Marios Chryssanthopoulos | University of Surrey (original) (raw)

Papers by Marios Chryssanthopoulos

Journal of Structural Engineering-asce, Sep 1, 1999

A methodology is presented for the probabilistic assessment of reinforced concrete (RC) frames su... more A methodology is presented for the probabilistic assessment of reinforced concrete (RC) frames subjected to seismic loading. Various aspects of structural modeling, including member capacity and stiffness, along with global and member failure criteria during the analysis, are thoroughly investigated and, where appropriate, the uncertainties inherent in these are quantified using appropriate statistical techniques. A statistical description of the critical interstory drift is derived using existing experimental results mainly from shaking table tests of small-scale bare frames. The required number of input motions and the effect of the spatial distribution of the random variables are also considered. An application of this procedure is illustrated by means of producing vulnerability curves for a 10-story, three-bay frame.

Composites Manufacturing, 1995

This paper presents a detailed statistical analysis on geometric imperfections recorded on two se... more This paper presents a detailed statistical analysis on geometric imperfections recorded on two series of nominally identical composite cylinders. These defects can be classified in two categories, both due to the particular manufacturing method used: out-of-roundness and change of thickness due to the overlapping of various layers. The statistical analysis is developed for various purposes: to evaluate the common properties of cylinders with different laminations, to build up a characteristic model for the geometric imperfections suitable for probabilistic simulations in buckling analysis and to identify the parameters for quality control processes. The analysis of the change in thickness due to overlapping layers allows evaluation of the stiffening effects of the manufacturing process that, in some cases, could affect the buckling behaviour of composite cylinders. A standard procedure for the characterization and qualification of manufacturing processes for composite shells, with particular attention to the factors that influence their buckling behaviour, is proposed.

Journal of Constructional Steel Research, Jul 1, 2003

Use of a fracture mechanics-based fatigue analysis for bridge details requires that the random na... more Use of a fracture mechanics-based fatigue analysis for bridge details requires that the random nature of fabrication, crack growth, fatigue-fracture failure and applied loading be properly accounted for. Prior to investigating the last item, the others may be addressed by comparing with corresponding S-N curves, which have been established over many years of experimental code development. In this paper, four typical fatigue-sensitive details are examined under constant amplitude loading and the 50 and 97.7% probability of survival lines are obtained using appropriately selected stress intensity factors, a bi-linear crack growth model and a failure assessment diagram. To this end, various material and geometric parameters are treated as random. The good agreement observed between the fracture mechanics-based S-N curves and their code-specified counterparts, especially for low stress ranges, increases confidence in the model parameters used and hence in subsequent bridge reliability analyses using probabilistic fracture mechanics.

Engineering Structures, Mar 1, 1999

The strength and ductility of reinforced concrete beam and column cross-sections with varying geo... more The strength and ductility of reinforced concrete beam and column cross-sections with varying geometries and levels of confinement are investigated. Material properties are modelled as random variables and their effect on section behaviour is assessed through fibre modelling and the Response Surface Methodology. The section ductility is in many cases found to be mainly dependent on the ultimate concrete strain. The uncertainty involved in the estimation of the latter using various models for confined concrete is examined with the aid of existing experimental data. Other failure criteria such as first hoop fracture and buckling of the longitudinal bars are also considered. Monte Carlo simulations show that a significant amount of variability exists in both the strength and ductility of confined concrete sections due to variations in material properties. In the case of ductility, this variability is greatly enhanced if model uncertainty is taken into account, especially for high axial loads. Furthermore, simple expressions are derived for the estimation of the strength parameters for any cross-section subject to varying material properties. Finally, the confined concrete model and curvature ductility provisions of Eurocode 8 are evaluated.

Routledge eBooks, Apr 26, 2022

IABSE Conference, Rotterdam 2013: Assessment, Upgrading and Refurbishment of Infrastructures, 2013

Chloride induced corrosion, caused primarily by de-icing salts or salt spray in marine environmen... more Chloride induced corrosion, caused primarily by de-icing salts or salt spray in marine environments, is one of the most common deterioration processes in reinforced concrete. It often causes a localized loss of section, known as pitting, which can lead to a significant reduction of the structure's service life. In order to predict the impact of this phenomenon on the mechanical properties of the reinforcing bars in concrete a thorough analysis of its characteristics is needed. At present, most of the models found in literature describe uniform corrosion and those that do address localized corrosion focus on a simplified definition of the reduced cross-sectional area of corroded rebars without due attention to physical characteristics and spatial variability. This may be attributed to the limitations of current non-automated and largely heuristic methods used in evaluating the corrosion characteristics on the surface of reinforcement. Automation of the corrosion measurement method would lead to the development of comprehensive corrosion models considering both systematic and random features of the deterioration process. In this paper, experimental results from corroded bars are processed using 3D scanning techniques and characterised using spatial analysis tools, thus preparing the ground for probabilistic corrosion modelling based on random field concepts.

Composite Structures, May 1, 1999

The experimental behaviour of laminated glass fibre-reinforced plastic (GFRP) cylinders under com... more The experimental behaviour of laminated glass fibre-reinforced plastic (GFRP) cylinders under compression and bending is examined in this paper. The laminates are of type `Rovimat 1200&amp;#39; consisting of woven glass fibre roving, with a chopped mat on one side, within a polyester resin matrix. Two and three-ply cylinders with various orthogonal orientations were considered, for which the nominal radius-to-thickness ratio

CRC Press eBooks, Jan 9, 2014

Chloride induced corrosion, caused primarily by salt spray in marine environments, airborne salts... more Chloride induced corrosion, caused primarily by salt spray in marine environments, airborne salts and de-icing salts, is one of the most common deterioration processes in reinforced concrete structures. At present, most of the models found in literature describe uniform corrosion and those that do address localized corrosion focus on a simplified definition of the reduced cross-sectional area of corroded rebars without due attention to physical characteristics and spatial variability. This may be attributed to the limitations of current manual methods used in evaluating the corrosion characteristics on the surface of reinforcement. In this paper, an automated procedure for the acquisition of corrosion depth data on rebars based on 3D laser scanning is investigated. Moreover, the first results of an analysis process based on image analysis using wavelet theory are presented. These results show a promising way of improving the classification of corrosion depths. This can be useful for the relation between spatial distribution of corrosion and mechanical properties of the corroded element. © 2013 Taylor & Francis Group, London.

Journal of Structural Engineering-asce, Mar 1, 2001

This study focuses on the probabilistic assessment of reinforced concrete (RC) frames infilled wi... more This study focuses on the probabilistic assessment of reinforced concrete (RC) frames infilled with clay brick walls and subjected to earthquake loading. The adopted methodology extends from that previously developed by the writers for bare RC frames by the introduction of additional random variables to account for the uncertainty in the masonry properties. Quantification of the latter is achieved through the use of experimental data describing the difference in force-displacement behavior between bare and infilled frames. The vulnerability and seismic reliability of two 10-story, three-bay infilled frames (a fully infilled one and one with a soft ground story) are derived and subsequently compared with values corresponding to the bare frame counterpart. It is found that failure probabilities, especially at the ultimate limit state, are highly sensitive to the structural stiffness; hence, bare frames benefit from lower spectral ordinates than infilled ones. Nonetheless, all structural systems studied appear to be exposed to a reasonably low seismic risk.

A new methodology for bridge management is proposed which encompasses whole life costing and life... more A new methodology for bridge management is proposed which encompasses whole life costing and life cycle assessment objectives under conditions of uncertainty. Stochastic multi-criteria decision analysis is used in order to calculate the most preferable maintenance scenario in terms of a linear combination of whole life cost and environmental score defined through the decision-maker's preference. The proposed methodology, which could be of use at project or network level, is demonstrated through a simple example of a reinforced concrete bridge element. For the covering abstract see ITRD E126028.

Among civil infrastructure systems, significant attention has been given in recent years to highw... more Among civil infrastructure systems, significant attention has been given in recent years to highway and railway bridges, whose criticality in overstretched transport networks across the world is self-evident. This study develops a methodology for multi-stage performance updating of deterioration-prone uncertain systems. This implies having to incorporate information from different sources obtained at different points-in-time during long service lives, from example either from detailed inspections and monitoring or from qualitative methods, such as visual inspections or service records, in order to improve confidence in performance prediction under uncertainty. A Bayesian framework is adopted in this research for merging data and information in order to reduce uncertainty and improve performance prediction. These concepts are applied to chloride-induced deterioration of concrete bridge structures, which has been identified as the principal cause of deterioration of UK highway bridges. For the covering abstract see ITRD E143091.

A contribution towards better understanding, and communication to any interested parties, of seis... more A contribution towards better understanding, and communication to any interested parties, of seismic risk in loss estimation studies is believed to be the distinct treatment of inherent uncertainties (aleatory) from those associated with the models that could, in principle, be reduced (epistemic). In pursuing this objective, this paper treats separately and explicitly these sources of uncertainty through a two-stage Monte Carlo methodology, which may offer some advantages over existing simplified and/or approximate procedures. The methodology can be applied under general conditions, with fragility and exposure curves obtained by any of the generally accepted procedures. It has been implemented in the estimation of the direct financial loss of a single building, though other loss measures could also be incorporated. A three storey moment resisting frame is used to appraise the proposed methodology and highlight the relative importance of uncertainty sources in risk-based scenario loss. © 2011 Taylor & Francis Group, London.

The development of a methodology to model network level bridge deterioration using a Bayesian Bel... more The development of a methodology to model network level bridge deterioration using a Bayesian Belief Network (BBN) is presented in this paper. BBN's are capable of handling complex relationships between elements (e.g. beams, columns, etc.) and the system (e.g. stock of bridges) by means of conditional probabilities specified on a fixed model structure. The advantages and limitations of BBN's for such applications are discussed. The application of the methodology is presented through a case study on a group of UK railway masonry arch bridges. The condition of elements within a selected sample of bridges is used as input in the BBN, together with a set of conditional probabilities based on inspection experience, to yield, in probabilistic terms, the overall condition of the bridge group. Sensitivity of various input parameters, as well as underlying assumptions, on group performance is investigated, which can help with the prioritization of assessment and maintenance intervention activities. © 2010 Taylor & Francis Group, London.

In recent years, a significant amount of research has been directed towards experimental modellin... more In recent years, a significant amount of research has been directed towards experimental modelling of cylinders typically used in offshore construction, as well as towards the development of analytical and numerical methods to improve design against buckling. This paper presents techniques for probabilistic buckling analysis and reliability assessment of stiffened cylinders taking advantage of data produced in preceding studies. In particular, the effect of initial geometric imperfections on elasto-plastic buckling strength and reliability predictions is examined in detail, and simple rules are proposed that clarify imperfection modelling assumptions in finite element studies. The application of these rules is demonstrated for a particular stringer-stiffened cylinder under axial compression.