Bolted end-plate steel connections have become more popular due to ease of fabrication. This paper presents a three dimension Finite Element Model (FEM), using the multi-purpose software ABAQUS, to study the effect of different geometrical parameters on the ultimate behavior of the connection. The proposed model takes into account material and geometrical non-linearities, initial imperfection, contact between adjacent surfaces and the pretension force in the bolts. The Finite Element results are calibrated with published experimental results ''briefly reviewed in this paper'' and verified that the numerical model can simulate and analyze the overall and detailed behavior of different types of bolted endplate steel connections. Using verified FEM, parametric study is then carried out to study the ultimate behavior with variations in: bolt diameter, end-plate thickness, length of column stiffener, angle of rib stiffener. The results are examined with respect to the failure modes, the evolution of the resistance, the initial stiffness, and the rotation capacity. Finally, the ultimate behavior of the bolted end-plate steel connection is discussed in detail, and recommendations for the design purpose are made.

A stub-girder floor system is a composite system constructed from a continuous steel beam and a reinforced concrete slab separated by a series of short, typically wide, flange sections called stubs. The finite element method has been used in the analysis of this composite system where it is capable to represent the constituent parts, adopt adequate elements and use appropriate solution techniques. As the behavior of stub-girders presents significant nonlinear effects, it is fundamental that the interaction of all different components should be properly modeled as well as the interface behavior. The present work focuses on the modeling of stub-girders with full and partial shear connection in two and three dimensions. The proposed model contains all the main structural parameters and their associated nonlinearities (concrete slab, steel beam, stubs, and shear connectors). In this model, the shear connectors are modeled as springs to consider the geometry of studs in addition to the nonlinearity due to the interaction between the shear connector and the concrete slab. Tests and numerical results available in the literature are used to validate the models. Based on the proposed finite element model, an extensive parametric study of stub-girders is performed, considering the material properties, relative dimensions and shear connector characteristics, where valuable recommendations and conclusions are achieved.ª 2010 Faculty of Engineering, Alexandria University. Production and hosting by Elsevier B.V.All rights reserved.

The aim of this paper is to carry out extensive numerical investigations about the effect of various parameters on both buckling loads and ultimate behavior of continuous partially composite castellated beams under vertical loads. Efficient nonlinear 3D Finite Element Model using ABAQUS software is developed. The initial geometric imperfection and material nonlinearities were carefully considered in the analysis. At first, Eigenvalue analysis is carried out to obtain the elastic buckling load and the corresponding buckling mode. In order to trace the entire load-deflection curve, the first buckling mode is factored and inserted into the inelastic geometrical nonlinear analysis of the beam as initial imperfection. The reliability of the model is demonstrated by comparisons with experiments and with alternative numerical and analytical analyses for continuous composite beam. Different modeling techniques available in ABAQUS are used for the modeling of the shear connectors. In addition, a parametric study is carried out to investigate the effect of change in cross-section geometries, beam length, alignment of stiffeners, concrete strength, steel strength and concrete slab thickness on the both buckling and the overall structural behavior of continuous partially composite castellated beams under vertical loads. A total of 96 partially composite castellated beams are studied. Based on the findings of the finite element results, a number of recommendations on the methods of modeling and on the design of continuous steel-concrete composite castellated beams are suggested.

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This paper presents a direct time-domain three dimensional (3D) numerical procedure to simulate the transient response of very large floating structures (VLFS) subjected to unsteady external loads as well as moving mass. The proposed procedure employs the Boundary Element and Finite Element methods (FEM-BEM).The floating structure and the surrounding fluid are discretized by 4-node isoparametric finite elements (FE) and by 4-node constant boundary elements (BE), respectively. Structural analysis is based on Mindlin's plate theory. The equation of motion is constructed taking into account the effect of inertia loading due to the moving mass. In order to obtain the hydrodynamic forces (added mass and radiation damping), the coupled natural frequencies are first obtained by an iterative method, since hydrodynamic forces become frequency-dependent. Then the Newark integration method is employed to solve the equation of motion for structural system. In order to prove the validity of the present method, a FORTRAN program is developed and numerical examples are carried out to compare its results with those of published experimental results of a scale model of VLFS under a weight drop and airplane landing and takeoff in still water condition. The comparisons show very good agreement.