Inelastic Analysis of Jacket Type Offshore Structures Using Fiber Elements

2002 ◽  
Author(s):  
Ali Akbar Aghakouchak ◽  
Behrouz Asgarian
Keyword(s):  
Cyclic Loading ◽  
Static Analysis ◽  
Cyclic Load ◽  
Offshore Structures ◽  
Linear Program ◽  
Braced Frame ◽  
Overall Response ◽  
Inelastic Analysis ◽  
Post Buckling ◽  
Hysteresis Behaviour

The fiber beam-column post-buckling element has been formulated and implemented in the non-linear program DRAIN-3DX to predict Buckling, Post-buckling and hysteresis behaviour of tubular Struts and Portals. In this element both material and geometric non-linearities are considered. The element is applied to simulate post buckling and hysteric response of tubular members subjected to cyclic loading. Also Psuedo-Static analysis of X-braced frame subjected to cyclic load has been perfomed. The predicted overall response matched well with the available experimental and other analytical results.

scholarly journals Vertical cyclic loading response of shallow skirted foundation in soft normally consolidated clay

2019 ◽  
Vol 56 (4) ◽  
pp. 473-483 ◽  
Author(s):  
Dimitra Zografou ◽  
Susan Gourvenec ◽  
Conleth O’Loughlin
Keyword(s):  
Steady State ◽  
Cyclic Loading ◽  
Threshold Stress ◽  
Cyclic Load ◽  
Vertical Displacement ◽  
Offshore Structures ◽  
Kaolin Clay ◽  
Centrifuge Tests ◽  
Number Of Cycles ◽  
Mode A

Skirted foundations are a potential foundation solution for a range of offshore structures, including hydrocarbon and renewable energy platforms and subsea structures. Offshore foundations can be subject to cyclic loading from environmental, installation, and operational events affecting the geotechnical response. A series of centrifuge tests have been performed on a shallow skirted foundation on normally consolidated kaolin clay under a range of vertical cyclic load sequences to investigate the effect of tensile or compressive average stress, the magnitude of the applied stress, and the effect of cyclic loading of low magnitude followed by consolidation on the foundation response. Results are presented as vertical foundation displacements normalized by the foundation geometry and interpreted within the traditional shear-strain contour approach. The findings indicate that the average, rather than maximum, vertical stress defines the foundation vertical displacement response and failure mode, a threshold stress exists below which a steady state is maintained even at a high number of cycles, and geotechnical resistance increases as a result of low-level cyclic loading followed by consolidation.

Post-buckling inelastic analysis of thin-walled metal members using the Generalised Beam Theory

2019 ◽  
Author(s):  
Miguel Abambres ◽  
Dinar Camotim ◽  
Miguel Abambres
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Beam Theory ◽  
Flow Theory ◽  
Promising Alternative ◽  
Inelastic Analysis ◽  
Post Buckling ◽  
Thin Walled ◽  
Shell Finite Element ◽  
Generalised Beam Theory

A 2nd order inelastic Generalised Beam Theory (GBT) formulation based on the J2 flow theory is proposed, being a promising alternative to the shell finite element method. Its application is illustrated for an I-section beam and a lipped-C column. GBT results were validated against ABAQUS, namely concerning equilibrium paths, deformed configurations, and displacement profiles. It was concluded that the GBT modal nature allows (i) precise results with only 22% of the number of dof required in ABAQUS, as well as (ii) the understanding (by means of modal participation diagrams) of the behavioral mechanics in any elastoplastic stage of member deformation .

In Vitro Stain Transport in Canaliculi of Rat Femora Under Cyclic Loading

2000 ◽  
Author(s):  
Bixia Li ◽  
Timothy L. Norman
Keyword(s):  
Fluid Flow ◽  
Cyclic Loading ◽  
Confocal Microscopy ◽  
Mechanical Loading ◽  
Cyclic Load ◽  
Flow Behavior ◽  
Load Level ◽  
Static Conditions ◽  
Rat Bone

Abstract In this study, rat femurs were used to test the diffusion and mechanical transport properties of a fluroscein stain tracer in microvessels of bone. Fluroscein was used as a tracer to visualize the fluid flow behavior using confocal microscopy. It was found that stain transport occurs due to diffusion under static conditions and due to mechanical loading. The transport increased with cyclic load level and frequency. Our results also show that stain transport at the canaliculi level occurs rapidly in rat bone.

scholarly journals The Effect of Vertical Loads and the Pile Shape on Pile Group Response under Lateral Two-Way Cyclic Loading

2019 ◽  
Vol 5 (11) ◽  
pp. 2377-2391
Author(s):  
Aseel Kahlan Mahmood ◽  
Jasim M Abbas
Keyword(s):  
Cyclic Loading ◽  
Cyclic Load ◽  
Lateral Displacement ◽  
Load Ratio ◽  
Pile Group ◽  
Pile Groups ◽  
Group Response ◽  
Load Intensity ◽  
Number Of Cycles ◽  
Aluminum Pipe

This paper is presented the lateral dynamic response of pile groups embedded in dry sand under influence of vertical loads and the pile shape in-group, which are subjected to the lateral two-way cyclic loads. The laboratory typical tests with pile groups (2×1) have an aluminum-pipe (i.e. circular, square) pile, embedded length to diameter of pile ratio (L/D=40) and spacing to diameter ratio (S/D) of 3, 5, 7 and 9 are used with different cyclic-load ratio (CLR) 0.4, 0.6 and 0.8. The experimental results are revealed that both the vertical and lateral pile capacity and displacement is significantly affected by the cyclic-loading factors i.e. (number of cycles, cyclic load ratio, and shape of pile) .In this study, important design references are presented. Which are explained that the response of the pile groups under cyclic lateral loading are clear affected by the attendance of vertical load and pile shape. Where, it is reduction the lateral displacement of group piles head and increase lateral capacity about (50) % compared without vertical loads. On the other side, the pile shape is a well affected to the pile response where the level of decline in lateral displacement at the pile groups head in the square pile is more than circular pile about 20 % at the same load intensity.

scholarly journals Study on the Fatigue and Durability Behavior of Structural Expanded Polystyrene Concretes

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2882 ◽  
Author(s):  
Quan You ◽  
Linchang Miao ◽  
Chao Li ◽  
Huanglei Fang ◽  
Xiaodong Liang
Keyword(s):  
Cyclic Loading ◽  
Cyclic Load ◽  
Dynamic Performance ◽  
Plain Concrete ◽  
Expanded Polystyrene ◽  
Structural Elements ◽  
Sulfate Resistance ◽  
Erosion Test ◽  
Test Process

The fatigue and durability characteristics of structural expanded polystyrene concrete (EPS) are especially important when it was applied for structural elements in long-term service. In order to study the fatigue and durability behavior of structural EPS concrete, the long-term cyclic loading experiments and wetting–drying (W-D) cyclic experiments were conducted, respectively. The structural EPS concrete was found to have a relatively large damping and a fairly low dynamic elastic modulus under long-term cyclic load, which illustrated that it had a better energy absorption effect and toughness than plain concrete of the same strength level. Even if fine cracks appeared during the cyclic loading process, the relevant dynamic performance remained stable, which indicated that the structural EPS concrete had superior fatigue stability. In W-D cyclic experiments, the structural EPS concrete exhibited superior sulfate resistance. During the erosion test process, there was a positive correlation between the mass change and the evolution of the compressive strength of the structural EPS concrete, which indicated that ΔmB could be substituted for Δf to evaluate the degree of the structural EPS concrete eroded by sulfate attack. The study focuses on the fatigue performance and sulfate resistance of structural EPS concrete and is of important engineering value for promoting practical long-term operations.

scholarly journals Small-strain behaviour and crushability of Ballyconnelly carbonate sand under monotonic and cyclic loading

2018 ◽  
Vol 55 (7) ◽  
pp. 979-987 ◽  
Author(s):  
S. Nanda ◽  
V. Sivakumar ◽  
S. Donohue ◽  
S. Graham
Keyword(s):  
Cyclic Loading ◽  
Large Scale ◽  
Sea Water ◽  
High Stress ◽  
Small Strain ◽  
Offshore Structures ◽  
Particle Breakage ◽  
Triaxial Tests ◽  
Bender Element ◽  
Carbonate Sand

In various parts of the globe, carbonate sands are found at shallow sea water depth. These types of sands are very susceptible to large-scale particle breakage. Offshore structures like wind turbines and sea defences are constructed on these types of soils. From a design perspective, it is essential to assess the extent of particle breakage and the subsequent change in soil properties that occur under working load conditions. This paper presents the data obtained from a number of drained monotonic and cyclic triaxial tests on crushable carbonate sand (“Ballyconnelly sand”) in conjunction with small-strain shear stiffness (Gmax) measurements using the bender element technique. The soils were allowed to shear under three different loading patterns to understand the factors influencing the breakage of particles. The degree of crushing was quantified and analysed based on the total energy input. It was observed that, apart from applied stress, the total strain accumulation governs the amount of particle breakage. It was observed that Gmax increased significantly under high stress ratio. Gmax also increased noticeably during resting periods without any change in loading conditions as a result of creep, and subsequently during cyclic loading although at a reduced rate.

Development and Performance Study of an Apparatus for Imparting Lateral Cyclic Load on Model Pile Foundation

2006 ◽  
Author(s):  
Sudip Basak
Keyword(s):  
Pile Foundation ◽  
Cyclic Load ◽  
Pile Group ◽  
Offshore Structures ◽  
Performance Study ◽  
Model Pile ◽  
New Apparatus ◽  
Group A ◽  
And Performance ◽  
Strength And Stiffness

The environment prevalent in ocean necessitates the pile foundations supporting offshore structures to be designed against lateral cyclic loading initiated by wave action. Such quasi-static load reversal induces deterioration in the strength and stiffness of the soil-pile system introducing progressive reduction in the bearing capacity as well as settlement of the pile foundation. To understand the effect of lateral cyclic load on pile group, a new apparatus, consisting of mechanically and electrically controlled components, has been designed and fabricated. Each of the components of this apparatus is calibrated and a series of trial tests are performed for its performance study. This paper presents detailed description of the apparatus, calibration and operating principle of each of its components, the observations made from trial experiments and the relevant conclusions drawn therefrom.

Evaluated Results of Seismic Design Approach Using Inelastic Dynamic Analysis for Equipment

2019 ◽  
Author(s):  
Ichiro Tamura ◽  
Atsushi Okubo ◽  
Yusuke Minakawa ◽  
Tadashi Iijima ◽  
Yoshio Namita ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
Static Analysis ◽  
Seismic Design ◽  
Evaluation Method ◽  
Design Approach ◽  
Model Parameters ◽  
Seismic Safety ◽  
Inelastic Analysis ◽  
Safety Margins ◽  
Core Shroud

Abstract Securing adequate seismic safety margins has been important in safety reviews regarding the seismic design of equipment and piping systems in nuclear power plants, and there exists an increasing need for a more exact method for evaluating these margins. To this end, it is reasonable to take into account the reduction of seismic responses resulting from inelastic deformation. The authors studied this approach utilizing an elastic allowable limit in existing standard. The applicability of the proposed evaluation method was investigated by comparison with the conventional evaluation method. The proposed method consists of an inelastic dynamic analysis and an elastic-static analysis. The elastic-static analysis uses a load obtained from the inelastic dynamic analysis. For the investigation, the result obtained from the proposed method was compared with that obtained from the conventional elastic analysis to quantify the reduction in responses leading to seismic safety margins. For the comparison, the authors constructed three models that simulate a cantilever-type beam, four-legged tank, and core shroud and applied them to the analysis herein, and the applicability of our method was discussed for these models. In this paper, we present three topics. First, we present a scheme for developing the design approach of using inelastic analysis. Second, we report a sensitivity study of model parameters, such as yielding stress and second stiffness, done by analyzing the cantilever-type beam for the proposed method. Finally, we report the application of the method to the four-legged tank and core shroud.

Offshore Pile Foundation Subjected to Lateral Cyclic Load in Layered Soil

2014 ◽  
Vol 891-892 ◽  
pp. 24-29 ◽  
Author(s):  
Sudip Basack ◽  
Abhik Kumar Banerjee
Keyword(s):  
Numerical Model ◽  
Pile Foundation ◽  
Loading Condition ◽  
Cyclic Load ◽  
Complex Loading ◽  
Offshore Structures ◽  
Layered Soil ◽  
Interactive Performance ◽  
Parametric Studies ◽  
Combined Action

The pile foundations supporting offshore structures are required to be designed against cyclic load, moments and torques initiated by a combined action of waves, wind, tides, currents, etc. Such a complex loading condition produces progressive degradation in the pile-soil interactive performance which is likely to introduce significant reduction in bearing capacity with increased settlement and displacements. This paper is based on a numerical model developed by the Authors to study the response of pile foundation under lateral cyclic load in layered soil. The model is validated with a field test data and thereafter, parametric studies have been carried out. A brief description of the works conducted and the major conclusions drawn are highlighted in this paper.

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