scholarly journals Design With SADSF Method and Analyses of Elastic Properties of Torsion-Loaded Double-Tee Section With Torsional Box

2019 ◽  
Vol 24 (1) ◽  
pp. 79-89
Author(s):  
I. Markiewicz
Keyword(s):  
Elastic Properties ◽  
Limit State ◽  
Equivalent Stress ◽  
Stress Fields ◽  
Strength Design ◽  
Torsion Moment ◽  
Load Carrying ◽  
Thin Walled ◽  
Better Than

Abstract The work presents the results of preliminary strength design of a thin-walled structure based on double-tee section loaded with a torsion moment. One of the solutions to this problem is considered, in which the torsional box is introduced in the central part. Then, one constructs a series of solution variants that differ in the torsional box length. In the design one uses the method of statically admissible discontinuous stress fields (SADSF) assuming the condition of equalized equivalent stress in the limit state. The work is complemented with elastic FEM analyses of one of the solution variants. Using this example, one shows good load-carrying properties of structures designed with the SADSF method, and proves that they could be several times better than the properties of structures designed with traditional or intuitive ways.

Elasto-Plastic Properties of Thin-Walled Structures Designed with the SADSF Method

2015 ◽  
Vol 240 ◽  
pp. 206-211
Author(s):  
Ireneusz Markiewicz
Keyword(s):  
Lower Bound ◽  
Approximate Method ◽  
Limit Analysis ◽  
Limit State ◽  
Stress Fields ◽  
Application Software ◽  
Plastic Properties ◽  
Thin Walled Structures ◽  
Bound Theorem ◽  
Thin Walled

The paper presents a selected example of investigations, carried out by the author, on complex thin-walled structures [3] that were designed based on the method of statically admissible discontinuous stress fields (the SADSF method, [1,2,4,5]) with the condition of equalized effort in the limit state. The SADSF method is substantiated based on the conclusions that follow on the lower bound theorem of limit analysis, and is an approximate method. The aim of the investigations was practical verification of solutions of the SADSF method in elasto-plastic and elastic range of stress, because these ranges are not taken into account in the method. The existing application software of the SADSF method allows one to design very complex thin-walled structures which are free of cardinal errors. Moreover, the method can be easily used by practically any engineer.

scholarly journals Eigenproblem Versus the Load-Carrying Capacity of Hybrid Thin-Walled Columns with Open Cross-Sections in the Elastic Range

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3468
Author(s):  
Zbigniew Kolakowski ◽  
Andrzej Teter
Keyword(s):  
Cross Sections ◽  
Carrying Capacity ◽  
Ultimate Load ◽  
Equilibrium Path ◽  
Load Carrying Capacity ◽  
Nonlinear Buckling ◽  
Elastic Range ◽  
Load Carrying ◽  
Thin Walled ◽  
Ultimate Load Carrying Capacity

The phenomena that occur during compression of hybrid thin-walled columns with open cross-sections in the elastic range are discussed. Nonlinear buckling problems were solved within Koiter’s approximation theory. A multimodal approach was assumed to investigate an effect of symmetrical and anti-symmetrical buckling modes on the ultimate load-carrying capacity. Detailed simulations were carried out for freely supported columns with a C-section and a top-hat type section of medium lengths. The columns under analysis were made of two layers of isotropic materials characterized by various mechanical properties. The results attained were verified with the finite element method (FEM). The boundary conditions applied in the FEM allowed us to confirm the eigensolutions obtained within Koiter’s theory with very high accuracy. Nonlinear solutions comply within these two approaches for low and medium overloads. To trace the correctness of the solutions, the Riks algorithm, which allows for investigating unsteady paths, was used in the FEM. The results for the ultimate load-carrying capacity obtained within the FEM are higher than those attained with Koiter’s approximation method, but the leap takes place on the identical equilibrium path as the one determined from Koiter’s theory.

Analysis of circumferentially welded thin-walled cylinders to study the effects of tack weld orientations and joint root opening on residual stress fields

2009 ◽  
Vol 223 (5) ◽  
pp. 1037-1049 ◽  
Author(s):  
N U Dar ◽  
E M Qureshi ◽  
A M Malik ◽  
M M I Hammouda ◽  
R A Azeem
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Arc Welding ◽  
Operating Conditions ◽  
Stress Fields ◽  
Welded Structures ◽  
Prime Concern ◽  
Thin Walled ◽  
Tack Weld ◽  
Welding Processes

In recent years, the demand for resilient welded structures with excellent in-service load-bearing capacity has been growing rapidly. The operating conditions (thermal and/or structural loads) are becoming more stringent, putting immense pressure on welding engineers to secure excellent quality welded structures. The local, non-uniform heating and subsequent cooling during the welding processes cause complex thermal stress—strain fields to develop, which finally leads to residual stresses, distortions, and their adverse consequences. Residual stresses are of prime concern to industries producing weld-integrated structures around the globe because of their obvious potential to cause dimensional instability in welded structures, and contribute to premature fracture/failure along with significant reduction in fatigue strength and in-service performance of welded structures. Arc welding with single or multiple weld runs is an appropriate and cost-effective joining method to produce high-strength structures in these industries. Multi-field interaction in arc welding makes it a complex manufacturing process. A number of geometric and process parameters contribute significant stress levels in arc-welded structures. In the present analysis, parametric studies have been conducted for the effects of a critical geometric parameter (i.e. tack weld) on the corresponding residual stress fields in circumferentially welded thin-walled cylinders. Tack weld offers considerable resistance to the shrinkage, and the orientation and size of tacks can altogether alter stress patterns within the weldments. Hence, a critical analysis for the effects of tack weld orientation is desirable.

Analysis of circumferentially arc welded thin-walled cylinders to investigate the residual stress fields

2008 ◽  
Vol 46 (12) ◽  
pp. 1391-1401 ◽  
Author(s):  
Afzaal M. Malik ◽  
Ejaz M. Qureshi ◽  
Naeem Ullah Dar ◽  
Iqbal Khan
Keyword(s):  
Residual Stress ◽  
Stress Fields ◽  
Thin Walled

scholarly journals Comprehensive analysis of the strength and safety of potentially hazardous facilities subject to uncertainties

Dependability ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 47-56
Author(s):  
N. A. Makhutov ◽  
D. O. Reznikov
Keyword(s):  
Human Error ◽  
Human Factor ◽  
Structural Strength ◽  
Limit State ◽  
Probabilistic Approach ◽  
Deterministic Approach ◽  
Target Values ◽  
Load Carrying ◽  
Standard Value ◽  
High Level

Aim. This paper aims to compare the two primary approaches to ensuring the structural strength and safety of potentially hazardous facilities, i.e. the deterministic approach that is based on ensuring standard values of a strength margin per primary limit state mechanisms, and the probabilistic approach, under which the strength condition criterion is the nonexceedance by the target values of probability of damage per various damage modes of the standard maximum allowable values. . The key problem of ensuring the structural strength is the high level of uncertainties that are conventionally subdivided into two types: (1) the uncertainties due to the natural variation of the parameters that define the load-carrying ability of a system and the load it is exposed to, and (2) the uncertainties due to the human factor (the limited nature of human knowledge of a system and possibility of human error at various stages of system operation). The methods of uncertainty mitigation depend on the approach applied to strength assurance: under the deterministic approach the random variables “load” and “carrying capacity” are replaced with deterministic values, i.e. their mathematical expectations, while the fulfillment of the strength conditions subject to uncertainties is ensured by introducing the condition that the relation of the mathematical expectation of the loadcarrying capacity and strength must exceed the standard value of strength margin that, in turn, must be greater than unity. As part of the probabilistic approach, the structural strength is assumed to be ensured if the estimated probability of damage per the given mechanism of limit state attainment does not exceed the standard value of the probability of damage.Conclusions. The two approaches (deterministic and probabilistic) can be deemed equivalent only in particular cases. The disadvantage of both is the limited capability to mitigate the uncertainties of the second type defined by the effects of the human factor, as well as the absence of a correct procedure of accounting for the severity of consequences caused by the attainment of the limit state. The above disadvantages can be overcome if risk-based methods are used in ensuring structural strength and safety. Such methods allow considering uncertainties of the second type and explicitly taking into consideration the criticality of consequences of facility destruction.

FEM/DEM Approach for the Analysis of Masonry Arch Bridges

2016 ◽  
pp. 367-392 ◽  
Author(s):  
Emanuele Reccia ◽  
Antonella Cecchi ◽  
Gabriele Milani
Keyword(s):  
Elastic Strain ◽  
Limit State ◽  
Numerical Approach ◽  
State Behavior ◽  
Masonry Arch ◽  
Preliminary Validation ◽  
Load Carrying ◽  
Arch Bridges ◽  
Embedded Crack ◽  
External Loads

The problem of masonry arch bridges load carrying capacity is studied by means of a coupled FEM/DEM 2D approach. The numerical model relies into a triangular discretization of the domain with embedded crack elements that activate whenever the peak strength is reached. The proposed approach can be regarded as a combination between Finite Elements allowing for the reproduction of elastic strain into continuum and DEM, suitable to model frictional cohesive behavior exhibited by masonry structures even at very low levels of external loads. The aforementioned numerical approach is applied to masonry arch bridges interacting with infill. A preliminary validation of the procedure is addressed for the prediction of the masonry arches limit state behavior where the stones are supposed infinite resistant and plastic hinges can occur exclusively on mortar joints, modeled as cohesive frictional interfaces. The sensitivity of the infill role varying mechanical properties of the infill is extensively discussed.

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