Elastic-plastic failure loads of plane frames

1963 ◽  
Vol 274 (1358) ◽  
pp. 343-364 ◽  
Keyword(s):  
Failure Load ◽  
Load Factor ◽  
Proportional Loading ◽  
Rigid Plastic ◽  
Plastic Failure ◽  
Elastic Plastic ◽  
Plane Frames ◽  
Plane Frame ◽  
Failure Loads ◽  
Close Estimate

When deformations become finite, the load factor required to produce rigid-plastic deformation of a plane frame under proportional loading differs from the load factor at collapse as given by simple plastic theory. The effect of all work terms involving the squares of member rotations is investigated and a simple formula derived. The effect of finite deformations on the load capacities of elastic-plastic frames is then studied. It is shown theoretically that, if certain approximations are made, the Rankin© load, based on the rigid-plastic failure load and the lowest critical load, give a close estimate of the actual failure load of such a structure. The nature of the approximations made to arrive at this result shows under what circumstances the Rankine load cannot be expected to provide a close estimate of failure. Experimental and theoretical results illustrating the degree of correlation are presented and discussed.

The effect of finite deformations in the elastic stability of plane frames

1962 ◽  
Vol 266 (1324) ◽  
pp. 47-67 ◽  
Keyword(s):  
Critical Load ◽  
Failure Load ◽  
Elastic Stability ◽  
Load Level ◽  
Load Factor ◽  
Proportional Loading ◽  
Arbitrary Load ◽  
Plane Frames ◽  
The Difference ◽  
Rigid Joints

The circumstances are discussed under which orthogonal relations exist between the elastic critical modes of plane frames subjected to proportional loading. Orthogonal relations may be obtained provided the loading does not produce any components of deformation associated with any of the critical modes at arbitrary levels of the load factor, and provided no part of the structure remains statically indeterminate due to bar forces when all rigid joints are replaced by pin joints. When at arbitrary load factors, the structure deforms with components associated with any of the buckling modes, the elastic failure load is not identical with the lowest elastic critical load, although for many frames the two loads may be very close. A general expression is obtained which reveals the relation between the deformations at an arbitrary load level and the deflexions given by linear analysis. The difference between the elastic failure load and the elastic critical load is discussed, and an approximate treatment applicable to certain types of frame and associated loading is developed.

The evaluation of the failure loads of plane frames

1968 ◽  
Vol 306 (1486) ◽  
pp. 297-311 ◽  
Keyword(s):  
Failure Load ◽  
Plastic Hinge ◽  
Second Order ◽  
Order Effects ◽  
Deformation Characteristics ◽  
Computer Approach ◽  
Ultimate Failure Load ◽  
Plane Frames ◽  
Failure Loads ◽  
Ultimate Failure

The significance of the ultimate failure load of a structure is widely recognized, yet its determination has been a considerable task. Various propositions have been put forward since the formulation of the well-known plastic theory. These have been either of empirical nature such as the Merchant-Rankine formula or laborious such as the method of following the sequence of hinge formation. In this paper the main propositions are discussed briefly. A method is then presented to evaluate the failure loads of plane frames without following the sequence of plastic hinge formation. Instead the method utilizes the elastic as well as plastic load-deformation characteristics of frames, including the second-order effects involved in both. The theoretical validity of the proposed method is studied and illustrative examples are given. Comparisons are then made with experimental observations on frames loaded proportionally up to collapse. A summary of a computer approach is presented, but throughout the paper atten­tion is also paid to manual procedures.

Elastic-Plastic Fracture Mechanics Analysis of Cast Stainless Steel Pipes (Comparison of Z-Factor, Two-Parameter and J-T Methods)

2012 ◽  
Author(s):  
Masayuki Kamaya ◽  
Kiminobu Hojo
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Failure Load ◽  
Parameter Method ◽  
Steel Pipes ◽  
Integrity Assessment ◽  
Plastic Failure ◽  
Elastic Plastic ◽  
The Difference ◽  
Two Parameter

Since the ductility of cast austenitic stainless steel pipes decreases due to thermal aging embrittlement after long term operation, not only plastic collapse failure but also unstable ductile crack propagation (elastic-plastic failure) should be taken into account for the structural integrity assessment of a cracked pipe. There are mainly three procedures to obtain the elastic-plastic failure load; Z-factor, two-parameter and J-T methods. In this study, the difference in the failure load derived using these three methods was compared. The same material properties and J-integral solutions were used in order to investigate the influence of each analytical procedure. It was shown that failure loads obtained by the two-parameter method was more conservative than those obtained by the J-T method. An optimized failure assessment curve (FAC) was obtained for aged cast austenitic stainless steel. The reference stress method was also suitable for evaluating the FAC. It was concluded that the difference in the failure load obtained by the three methods was small enough from the viewpoit of engineering.

scholarly journals Finite Pure Plane Strain Bending of Inhomogeneous Anisotropic Sheets

Symmetry ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 145
Author(s):  
Sergei Alexandrov ◽  
Elena Lyamina ◽  
Yeong-Maw Hwang
Keyword(s):  
Plane Strain ◽  
Yield Criterion ◽  
Large Strains ◽  
Rigid Plastic ◽  
Plastic Properties ◽  
Elastic Plastic ◽  
Starting Point ◽  
The Difference ◽  
Inside Radius ◽  
Elastic Unloading

The present paper concerns the general solution for finite plane strain pure bending of incompressible, orthotropic sheets. In contrast to available solutions, the new solution is valid for inhomogeneous distributions of plastic properties. The solution is semi-analytic. A numerical treatment is only necessary for solving transcendent equations and evaluating ordinary integrals. The solution’s starting point is a transformation between Eulerian and Lagrangian coordinates that is valid for a wide class of constitutive equations. The symmetric distribution relative to the center line of the sheet is separately treated where it is advantageous. It is shown that this type of symmetry simplifies the solution. Hill’s quadratic yield criterion is adopted. Both elastic/plastic and rigid/plastic solutions are derived. Elastic unloading is also considered, and it is shown that reverse plastic yielding occurs at a relatively large inside radius. An illustrative example uses real experimental data. The distribution of plastic properties is symmetric in this example. It is shown that the difference between the elastic/plastic and rigid/plastic solutions is negligible, except at the very beginning of the process. However, the rigid/plastic solution is much simpler and, therefore, can be recommended for practical use at large strains, including calculating the residual stresses.

scholarly journals Application of ANN to evaluate effective parameters affecting failure load and displacement of RC buildings

2009 ◽  
Vol 9 (3) ◽  
pp. 967-977 ◽  
Author(s):  
M. Hakan Arslan
Keyword(s):  
Failure Load ◽  
Back Propagation ◽  
Load Level ◽  
Effective Parameters ◽  
Rc Buildings ◽  
Building Stock ◽  
Capacity Curves ◽  
Rc Building ◽  
Failure Loads ◽  
Turkish Earthquake Code

Abstract. This study investigated the efficiency of an artificial neural network (ANN) in predicting and determining failure load and failure displacement of multi story reinforced concrete (RC) buildings. The study modeled a RC building with four stories and three bays, with a load bearing system composed of columns and beams. Non-linear static pushover analysis of the key parameters in change defined in Turkish Earthquake Code (TEC-2007) for columns and beams was carried out and the capacity curves, failure loads and displacements were obtained. Totally 720 RC buildings were analyzed according to the change intervals of the parameters chosen. The input parameters were selected as longitudinal bar ratio (ρl) of columns, transverse reinforcement ratio (Asw/sc), axial load level (N/No), column and beam cross section, strength of concrete (fc) and the compression bar ratio (ρ'/ρ) on the beam supports. Data from the nonlinear analysis were assessed with ANN in terms of failure load and failure displacement. For all outputs, ANN was trained and tested using of 11 back-propagation methods. All of the ANN models were found to perform well for both failure loads and displacements. The analyses also indicated that a considerable portion of existing RC building stock in Turkey may not meet the safety standards of the Turkish Earthquake Code (TEC-2007).

Elastic-Plastic Fracture Mechanics Analysis of Cast Stainless Steel Pipes (Influence of Axial Load on Z-Factor of Pipes With Circumferential Crack Under Bending Load)

2013 ◽  
Author(s):  
Masayuki Kamaya ◽  
Kiminobu Hojo
Keyword(s):  
Stainless Steel ◽  
Axial Load ◽  
Power Plants ◽  
Structural Integrity ◽  
Term Operation ◽  
Steel Pipes ◽  
Integrity Assessment ◽  
Plastic Failure ◽  
Elastic Plastic ◽  
Bending Load

Since the ductility of cast austenitic stainless steel pipes decreases due to thermal aging embrittlement after long term operation, not only plastic collapse failure but also unstable ductile crack propagation (elastic-plastic failure) should be taken into account for the structural integrity assessment of cracked pipes. In the ASME Section XI, the load multiplier (Z-factor) is used to derive the elastic-plastic failure of the cracked components. The Z-factor of cracked pipes under bending load has been obtained without considering the axial load. In this study, the influence of the axial load on Z-factor was quantified through elastic-plastic failure analyses under various conditions. It was concluded that the axial load increased the Z-factor; however, the magnitude of the increase was not significant, particularly for the main coolant pipes of PWR nuclear power plants.

scholarly journals Failure assessment of steel/CFRP double strap joints

2017 ◽  
Author(s):  
Hamid Reza Majidi ◽  
Seyed Mohammad Javad Razavi ◽  
Filippo Berto
Keyword(s):  
Failure Load ◽  
Steel Structures ◽  
Predictive Modelling ◽  
Failure Behavior ◽  
Static Tensile Loading ◽  
Failure Assessment ◽  
Theoretical Predictions ◽  
Static Tensile ◽  
Failure Loads ◽  
Good Agreement

In the current study, the failure behavior of retrofitted steel structures was studied experimentally and theoretically with steel/CFRP double strap joints (DSJs) under quasi-static tensile loading. A series of DSJs with different bonding lengths are also considered and examined to experimentally assess the effective bond length. To predict the failure load values of the tested specimens, a new stress-based criterion, namely the point stress (PS) criterion is proposed. Although some theoretical predictive modelling for the strength between steel/CFRP joints under various loading conditions has been presented, in this work by using the new proposed approach, one can calculate rapidly and conveniently the failure loads of the steel/CFRP specimens. Furthermore, to assess the validity of the new proposed criterion, further experimental data on steel/CFRP DSJs available in the open literature are predicted using the PS criterion. Finally, it was found that a good agreement exists between the experimental results and the theoretical predictions based on the PS criterion.

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