Determination of the collapse load of plastic structures by the use of an upper bounding algorithm

1991 ◽  
Vol 40 (4) ◽  
pp. 1003-1008 ◽  
Author(s):  
A.V. Avdelas
Keyword(s):  
Collapse Load

Generation of Plastic Collapse Load Boundaries of a Pressurized Cylindrical Vessel/Radial Nozzle Structure Subjected to Nozzle Bending Loadings Utilizing Various Plastic Collapse Load Techniques

2020 ◽  
pp. 2050115
Author(s):  
Hany Fayek Abdalla
Keyword(s):  
Validation Study ◽  
Cylindrical Vessel ◽  
Plastic Work ◽  
Plastic Collapse ◽  
Collapse Load ◽  
Pipe Bend ◽  
Out Of Plane ◽  
Radial Nozzle ◽  
Nozzle Structure

This research focuses on generating the plastic collapse load boundaries of a cylindrical vessel with a radial nozzle via employing three different plastic collapse load techniques. The three plastic collapse load techniques employed are the plastic work curvature (PWC) criterion, the plastic work (PW) criterion, and the twice-elastic-slope (TES) method. Mathematical based determination of plastic collapse loads is presented and employed concerning both the PWC and the PW criteria. A validation study is initially conducted on a pressurized 90-degree pipe bend structure subjected to in-plane closing bending via finite element analyses along with an elaborate explanation of the mathematical approaches for determining the plastic collapse loads via the PWC and the PW criteria. Outcomes of the validation study revealed very good outcomes for the three techniques. Accordingly, the aforementioned three techniques are utilized to determine the plastic collapse load boundaries of a pressurized cylindrical vessel/nozzle structure subjected to in-plane (IP) and out-of-plane (OP) bending loadings applied on the nozzle one at a time. The TES method revealed considerate limitations when applied within the medium to the high internal pressure spectra. It is shown that both the PWC and the PW criteria outperform the TES method in computing the plastic collapse loads. The vessel/nozzle structure revealed relatively higher plastic collapse moment boundaries under IP bending as compared to OP bending. Conclusively, methodical steps are devised for determining the plastic collapse loads via the PWC and the PW criteria for the ease of systematic application on pressurized structures in general.

On Reinforced Circular Cutouts

1953 ◽  
Vol 20 (4) ◽  
pp. 546-552
Author(s):  
E. Levin
Keyword(s):  
Lower Bound ◽  
Arbitrary Shape ◽  
Collapse Load ◽  
Circular Cutout

Abstract A slab with a circular cutout is subjected to stresses in the plane of the slab. The cutout has removed material which would have participated in carrying the load; hence the slab with cutout will fail under the application of stresses which the complete slab could have supported. In order to eliminate at least part of this weakening, the slab with cutout may be reinforced by the addition of material about the cutout. Such a reinforcement may be designed in any shape. The paper is concerned with extending the results of Weiss, Prager, and Hodge (1) for a cylindrical reinforcement to a reinforcement of arbitrary shape. In particular, a method will be described for the determination of a lower bound on the collapse load for a slab with circular cutout and a general reinforcement.

FEM Stress Analysis of Tee Intersections With LTA

2008 ◽  
Author(s):  
T. Ahmad ◽  
M. Qadir ◽  
D. Redekop
Keyword(s):  
Stress Analysis ◽  
Three Dimensional ◽  
Local Area ◽  
Collapse Load ◽  
Wall Thinning ◽  
Dimensional Finite Element ◽  
Cyclical Loading ◽  
Different Depths ◽  
Three Dimensional Finite Element

In this work a three-dimensional finite element study is carried out of pressurized piping tee (tee) intersections, with local area wall thinning (LTA). Two types of stress analysis are carried out, dealing respectively with the determination of the stress concentration factor (SCF), and of the plastic collapse load. Stress values determined for vessels with uniform thickness are compared with previously published work. An evaluation is then made of the effect on the SCF values of varying the size and shape of the LTA around the intersection. This is followed by a parametric study in which the SCF and the collapse load are computed for intersections with different depths of wall thinning. Finally, comments are made on the fatigue of tees with LTA having cyclical loading superimposed on the constant pressure loading.

Dynamic Simulation Method for Hard-Rock Pillar Failure in Open-Stope Goaf

2014 ◽  
Vol 556-562 ◽  
pp. 4055-4060
Author(s):  
Hai Tao Ma ◽  
Jin An Wang
Keyword(s):  
Stability Analysis ◽  
Load Transfer ◽  
Hard Rock ◽  
Simulation Method ◽  
Collapse Load ◽  
Quantitative Criterion ◽  
The Stability ◽  
Made In ◽  
Area Data

An attempt to simulate the cascading pillar collapse is made in this paper for a quick evaluation of a large number of mined-out area data that have been collected throughout China. Pillar collapse, load transfer and load redistribution are modeled by the area-apportioned method, and this methodology is general in sense and has been implemented in the expert system developed by the authors as an independent module. The proposed method can provide a quantitative criterion for determination of the failure pattern and identification of the key pillars in the stability analysis of the mined-out area formed by a pillar-room method.

The Determination of Safe Loads of Beams Subjected to Combined Twisting and Biaxial Bending Moments

1959 ◽  
Vol 26 (3) ◽  
pp. 442-447
Author(s):  
P. G. Hodge ◽  
R. Sankaranarayanan
Keyword(s):  
Yield Criterion ◽  
Piecewise Linear ◽  
Yield Condition ◽  
Bending Moments ◽  
Collapse Load ◽  
Biaxial Bending ◽  
Suitable Parameter ◽  
Bound Theorem ◽  
Safe Load

Abstract Using the lower-bound theorem of limit analysis, a yield criterion is obtained in terms of the stress resultants for a beam, subjected to combined twisting and biaxial bending moments. Based on a piecewise linear approximate yield condition, the “collapse load” is determined for a right-angle bent, subjected to a load in an arbitrary direction applied to the mid-point of one leg. Such a collapse load, which is a “safe load” for the beam, is plotted as a function of a suitable parameter.

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