Elastic-plastic Analysis Method Research Articles

Study on Multi-Index Evaluation Technology of Seismic Performance of Green Ecological Building Structure

Traditional evaluation methods based on static elastic-plastic analysis usually produce results with low fitting degree compared with actual data. In this paper, a new seismic performance evaluation method is proposed. Firstly, several evaluation indexes of green ecological building structure are calculated. Subsequently, a cumulative damage model is established based on fatigue life curve and Miner criterion, which allows to determine the total dissipated strain energy and damage index. In order to verify the effectiveness of this method, it is compared with the traditional static elastic-plastic analysis method through experimental tests. The results show that compared with the traditional method of 50% to 60%, the proposed method achieves a significantly higher fitting degree with the actual data, ranging from 70% to 92%. This emphasizes the superiority and reliability of the proposed method in evaluating the seismic performance of green ecological building structures, and provides insights for safer and more flexible building practices.

Research on seismic performance of corrugated web rigid structures

Abstract: Corrugated web H-beam refers to a steel beam with a wavy shape along its length, which is extensively utilized in various parts of building structures such as beams, columns, and walls. It serves the purpose of connection and support, while the corrugated or folded design enhances the shear resistance and out-of-plane stiffness of the web to some extent. However, despite their advantages including high strength, stiffness, and lightweight construction, relevant regulations stipulate that these members can only be used in lower-intensity applications or higher-intensity scenarios if specific conditions are met. One crucial condition is that the ratio between the design value of axial force subjected to seismic action and the product of the member's flange section area and steel's tensile strength should not exceed 0.4. In this study, we aim to further investigate the seismic characteristics and applicable intensity of corrugated steel structures under earthquakes through large-scale finite element ABAQUS simulations. We will observe dynamic characteristics and failure modes of corrugated rigid frame structures using elastic-plastic time-history analysis methods as well as examine plastic deformation features of steel beam members under low cyclic loads via hysteretic analysis methods. The findings demonstrate that when properly designed with reasonable beam spans, corrugated web rigid frame structures can still be employed in high-intensity areas above 7 degrees even when subjected to an axial compression ratio up to 0.5.

Load Bearing Capacity of Lateral Loaded Piles in Watered Carpathian Flysch

In this paper, flysch is presented as a representative material of a wide section of the Carpathian Mountains, with some areas in Poland highlighted. The geological structure of this area is complex due to the alternating layers of blocky rock masses and soil (Vessia et al., 2017). Such a complex pattern is seen in some Alpine flysch slopes, such as the Ingelsberg landslide area (Romeo et al., 2015). Many authors are monitored, predicted landslides (Allasia et al., 2013; Bertacchini et al., 2009; Casagli et al., 2010) by sophisticated sensors. The rock-soil flysch successions have become intensively fissured as a result of their geological history, weathering (precipitation and snowmelt), and long-term water retention, especially on the surface layers. These complex materials are characterised by heterogeneous lithologies, whose mechanical properties are largely uncertain. These geological structures have also been confirmed by monitoring and control studies performed on a large number of landslides (Bednarczyk, 2014). One of the most striking phenomena is the sudden decrease in the strength parameters in the studied rocks in the direction parallel to the layers due to watering. The process is made possible by heterogeneous fractured strong rock layers with high permeability coefficients for water. This study precisely describes the phenomena occurring at the contact area between the component layers of flysch under the wet conditions of a weak plane. An elastic-plastic analysis method that considers the developed strength model at the surfaces of the contact areas (Biernatowski & Pula, 1988; Pula, 1997) has been used to estimate the load capacity for piles working under a horizontal load. The piles are part of a reliability chain (Pula, 1997) in a given construction and are the first element of concern for monitoring (Muszynski & Rybak, 2017). A particular device intended to study the dependence of the shear stress on a fixed failure surface in a controlled consolidation condition was utilized. The study was conducted for a wide range of displacements and for different values of stabilized vertical stresses of consolidation. The complexity of the processes occurring in the shear zone, presented as a detailed study of the material crack mechanics, is highlighted. The laboratory results were used to construct the mechanical model of the slip surface between the soil and rock with the description supported by a neural network (NN) approximation. The artificial NN was created as a multi-layered, easy to use approach for interpreting results and for quick reconstruction of approximated values useful for the calculations presented in laterally loaded piles. For the calculations, long, sheared strips of material were considered in a semi-analytical procedure to solve a differential equation of stability. The calculations are intended to reveal the safety indexes for a wide range of boundary tasks as the most significant indicator for design decisions.

A new numerical method for elastic-plastic plate analysis: Theoretical-experimental validation and its application in ratcheting phenomenon

In the present paper, two different numerical methods, generalized differential quadrature (GDQ) and dynamic relaxation method (DR) are employed to analyze elastic-plastic plates. These methods are initially evaluated for elastic beams and then they are utilized for elastic-plastic plates analysis. A new method, GDDR (Generalized Differential Dynamic Relaxation), is developed by the combination of two mentioned methods. The proposed method is validated by theoretical analysis for elastic problems, Abaqus simulation and experimental study for elastic-plastic plates. Reduction in the number of required discretizing nodes, lower computational time and decrease in the number of iterations (about 80%) are the advantages of introduced method compared with the conventional ones. Moreover, this method improves the accuracy of solutions, especially in terms of stresses, by increasing the differentiation accuracy of nodes for elastic-plastic analysis. Comparing the errors of proposed GDDR method with conventional DR method shows about 70% reduction in mean squared error. Moreover, this new method is able to solve problems by using only 3 nodes in each direction, while other methods need at least 8.

Seismic Performance of Super High-Rise Building Structure with Dual Lines of Defense Based on Response Surface Optimization Algorithm

In order to improve the safety performance of supertall buildings under earthquake, a seismic performance analysis method of double lines of supertall buildings based on a response surface optimization algorithm is proposed. Firstly, the structural performance indexes of super high-rise buildings are selected, and on this basis, the material constitutive model is constructed by the structural elastic-plastic analysis method to complete the seismic design of the first line of defense. Then, the response surface method is used to optimize the material constitutive model and complete the seismic design of the second line. Finally, the anticollapse limit state analysis method is used to determine the seismic performance of the double line of super high-rise building structures. The experimental results show that the proposed analysis method has high seismic performance, and the axial compression ratio of wall and column is always stable, in which the column is always at about 0.5 and the wall is always at about 0.26, which lays a foundation for the safety performance of super high-rise building structures under earthquake.

An Automatic Finite Element Method-Boundary Element Method Coupling Method for Elastic–Plastic Problems of Multiscale Structures in Electronic Packaging

Abstract We introduce a coupled finite and boundary element method for elastic-plastic analysis over multiscale electronic packaging structures. Based on the finite element-boundary element (FE-BE) coupling algorithm, an automatic implementation procedure for the coupling of the abaqus with a self-written elastic BE code is introduced for elastic problems. In the mixed finite element method (FEM)-boundary element method (BEM) model, the effective stiffness and effective forces at the interfacial boundary are evaluated by the self-written BE code. Then, the obtained effective stiffness and effective forces are assembled to the global FE formulations by using the user subroutine (UEL) in abaqus. Numerical simulation of structures with plastic deformation, stress concentration, etc. is carried out by using FEM theory. The boundary element method is used for linear elastic domains with large-scale structures. The proposed method offers several key improvements compared with current analysis methods available for multiscale electronic packaging structures. The benefits are: (i) the powerful pre- and postprocessing of abaqus; (ii) the higher accuracy of the solution; (iii) the computational cost and time can be reduced by using the scheme; and (iv) solving systems with infinite extension by using the BEM as a supplement. Furthermore, we demonstrate the ability of the proposed approach to handle multiscale structures in electronic packaging problems.

A coupling model of element-based peridynamics and finite element method for elastic-plastic deformation and fracture analysis

An element-based peridynamics (EBPD) and finite element method (FEM) coupling model is proposed to solve the elastic-plastic deformation and failure problems. The FEM and EBPD are used in the boundary region and the interior elastic-plastic crack growth region, respectively. A scheme is proposed to improve the computation efficiency of EBPD by deleting the bad quality elements in the horizon of each PD node. EBPD has the non-local stress and non-local strain concepts to conveniently describe the yield stress and equivalent plastic strain, and does not have instability problems. The elastic-plastic computation framework is used in the coupling model solved by the incremental method to calculate the elastic-plastic deformation and failure process. The coupling model can calculate the elastic-plastic problem with the linear and nonlinear hardening laws. A 2D elastic-plastic crack propagation process is also simulated by the proposed coupling model.

Proposal of analysis method of global-local finite element method for finite strain elastic-plastic fracture mechanics analysis

The purpose of this study is to make it possible to perform a large number of paratric analyzes on the position and shape of cracks under finite elasto-plastic deformation. In this report, we propose a one-way coupled analysis method using displacement interpolation between a global finite element method analysis model created without assuming cracks and a local finite element method analysis model assuming cracks. The proposed method is based on the superconvergent patch recovery, and uses the least-squares method to apply the nodal displacements of the global finite element model to the nodes of the local finite element model as displacement boundary conditions. In addition, we will create an merged finite element method analysis model assuming a crack directly in the global finite element method analysis model and identify the application conditions that can be applied to the problem without loss of accuracy through relative comparison by J-integral calculation at the crack tip which is nonlinear fracture mechanics parameter.

A semi-analytical method for elastic-plastic analysis of a deep-buried elliptical tunnel

The elastic–plastic problem of an elliptical tunnel is of great significance in engineering. Previous studies were mainly focused on the circular tunnel. An elastic–plastic analysis is performed for determining the plastic zone around a deep-buried elliptical tunnel subjected to far-field uniform in-situ stresses. The yielding of the rock mass obeys the Mohr-coulomb criterion. The elastic stress field is given by the complex variable method and the plastic stress field is numerically determined by the slip line theory. The solution is obtained according to the stress continuity condition along the elastic–plastic interface. Correspondingly, a set of nonlinear equations involves the mapping function coefficients is established and solved with the help of differential-evolution algorithm. The validity of the method is verified by comparing the results with the numerical simulation of FLAC3D software. Estimates of the size and shape of the plastic zone are then presented for varying parameters including in-situ stress, cohesion, internal friction angle and axis ratio.

Analysis of Plastic Zone and Pressure Variance Features of Surrounding Rock of High-Altitude Macker Tunnel: A Case Study in Jiangluling Macker Tunnel in Qinghai

Due to the special mechanical properties of macker rock, problems may be caused easily if the pressure of the surrounding rock calculated from the standard empirical equation is used in the structural design of tunnel support, such as obviously insufficient bearing capacity of the support structure, large deformation, and collapse. Taking the Jiangluling Macker Tunnel in Gonghe-Yushu Highway as an example, the distribution pattern of plastic zone of the surrounding rock and the calculation method and reasonable values of pressure of the surrounding rock are studied in this paper, by means of theoretical analysis, numerical computation, and field measurement data. The results show that the elastic-plastic analysis method is suitable for the pressure of the surrounding rock of macker tunnel. The influence radius of the plastic zone of the surrounding rock can be 32 m, and the lateral pressure of the surrounding rock of the tunnel is equivalent to the vertical pressure. In the absence of test conditions and measured data, the pressure of the surrounding rock can be approximately 0.83 MPa for the purpose of design of tunnel support structure. This conclusion provides technical support for projects in similar conditions.

Static Elastoplastic Analysis of Turbine House under Different Lateral Loading MoDES in Conventional Island of Nuclear Power Plant

Nuclear island in nuclear power plant requires that under the extreme safety shutdown earthquake action, the collapse of the turbine house of conventional island shall not affect the safety of nuclear island, so as to ensure the functional integrity of nuclear island. At present, the way to meet this requirement is to carry out elastoplastic analysis on the turbine house of the regular island under the action of the ultimate safe earthquake to ensure that it does not collapse and its deformation meets the deformation requirements of the standard rare earthquake. Structure elastic-plastic analysis method with static analysis and dynamic elastic-plastic time history analysis, in this paper, the ci turbine room nappe analyzed, and compared the five kinds of lateral load loading mode of static elastoplastic analysis results, the seismic performance of the structure, puts forward the layer shear lateral loading mode suitable for ci turbine room structure static elastoplastic analysis.

Performance‐based seismic design of the outrigger of a high‐rise overrun building with asymmetric vertical setback in a strong earthquake area

SummaryOutriggers, which should be systematically analyzed and designed based on seismic performance methods in the different seismic level actions, can improve the lateral stiffness of irregular high‐rise structures. In this paper, a concrete‐filled steel frame‐core tube‐outrigger structural system is adopted for a practical overrun high‐rise building with an obviously asymmetrical vertical setback in a high‐intensity seismic region. To ensure the seismic safety of irregular high‐rise building structures, the members of the outrigger are designed based on the seismic performance analysis method, and the complex joint region and slab of the outrigger floor are also refined and analyzed. In addition, the effect of outrigger on the damage states of the structural and member is evaluated using the elastic–plastic analysis method in the rare earthquake action. Finally, the seismic mitigation efficiency of the high‐rise structure with the viscous dampers installed on the outrigger floor is analyzed. The results indicate that the member size of the outrigger should be determined based on the performance objectives of the moderate earthquake action rather than the frequent earthquake action. The shear force distribution ratio of the outer frame located at the outrigger floor is obviously amplified, which shows that the cooperative bearing ability of the outer frame and the core tube is improved because of the outrigger action. The stress in the complex joint region of the outrigger, which satisfies the material strength requirement, is analyzed by the refined finite element analysis method. The slab of the outrigger floor, which should be strengthened to effectively transfer larger horizontal seismic shear force, has obvious damage in the rare earthquake action. The region of the structure with an outrigger that experiences significant damage in the rare earthquake action is located at the outrigger floor and adjacent upper domains rather than the bottom domains, which is different from that of a structure without an outrigger. The internal force of the outrigger member can be reduced by considering viscous damper action, but the seismic mitigation efficiency is not significant because of the limited number of dampers.

Stress Analysis of Friction Stir Spot Welded Magnesium Alloy Sheet under Tensile-Shear Load

The strength, failure location and modes of AZ31B Magnesium sheets with 1.5 mm thickness, joined using friction stir spot welding (FSSW), can be determined using tension-shear tests. However, the joined materials have different tension test and elastic-plastic characteristics. Elastic analysis methods for spot welding have been examined in detail in literature. However, if the material has narrow elastic and large plastic area characteristics, such as AZ31B, elastic-elastic analysis methods are deficient. The development and application of elastic-plastic analysis methods are required for such soft metal materials. In this study, the elastic-elastic and elastic-plastic analytical stress mechanisms were investigated. Strain and force equations were then derived using an analytical approach. These developed equations were based on the FSSW-Tension-Shear-Test and verified using Finite Element Method (FEM)-Analysis and tension-shear tests. In addition, the location of failure was also determined. It is possible to predict failures without performing tension-shear tests using the proposed analytical equations.

Application of elastic-plastic analysis method in high pressure heater tubesheet design

The design method of pressure vessel consists of the elastic analysis method and the elastic-plastic analysis method. The design method based on elastic-plastic theory with more complex computation process contributes to lightweight design, and avoids uncertainty of stress classification in the complex structures. Tubesheet is the main part of high pressure heater, which is very thick based on Chinese code GB151 for the design of heat exchangers. Increased tubesheet with large thermal stress are not conducive to manufacture, heat transmission and detection. The application of limit load method and elastic-plastic method in the analysis and design of high pressure heater tube is to provide direction for the lightweight research of tubesheet. It is shown that high stress appears on the inner wall of jointing of tubesheet with the head due to the original tubesheet owning enough rigidity related to thickness, which should be noted in the design. The limit load method and elastoplastic method could be assessed in the plastic collapse assessment after optimizing the thickness of the tube plate by 5% on the basis of the existing rule design. Compared with the limit load method, the elastic-plastic method could obtain higher limit load due to its higher computational precision. On the other hand, the design method of elastic-plastic analysis method is not required to consider the determination of limit load per ASME VIII-2 judged by its convergence. The elastic-plastic analysis method is worth further study, which is helpful to the revision and improvement of relevant standards in China.

Effect of Geometrical Imperfection on Buckling Failure of ITER VVPSS Tank

The ‘Vacuum Vessel Pressure Suppression System’ (VVPSS) is part of ITER machine, which is designed to protect the ITER Vacuum Vessel and its connected systems, from an over-pressure situation. It is comprised of a partially evacuated tank of stainless steel approximately 46 m long and 6 m in diameter and thickness 30 mm. It is to hold approximately 675 tonnes of water at room temperature to condense the steam resulting from the adverse water leakage into the Vacuum Vessel chamber. For any vacuum vessel, geometrical imperfection has significant effect on buckling failure and structural integrity. Major geometrical imperfection in VVPSS tank depends on form tolerances. To study the effect of geometrical imperfection on buckling failure of VVPSS tank, finite element analysis (FEA) has been performed in line with ASME section VIII division 2 part 5 [1], ‘design by analysis method’. Linear buckling analysis has been performed to get the buckled shape and displacement. Geometrical imperfection due to form tolerance is incorporated in FEA model of VVPSS tank by scaling the resulted buckled shape by a factor ‘60’. This buckled shape model is used as input geometry for plastic collapse and buckling failure assessment. Plastic collapse and buckling failure of VVPSS tank has been assessed by using the elastic-plastic analysis method. This analysis has been performed for different values of form tolerance. The results of analysis show that displacement and load proportionality factor (LPF) vary inversely with form tolerance. For higher values of form tolerance LPF reduces significantly with high values of displacement.

Numerical analysis of residual stress distribution on peening process

Various peening techniques are employed to prevent stress corrosion cracking or to extend the fatigue life of structures. In this study, to investigate the effect of shot peening on operation, an analysis method that predicts the stress distribution due to shot peening was proposed. Using the proposed method, the load distribution from the shot collisions was modeled, and it was integrated with a dynamic analysis method based on the idealized explicit FEM (IEFEM). The accuracy of the proposed method was confirmed by comparing the stress distribution from the collision of a single shot with the results analyzed using ABAQUS. A thermal elastic-plastic analysis method using IEFEM was applied to the analysis of the residual stress distribution of a multi-pass-welded pipe joint. The calculated residual stress distribution was compared with the measured residual stress distribution measured using X-ray diffraction (XRD). The results showed that the two welding residual distributions were in good agreement. Considering the calculated welding residual stress distribution, the modification of the stress distribution due to shot peening was predicted using the proposed method. A similar stress distribution was obtained using XRD for the case where a large number of collisions were considered.

Simulation on the Springback Property of Sealing Ring in Nuclear Power Plant

In order to simulate the thermal influence on springback property of O-ring, based on elastic-plastic contact analysis method of finite element analysis (FEA), numerical simulation of compression-springback course of O-ring was carried out by ANSYS software. The results show that it causes a sharp decrease in the peak force applied on O-ring, corresponding to a decline on the contact stress distribution which may influence the seal ability of the O-ring. The simulation results are in good agreement with the experimental results.

Progress in Study on Elastic-Plastic Time History Analysis of Tall Building

This paper summarizes both advantages and disadvantages of elastic-plastic static and dynamics analysis methods and points out that dynamics analysis is more applicable and accurate for high-rise building analysis, compared to elastic-plastic static analysis. Then, some key issues of elastic-plastic dynamics time history analysis are introduced, based on the understanding of the latest progress of it, including element models of beam, column and shear wall, constitutive laws of steel and concrete, algorithm and analysis software. The research results provide helpful referencesto the application and population of dynamics analysis of tall building.

Analysis on Seismic Behavior of Structures Supported by Foundations with Different Locations

In order to know more about the seismic behavior of structures supported by foundations with different locations, using the elastic and static elastic-plastic analysis method, the research is respectively from the aspects of the distribution characteristic of elastic inter-story displacement angle, the distribution law of story shear, and the distribution characteristic of elastic-plastic displacement angle and the sequence of plastic hinges. In the end, it is got that the characteristics of force and deformation of structures supported by foundations with different locations. It is found that the position of weak story would change along with the change of story stiffness. In order to guarantee the structures supported by foundations with different locations to have good seismic behavior, it needs to take the necessary internal force adjust measures and details of seismic design.

Slope stability analysis based on a multigrid method using a nonlinear 3D finite element model

The rigid-body limit equilibrium method cannot reflect the actual stress distribution in a rock mass, and the finite-element-based strength reduction method also has some problems with respect to convergence. To address these problems, a multi-grid method was adopted in this study to establish a structural grid for finite element computation and a slip surface grid for computing slope stability safety factors. This method can be used to determine the stability safety factor for any slip surface or slide block through a combination of nonlinear finite element analysis and limit equilibrium analysis. An ideal elastic-plastic incremental analysis method based on the Drucker-Prager yield criterion was adopted in the nonlinear finite element computation. Elasto-plastic computation achieves good convergence for both small load steps and large load steps and can increase computation precision to a certain extent. To increase the scale and accuracy of the computation, TFINE, a finite element parallel computation program, was used to analyze the influence of grid density on the accuracy of the computation results and was then applied to analysis of the stability of the Jinping high slope. A comparison of the results with results obtained using the rigid-body limit equilibrium method showed that the slope stability safety factors determined using finite element analysis were greater than those obtained using the rigid-body limit equilibrium method and were in better agreement with actual values because nonlinear stress adjustment was considered in the calculation.