Buckling strength and imperfection sensitivity are major considerations in the analysis and design of structural shell forms. In this paper, the buckling load and its sensitivity to through cracks with variable length and orientation, and buckling mode shapes of cylindrical shells under torsional loading are studied. A general FINITE ELEMENT model has been proposed and capability of this model in predicting the torsional buckling load has been verified. The model is then applied to the analysis of cylindrical shells with circumferential, axial and angled cracks of various lengths. The results are presented in the form of tables and normalized figures.      

In this research a comprehensive FINITE ELEMENT program was developed in order to carry out an elasto perfectly plastic analysis of geogrid reinforcement of a model pavement. Qualitative agreement is seen between the numerical results and experiment. The results indicate the influence of geogrid in reduction of vertical deformation of pavements. It is also seen that for strong subgrade, the optimum position of geogrid in base layer is at the level of maximum lateral displacement. This indicates that the main mechanism of geogrid is to restrain soils from lateral displacement through interlocking with the particles. Furthermore, the results show that if deformation of subgrade is concerned (e.g. weak subgrade) the optimum position of geogrid is at the base-subgrade interface due to substantial reduction of horizontal stress transferred subgrade.

This paper presents the nonlinear FINITE ELEMENT Analysis (FEA) that has been carried out to simulate the behaviour of failure modes of Reinforced Concrete (RC) beams strengthened in flexure and shear by Fibre Reinforced Polymer (FRP) laminates. Four beams were modeled in FEM software using ANSYS. In those four beams, two beams were control beams without FRP and other two beams were Carbon Fibre Reinforced Polymer (CFRP) strengthened beams. A quarter of the full beam was used for modelling by taking advantage of the symmetry of the beam, loading and boundary conditions. From the analyses the load deflection relationships until failure, and crack patterns were obtained and compared with the experimental results available in the Literatures. The load deflection plots obtained from numerical studies show good agreement with the experimental plots reported by Balamuralikrishnan & Antony Jeyasehar, and Amer M. Ibrahim & Mohammed Sh. Mahmood. There was a difference in behaviour between the RC beams strengthened with and without CFRP layers. The crack patterns obtained in FEA in the beams were also presented. The use of computer software to model these ELEMENTs is much faster, and extremely cost-effective. Therefore, modelling of experimental beams can be adoptable in ANSYS. Validation of experimental results can also be done using ANSYS.

In recent years, linked bridge deck ELEMENTs have gained popularity for facilitating more durable components in bridgedecks, but these components require field-applied connections for constructing the entire bridge. Ultra-high-performanceconcrete (UHPC) is started to be a major material for closure pours in bridges and various Department of Transportationshave been developing guidelines. UHPC is known by its superior quality than conventional concrete in terms of constructability, strength and durability. So far, very limited data are available on the FINITE-ELEMENT modeling (FEM) of hybrid bridgedeck connections. In this study, FEMs have been presented to define the crucial factors affecting the response of bridgehybrid deck panel system under monotonic loads. The commercial software ABAQUS was used to validate the modes andto generate the data presented herein and the concrete damage plasticity was used to simulate both conventional concrete andUHPC. Numerical results were validated using available experimental data. The key parameters studied were the mesh size, the dilation angle, reinforcement type, concrete models, steel properties, and the contact behavior between the UHPC andthe conventional concrete. The models were found to capture the load– deflection response of experimental results, failuremodes, crack patterns and ductility indices show satisfactorily response. A sensitivity test was also conducted by consideringvarious key parameters such as concrete and steel constitutive models and their associated parameters, mesh size, andcontact behavior. It is perceived that increasing the dilation angle leads to an increase in the initial stiffness of the model. Thedamage in concrete under monotonic loading is found higher in normal concrete than UHPC with no signs of de-bondingbetween the two materials. Changing the dilation angle from 20° to 40° results in an increase of 7. 81% in ultimate load for thepanel with straight reinforcing bars, whereas for the panel with headed bars, the increase in ultimate load was found 8. 56%.

In this paper, an efficient numerical model for solution of the two-dimensional unsteady dam-break problem is described. The model solves the shallow water equations through Characteristic-Based Split (CBS) FINITE ELEMENT method. The formulation of the model is based upon the fractional time step technique primarily used in the FINITE difference method for the incompressible Navier-Stokes equations. In addition to well-known advantages of the FINITE ELEMENT discretization in introducing complex geometries and making accurate results near the boundaries, the CBS utilizes interesting advantages. These include the ability of the method to simulate both compressible and incompressible flows using the same formulation. Improved stability of the CBS algorithm along with its capability to simulate both sub-and super-critical flows are other main advantages of the method. These useful advantages of the algorithm introduce the CBS as a unique procedure to solve fluid dynamics problems under various conditions. Since dam-break problem has principally a high non-linear nature, the model is verified firstly by modeling one-dimensional problems of dam-break and bore formation problems. Furthermore, application of the model to a two-dimensional hypothetical dam-break problem shows the robustness and efficiency of the procedure. Despite the high non-linearity nature of the solved problems, the computational results, compared with the analytical solutions and reported results of other numerical models, indicate the favorable performance of the used procedure in modeling the dam-break problems.

This article demonstrates a new approach for nonlinear FINITE ELEMENT analysis. The methodology is very suitable and gives very accurate results in linear as well as in nonlinear range of the material behavior. Proposed methodology can be regarded as stress based FINITE ELEMENT analysis as it is required to define the stress distribution within the structural body with structural idealization and modelling assumptions. The methodology eliminates the lengthy and tedious procedure of step by step and then iterative procedure adopted classically for nonlinear analysis problems. One dimensional problem of a simple bar loaded axially is solved to formulate the basic principles. Two dimensional problem of a cantilever beam bending and a torsional problem are solved for further demonstrating and strengthening the method. Results of torsional problem are verified with experimental results. The method is applicable for material nonlinear analysis only.

Graph theoretical force methods are highly efficient for the generation of sparse and banded null bases and flexibility matrices, however, these methods require special considerations when the support conditions are indeterminate. These considerations with special methods are presented in this paper which leads to efficient utilization of graph theoretical force method for indeterminate support conditions with no substantial decrease in sparsity.