Daniel Honfi

Numerical Analysis and 1D/2D Sensitivity Study for Monolithic and Laminated Structural Glass Elements under Thermal Exposure

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’ 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.

Incorporation of resilience assessment in critical infrastructure risk assessment frameworks

This paper explores the concept of Critical Infrastructure (CI) resilience and its relationship with current Risk Assessment (RA) processes. It proposes a framework for resilience assessment of CI, which integrates the resilience paradigm into the RA process according to ISO 31000. The framework consists of three levels, namely (a) asset (focus on individual CI assets), (b) system (focus on dependencies between CI assets) and (c) national or regional (focus on societal aspects). It is applicable to individual CI or their combinations, accounting both for existing RA processes, for interdependencies and their effect on interconnected CI, while at the same time employing current, available resilience analysis tools and methodologies. This approach is also compatible with the current European guidelines for national RA applied by the EU Member States.

Probabilistic metric of infrastructure resilience considering time-dependent and time-independent covariates

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 ...

Practical Bond Model for Corroded RC Bridges

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.

Structural performance of GFRP connectors in composite sandwich facade elements

To take structural aspects into consideration in the SESBE research project, focusing on the development of “smart” facade elements a systematic testing and modelling program has been developed for the verification of the structural performance of the facade sandwich 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 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.

Novel techniques and approaches for risk based application of resilience concepts to critical infrastructure: an introduction to the IMPROVER project

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.