Parametric Study on the Effect of Geometric Imperfections on the Bending Capacity of High-Strength Linepipes

2008 ◽  
Author(s):  
Takashi Sato ◽  
Yoshiki Mikami ◽  
Masahito Mochizuki ◽  
Nobuhisa Suzuki ◽  
Masao Toyoda
Keyword(s):  
Internal Pressure ◽  
Parametric Study ◽  
High Strength ◽  
Yield Ratio ◽  
Experimental Results ◽  
Material Strength ◽  
Empirical Formulas ◽  
Geometric Imperfections ◽  
Geometric Imperfection ◽  
Bending Capacity

It is important to determine the bending capacity of linepipes for strain-based design. Several empirical formulas have been proposed in order to evaluate the bending capacity of linepipes, which are presented in terms of the D/t ratio, the internal pressure, the yield ratio and the material strength. FEAs considering these parameters have been performed, however, it has been reported that the results do not always agree with experimental results. It has already been clarified that the geometric imperfections must be considered so that two types of results agree. This paper presents the results of a parametric study examining the effect of geometric imperfections on the bending capacity of linepipes. In addition, the effect of combining two or all of three types of geometric imperfections on the bending capacity was also investigated. When a single imperfection was taken into consideration in the FE models, it was quantitatively clarified that the bending capacity of linepipes improves with a decreasing geometric imperfection. Moreover, when combined geometric imperfections were taken into consideration in the FE models, it was also clarified that the largest imperfection tends to dominate the results and the smallest imperfection does not necessarily affect the bending capacity of the linepipes.

scholarly journals EFFECT OF IMPACT LOAD ON THE PERFORMANCE OF CONCRETE SLABS REINFORCED BY CFRP BARS

2021 ◽  
Vol 25 (01) ◽  
pp. 68-79
Author(s):  
Hind T. Khamies ◽  
◽  
Mu’taz K. Medhlom ◽  
Keyword(s):  
Impact Load ◽  
High Strength ◽  
Shear Capacity ◽  
Experimental Results ◽  
Slab Thickness ◽  
Empirical Formulas ◽  
Steel Bars ◽  
Rc Slabs ◽  
The Cost ◽  
Frp Bars

Using FRP bars in the concrete structures under harsh environment produces extension of those service life and dropping of the cost of their lifecycle. This study investigated the influence of slab thickness, material of rebar, arrangement of reinforcement and mass’s dropped on the dynamic behavior of RC slabs by using laboratory experiments. Seven specimens 1550×1550 mm dimension with two thickness 120 and 150mm, single control specimen reinforced with steel bars and six specimens reinforced by CFRP bars were experimentally investigated under sequential dropping-weight ranged from 50 to 150kg, it was a rigid steel projectile, used to apply impacting load. 2.5m was the height of dropping. For estimated penetration depth, three empirical formulas have been used, ACE formulae was preferable predictor than other formulas. Different codes were used to calculation punching shear capacity and critical velocity of perforation and compared the experimental results with these codes. The experimental results showed that the shear properties of slabs have a significant effect in their general behavior. And preferable performance in FRP slabs than slabs reinforced with steel can be achieved which considering high strength and corrosion resistance of this material, which makes it a suitable choice for reinforcing materials.

Bending Capacity Analyses of Corroded Pipelines

2009 ◽  
Author(s):  
Weiwei Yu ◽  
Pedro M. Vargas ◽  
Dale G. Karr
Keyword(s):  
Internal Pressure ◽  
Carrying Capacity ◽  
Full Scale ◽  
Experimental Results ◽  
Secondary Effects ◽  
Moment Capacity ◽  
Bend Testing ◽  
Bending Capacity ◽  
Point Bend

Appendix G of the ASME B31 pipeline and piping codes addresses the pressure containment capacity of pipelines and vessels with locally corroded sections. However, the ability of corroded sections to carry moment, for example in thermal loops, is not addressed in fitness-for-service codes today. This paper presents nonlinear FEA and full-scale 4-point-bend testing of pipes with locally-thinned-areas (LTAs) to simulate corrosion. The LTAs are loaded in compression, and the buckle moment is used as the carrying capacity of the corroded section. The nonlinear FEA is found to match the experimental results, validating this methodology for computing moment capacity in corroded sections. Significant secondary effects were found to affect the testing results. This paper identifies and quantifies these effects. Also, somewhat contrary to intuition, internal pressure is demonstrated to adversely affect the bending capacity for the intermediate-low D/t ratio (17.25) pipe tested.

scholarly journals Equivalent Geometric Imperfections for Local Buckling of Slender Box-section Columns

2021 ◽  
Author(s):  
Mohammad Radwan ◽  
Balázs Kövesdi
Keyword(s):  
Parametric Study ◽  
Local Buckling ◽  
Special Role ◽  
Geometric Imperfections ◽  
Geometric Imperfection ◽  
Box Section ◽  
Buckling Resistance ◽  
Pure Compression ◽  
Design Calculations ◽  
Numerical Parametric Study

Determining the plate or the local buckling resistance is highly important in designing steel buildings and bridges. The EN 1993-1-5Annex C provides a FEM-based design approach to calculate the buckling resistance based on numerical design calculations (geometrical and material nonlinear analysis - GMNIA). Within the GMNIA analysis-based stability design, the application of the imperfections has a special role. Thus, the applicability of the EN 1993-1-5 based buckling curve (Winter curve) has been questioned for pure compression, and previous investigations showed the buckling curve of EN 1993-1-5 Annex B is more appropriate for the design of slender box-section columns subjected to pure compression, the magnitude of the equivalent geometric imperfection to be applied in numerical models for local buckling is also questioned and investigated by the authors within the current paper. The aim of the current research program is to investigate the necessary equivalent geometric imperfections to be applied in FEM-based design calculations using GMNIA calculations. A numerical parametric study is executed to investigate the imperfection sensitivity of box-section columns having different local slenderness. The necessary imperfection magnitudes are determined to each analyzed geometry leading to the buckling resistance predicted by the standardized buckling curves. Based on the numerical parametric study, a proposal for the applicable equivalent geometric imperfection magnitude is developed, which conforms to the plate buckling curves of the EN 1993-1-5 and giving an improvement proposal to the local buckling imperfection magnitudes of the prEN 1993-1-14, which is currently under development.

Effects of the Initial Geometric Imperfections on the Buckling Behavior of High-Strength UOE Manufactured Steel Pipes

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Muntaseer Kainat ◽  
Meng Lin ◽  
J. J. Roger Cheng ◽  
Michael Martens ◽  
Samer Adeeb
Keyword(s):  
High Strength ◽  
Sensitivity Study ◽  
Element Analysis ◽  
Geometric Imperfections ◽  
Geometric Imperfection ◽  
Steel Pipes ◽  
Buckling Behavior ◽  
Measurement Results ◽  
Buckling Resistance ◽  
Initial Geometric Imperfections

The effects of the initial geometric imperfections on the buckling response of grade X-100 UOE manufactured pipes are studied through finite element analysis (FEA). The initial geometric imperfections had been previously measured and quantified in terms of deviations in outside radius (OR) and wall thickness. The measurement results are used to develop imperfection models to be incorporated into buckling analysis. The OR deviation is seen to have insignificant effects on the buckling behavior, while the effects of thickness deviation are seen to be profound for both unpressurized and pressurized pipes. The geometric imperfection models are further investigated through a sensitivity study to isolate the most influential imperfection aspects on the buckling resistance of UOE pipes. A parametric study is carried out using these models and shows that excluding geometric imperfections will always result in overprediction of buckling capacity irrespective of D/t ratios.

scholarly journals Hot Deformation Behavior and Dynamic Recrystallization of Ultra High Strength Steel

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1239
Author(s):  
Liping Zhong ◽  
Bo Wang ◽  
Chundong Hu ◽  
Jieyu Zhang ◽  
Yu Yao
Keyword(s):  
Martensitic Steel ◽  
High Strength ◽  
Experimental Results ◽  
Hot Deformation Behavior ◽  
Thermal Compression ◽  
Forging Process ◽  
Finite Element Software ◽  
Ultra High Strength Steel ◽  
Recrystallized Grain Size ◽  
Deform 3D

In this paper, in order to improve the microstructure uniformity of an ultra-high strength martensitic steel with a strength greater than 2500 MPa developed by multi-directional forging in the laboratory, a single-pass hot compression experiment with the strain rate of 0.01 to 1 s−1 and a temperature of 800 to 1150 °C was conducted. Based on the experimental data, the material parameters were determined, the constitutive model considering the influence of work hardening, the recrystallization softening on the dislocation density, and the recrystallized grain size model were established. After introducing the model into the finite element software DEFORM-3D, the thermal compression experiment was simulated, and the results were consistent with the experimental results. The rule for obtaining forging stock with a uniform and refinement microstructure was acquired by comparing the simulation and the experimental results, which are helpful to formulate an appropriate forging process.

A Comparison of Theoretical and Experimental Results From Spherical Shells With a Single Radially Attached Nozzle

1967 ◽  
Vol 89 (3) ◽  
pp. 333-338 ◽  
Author(s):  
F. J. Witt ◽  
R. C. Gwaltney ◽  
R. L. Maxwell ◽  
R. W. Holland
Keyword(s):  
Spherical Shell ◽  
Internal Pressure ◽  
Experimental Results ◽  
Strain Gages ◽  
Spherical Shells ◽  
Axial Thrust ◽  
Outside Diameter ◽  
Theoretical Results

A series of steel models having single nozzles radially and nonradially attached to a spherical shell is presently being examined by means of strain gages. Parameters being studied are nozzle dimensions, length of internal nozzle protrusions, and angles of attachment. The loads are internal pressure and axial thrust and moment loadings on the nozzle. This paper presents both experimental and theoretical results from six of the configurations having radially attached nozzles for which the sphere dimensions are equal and the outside diameter of the attached nozzle is constant. In some instances the nozzle protrudes through the vessel.

Parametric Study of External Pressure on Steam Generator Tube Bends

2012 ◽  
Author(s):  
Mitch Hokazono ◽  
Clayton T. Smith
Keyword(s):  
Steam Generator ◽  
Parametric Study ◽  
External Pressure ◽  
Light Water Reactor ◽  
Material Strength ◽  
Steam Generators ◽  
Elliptical Cross ◽  
Light Water ◽  
Water Reactor ◽  
Steam Generator Tubes

Integral light-water reactor designs propose the use of steam generators located within the reactor vessel. Steam generator tubes in these designs must withstand external pressure loadings to prevent buckling, which is affected by material strength, fabrication techniques, chemical environment and tube geometry. Experience with fired tube boilers has shown that buckling in boiler tubes is greatly alleviated by controlling ovality in bends when the tubes are fabricated. Light water reactor steam generator pressures will not cause a buckling problem in steam generators with reasonable fabrication limits on tube ovality and wall thinning. Utilizing existing Code rules, there is a significant design margin, even for the maximum differential pressure case. With reasonable bend design and fabrication limits the helical steam generator thermodynamic advantages can be realized without a buckling concern. This paper describes a theoretical methodology for determining allowable external pressure for steam generator tubes subject to tube ovality based on ASME Section III Code Case N-759-2 rules. A parametric study of the results of this methodology applied to an elliptical cross section with varying wall thicknesses, tube diameters, and ovality values is also presented.

A Noncyclic Method for Determination of Accumulated Strain in Stainless Steel 304 Pressure Vessels

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Gongfeng Jiang ◽  
Gang Chen ◽  
Liang Sun ◽  
Yiliang Zhang ◽  
Xiaoliang Jia ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
Peak Stress ◽  
Pressure Vessels ◽  
Experimental Results ◽  
Elastic Domain ◽  
Ratcheting Strain ◽  
Stainless Steel 304 ◽  
Accumulated Strain

Experimental results of uniaxial ratcheting tests for stainless steel 304 (SS304) under stress-controlled condition at room temperature showed that the elastic domain defined in this paper expands with accumulation of plastic strain. Both ratcheting strain and viscoplastic strain rates reduce with the increase of elastic domain, and the total strain will be saturated finally. If the saturated strain and corresponded peak stress of different experimental results under the stress ratio R ≥ 0 are plotted, a curve demonstrating the material shakedown states of SS304 can be constituted. Using this curve, the accumulated strain in a pressure vessel subjected to cyclic internal pressure can be determined by only an elastic-plastic analysis, and without the cycle-by-cycle analysis. Meanwhile, a physical experiment of a thin-walled pressure vessel subjected to cyclic internal pressure has been carried out to verify the feasibility and effectiveness of this noncyclic method. By comparison, the accumulated strains evaluated by the noncyclic method agreed well with those obtained from the experiments. The noncyclic method is simpler and more practical than the cycle-by-cycle method for engineering design.

scholarly journals Numerical and experimental evaluation of masonry prisms by finite element method

2017 ◽  
Vol 10 (2) ◽  
pp. 477-508 ◽  
Author(s):  
C. F.R. SANTOS ◽  
R. C. S. S. ALVARENGA ◽  
J. C. L. RIBEIRO ◽  
L. O CASTRO ◽  
R. M. SILVA ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
High Strength Concrete ◽  
Numerical Models ◽  
High Strength ◽  
Experimental Tests ◽  
Experimental Results ◽  
Concrete Blocks ◽  
Micro Modeling ◽  
Modeling Strategy

Abstract This work developed experimental tests and numerical models able to represent the mechanical behavior of prisms made of ordinary and high strength concrete blocks. Experimental tests of prisms were performed and a detailed micro-modeling strategy was adopted for numerical analysis. In this modeling technique, each material (block and mortar) was represented by its own mechanical properties. The validation of numerical models was based on experimental results. It was found that the obtained numerical values of compressive strength and modulus of elasticity differ by 5% from the experimentally observed values. Moreover, mechanisms responsible for the rupture of the prisms were evaluated and compared to the behaviors observed in the tests and those described in the literature. Through experimental results it is possible to conclude that the numerical models have been able to represent both the mechanical properties and the mechanisms responsible for failure.

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