Civil Engineering

In the conventional displacement-based finite element analysis of composite beam–columns that consist of two Euler–Bernoulli beams juxtaposed with a deformable shear connection, the coupling of the transverse and longitudinal displacement fields may cause oscillations in slip field and reduction in optimal convergence rate, known as slip locking. This locking phenomenon is typical of multi-field problems of this type, and is known to produce erroneous results for the displacement-based finite element analysis of composite beam–columns based on cubic transverse and linear longitudinal interpolation fields. This paper introduces strategies including the assumed strain method, discrete strain gap method, and kinematic interpolatory technique to alleviate the oscillations in slip and curvature, and improve the convergence performance of the displacement-based finite element analysis of composite beam–columns. A systematic solution of the differential equations of equilibrium is also provided, and a superconvergent element is developed in this paper. Numerical results presented illustrate the accuracy of the proposed modifications. The solutions based on the superconvergent element provide benchmark results for the performance of these proposed formulations. Copyright © 2010 John Wiley & Sons, Ltd.

In the numerical analysis of composite beam-columns inconsistencies in the shape functions of the transverse and longitudinal displacement fields may cause oscillations in the slip field and reduction in the accuracy of the results known as slip-locking which is typical of multi-field problems of this type. In order to eliminate slip-locking, matching field strategy is adopted herein by using the element free Galerkin method in which shape functions of the longitudinal displacement fields are obtained from the derivatives of shape functions of the transverse displacement fields. Continuous blending method is modified in order to couple element-free Galerkin and finite element methods when the matching field approach is used in the meshfree region. This modification allows for direct assembly of the stiffness matrices that are built for separate finite element and meshfree regions, the boundary conditions can be directly applied and the reaction forces can also be calculated directly from the structural stiffness matrix.

This paper presents a novel method to localize and quantify damage in a jack arch structure by introducing a linkage modeling technique to overcome issues caused by having limited sensors. The main strategy in the proposed Frequency Response Function (FRF)-based sensitivity model updating approach is to divide the specimen into partitions. The Young’s modulus of each partition is then updated to detect stiffness reduction caused by damage. System Equivalent Reduction Expansion Process (SEREP) is used to reduce the full finite element (FE) model to a linkage model. The number of measured degrees of freedom (DOFs) is then expanded to the linkage model using the mass and stiffness matrices of the linkage model for the synthesis of interpolated FRFs. The FRF sensitivities are then formulated using the linkage model along with the interpolated FRFs to iteratively calculate the values of the updating parameters until convergence is achieved. The methodology and theory behind this procedur...

Thin-walled member composed of fibre-reinforced polymer composite laminates that have one dimension relatively large in comparison to their cross-sectional dimensions are conventionally modelled by one dimensional beam-type finite elements. Due to the rigid cross section assumption in the formulation of this class of elements, only beam-axis-related deformations can be considered, including flexural, torsional and lateral buckling. However, local deformations such as local buckling of web and flanges, which might have significant effects on the global response of the member, are ignored. In order to model these types of deformations, shell-type elements are used throughout the domain of the member. While the former lacks accuracy in some cases, the latter creates oversized models that are computationally uneconomical. The purpose of the current study is to develop a finite element model to consider the local effects by a multi-scale overlapping decomposition method. In this method, ...

A constitutive model based on a novel coupled elastoplastic-damage framework is adopted for the modelling of concrete under cyclic loads. Coupled elastoplastic-damage models have been used to capture both the material degradation and the permanent deformations under inelastic deformations. In this study, a multisurface plasticity framework is implemented for the modelling of concrete under compressive and tensile cyclic loads. The elastoplastic-damage framework is based on the ‘direct-coupling’ method in which an a-priori relationship between the total strain and the damage strain is postulated. The model is easy to calibrate since it utilises the same yield and potential functions for plasticity and damage calculations. Concrete is modelled using a pair of yield surfaces in order to capture its compressive and tensile behaviour while utilising corresponding isotropic damage variables to capture the stiffness degradations in the compressive and tensile regimes. Material parameters a...

BACKGROUND Mechanics of Solids is a second year undergraduate subject, undertaken by both Civil and Mechanical engineering students at the University of Technology, Sydney (UTS). Mechanics of Solids has been delivered for many years in a traditional format with lectures and problem solving tutorials. As part of a national Australian project “Enhancing Industry Exposure in Engineering Degrees”, UTS in partnership with other universities and industry partners in Australia has sought industry involvement to engage students with the real-world challenges of engineering practice.

BACKGROUND Mechanics of Solids is a second year undergraduate subject, undertaken by both Civil and Mechanical engineering students at the University of Technology, Sydney (UTS). Mechanics of Solids has been delivered for many years in a traditional format with lectures and problem solving tutorials. As part of a national Australian project "Enhancing Industry Exposure in Engineering Degrees", UTS in partnership with other universities and industry partners in Australia has sought industry involvement to engage students with the real-world challenges of engineering practice. PURPOSE The main objective of this project is to design, develop and implement learning modules in Mechanis of Solids that integrate industry exposure to provide context for the concepts included in this subject. DESIGN The project consisted of six guest lectures by industry representatives on topics related to typical Mechanics of Solids subject matter and two seminars on using MDSolids software. Stud...

This paper introduces a new shell element formulation and investigates the buckling behavior of thin-walled beams composed of fiber-reinforced polymer composite-laminates, which is a primary design concern for thin-walled beams composed of fiber-reinforced polymer composite-laminates due to their slenderness. Although global buckling behavior can be captured using beam-column type two-node simple finite element formulations, shell-type more sophisticated elements are needed in order to be able to capture the effects due to cross-sectional deformations. Pursuit of an efficient shell element formulation continues to date and in this study, a new flat rectangular shell element formulation is developed for the buckling analysis of thin-walled composite-laminated members. The plate component of the shell is locking-free and based on the twist-Kirchhoff theory. For the membrane component of the shell element, variational formulation employing drilling degrees of freedom is adopted. Conver...