, which can considerably enhance the load-carrying capacity. This can delay or even prevent a progressive collapse, increase the structural reliability of components and consequently increase the robustness of concrete structures. Currently, only limited research has been focusing on tensile membrane action, and therefore a novel real-scale test set-up has been developed in order to assess these actions in real-scale concrete plates. Considering the experimental findings and validated numerical modelling, the influence of tensile membrane action on the structural reliability of concrete slabs is quantified. Probabilistic models for the most important basic variables are gathered and the structural reliability is assessed using Latin Hypercube sampling. The framework and first results as proposed in this contribution are consequently used as input for quantifying the robustness of structural systems through some common robustness indicators. Further, a global resistance factor is derived based on the results of the Latin Hypercube simulations and the obtained design values are compared.

Structural robustness has become an important design variable. However, based on the existing definitions of structural robustness it is often difficult to analyse and evaluate structural robustness, and sometimes not efficient since they mix structural robustness with several other structural variables. This paper concerns the development of a new structural robustness definition, and structural robustness and structural fragility indices. The basis for the development of the new indices is the analysis of the damage energy of structural systems for a given hazard scenario and involves a criterion to define an " unavoidable collapse " state. Illustrative examples are given detailing the steps and calculations needed to obtain values for both the structural robustness and the structural fragility indices. Finally, this paper presents the main advantages of the newly proposed definition and indices for the structural risk analysis over existing traditional methods.

The present paper focus on the robustness problem for systems described in their state space form. It is shown that equivalent frequency response robustness results are linked to robustness problems in state space models in which individual entries of the characteristic state space matrices are perturbed. It is also shown how the state feedback compensation and the output feedback compensation are related to the sensitivity problem.

Structural robustness has become an important design variable. However, based on the existing definitions of structural robustness it is often difficult to analyse and evaluate structural robustness, and sometimes not efficient since they mix structural robustness with several other structural variables. This paper concerns the development of a new structural robustness definition, and structural robustness and structural fragility indices. The basis for the development of the new indices is the analysis of the damage energy of structural systems for a given hazard scenario and involves a criterion to define an "unavoidable collapse" state. Illustrative examples are given detailing the steps and calculations needed to obtain values for both the structural robustness and the structural fragility indices. Finally, this paper presents the main advantages of the newly proposed definition and indices for the structural risk analysis over existing traditional methods.

Robustness, structural integrity and prevention risk of progressive collapse (PC) are among main design objectives for structures. After the (PC) of many remarkable structures, the need for better designing techniques has motivated engineers to prevent similar incidents. The main objective of this study is to investigate different structural systems to detect more practical and cost effective systems to enhance the (PC) resisting capacity. The study is extended to numerically investigate the effectiveness of these systems by analyzing a ten storey steel office building using alternative pass method discussed by UFC09 code. The study shows that one of the preferred practices to reduce the potentiality for (PC) is the use of belt trusses at the top of the building. The use of belt truss system holds the initial failure of the damaged elements and redistributes the loads supported by the failed elements with the least increase in the structure’s weight.

Robustness, structural integrity and prevention risk of progressive collapse (PC) are among main design objectives for structures. After the (PC) of many remarkable structures, the need for better designing techniques has motivated engineers to prevent similar incidents. The main objective of this study is to investigate different structural systems to detect more practical and cost effective systems to enhance the (PC) resisting capacity. The study is extended to numerically investigate the effectiveness of these systems by analyzing a ten storey steel office building using alternative pass method discussed by UFC09 code. The study shows that one of the preferred practices to reduce the potentiality for (PC) is the use of belt trusses at the top of the building. The use of belt truss system holds the initial failure of the damaged elements and redistributes the loads supported by the failed elements with the least increase in the structure’s weight.

Deterioration of existing structures due to corrosion of reinforcement has been a growing concern in the last decades since the associated reduction of the steel results in a decrease of the structural reliability. Apart from deterioration, also the assessment of structural robustness has been of particular interest. One way to quantify robustness is through a reliability-based robustness index based on the reliability index of the damaged and undamaged system. Determination of these reliability indices requires the selection of probabilistic and physical models and the estimation of the associated parameters. This introduces uncertainties in the probabilistic models, the reliability indices and hence in the robustness index. These uncertainties are usually not considered. In this contribution, an approximate quantification method is derived in order to assess the influence of uncertainties on the robustness index of deteriorated concrete beams. As an example, a reinforced concrete beam subjected to corrosion is analyzed to demonstrate the influence of uncertainties on the robustness index.

The overall level of risk for buildings, bridges and other engineering structures depends on the intensity of the hazards and the susceptibility to damage, which can result in economic losses for the stakeholders (including repair, reconstruction and loss of use) as well as injuries and casualties to the occupants. Non­‐engineering solutions of risk mitigation consist of reducing the hazard (e.g. limiting the access to facilities which can be targeted by terroristic attacks) or the social vulnerability (e.g. developing awareness and preparedness programmes against natural disasters). While such approaches can be effective in may situations, at least to alleviate the impact that natural and man­‐made threats can have on communities and economies, structural engineers always strive to develop new and improved technical solutions to accurately estimate the risk and to achieve better performance for structural and non-­structural components. The aim of this special session is to provide a forum for researchers and practitioners working on risk quantification and risk mitigation in various sub-­fields of structural engineering, including (but not limited to) earthquake engineering, wind engineering, fire engineering and blast engineering. The focus will be on the use of advanced computational models and methods to tackle the above challenges. Contributions addressing both theoretical developments and practical applications of performance-­based design, reliability-based design and risk-­based design are particularly welcome. Papers devoted to non­‐conventional strategies of structural design under dynamic loads, using deterministic or stochastic approaches, would also fit within the scope of the special session.

Die zunehmende Gefahr von Anschlägen und Industrieunfällen haben zu neuen Anforderungen an die Auslegung und Bemessung von Bauwerken geführt. Diesen neuen Anforderungen wird derzeit in Normen jedoch nur unzureichend Rechnung getragen. Insbesondere für Bauwerke in Stahl- und Verbundbauweise führen die gegenwärtig üblichen Auslegungskonzepte nicht zu wirtschaftlichen Bemessungen. Das bauforumstahl hat daher in Zusammenarbeit mit dem Institut für Stahlbau der RWTH Aachen und HOCHTIEF Construction AG einen Bemessungsleitfaden für Anprall- und Explosionslasten erarbeitet, mit dem die Möglichkeiten des Werkstoffes Stahl wesentlich effizienter ausgenutzt werden können. In diesem Beitrag werden die wesentlichen Elemente dieses Leitfadens vorgestellt, der sowohl eine Bewertung von Entwurfsstrategien für robuste Bauwerke enthält, als auch ein Bemessungskonzept zur Auslegung von Stahlbauten gegen spezifische kurzzeit-dynamische Einwirkungen bereitstellt.Design of steel structures against impact and blast loads. The increasing threat of terroristic attacks as well as industrial hazards have led to new demands for the conception and design of buildings. Current standards, however, do not provide sufficient guidance to cope with these new requirements. Particularly for steel and composite structures there is a lack of appropriate and therefore economic design concepts. Hence, bauforumstahl in cooperation with the Institute for Steel Structures at RWTH Aachen University and HOCHTIEF Construction AG has published a new design guide to exploit the capabilities of steel more efficiently. This paper presents the main aspects of this design guide. It includes the assessment of strategies for robust structures and a concept to design steel structures against specific high dynamic loads.

... A. Elena & J. Demongeot TIMC-IMAG, UMR CNRS 5525 Faculty of Medicine of Grenoble University J. Fourier 38 700 La Tronche France E-mail: Adrien.Elena@imag.fr, Jacques. Demongeot@imag.fr Abstract ... Am., Vol. 244, pp. 88-92. [26] Fatès, N. and Morvan, M. (2004 ...

The overall level of risk for buildings, bridges and other engineering structures depends on the intensity of the hazards and the susceptibility to damage, which can result in economic losses for the stakeholders (including repair, reconstruction and loss of use) as well as injuries and casualties to the occupants. Non­‐engineering solutions of risk mitigation consist of reducing the hazard (e.g. limiting the access to facilities which can be targeted by terroristic attacks) or the social vulnerability (e.g. developing awareness and preparedness programmes against natural disasters). While such approaches can be effective in may situations, at least to alleviate the impact that natural and man­‐made threats can have on communities and economies, structural engineers always strive to develop new and improved technical solutions to accurately estimate the risk and to achieve better performance for structural and non-­structural components. The aim of this special session is to provide...

Robustness, structural integrity and prevention risk of progressive collapse (PC) are among main design objectives for structures. After the (PC) of many remarkable structures, the need for better designing techniques has motivated engineers to prevent similar incidents. The main objective of this study is to investigate different structural systems to detect more practical and cost effective systems to enhance the (PC) resisting capacity. The study is extended to numerically investigate the effectiveness of these systems by analyzing a ten storey steel office building using alternative pass method discussed by UFC09 code. The study shows that one of the preferred practices to reduce the potentiality for (PC) is the use of belt trusses at the top of the building. The use of belt truss system holds the initial failure of the damaged elements and redistributes the loads supported by the failed elements with the least increase in the structure's weight.

Accidental events, such as impact loading or explosions, are rare events with a very low probability of occurrence. However, their effects often lead to very high human losses and economic consequences. An adequate design against these events should reduce the risk for the life of the occupancy, minimize the damage extension and enable a quick rebuilding and reuse. A structure fulfilling these requirements is 'robust'. Different strategies can be pursued for accidental events, and among them, methods based on the residual strength or the alternate load path are frequently adopted because applicable to a vast range of structures. Adequate design strategies based on them require an in-deep knowledge of load transfer mechanisms from the damaged to the undamaged part of the structure. As to the frames, the important role of joint ductility was pointed out in recent studies. Besides, the flooring systems substantially affect the spread of the damage, but the research on this subject is still very limited. The present study focuses on steel-concrete composite frames under the column loss scenario. It aims to better understand the influence of both frame continuity and floor systems in the development of 3D membrane action. Two geometrically different 3D steel-concrete composite full-scale substructures were extracted from reference buildings and tested simulating the column collapse scenario. This paper illustrates the preparatory studies , the main features of the specimens and the outcomes of the first test. The test provided an insight in the need for an enhanced design of joints and pointed out the key features of the response of the floor system.

Robustness is a property that pervades all aspects of nature. The ability of a system to adapt to perturbations due to internal and external agents, aging, wear, or to environmental changes is one of the driving forces of evolution. At the molecular level, understanding the ro-bustness of a protein has a great impact on the in-silico design of polypep-tide chains and drugs. The chance of computationally checking the ability of a protein to preserve its structure in the native state may lead to the design of new compounds that can work in a living cell more effectively. Inspired by the well known robustness analysis framework used in Electronic Design Automation, we introduce a formal definition of robustness for proteins and a dimensionless quantity, called yield, to quantify the robustness of a protein. Then, we introduce a new robustness-centered protein design algorithm called Design-For-Yield. The aim of the algorithm is to discover new conformations with a specific functionality and high yield values. We present extensive characterizations of the robust-ness properties of many peptides, proteins, and drugs. Finally, we apply the DFY algorithm on the Crambin protein (1CRN) and on the Oxic-itin drug (DB00107). The obtained results confirm that the algorithm is able to discover a Crambin-like protein that is 23.61% more robust than the wild type. Concerning the Oxicitin drug a new protein sequence and the corresponding protein structure was discovered with an improved robustness of 3% at the global level.

Deterioration of existing structures due to corrosion of reinforcement has been a growing concern in the last decades since the associated reduction of the steel results in a decrease of the structural reliability. Apart from deterioration, also the assessment of structural robustness has been of particular interest. One way to quantify robustness is through a reliability-based robustness index based on the reliability index of the damaged and undamaged system. Determination of these reliability indices requires the selection of probabilistic and physical models and the estimation of the associated parameters. This introduces uncertainties in the probabilistic models, the reliability indices and hence in the robustness index. These uncertainties are usually not considered. In this contribution, an approximate quantification method is derived in order to assess the influence of uncertainties on the robustness index of deteriorated concrete beams. As an example, a reinforced concrete beam subjected to corrosion is analyzed to demonstrate the influence of uncertainties on the robustness index.