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For practical decisions on common recurring maintenance actions, the information from routine inspections form a decision basis for the bridge manager. It is often difficult to assess whether this ...

Glass structures have been increasingly utilised in modern construction for decades with load-bearing walls or facades as the most common elements. However, the use of glass beams has recently been given more attention but its application as load-bearing elements has been limited by the low tensile resistance, its brittle behaviour during failure and concerns of its performance in case of fire. Parts of these aspects can be covered by using Timber-Glass composites beams, with timber flanges and a glass web. Previous research and practical application show high potential for this type of composites in ambient temperatures but its performance in fire has not yet been assessed and thus not completely understood. This study describes what to our knowledge is the first full scale fire resistance tests of Timber-Glass composites beams. These tests results are also analysed using finite-element simulations in order to understand the mechanisms of failure during the tests. It was shown that adding a timber flange to a glass web can have severe complications for the fire resistance, however, there are many possible ways to circumvent these issues.

Climate change may have multifaceted impacts on the safety and performance of infrastructure. Accounting for the different ways in which potential climate change scenarios can affect our infrastructure is paramount in determining appropriate adaptation and risk management strategies. Despite gaining some attention among researchers in recent years, this research area is still largely uninvestigated. Several studies have indicated bridges to be especially susceptible to the effects of climate change. This article presents the potential impacts of climate change on bridges and combines the findings of close to 70 research articles to construct a broad list of their possible adaptation techniques. Although this study focuses on bridges, many of the presented climate change impacts and their adaptations are of relevance also to other types of infrastructure. Funding details: Energimyndigheten; Funding details: Trafikverket; Funding details: Vetenskapsrådet, VR; Funding text 1: The authors gratefully acknowledge the financial support provided by the Swedish Transport Administration (Trafikverket) and the strategic innovation program InfraSweden2030, a joint effort of Sweden's Innovation Agency (Vinnova), the Swedish Research Council (Formas) and the Swedish Energy Agency (Energimyndigheten). The first author would also like to thank Oskar Ranefjärd for providing assistance in translating Liljegren ( 2016 ). Any opinions, findings, or conclusions stated herein are those of the authors and do not necessarily reflect the opinions of the financiers.

Dowel-type connections in timber structures should be typically designed in a way that, if the load bearing capacity is exceeded, desirable ductile failure should likely occur, i.e. yielding of the metal dowel or embedment of the timber. However, the probability of brittle failures cannot be completely avoided in many cases. If the connection is loaded parallel to the grain direction, splitting, row-shear, plug/block shear and tensile failure are examples of such brittle failure modes. To ensure a beneficial structural performance locally and sufficient structural robustness globally, the probability of such brittle failures should be kept at a sufficiently low level. However, in the current version of EN1995, the probability of such failure is not considered explicitly. The final aim of the presented research study is to develop a rational approach for the consideration of brittle failure in timber connections with dowel-type fasteners and steel plates loaded parallel to the grain, consistently with the partial factor method. As a first step, a probabilistic model has been used to study the susceptibility to brittle failure and provide a rational basis for the calibration of a “brittle overstrength factor”. The results of this study are reported in the current contribution.

When assessing the resilience of road transport networks, users’ response should be considered as they represent the main capability of the system to adapt to changes when any disruptive event occurs and to recover afterwards. Given the variability in users’ response, it seems deterministic approaches might not be adequate to represent the real system performance, thus, a stochastic perspective is required. This paper presents a new approach to assess the resilience of a traffic network when suffering from a disruptive event, considering the stochastic behaviour of the users, where their decisions will be biased by their perception of the traffic conditions rather than by the actual conditions. This approach provides more realistic patterns than the deterministic approach, mainly in terms of recovery times. The real traffic network Luxembourg-Metz has been used to illustrate the approach.

An overabundance of evidence, both observational and from model projections, indicate that changes to the climate system are taking place at unprecedented rates. Although the magnitudes of these ch...

Risk assessment in communities or regions typically relies on the determination of hazard scenarios and an evaluation of their impact on local systems and structures. One of the challenges of risk assessment for infrastructure operators is how to identify the most critical scenarios that are likely to represent unacceptable risks to such assets in a given time frame. This study develops a novel approach for prioritizing hazards for the risk assessment of infrastructure. Central to the proposed methodology is an expert elicitation technique termed paired comparison which is based on a formal mathematical technique for quantifying the range and variance in the judgements of a group of stakeholders. The methodology is applied here to identify and rank natural and operational hazard scenarios that could cause serious disruption or have disastrous effects to the infrastructure in the transnational Øresund region over a period of five years. The application highlighted substantial divergences of views among the stakeholders on identifying a single ‘most critical’ natural or operational hazard scenario. Despite these differences, it was possible to flag up certain cases as critical among the natural hazard scenarios, and others among the operational hazards.

Creep of concrete structures is in most cases regarded as a serviceability problem that may have impacts on maintenance and repair costs but cannot lead to structural collapse. However, several structural collapses during the past decades have been, at least partly, attributed to excessive creep deformations. Recent studies suggest that concrete creep may be further exacerbated by climate change. The current study demonstrates how this effect can be quantitatively assessed. For this purpose, six different creep models (i.e, Model Code 1999, Model Code 2010, MPF, B3, B4, and B4s models) are used under considerations of historical and future climatic conditions in southernmost Sweden as given by a regional climate model. Furthermore, two different simulations were performed as follows: 1) considering only climate uncertainty represented by the climate model, and 2) considering climate uncertainty, parameter uncertainty, and creep model uncertainty. The highest impact of climate change on end of century creep coefficient is observed using model B4 where the 75th percentile of the increase in creep coefficient is found to range from 8% to ∼14% depending on the climate scenario. The results of the assessment in this article show that the uncertainty related to climate change on creep of concrete structures (higher effect in RCP8.5 than in RCP2.6 and RCP4.5 which have very similar results) is much smaller than uncertainties resulting from creep modelling.

The construction and usage of transport infrastructure are major causes of greenhouse gas emissions and energy consumption. The effects of resource consumption and pollutant emissions are often quantified through Life Cycle Assessment (LCA) models. All decisions made in infrastructure projects during the whole life cycle are afflicted by uncertainty, e.g. physical properties of materials or amount of pollutants emitted by certain processes. The pervasive role of uncertainty is reflected in LCA models, which therefore should consider uncertainty from various sources and provide a sound quantification of their effects. The aim of the work presented in this paper is to give an overview of different sources of uncertainty in LCA of infrastructure projects and to describe systematic methods to evaluate their influence on the results. The possibility of including uncertainty in a LCA-tool for infrastructure is presented, studying the sensitivity of the model output to the input parameters and two alternative approaches for propagation of uncertainty using two case studies. It is shown that, besides the influence of uncertainty in emission factors, other inputs such as material amounts and service life could contribute significantly to the variability of model output and has to be considered if reliable results are sought. (Less)

Many reinforced concrete bridges in Europe and around the world are damaged by reinforcement corrosion and the annual maintenance costs are enormous. It is therefore important to develop reliable methods to assess the structural capacity of corroded reinforced concrete structures and avoid unnecessary maintenance costs. Although there are advanced models for determining the load carrying capacity of structures, it is not obvious how they should be used to verify the performance of existing structures. To confidently assess the bond of corroded reinforcement in concrete, for example, the calculation model must give a sufficient safety margin. When designing new structures, semi-probabilistic approaches (such as the partial safety factor method) are adopted to achieve the target reliabilities specified in structural design codes. This paper uses probabilistic methods to develop partial factors for application in an existing bond model, to assess the safety of corroded reinforced concrete structures. The response of the bond model was studied using Monte Carlo (MC) simulations for several design cases, with probability distributions fitted to the results. Partial factors were then derived, based on these distributions. Furthermore, an MC-based simulation technique called “importance sampling” was used to study the reliability of several deterministic bond assessments conducted using these partial factors. The results show that deterministic assessments which use the proposed partial factors lead to a safety level at least equal to the target value. The results presented in this paper will support the assessment of reinforced concrete structures with anchorage problems and give a reasonable approximation of the anchorage capacity with sufficient safety margin. When generalised to cover other failure modes and structural configurations, this will enable better utilisation of damaged structures and lead to major environmental and economical savings for society.

The use of glass as a structural material has increased in the built environment over the last decades. Despite the large number of research projects and studies, it still poses difficulties in structural design. This particularly applies to the behaviour of glass in fire and under elevated temperatures since the available data on temperature dependent mechanical and thermal properties of glass is still limited. This contribution provides a brief overview of material properties of glass at elevated temperature and elaborates on current requirements for the fire safety included in standards.

Many bridges are approaching or have already passed their expected service life. For steel bridges, fatigue is often the decisive degradation phenomenon that theoretically puts restrictions on a co ...

International audience; Glass has been overwhelmingly used for windows and facades in modern constructions, for many practical reasons, including thermal, energy, light and aesthetics. Nevertheless, due to the relatively low tensile strength and mostly brittle behaviour of glass, compared to other traditional materials, as well as to a multitude of interacting structural and non-structural components, windows/facades are one of the most fragile and vulnerable components of buildings, being representative of the physical line of separation between interior and exterior spaces. As such, multidisciplinary approaches, as well as specific fail-safe design criteria and analysis methods are required, especially under extreme loading conditions, so that casualties and injuries in the event of failure could be avoided and appropriate safety levels could be guaranteed. In this context, this paper presents a review of the state of art on analysis and design methods in use for glass facades, with careful consideration for extreme loading configurations, including natural events, such as seismic events, extreme wind or other climatic exposures, and man-made threats, i.e. blast loads and fire. Major results of available experimental outcomes, current issues and trends are also reported, summarising still open challenges.

In order to achieve a consistent level of failure probability, structural design codes are optimized using probabilistic methods. This optimization process traditionally focuses on the ultimate limit states (ULS). However, in the design of timber structures the performance of the structural members is often governed by the serviceability limit state (SLS) associated with different load levels than applied in the ULS. The probability of serviceability failure is strongly dependent on the loading sequence and the time-dependent response of timber; therefore, a time-variant probabilistic model is recommended to estimate them properly. This study aims to investigate the time-dependent reliability for long-term deflections of timber office and residential floor beams according to the specifications of the Eurocodes. A simple creep model is used to calculate the deflections and Monte Carlo simulation is carried out to determine the reliability index. It was found that the creep factor and the suggested deflection limits given in Eurocode 5 might not be appropriate to achieve the expected target reliabilities. To obtain a more consistent reliability, more suitable values for the mentioned parameters were suggested. However, the primary aim was to present a framework to determine appropriate deflection limits for structural codes.

Climate change and its impacts on infrastructures may seriously affect the functionality of societies. Despite the alarming potential consequences climate change pose, not enough effort has been directed towards averting these impacts or managing them in some other way (e.g. mitigation, reduction, etc.). Well-functioning infrastructure networks play a key role in societies’ resilience and their ability to cope with climate-induced hazards. Therefore, ensuring the efficient performance of infrastructure networks, even during climate related emergencies, is central to the resilience of societies in the face of climate change. At the heart of a resilient transportation infrastructure network lays robust bridge structures. This paper builds on previous work where the potential risks from climate change on bridges were surveyed. Here, a qualitative risk prioritization scheme for bridges to rank these risks is presented. The aim of this work is hence to provide a tool for determining which of these risks are more worthy of closer investigation. The suggested framework is based on the basic elements of risk; i.e. hazard, exposure, vulnerability, and consequences. Several indices reflecting these four components and their different characteristics are introduced. Subsequently, a method for ranking the different risks based on these indices is presented. This framework can be used to optimize investments in adapting bridges to climate change.

In this contribution a practical and rational decision-making approach is presented to be applied for common bridges typically managed by public authorities. The authors have developed a model with the intention to be applicable for practical cases for common bridges in the daily work of bride operators responsible for a large number of assets, yet still maintain the principles of more generic frameworks based on probabilistic decision-theory.Three main attributes of the verification of sufficiency of structural performance are considered, namely: 1) the level of sophistication of modelling performance, 2) the degree of verification and acceptance criteria in terms of dealing with uncertainties and consequences, 3) the extent of information is obtained and incorporated in the verification.The simplicity of the approach is demonstrated through an illustrative case study inspired by practical condition assessment decision problems. It is argued that in practical cases it may be desirable to utilize less advanced methods owing to constraints in resources or lack of reliable data (e.g. based on structural health monitoring or other on-site measurement techniques).

Adaptive facades are increasingly used in modern buildings, where they can take the form of complex systems and manifest their adaptivity in several ways. Adaptive envelopes must meet the requirements defined by structural considerations, which include structural safety, serviceability , durability, robustness and fire safety. For these novel skins, based on innovative design solutions, experimentation at the component and / or assembly level is required to prove that these requirements are fulfilled. The definition of appropriate metrics is hence also recommended. A more complex combination of material-related, kinematic, geometrical and mechanical aspects should in fact be properly taken into account, compared to traditional, static facades. Accordingly, specific experimental methods and regulations are required for these novel skins. As an outcome of the European COST Action TU1403 ‘Adaptive facades network’ - ‘Structural’ Task Group, this paper collects some recent examples and design concepts of adaptive systems, specifically including a new classification proposal and the definition of some possible metrics for their structural performance assessment. The aim is to provide a robust background and detailed state-of-the-art information for these novel structural systems, towards the development of standardised and reliable procedures for their mechanical and thermo-physical characterisation.

Practicing structural engineers may be familiar with the main principles of structural reliability but may not necessarily be experts in using such methods. This may lead to a lack in understanding the effect of uncertainties on the ensuing structural safety and to sub-optimization of more traditional structural engineering aspects. The aim of the current paper is to highlight the importance of considering risks and uncertainties in design and to improve the awareness of practicing engineers to such considerations. The importance of a consistent treatment of uncertainties in structural engineering is brought to attention with focus on the modelling approaches which often underlie decisions. Different aspects discussed are: decision making in light of uncertainty, principles of consistent crudeness and the influence of engineering performance in practice on the safety of structures. A simplified model, considering strategies for improving engineering models, is considered and examples, based on simplified decision models, are also provided.

Although the projected changes in the climate include considerable uncertainties, especially with downscaling, there is irrefutable evidence that the climate is changing at an unprecedented and alarming rate. In recent studies, some of the potential climate-change risks on bridges have been identified. The sheer number of these potential risks provokes two questions. Firstly, for a certain risk of interest (e.g. increased scour rate) which bridges should be prioritized from an inventory of bridges? Secondly, for a specific bridge, which of these risks are more critical? This paper proposes a method that can be used for addressing these two questions while considering the uncertainties intrinsic to the problem. Although this paper focuses on addressing the first question, a discussion on how the proposed method can be used for answering the second is also presented. The suggested method is based on four risk components The financial support provided by the Swedish Transport Administration and the strategic innovation program InfraSweden2030 is gratefully acknowledged.

The benefits of implementing appropriate resilience management strategies into transportation systems can be measured in terms of safety, efficiency and even sustainability. To objectively identify ...

Glass is largely used in architectural and engineering applications (i.e., buildings and vehicles) as a structural material, especially in the form of laminated glass (LG) sections. To achieve adequate and controlled safety levels in these applications, the well-known temperature-dependent behavior of viscoelastic interlayers for LG sections should be properly accounted for during the design process. Furthermore, the materials&rsquo, thermomechanical degradation with increases of temperature could severely affect the load-bearing performance of glass assemblies. In this context, uncoupled thermomechanical finite element (FE) numerical models could represent a robust tool and support for design engineers. Key input parameters and possible limits of the FE method, however, should be properly calibrated and assessed, so as to enable reliable estimations for the real behavior of glazing systems. In this paper, FE simulations are proposed for monolithic (MG) and LG specimens under radiant heating, based on one-dimensional (1D) and two-dimensional (2D) models. A special attention is focused on thermal effects, being representative of the first step for conventional uncoupled, thermomechanical analyses. Based on experimental results available in the literature, FE parametric studies are discussed, giving evidence of limits and issues due to several modeling assumptions. In particular, careful consideration is paid for various thermal material properties (conductivity, specific heat) and thermal boundaries (conductivity, emissivity), but also for other influencing parameters like the geometrical features of samples (thickness tolerances, cross-sectional properties, etc.), the composition of LG sections (interlayer type, thickness), the loading pattern (heat transfer distribution) and the presence of additional mechanical restraints (i.e., supports of different materials). Comparative FE results are hence critically discussed, highlighting the major effects of such influencing parameters.

Glass is largely used in engineering applications as a structural material, especially for laminated glass (LG) sections. However, the well-known temperature-dependent behaviour of visco-elastic in ...

Adaptive facades are getting more and more widespread in modern buildings. These facade systems, among many others, need to fulfil the requirements of several structural considerations, such as structural safety, serviceability, durability, robustness and fire safety, being typically defined for standard facades and building enclosures in general. The current paper discusses special structural characteristics which need to be taken into account when designing adaptive facades and summarizes some recent efforts of the activities in progress carried out by the ‘Structural’ Task Group (TG2.4) of the European COST Action TU1403 ‘Adaptive Facades Network’.

Corrosion of steel reinforcement is a common cause of deterioration in reinforced concrete bridges and many existing bridges are damaged to varying degrees. The rate of deterioration of the bridge stock has been shown to increase due to climate change. Unsympathetically, the demand for load-carrying capacity is however often increased with time. Therefore there is an increasing need for reliable methods to assess the load-carrying capacity and remaining service-life of existing infrastructure. A simple model for the assessment of Anchorage in corroded Reinforced Concrete structures (ARC) has previously been developed. It was originally based on fib Model Code 1990 and has been verified with experiments and three-dimensional nonlinear finite element (3D NLFE) analyses for both accelerated and natural corrosion as well as for different degrees of corrosion. The model was applied when assessing two road bridges in Sweden. The investigation demonstrated great cost savings but also areas for improvement, in particular regarding (a) applicability to practical cases and (b) incorporation of uncertainties in the assessment. The primary focal point of this paper is to present an overview of the development of the ARC model together with recent verifications against a large bond test database as well as foreseen future developments. It was found that the ARC model represents the physical behaviour reasonably well, and gives conservative values of bond strength compared to the bond tests database. In future works, among others, uncertainties of the input variables will be incorporated by means of probabilistic modelling, making way for implementation of the ARC model into semi-probabilistic safety concepts by extraction of modification factors. Overall, with more accurate and reliable assessment methods for corroded RC structures, environmental and economic savings are imminent as more of the potential of existing structures can be realized.

In recent years, the importance of resilient critical infrastructures has become more evident. More frequent extreme weather conditions and human-induced disasters, such as terror attacks, cause se ...

Serviceability of structures has to be verified for a lower load level than the design load used for safety considerations. Representative values of actions used in serviceability load combinations are often defined in a way that the fraction of time spent above a given load level should be limited to a certain value. To determine these load levels more information on the stochastic nature of the loading process is needed than to estimate the design load. A convenient way in structural design codes is to express representative values (rare, frequent and quasi-permanent) as a fraction of the characteristic value by using load reduction factors. However, the characteristic value is usually defined in a different way i.e. with a certain probability of not being exceeded (in a chosen period of time). The current paper estimates representative values of floor live loads by numerical simulation using stochastic live load models with a special focus on serviceability. The results are compared to values given in existing standards (Eurocode on first place). Improvements are suggested concerning the load reduction factors, the definitions of the representative values and the stochastic load parameters.

A Multi-Level Assessment Strategy has previously been proposed and proved feasible for structural analysis of existing RC slabs. In this paper, the Multi-Level Assessment Strategy, which focuses on sophisticated structural analysis, was used to investigate the load-carrying capacity and structural behaviour of a composite bridge with an RC bridge deck slab subjected to a concentrated load. In addition to more sophisticated structural analysis, improved knowledge content about the structure and more advanced models for uncertainty consideration were also incorporated in a systematic way for higher levels of assessment. Furthermore, a decision support system was adopted, in which the cost for different alternatives regarding if and how the assessment should be enhanced with respect to model sophistication, knowledge content and modelling uncertainty were compared in a systematic way. The results show not only that the load-carrying capacity and the structural behaviour can be assessed with different level of detailing, but also that the cost for each level of assessment can be evaluated with a decision support system, facilitating more sustainable management of infrastructure.

An essential aspect in the maintenance of existing bridges is the ability to adequately and accurately assess and evaluate the condition of the structure. Condition assessments, which can be carried out in any number of ways, provide valuable information concerning the actual state of a bridge, including the severity of potential damages, and form the basis for further maintenance decisions. Any decision support concerning the management of existing structures thus requires attention towards the uncertainties associated with the assessment methods when applied in practice as well as the maintenance actions these support. These uncertainties cannot be solely described as model uncertainties but are also a result of the variation in engineering performance observed in practice. In the current paper a rational and systematic framework is presented which provides practical decision support concerning whether condition assessments are necessary, what assessment methods are recommended, if invasive actions are needed, or if some other non-invasive option may be more appropriate. The framework takes into account three main attributes of an enhanced condition assessment, namely, modelling sophistication, considerations of uncertainties and risks, and knowledge/information content. Increasing the level of one or more of these attributes may be advantageous only if the expected benefits or added value of information is considered appropriate in relation to the cost of implementation in practice. A decision making model, based on Bayesian decision theory, is adopted to evaluate this problem. Two case studies, in which the framework is applied, are provided for illustrative purposes; the first is a generic numerical example and the second a decision scenario related to the fatigue assessment of an existing railway bridge.

Given their intrinsic features, adaptive facades are required to strictly satisfy rigid structural performances, in addition to typical insulation, thermal and energy requirements. These include a minimum of safety and serviceability levels under ordinary design loads, durability, robustness, fire resistance, capacity to sustain severe seismic events or other natural hazards, etc. The overall design process of adaptive facades may include further challenges and uncertainties especially in the case of complex assemblies, where even multiple combinations of material-related phenomena, kinematic effects, geometrical and mechanical characteristics could take place. In this context, experimental testing at the component and/or at the full-scale assembly level has a fundamental role, to prove that all the expected performance parameters are properly fulfilled. Several standards and guideline documents are available in the literature, and provide recommendations and procedures in support of conventional testing approaches for the certification and performance assessment of facades. These documents, however, are specifically focused on ordinary, static envelopes, and no provisions are given for the experimental testing of dynamic, adaptive skins. In this regard, it is hence expected that a minimum of conventional experimental procedures may be directly extended from static to dynamic facades. However, the validity of standardized procedures for adaptive skins is still an open issue. Novel and specific experimental approaches are then necessarily required, to assess the structural characteristics of adaptive facades, depending on their properties and on the design detailing. In this paper, existing fundamental standards for testing traditional facades are first recalled and commented. Special care is spent for the validity and reliability of conventional testing methods for innovative, adaptive envelopes, including a discussion on selected experimental methods for facade components and systems. Non-conventional testing procedures which may be useful for adaptive skins are then also discussed in the paper, as resulting from the research efforts of the European COST Action TU1403 ‘Adaptive facades network’ - ‘Structural’ Task Group.

In the current project, a finite element model is developed to analyse the long-term behaviour of timber beams. The time-dependent response of wood subjected to bending and moisture changes is investigated in terms of strains and stresses. A rheological model is implemented to capture the effects of creep, mechano-sorption and hygroexpansion. The model is validated against test results from Bengtsson and Kliger (Holzforschung 57:95–100, 2003). The results of the analysis showed that the mechano-sorptive creep of low- (LT) and high-temperature-dried (HT) timber beams can be sufficiently modelled with a spring and a single Kelvin body. The different mechano-sorptive behaviour of LT- and HT-dried specimens is considered with different mechano-sorptive and shrinkage–swelling parameters. The presented model could be used to derive general mechano-sorptive parameters: (1) for better prediction of creep over the service life and (2) to provide a basis of time-dependent probabilistic calculations for structural-sized timber in serviceability limit state.

Glass is seeing a growing interest as a structural material as a result of its relatively good strength to weight ratio and the obvious aesthetic benefits of its use in buildings. However due to the sensitivity of glass to thermal shock and the considerably temperature-dependent behaviour of interlayer materials as a result of their visco-elastic nature, the mechanical behaviour of laminated glass will be severely influenced by exposure to fire. Relatively little research has been conducted in the past to study the response of load bearing structural glass, and laminated glass in particular to radiant heating. This paper represents an effort to try to understand the effects of through depth radiation absorption and temperature conduction through laminated glass with a view to ultimately developing a model for studying load bearing glass exposed to elevated temperatures, such as those that would be expected in a fire. The paper reports on an experimental research programme in which several monolithic and laminated glass configurations were exposed to a radiant heat flux to study the different phenomena that occur upon exposure to fire conditions, including the ratios of absorbed, transmitted and reflected heat flux to the incident heat flux. The paper then presents a numerical heat transfer model which is developed based on these experimental results and that is able to determine the evolution of the temperature profile as a result of a given incident heat flux. The effectiveness of the heat transfer model is demonstrated through comparison with the temperatures measured during the experimental work.

Modern building envelopes are high-tech components that must meet requirements and constraints regarding architecture/urban planning/aesthetics, energy efficiency, indoor environmental quality, buildability and value. If a facade can respond to all the transient conditions while maintaining occupant satisfaction without imposing additional loads on the building services, it can be considered “fully adaptive”. However, an adaptive facade needs to fulfil a fundamental role as assigned to the structural performance of the same assemblies, under ordinary as well as exceptional loads, hence requiring specific safety levels and design concepts. Most of the systems representative of this next generation of facades typically consist of highly adaptive envelopes, generally involving smart materials, kinematic mechanisms, etc

Maintenance of transportation infrastructure assets can be relatively expensive, since it does not only include the direct cost of interventions, but also the indirect consequences of traffic disruptions. To make optimal decisions about maintenance actions, including rehabilitation and upgrading, reliable information about the performance of existing structures is needed. However, obtaining such information might require significant efforts and can be done in various ways. The purpose of an ongoing Swedish research project BIG BRO is to develop a framework for a decision support methodology that can be used for implementing maintenance strategies for bridges on a rational basis. The present paper provides a brief overview about the project as well as describes some of the ongoing work.

Large scale crises are affecting critical infrastructures with a growing frequency. This is a result of both basic exposure and dependencies between infrastructures. Because of prohibitive costs, the paradigm of protection against extreme events is expanding and now also encompasses the paradigm of resilience. In addition to strengthening and securing systems; system design objectives are now being set, and response planning is being carried out, to facilitate a fast recovery of infrastructure following a large scale incident. The IMPROVER project is funded under the Horizon 2020 Secure Societies work program and aims to improve European critical infrastructure resilience to crises and disasters through the implementation of combinations of societal, organisational and technological resilience concepts to real life examples of pan-European significance, including cross-border examples.The project comprises three phases: an international survey to identify methods for implementing resilience concepts to critical infrastructure; an evaluation of these methods; and the further development of promising methods for application to European critical infrastructure. At the time of writing, the project is approaching the end of the first stage and looking towards the challenges of the second and third stages. This paper provides a brief discussion of some of the novel methods which we are employing in order to achieve the projects objectives and overcome some of the challenges inherent in the field. These methods include crowdsourcing as a source of information and to promote engagement of the population during recovery; as well as structured expert elicitation of expert judgement for hazard identification and ranking and fragility curve definition. These are combined with more traditional systems analysis and engineering analysis techniques to develop a toolkit to evaluate and promote the resilience of critical infrastructure. Within the project these will be exemplified by application to four living labs which represent critical infrastructure of pan-European significance.

To achieve a relatively consistent probability of failure for structural elements, most design codes apply reliability based code calibration process. Such approaches commonly focus on the strength of the structural members, which is related to the ultimate limit state (ULS). However in the design of beams the performance of the structural elements is often limited by the serviceability requirements, which are related to the serviceability limit state (SLS) using different load combinations than applied in the ultimate limit state. The current study aims to investigate the reliability for serviceability design for flexural members made of different materials (steel, concrete and timber) according to the specifications of the Eurocodes. Second-order reliability method (SORM) is applied to determine the reliability index for different design situations for beams subjected to bending. The probabilistic models of basic variables for time invariant analysis have been taken from the JCSS Probabilistic Model Code. The characteristic, the frequent and the quasi-permanent combination of actions are investigated and compared. The differences in service reliability for different materials are discussed. The results show that there are differences between the achieved reliability indices in the serviceability state between different materials and that for the given load combinations in the Eurocode the reliability index is often below the one given in the code. (C) 2011 Elsevier Ltd. All rights reserved. (Less)

The current paper reports about the progress in the ongoing European project IMPROVER (Improved risk evaluation and implementation of resilience concepts to critical infrastructure), in which a fundamental part is devoted to technological resilience concepts. Within the project a general methodology for resilience evaluation is developed, in which existing concepts in the field of structural engineering are aligned with non-technological domains (e.g. organizational and societal) contributing to resilience. A shift from protection to enhancing resilience leads to a shift in focus from traditional risk management towards crisis management. Some of these issues are exemplified here with the application on bridges as critical infrastructures.

A systematic testing and modelling program has been developed for the verification of the structural performance of facade sandwich elements to take structural aspects into consideration in the SESBE research project, focusing on the development of “smart” facade elements. The present paper mainly focuses on the verification of the mechanical performance of the glass fibre reinforced polymer (GFRP) connectors of the novel type of facade element composed of reactive powder concrete (RPC) panels with foam concrete insulation between them. Because of the reduced thickness of the large facade elements, the performance of the connectors is critical for the entire structural concept. The first series of the testing and modelling programme concerning connector performance are presented here. The results suggest that sufficient strength and ductility of the connectors can be ensured using GFRP in the proposed thin light-weight facade elements.

Despite the increasing research activity on structural use of glass in the past years, there is still a lack of comprehensive design codes and standards linked to real-life applications on a structural level. However, more and more ambitious buildings and structures are built every year. Thus the knowledge is out there. The aim of the presented project is to collect data on the existing design philosophy and glass failure cases. The investigation includes a survey about how practicing structural engineers deal with different design aspects of glass with a special focus on robustness and serviceability. The current document gives a brief overview about the findings of the interviews