Limit States for Deepwater Flowlines and Risers: Review of the Research Activities at the Submarine Technology Laboratory/COPPE

2003 ◽  
Author(s):  
S. F. Estefen ◽  
T. A. Netto ◽  
I. P. Pasqualino
Keyword(s):  
Ultimate Strength ◽  
Large Scale ◽  
Failure Modes ◽  
Numerical Models ◽  
Experimental Tests ◽  
Limit States ◽  
Collapse Pressure ◽  
Research Activities ◽  
Structural Resistance ◽  
Buckle Arrestors

Research activities related to the limit states of flowlines and risers conducted at the Submarine Technology Laboratory / COPPE in cooperation with PETROBRAS are presented. The motivation for most of the research programs is associated with deepwater challenges arising from the rigid pipe installations at Campos Basin. Initially ultimate strength of intact pipes are investigated together with aspects related to residual strength, buckling propagation and buckle arrestors. Based on the experimental results numerical models have been correlated in order to be used to generate results for full scale steel pipes. Ultimate strength curves have been then produced as well as the analytical equation representative of these curves. Experimental tests of buckling propagation for small and large scale pipes have also been performed to obtain the bias factor for different equations proposed in the literature. Based on this study an equation for propagation pressure has been recommended. In addition, ring and cylinder buckle arrestors have been tested in order to propose an expression relating crossing over pressure with the arrestor geometries. An overview of the studies aiming at establishing the influence of the reeling method of installation on the failure modes of flowlines and steel catenary risers is presented. It is emphasized the influence of cross-section ovality and weld defect amplification due to plastic bending on collapse pressure and fatigue life, respectively. Finally, the development of a new concept of sandwich pipe for ultra deepwater, combining structural resistance and thermal insulation is discussed.

Reeling Effect on the Ultimate Strength of Sandwich Pipes

2005 ◽  
Author(s):  
Xavier Castello ◽  
Segen F. Estefen
Keyword(s):  
Ultimate Strength ◽  
Numerical Models ◽  
Kinematic Hardening ◽  
External Pressure ◽  
Combined Loading ◽  
Collapse Pressure ◽  
Finite Element Software ◽  
Structural Resistance ◽  
Longitudinal Bending ◽  
Full Scale Tests

Sandwich pipes composed of two steel layers separated by a polypropylene annulus can be used for the transport of oil&gas in deepwaters, combining high structural resistance with thermal insulation in order to prevent blockage by paraffin and hydrates. In this work, sandwich pipes with typical inner diameters of those employed in the offshore production are analyzed numerically to evaluate the ultimate strength under external pressure and longitudinal bending as well as the effect of the reeling installation method on the collapse pressure. Numerical models were developed using the commercial finite element software ABAQUS. The validation was based on experimental results. The analyses for combined loading were performed using symmetry conditions and the pipe was reduced to a ring with unitary length. The analysis of bending under a rigid surface was simulated numerically according to the experiments performed using a bending apparatus especially built for full scale tests. Symmetry conditions were employed in order to reduce the analysis to a quarter of a pipe. Mesh sensitivity studies were performed to obtain an adequate mesh refinement in both analyses. The collapse pressure was simulated numerically either for the pre or post reeling process. Bauschinger effect was included by using kinematic hardening plasticity models. The influences of plasticity and out-of-roundness on the collapse pressure have been confirmed.

scholarly journals Displacement Study of a Large-Scale Freeform Timber Plate Structure Using a Total Station and a Terrestrial Laser Scanner

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 413 ◽  
Author(s):  
Anh Chi Nguyen ◽  
Yves Weinand
Keyword(s):  
Large Scale ◽  
Numerical Models ◽  
Laser Scanner ◽  
Experimental Tests ◽  
Point Clouds ◽  
Element Model ◽  
Experimental Investigations ◽  
Bottom Surface ◽  
Terrestrial Laser Scanner ◽  
Total Station

Recent advances in timber construction have led to the realization of complex timber plate structures assembled with wood-wood connections. Although advanced numerical modelling tools have been developed to perform their structural analysis, limited experimental tests have been carried out on large-scale structures. However, experimental investigations remain necessary to better understand their mechanical behaviour and assess the numerical models developed. In this paper, static loading tests performed on timber plate shells of about 25 m span are reported. Displacements were measured at 16 target positions on the structure using a total station and on its entire bottom surface using a terrestrial laser scanner. Both methods were compared to each other and to a finite element model in which the semi-rigidity of the connections was represented by springs. Total station measurements provided more consistent results than point clouds, which nonetheless allowed the visualization of displacement fields. Results predicted by the model were found to be in good agreement with the measurements compared to a rigid model. The semi-rigid behaviour of the connections was therefore proven to be crucial to precisely predict the behaviour of the structure. Furthermore, large variations were observed between as-built and designed geometries due to the accumulation of fabrication and construction tolerances.

scholarly journals Experimental Nondestructive Test for Estimation of Buckling Load on Unstiffened Cylindrical Shells Using Vibration Correlation Technique

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Kaspars Kalnins ◽  
Mariano A. Arbelo ◽  
Olgerts Ozolins ◽  
Eduards Skukis ◽  
Saullo G. P. Castro ◽  
...  
Keyword(s):  
Large Scale ◽  
Numerical Models ◽  
Cylindrical Shells ◽  
Laser Scanner ◽  
Experimental Tests ◽  
Buckling Load ◽  
Correlation Technique ◽  
Thin Walled Structures ◽  
Instability Point ◽  
Thin Walled

Nondestructive methods, to calculate the buckling load of imperfection sensitive thin-walled structures, such as large-scale aerospace structures, are one of the most important techniques for the evaluation of new structures and validation of numerical models. The vibration correlation technique (VCT) allows determining the buckling load for several types of structures without reaching the instability point, but this technique is still under development for thin-walled plates and shells. This paper presents and discusses an experimental verification of a novel approach using vibration correlation technique for the prediction of realistic buckling loads of unstiffened cylindrical shells loaded under axial compression. Four different test structures were manufactured and loaded up to buckling: two composite laminated cylindrical shells and two stainless steel cylinders. In order to characterize a relationship with the applied load, the first natural frequency of vibration and mode shape is measured during testing using a 3D laser scanner. The proposed vibration correlation technique allows one to predict the experimental buckling load with a very good approximation without actually reaching the instability point. Additional experimental tests and numerical models are currently under development to further validate the proposed approach for composite and metallic conical structures.

scholarly journals In-Plane Behaviour of Masonry Walls: Numerical Analysis and Design Formulations

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5780
Author(s):  
Thomas Celano ◽  
Luca Umberto Argiento ◽  
Francesca Ceroni ◽  
Claudia Casapulla
Keyword(s):  
Failure Modes ◽  
Shear Failure ◽  
Numerical Models ◽  
Experimental Tests ◽  
Element Model ◽  
Masonry Walls ◽  
Analysis And Design ◽  
Non Linear ◽  
Failure Loads ◽  
Modelling Approaches

This paper presents the results of several numerical analyses aimed at investigating the in-plane resistance of masonry walls by means of two modelling approaches: a finite element model (FEM) and a discrete macro-element model (DMEM). Non-linear analyses are developed, in both cases, by changing the mechanical properties of masonry (compressive and tensile strengths, fracture energy in compression and tension, shear strength) and the value of the vertical compression stress applied on the walls. The reliability of both numerical models is firstly checked by means of comparisons with experimental tests available in the literature. The analyses show that the numerical results provided by the two modelling approaches are in good agreement, in terms of both failure loads and modes, while some differences are observed in their load-displacement curves, especially in the non-linear field. Finally, the numerical in-plane resistances are compared with the theoretical formulations provided by the Italian building code for both flexural and shear failure modes and an amendment for the shape factor ‘b’ introduced in the code formulation for squat walls is proposed.

scholarly journals Estimation of friction contribution in the behavior of steel-concrete composite beams with flexible shear connectors

2014 ◽  
Vol 67 (3) ◽  
pp. 253-258 ◽  
Author(s):  
Gilson Queiroz ◽  
Hermes Carvalho ◽  
Francisco Rodrigues ◽  
Michèle Pfeilo
Keyword(s):  
Composite Beam ◽  
Numerical Models ◽  
Experimental Tests ◽  
Composite Beams ◽  
Shear Connector ◽  
Limit States ◽  
Shear Connectors ◽  
Composite Slabs ◽  
Strength And Stiffness ◽  
Ultimate Limit

A shear connector, developed to be applied to a composite beam whose steel profile is a thin-walled box profile, displayed much greater flexibility than the conventional welded shear connector, leading to particular issues in the composite beam behaviour. One of these issues is the role played by friction at the interface between the steel profile and the slab which, under particular circumstances, may be relevant for serviceability limit states and also for ultimate limit states. The Brazilian and American Standards do not yet recognize the friction contribution in the behaviour of composite beams, though they recognize this contribution in composite slabs. This paper presents the experimental tests carried out with and without friction contribution on simple supported composite beams with flexible connectors and the numerical models developed to simulate the behaviour of the tested beams. The experimental tests revealed significant increases in strength and stiffness of the composite beam due to friction contribution and the comparisons between numerical and experimental results displayed good correlations.

Parametric Study of Static Strength of Multiplanar KK-Joints：Square Chords and Circular Braces

2011 ◽  
Vol 250-253 ◽  
pp. 1527-1532
Author(s):  
Ai Guo Chen ◽  
Wei Liang Huang ◽  
Rui Zeng Shan ◽  
Qing Shan Yang
Keyword(s):  
Parametric Study ◽  
Large Scale ◽  
Failure Modes ◽  
Numerical Models ◽  
Axial Loading ◽  
Steel Structure ◽  
Geometric Parameters ◽  
Truss Structures ◽  
Hollow Section ◽  
Circular Hollow Section

Pre-stressed spatial tubular truss system is adopted in steel roof truss structures of China International Exhibition Center New Venue. Bottom chord joints are multiplanar KK-joints consisting of chord with square hollow section and brace with circular hollow section. However, not only that relatively little research has been carried out on such joints, but also that no detailed design guidance on KK-type joints consisting of chord with square hollow section and brace with circular hollow section can be found Current design code for steel structure (GB 50017-2003). This paper reports the study into the strength of this type of KK-joints under axial loading. The numerical models were adopted, and several various geometric parameters which affect the strength and failure modes, were investigated. It was indicated that the geometric parameters affects significantly the ultimate capacity and failure modes of the joints. The varied relationship of the strength and failure mode with parameter varying was studied in detail. The results of the work presented provide initial discussion on behavior of this type of KK-joints and lay the foundation for a future large-scale parametric study and put out design formula.

Adhesion Effect on the Ultimate Strength of Sandwich Pipes

2006 ◽  
Author(s):  
Xavier Castello ◽  
Segen F. Estefen
Keyword(s):  
Ultimate Strength ◽  
Structural Strength ◽  
Numerical Models ◽  
Maximum Shear Stress ◽  
Experimental Tests ◽  
External Pressure ◽  
Friction Model ◽  
Shear Loads ◽  
Longitudinal Bending ◽  
Contact Models

Sandwich pipes composed of two steel layers separated by a polypropylene annular can be used for deepwater oil&gas transportation. They combine high structural strength to resist external pressure with thermal insulation to prevent blockage by paraffin and hydrate. In this work, experimental tests and numerical models were employed to verify the influence of the inter-layer adhesion on the ultimate strength under external pressure and longitudinal bending of a sandwich pipe prototype. The maximum shear stress obtained from sandwich pipe specimens bonded with a specific adhesive indicated the adhesion levels to be adopted in the numerical simulations. Two contact models were employed to simulate the bonding and slipping conditions between layers, one adopting a friction model and the other including non-linear springs between metal and polymer nodes. The latter is an adapted solution to simulate both tension and shear loads. As expected for a sandwich structure, the structural strength is strongly dependent on the interface stickiness. The analyzed geometry is able to withstand a water depth up to 3,000 meters with a bonding strength corresponding to only 10% of the idealized perfect adhesion condition.

Experimental Investigation of Residual Ultimate Strength of Damaged Metallic Pipelines

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Jie Cai ◽  
Xiaoli Jiang ◽  
Gabriel Lodewijks ◽  
Zhiyong Pei ◽  
Ling Zhu
Keyword(s):  
Ultimate Strength ◽  
Structural Damage ◽  
Large Scale ◽  
Failure Modes ◽  
Bending Strength ◽  
Metal Loss ◽  
Pipe Surface ◽  
Comparison Results ◽  
Mechanical Interference ◽  
Bending Capacity

The ultimate strength of metallic pipelines will be inevitably affected when they have suffered from structural damage after mechanical interference. The present experiments aim to investigate the residual ultimate bending strength of metallic pipes with structural damage based on large-scale pipe tests. Artificial damage, such as a dent, metal loss, a crack, and combinations thereof, is introduced to the pipe surface in advance. Four-point bending tests are performed to investigate the structural behavior of metallic pipes in terms of bending moment–curvature diagrams, failure modes, bending capacity, and critical bending curvatures. Test results show that the occurrence of structural damage on the pipe compression side reduces the bending capacity significantly. Only a slight effect has been observed for pipes with damage on the tensile side as long as no fracture failure appears. The possible causes that have introduced experimental errors are presented and discussed. The test data obtained in this paper can be used to further quantify damage effects on bending capacity of seamless pipes with similar D/t ratios. The comparison results in this paper can facilitate the structural integrity design as well as the maintenance of damaged pipes when mechanical interference happens during the service life of pipelines.

scholarly journals A Preliminary Study of the Failure Modes and Process of Landslide Dams Due to Upstream Flow

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1115 ◽  
Author(s):  
Xinghua Zhu ◽  
Jianbing Peng ◽  
Cheng Jiang ◽  
Weilong Guo
Keyword(s):  
Large Scale ◽  
Failure Modes ◽  
Mine Waste ◽  
Failure Process ◽  
Landslide Dam ◽  
Experimental Tests ◽  
Field Investigation ◽  
Dam Failure ◽  
Experimental Conditions ◽  
Landslide Dams

In the process of mineral development, large-scale flash floods (or debris flows) can be induced by the failure of landslide dams formed by the disorganized stacking of mine waste. In this study, the modes and processes of mine waste dam failures were explored using 13 experimental tests based on the field investigation of landslide dams in the Xiaoqinling gold mining area in China. Our 13 mine waste dam experiments exhibited three failure modes: (i) Piping, overtopping, and erosion; (ii) overtopping and soil collapse; and (iii) overtopping and erosion. In addition, the failure processes of the landslide dams included impoundment, seepage, overtopping, and soil erosion. Different experimental conditions would inevitably lead to different failure processes and modes, with the failure modes being primarily determined by the seepage characteristics. Overtopping was the triggering condition for dam failure. The landslide dam failure process was determined based on the particle size of the mine waste and the shape of the dam. These findings will provide a scientific reference for the prevention and mitigation of natural hazards in mining areas.

Numerical Modelling of the Experimental Response of SRG Systems

2019 ◽  
Vol 817 ◽  
pp. 37-43
Author(s):  
Marialaura Malena ◽  
Marialuigia Sangirardi ◽  
Francesca Roscini ◽  
Gianmarco de Felice
Keyword(s):  
Numerical Modelling ◽  
Large Scale ◽  
Numerical Models ◽  
High Strength ◽  
Experimental Tests ◽  
Tensile Tests ◽  
Technical Committee ◽  
Structural Performance ◽  
Rilem Technical Committee ◽  
Test Procedures

Modern repairing and retrofitting methods for existing structures make use of composite materials, consisting of high strength textiles and a matrix, which can be either polymeric or inorganic. These kinds of techniques have been largely applied to masonry structures, since they significantly improve structural performance with a small increase of weight and a minimum invasiveness. However, the application of organic gluing agents on masonry has revealed some well-known drawbacks, which are almost all overcome resorting to inorganic matrixes, namely cement or lime mortars. An entire class of composites is thus identified as TRM (Textile Reinforced Mortars) or FRCM (Fibre Reinforced Cementitious Matrices). Among them, Steel Reinforced Grout (SRG) are characterized by Ultra High Tensile Strength Steel (UHTSS) cords embedded in mortar matrix and their use to improve the structural performance of existing historical masonry buildings is becoming more and more diffused. Qualification tests and acceptance criteria for SRG have just been defined. Nonetheless, numerical simulation of current available test procedures is mandatory to identify peculiar aspects of the response that at a following stage become an integral part of large scale models, when entire reinforced structures or portions need to be analysed. To this end, this work presents the numerical modelling of two different direct tensile tests on SRG systems: the Clamping-grip setup (RILEM Technical Committee 232-TDT 2016) and the Clevis-grip setup (ICC-ES AC434 2016). Numerical models able to replicate experimental tests and catch fundamental differences in their failure mechanisms are present

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