Local joint flexibility of completely overlapped tubular joints under in-plane bending

The work presents the Finite element study of the effect of elliptical chords on the static and dynamic strength of tubular T-joints using ANSYS. Two different geometry configurations of the T-joints have been used, namely Type-1 and Type-2. An elastic analysis has been considered. The Static loading conditions used are: axial load, compressive load, In-plane bending (IPB) and Out-plane bending (OPB). The natural frequencies analysis (dynamic loading condition) has also been carried out. The geometry configurations of the T-joints have been used, vertical tubes are called brace and horizontal tubes are called chords. The joint consists of brace joined perpendicular to the circular chord. In this case the ends of the chord are held fixed. The material used is mild steel. Using ANSYS, finite element modeling and analysis of T-joint has been done under the aforementioned loading cases. It is one of the most powerful methods in use but in many cases it is an expensive analysis especially due to elastic–plastic and creep problems. Usually, three dimensional solid elements or shell elements or the combination of two types of elements are used for generating the tubular joints mesh. In tubular joints, usually the fluid induced vibrations cause the joint to fail under resonance. Therefore the natural frequencies analysis is also an important issue here. Generally the empirical results are required as guide or comparison tool for finite element investigation. It is an effective way to obtain confidence in the results derived. Shell elements have been used to model the assembled geometry. Finite element ANSYS results have been validated with the LUSAS FEA and experimental results, that is within the experimentation error limit of ten percentage.

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A numerical investigation of static resistance of welded planar steel tubular joints under in-plane and out-of-plane bending at elevated temperatures

Engineering Structures ◽

10.1016/j.engstruct.2019.109622 ◽

2019 ◽

Vol 199 ◽

pp. 109622 ◽

Cited By ~ 1

Author(s):

E. Ozyurt ◽

Y.C. Wang

Keyword(s):

Numerical Investigation ◽

Elevated Temperatures ◽

Tubular Joints ◽

Out Of Plane ◽

Plane Bending ◽

Static Resistance

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Nonlinear Analysis of Offshore Platforms Subjected to Earthquake Loading Considering the Effects of Joint Flexibility

Volume 1: Offshore Technology ◽

10.1115/omae2009-79851 ◽

2009 ◽

Author(s):

S. Samadani ◽

A. A. Aghakouchak ◽

J. Mirzadeh Niasar

Keyword(s):

Structural Analysis ◽

Nonlinear Analysis ◽

Offshore Structures ◽

Offshore Platforms ◽

Joint Flexibility ◽

Modeling And Analysis ◽

Shell Elements ◽

Tubular Joints ◽

Two Samples ◽

Non Linear

In a conventional method of structural analysis, for modeling and analysis of jacket type offshore platforms, member connections are assumed to be rigid. In this method, members are rigidly connected which means there is no axial or rotational deformation at the end of brace member relative to chord axis. However in reality local deformations occur at chord surface due to applied loads from braces, which mean tubular joints are considerably flexible especially in non linear range of deformations. Therefore results of analysis based on rigid connections assumption differ from real behavior of the structure. Various research works have been carried out in the past on tubular joints and different methods have been presented in order to include the effect of joint flexibility in structural analysis. Most of these methods are just valid in elastic range but some non-linear methods have also been developed for simple tubular joints. In order to carry out a nonlinear analysis on a 3-D model of an offshore platform with multi-brace / multi-planar tubular joints, none of these simplified methods is applicable. In this case a complete model of tubular joints by non-linear shell elements is the most accurate one which is not only valid for non-linear analyses but also covers all type of tubular joints. In this paper two samples of offshore platforms are studied. These platforms are modeled using the following approaches: 1. No modeling of joints as structural elements (rigid connections). 2. Modeling of joint can with nonlinear shell elements (flexible connection). Different types of static non-linear analysis (Push over) are carried out and results are compared. In order to evaluate the results and compare this type of modeling with simplified methods included in professional software for the analysis of offshore structures, aforementioned platforms are also analyzed using the Fessler and MSL models to include effects of joint flexibility. The results of these types of modeling are also compared with the previous ones.

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An Improved Joint Model and Equations for Flexibility of Tubular Joints

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.2919850 ◽

1990 ◽

Vol 112 (2) ◽

pp. 157-168 ◽

Cited By ~ 20

Author(s):

Y. Ueda ◽

S. M. H. Rashed ◽

K. Nakacho

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Bending Moment ◽

Joint Model ◽

Initial Stiffness ◽

Element Analysis ◽

Joint Flexibility ◽

Elastic Plastic ◽

Tubular Joints ◽

Different Types

In tubular frames with simple joints, joints may show considerable flexibility in the elastic as well as the elastic-plastic ranges. Such flexibility may have large effects on the behavior of the structure as a whole. In a previous paper, an effective simple model of tubular joints is developed. The model takes account of joint flexibility in the elastic as well as the elastic-plastic ranges based on elastic-fully plastic load-displacement relatioships. In this paper an improved joint model is presented to provide better accuracy while maintaining simplicity. The accuracy of the model is confirmed through comparisons with results of finite element analysis. Equations to evaluate the initial stiffness of tubular T and Y-joints when braces are subjected to axial compression or in-plane bending moment are also presented. Such equations for different types of joints in different loading conditions are needed in order to avoid expensive calculations to evaluate the initial stiffness of joints.

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Stress Concentrations in DT/X Square-to-Square and Square-to-Round Tubular Joints

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.2920132 ◽

1994 ◽

Vol 116 (2) ◽

pp. 49-55 ◽

Cited By ~ 2

Author(s):

A. K. Soh ◽

C. K. Soh

Keyword(s):

Stress Concentration ◽

Bending Moment ◽

Bending Moments ◽

Axial Loads ◽

Stress Concentrations ◽

Tubular Joints ◽

Out Of Plane ◽

Concentration Factors ◽

Plane Bending ◽

Stress Concentration Factors

A parametric stress analysis of DT/X square-to-square and square-to-round tubular joints subjected to axial loads, in-plane, and out-of-plane bending moments has been performed using the finite element technique in order to provide a sound basis for using such sections in the design of complex structures. The results of this analysis are presented as a set of equations expressing the stress concentration factor as a function of the relevant geometric parameters for various loading conditions. A comparison is made between the results obtained for square-to-square and square-to-round tubular joints and those obtained for round-to-round tubular joints by other researchers. In general, the stress concentration factors for square-to-square tubular joints are the highest, followed by those of the corresponding round-to-round joints, with those of the corresponding square-to-round joints the lowest when the joints are subject to axial loads. In the case of in-plane bending moment, the stress concentration factors for square-to-square joints are generally still the highest, but followed by those of the corresponding square-to-round joints, with those of the corresponding round-to-round joints the lowest. However, the stress concentration factors for the three types of joint are comparable when they are subject to out-of-plane bending moments.

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