Finian McCann | London South Bank University (original) (raw)

Papers by Finian McCann

Composite Structures

Abstract The bending resistance of recycled glass bead sandwich panels is investigated through fl... more Abstract The bending resistance of recycled glass bead sandwich panels is investigated through flexural experiments conducted on a range of specimens. A method whereby the maximum strains at midspan are used to determine the elastic material properties is discussed and shown to provide similar results to a method based on midspan deflections; scopes of applicability of the two methods are discussed. The influences of adhesive strength, polymer content and previous damage are investigated, with the application of high-strength adhesive not leading to any improvement in structural performance whereas the increase in polymer content is shown to improve structural performance. Re-testing of previously damaged specimens demonstrates that residual compaction in the core leads to improved deformation capacity. A strain-based model to predict the ultimate moment resistance is shown to provide safe-sided results when compared to the experimental ultimate moments. A reliability analysis of the predictive model is conducted in accordance with the European structural design framework. For 1–2 mm bead cores, a partial factor of 1.40 is recommended for use with the design method, while a partial factor of 2.20 is recommended for 4–8 mm bead cores; it is confirmed that the design moment resistances are conservative and safe-sided when compared to the experimental results.

SSRN Electronic Journal, 2021

Tubular structural members with slender cross-sections are susceptible to failure through local b... more Tubular structural members with slender cross-sections are susceptible to failure through local buckling of their tube walls. Previous numerical studies of steel elliptical hollow sections in compression predicted the local buckling modes and the ultimate loads of particularly slender specimens, with the results used to calibrate design methods for slender elliptical sections. Although these numerical parametric studies were conducted across a wide slenderness range, it was only possible to validate the models against experimental results in the low slenderness range since commercially available steel EHS are intended to satisfy non-slender geometric limits prescribed by structural design codes. Such limitations to the experimental scope are circumvented in the present study through testing of highly slender specimens produced using additive manufacturing techniques. A total of eight specimens of various cross-sectional aspect ratios and tube wall thicknesses were fabricated at London South Bank University using additive manufacturing techniques, which were then tested in compression; the observed load-deflection behaviour, ultimate loads, longitudinal strains and failure modes are discussed. Through appropriate rescaling of relevant parameters, design predictions for the ultimate load of the 3D-printed analogues are obtained using a design method intended for use with steel elliptical hollow sections. It is shown that the design predictions are safe-sided when compared to the present experimental results, with the accuracy generally increasing with aspect ratio and slenderness.

Numerical analysis of the local buckling behaviour and ultimate cross-sectional strength of tubul... more Numerical analysis of the local buckling behaviour and ultimate cross-sectional strength of tubular elliptical profiles in compression has been performed. After validating the model against previous experimental results, a parametric study comprising a total of 270 elliptical sections was conducted in order to examine the influence of cross-section aspect ratio, geometric imperfections and local slendernesses. The obtained ultimate capacities, load–deformation responses and failure modes are discussed. It was found that for lower cross-section aspect ratios the behaviour of The Elliptical Hollow Sections (EHS) was similar to that of cylindrical shells across a number of metrics; as the aspect ratio increased, more plate-like stable postbuckling behaviour was observed. A design method has been proposed for Class 4 EHS members that reflects the reduction in capacity due to local buckling with increasing slenderness, but also recognises the improved postbuckling stability with increasi...

Construction and Building Materials, 2020

An investigation is conducted to determine the structural and acoustical properties of panels com... more An investigation is conducted to determine the structural and acoustical properties of panels comprising a core of recycled glass beads bound in a matrix of polyurethane resin enveloped by two fibreglass facing sheets. This investigation is conducted in order assess the suitability of recycled glass bead panels in multifunctional applications in the built environment, especially in urban, built-up or noisy environments where both structural resistance and acoustic insulation are beneficial. In order to assess the acoustical performance of the panels, experiments to determine the transmission loss and absorption coefficients are performed using the transfer function method. It is shown that the panels provide effective insulation for typical urban built environments. Experiments are also described that are conducted to determine the modulus of elasticity of the fibreglass sheets, the compressive strength of the bead cores and the behaviour of the recycled glass bead panels when loaded in bending. A design method to predict the ultimate moment resistance of a panel in bending is proposed, which is shown to provide conservative and safesided predictions when compared to the experimental results. It is shown that, when employed in a flooring system, recycled glass bead panels can achieve usable spans under typical floor loads expected in commercial and residential structural applications, while also possessing the acoustic insulation performance required of a modern and comfortable dwelling or workspace. This combination of structural and acoustic performance has considerable potential to increase material efficiency in construction.

Ocean Engineering, 2018

A numerical method to analyse the effect of the application of polymer coatings on the bending re... more A numerical method to analyse the effect of the application of polymer coatings on the bending resistance of steel pipeline joints is presented. Experiments were conducted to investigate the influence of the thickness of polymer field joint coatings and the cooldown time provided after applying the coatings on the behaviour of pipeline joints when being bent during reeling operations. Temperature readings were obtained from thermocouples inside the polymer field joint coating during the application process, and pipeline ovality measurements were taken during mechanical testing. Thermal modelling of the coating application procedure was developed using COMSOL Multiphysics modelling software; this model is validated against the thermocouple readings, while a mechanical model simulating the pipe being bent to a reel developed in Abaqus finite element modelling software is described. The temperature outputs, areas of stress concentration and pipe ovalities obtained from the experiments are shown to be predicted accurately by the numerical models. After successful validation of the numerical models, a parametric study assessing the influence of field joint coating thickness and cooldown times is described, whose results are used to find an optimal solution to reduce the cooldown time required prior to bending the pipe without buckling.

Engineering Structures, 2017

A numerical model simulating the behaviour of elliptical concrete-filled columns under either con... more A numerical model simulating the behaviour of elliptical concrete-filled columns under either concentric or eccentric compressive load has been developed in ABAQUS. The numerical results have been compared against a range of experimental results for ultimate load, load-deflection behaviour and failure modes, with good agreement observed. An extensive parametric study has been undertaken whereby the slenderness, load eccentricity, cross-sectional geometry and reinforcement ratio of the concrete-filled columns were varied, creating a data set upon which to formulate design guidance since currently there are no specific provisions in the European Standard EN 1994-1-1 [1] for the design of concrete-filled steel elliptical section columns or beam-columns. It is shown

Journal of Constructional Steel Research, 2015

Experiments on concrete-filled elliptical hollow section beam-columns have been conducted to exam... more Experiments on concrete-filled elliptical hollow section beam-columns have been conducted to examine their fundamental structural behaviour. A total of 27 specimens were tested-3 stub columns and 24 longer members of varying slenderness. Seven of the tested specimens also contained steel reinforcement. The specimens were loaded in compression, either concentrically or with different major or minor axis eccentricities. Measurements of the applied load, the strains at mid-height, the axial displacement and the lateral deflection at mid-height were recorded. Plots of load against the lateral deflection at mid-height and load against axial displacement are presented for the specimens, along with values of strength index and ductility index. Comparisons have been made between the test results and the provisions of the European Standard EN 1994-1-1:2004 for determining the ultimate load of concrete-filled circular and rectangular hollow section columns. It was found that the predicted resistances are safe for use in the design of concrete-filled elliptical hollow section columns either with or without reinforcement, and loaded either concentrically or eccentrically.

The stability of steel beams with discrete lateral restraints is analysed using the Rayleigh–Ritz... more The stability of steel beams with discrete lateral restraints is analysed using the Rayleigh–Ritz method, with the degrees-of-freedom being represented by Fourier series. Linear eigenvalue analysis of the system shows that the system buckles into one of two classes of mode, either node-displacing or between bracing nodes. Buckling mode progression behaviour is examined and limiting characteristics of the system are found. Comparison is made with a single harmonic representation of the DOFs, which is found to lead to erroneous predictions. Validation of the analysis is performed using the finite element method and numerical continuation. Finally, it is shown that design formulae based on analogous column behaviour can return both conservative and unsafe results, depending on brace location.

Journal of Engineering Mechanics, 2013

Journal of Constructional Steel Research, 2013

Discrete lateral restraints offer an effective means of stabilizing beams against lateraltorsiona... more Discrete lateral restraints offer an effective means of stabilizing beams against lateraltorsional buckling. Design expressions for simply-supported beams braced regularly along their span with elastic restraints, based on analytically-derived formulae, are presented herein. These include the minimum restraint stiffness required to force the beam to buckle in between the restraint nodes and the forces induced in the restraints, along with a brief treatment of the critical moment of the beam. It is demonstrated that there is close agreement between the values obtained from the design formulae and their original analytical counterparts. These are also compared with the results from design formulae based on analogous column behaviour, an approach commonly used in design codes. It is found that the column rules used by design codes return values that, when compared with the results of the current analysis, are overly conservative for cases where the restraints are positioned at the compression flange of the beam but unsafe for restraints positioned at the shear centre.

Engineering Structures, 2016

The local buckling behaviour and ultimate cross-sectional strength of tubular elliptical profiles... more The local buckling behaviour and ultimate cross-sectional strength of tubular elliptical profiles in compression is examined in this study through numerical modelling. The numerical models were first validated against previous experimental data with good agreement observed, enabling an extensive parametric study to be performed. A total of 270 elliptical sections were simulated in order to examine the influence of cross-section aspect ratio, geometric imperfections and local slendernesses. The obtained ultimate capacities, load-deformation responses and failure modes are discussed. It was found that for lower cross-section aspect ratios the behaviour of the elliptical hollow sections (EHS) was similar to that of cylindrical shells across a number of metrics; however, as the aspect ratio increased, more plate-like stable postbuckling behaviour was observed. Imperfection sensitivity was found to decrease with increasing slenderness and aspect ratio. The influence of the shape of the initial imperfection on the strengths of the EHS columns was also assessed and was found to be generally limited. Finally, a design method has been proposed for Class 4 EHS members that reflects the reduction in capacity due to local buckling with increasing slenderness, but also recognises the improved postbuckling stability with increasing aspect ratio; the proposals were shown to provide safe and accurate predictions for the strengths of the EHS columns with nondimensional local slendernesses up to 2.5 and aspect ratios from 1.1 to 5.0.

Thin-Walled Structures

The local buckling behaviour and ultimate cross-sectional resistance of slender tubular elliptica... more The local buckling behaviour and ultimate cross-sectional resistance of slender tubular elliptical profiles in bending are examined by means of numerical modelling. After successful validation of the numerical model against previous experimental results, a parametric study comprising 240 simulations was conducted in order to investigate the influence of cross-section aspect ratio, axis of bending, geometric imperfections and local slenderness on structural behaviour. The ultimate moments, moment-curvature relationships and failure modes obtained are discussed. It was found that, overall, postbuckling stability increases and imperfection sensitivity decreases with increasing elliptical hollow section (EHS) aspect ratio. A design method is proposed for Class 4 EHS members that reflects the reduction in resistance due to local buckling with increasing slenderness and extends the range of applicability of existing provisions. A reliability analysis was performed in accordance with EN 1990,

The current work analyses the lateral stability of imperfect discretely-braced steel beams using ... more The current work analyses the lateral stability of imperfect discretely-braced steel beams using variational methods. To facilitate the analysis, Rayleigh-Ritz approximations are used to model the lateral deflection and the angle of twist. The applicability of the methods is initially demonstrated for the cases of unrestrained

Thin-Walled Structures, 2015

ABSTRACT Elevated temperature material tests on cold-formed steel coupons cut from circular, rect... more ABSTRACT Elevated temperature material tests on cold-formed steel coupons cut from circular, rectangular and square hollow sections have been conducted, including both steady-state and transient-state tests. The experimental apparatus, methods of testing and results obtained are fully described. Temperature dependent retention factors for stiffness, strength and ductility were determined and compared to those provided in the European Standard EN 1993-1-2:2005 and the Australian Standard AS 4100:1998. It was found that the codified retention factors, despite being derived on the basis of tests on hot-finished material, are also applicable to cold-formed hollow sections. A design proposal from the literature for the prediction of ultimate strain has been also shown to be suitable for application to cold-formed hollow sections. A new expression for predicting strain at fracture has been proposed that provides a lower bound estimate of the test results derived in the current study.

A beam with nonlinearly‐elastic lateral restraints attached at discrete points along its span is ... more A beam with nonlinearly‐elastic lateral restraints attached at discrete points along its span is investigated via analytical and numerical methods. Previous results for the critical moment and the deflected shape based on an eigenvalue analysis of a similar beam with linearly‐elastic restraints are discussed, along with a validation of these results against an equivalent finite element model and results from numerical continuation. A beam with nonlinearly‐elastic restraints is then analysed with treatments for both quadratic and cubic restraint force–displacement relationships being provided. After formulation of the potential energy functionals, the governing differential equations of the system are derived via the calculus of variations and appropriate boundary conditions are applied. The equations are then solved using the numerical continuation software AUTO‐07p for a standard I‐section beam. The variation in elastic critical buckling moment with the linear component of the restraint stiffness is tracked via a two‐parameter numerical continuation, allowing determination of the stiffness values at which the critical buckling modes changes qualitatively. Using these stiffness values, subsequent analyses are conducted to examine the influence of the nonlinear component of the restraint stiffness, from which post‐buckling equilibrium paths and deformation modes are extracted. The results of these analyses are then compared with an equivalent Rayleigh–Ritz formulation whereby the displacement components are represented by Fourier series. Equilibrium equations are derived by minimizing the potential energy functional with respect to the amplitudes of the constituent harmonics of the Fourier series. The amplitudes are solved for in the post‐buckling range by AUTO‐O7p and equilibrium paths are produced and compared to the equivalent solutions of the differential equations, with good agreement observed.

Composite Structures

SSRN Electronic Journal, 2021

Construction and Building Materials, 2020

Ocean Engineering, 2018

Engineering Structures, 2017

Journal of Constructional Steel Research, 2015

Journal of Engineering Mechanics, 2013

Journal of Constructional Steel Research, 2013

Engineering Structures, 2016

Thin-Walled Structures

Thin-Walled Structures, 2015

A comprehensive programme of testing of concrete-filled elliptical section steel tubular columns ... more A comprehensive programme of testing of concrete-filled elliptical section steel tubular columns of varying slenderness has been undertaken at Imperial College London. A total of 27 specimens were prepared of varying lengths, including three stub columns, with seven of the tested specimens also possessing steel reinforcement. The specimens were then loaded in compression, either concentrically or with different major axis or minor axis eccentricities. Load, end-shortening, mid-height strains, lateral deflection at mid-height and end rotations were measured. These results were then used to validate a finite element model developed in ABAQUS, which incorporated steel material stress–strain properties from tensile testing and a confined concrete model using the measured concrete strengths. The numerical results are shown to agree well with those obtained from the experiments when comparing ultimate load, load–deflection behaviour and failure modes. This allowed a parametric study to be undertaken where the slenderness and load eccentricity of the concrete-filled columns were varied, creating a data set to be used as the basis for developing simplified design rules for inclusion in codes such as Eurocode 4.