Elastic Part Research Articles

A CDM-like constitutive law for predicting degradation of strength and ductility of steel subjected to cyclic loading

This paper presents a continuum-damage-model-like constitutive law embedding cohesive cracks with plasticity-induced damage to represent the degradation of strength and ductility of steel under cyclic loading. The proposed constitutive law accommodates an arbitrary hyperelasticity-based plastic model with the use of the deformation gradient multiplicatively decomposed into separation-induced, elastic and plastic parts, and incorporated with an additional isotropic hardening rule endowed with a memory surface. While the elastic–plastic deformation along with isotropic and kinematic hardening is represented by a Hencky-type model, the separation-induced deformation gradient due to material separation is employed to embed an arbitrary cohesive traction separation law (CTSL) into the hyperelasticity-based plastic model. Also, a plasticity-induced damage variable is added to the selected CTSL to degrade the critical energy release rate. In addition, a new material constant is introduced to adjust the ratio between the critical values of cohesive traction and material separation width in the CTSL. On the other hand, the additional hardening rule depending on memory surface is appended in conjunction with the conventional isotropic and kinematic hardening rules to reflect the difference in plastic deformation with various ranges of cyclic loading. Several experiments are conducted to identify the material parameters and verify the validity of the proposed model. By reference to the experimental results, the capability of our proposed constitutive law is demonstrated in predicting the degradation of tensile strength and breaking elongation of a steel after cyclic loading.

Justification of parameters of a finger hump of potato harvesters when vibrating canvas

Potato harvesting in Ryazan region is due to the short harvesting period and difficult soil and climatic conditions, making the process of soil separation difficult because soil sifting by separating working bodies is difficult. Therefore, a significant part of the load falls on external separation organs or a finger hump. To intensify the separation, a multi-cam shaker was installed under the canvas of the finger hump, which made it possible to select the required frequency and amplitude of oscillations. To improve the quality of the separation of components when finger humps working, it is important to ensure the relative movement of the components of the potato heap through the fingers of the hump. The direct transverse bending of the finger under the influence of the potato heap weight was studied, considering the dynamic loads when the canvas is tossed. Knowing the dependence of the vibration accelerations of the finger hump, the frequency of rotation of the multi-cam shaker in the range from 50 to 150 rpm and the angle of inclination of the finger hump from 25° to 35°, the velocities and acceleration of vibrations were obtained on the basis of which the parameters of the finger hump were calculated. They were as follows: Young’s modulus - E was 20·106 Pa, the height of the elastic part of the finger was 0.06 m, the diameter of the finger was 0.012-0.016 m, the stiffness of the finger was 3.7-4.8 N/m.To check the obtained parameters of the longitudinal finger hump with an installed shaker, a laboratory setup was developed. When conducting experimental studies, it was found that the highest values of the completeness of separation corresponded to the following values of factors: the rotational speed of the shaker was 130 rpm and the angle of inclination of the hump canvas was 34°.

3D hygro-elastic shell model for the analysis of composite and sandwich structures

The present work proposes the study of the hygrometric loading effects in the static analysis of multilayered composite and sandwich plates and shells. The employed model is based on a general exact 3D shell theory valid for one-layered and multilayered sandwich and composite plates, cylinders and cylindrical/spherical shell panels. The employed 3D equilibrium equations are developed in an orthogonal mixed curvilinear coordinate system for spherical shells in order to obtain the other simpler geometries as particular cases. A layer-wise approach is employed and equilibrium equations are solved in the thickness direction via the exponential matrix method. The partial derivatives in the in-plane directions are exactly calculated by assuming simply-supported edges and harmonic forms for the variables. The presented 3D shell model is extended to hygro-elastic cases by considering moisture content amplitudes imposed at the external surfaces of the structures in steady-state conditions. The moisture content profile through the thickness of the structures can be included in the 3D shell model using three different methodologies: it can be calculated by solving the steady-state 3D or 1D version of the Fick diffusion law, or it can be “a priori” assumed as linear through the thickness. Therefore, the developed system includes three non-homogeneous second order differential equilibrium equations that are solved after the introduction of opportune mathematical layers to consider the curvature effects through the thickness. The reduction to a first order differential equation system is obtained by redoubling the number of variables. The exponential matrix method is employed to accurately define both general and particular solutions. The implemented 3D hygro-elastic shell model is firstly validated and then it is employed with confidence for new benchmarks where the effects of thickness ratio, geometry, lamination scheme, material, thickness layer and imposed moisture content values at the external surfaces are investigated for composite and sandwich plates and shells. Showed results demonstrate the importance of an accurate developing of the elastic part of the 3D shell model combined with an appropriate evaluation of the moisture content profile through the thickness. Assumed linear moisture content profiles are correct only for thin one-layered isotropic structures, the use of the 1D Fick diffusion law allows only the correct definition of the material layer effect, the use of its 3D version allows the correct definition of both material and thickness layer effects.

Phase-field implicit material point method with the convected particle domain interpolation for brittle–ductile failure transition in geomaterials involving finite deformation

A phase-field implicit material point method with the convected particle domain interpolation (PF-ICPDI) is proposed to model the brittle–ductile failure transition in pressure-sensitive geomaterials involving finite deformation. In this method, the phase-field fracture formulation relying on the microforce balance law and the second law of thermodynamics is adopted as a nonlocal damage function for the elastoplastic fracture analysis. A smooth two-yield-surface plasticity constitutive model is utilized to evaluate the brittle–ductile failure transition behavior of pressure-sensitive geomaterials. The coupling effect of phase-field fracture model and cap plasticity model is established by introducing an effective phase-field stress and splitting the total stored energy into elastic and plastic parts. The implicit material point method that can avoid severe mesh distortion and improve numerical stability is then developed to solve the quasi-static elastoplastic fracture finite deformation problem. Furthermore, the convected particle domain interpolation technique is adopted to eliminate numerical noises and improve computational accuracy while material points crossing cell boundaries in modeling the large deformation brittle–ductile failure transition process. The staggered incremental iterative scheme is carried out to solve the coupled discrete governing equations. The accuracy and capability of the proposed PF-ICPDI method are demonstrated through several representative numerical examples, as well as the effects of main material parameters on the phase-field brittle–ductile failure transition modeling of geomaterials are discussed.

Modelling and simulation of coupled fluid transport and time-dependent fracture in fibre-reinforced hydrogel composites

Physicochemical and mechanical stimuli can trigger fluid transport and inelastic solid deformations in the fracture process of anisotropic hydrogel composites. The underlying mechanisms for the time-dependent deformation and fracture behaviour of hydrogel composites remain elusive and poorly understood. The present work develops an anisotropic poro-visco-hyperelastic-damage model based on the theory of porous media (TPM) to analyse the relationship between the coupled time-dependent behaviours, i.e.visco-hyperelasticity and fluid transport, and the fracture behaviour of hydrogel composites. The visco-hyperelasticity of the polymer networks resulting from the breaking and reforming kinetics of physical bonds is described by introducing internal variables based on the multiplicative decomposition of the deformation gradient tensor into elastic and inelastic parts. The fluid transport through the porous polymer networks is governed by Darcy’s law. A continuum damage model is proposed to describe the mechanical degradation of the anisotropic hydrogel composites, e.g., the cross-link unzipping and chain scission in polymer networks as well as the damage and breaking of embedded nanofibres. An integral-type nonlocal averaging algorithm is employed in the proposed damage model to eliminate the mesh dependence of numerical simulations. Furthermore, an operator split integration algorithm and an exponential mapping algorithm are applied to integrate evolution equations for internal variables and stresses. The resulting exponential tensor function is computed via spectral decompositions. The consistent tangent operators for an implicit finite element procedure are derived in detail in this contribution. Three representative numerical examples are used to validate the proposed model and investigate the mechanisms of the time-dependent fracture behaviour of anisotropic hydrogel composites. The computational results demonstrate that the proposed model can capture the fracture behaviour of hydrogel composites with different fibre orientations.

Mechanical properties of metal and polymeric viscoelastic materials and their applications

Nowadays, With the wide application of metals and polymeric materials, how to describe the property of Viscoelastic material and how to apply them in engineering has become more and more critical. Due to the lack of insight into the mechanical properties of viscoelastic materials, many scholars have done a lot of experiments in studying the behavior of viscoelastic materials. Axial tensile tests were conducted on specimens to derive different mechanical behaviors of metals, polymers, and other materials at different temperatures and loading rates. Metal can generally be divided into elastic and plastic parts, while polymeric materials have the phases of the linear elastic region, drawing region, and oriented molecular strength region. This paper also shows a test conducted by Argon, Ali S., and M. I. Bessonov of four different kinds of polymers at different circumstances of temperature. After that, the paper shows the application of viscoelastic materials as CLD in damping and some engineering problems caused by the mechanical properties of viscoelastic materials. Currently, research on viscoelasticity should mainly focus on the application of Finite Element Methods and the acquisition of more experimental data to establish a complete theoretical system.

Springback control and large skin manufacturing by high-speed vibration using electromagnetic forming

In this paper, a novel method of electromagnetic partitioning forming with elastic cushion is proposed. Its main principle is based on that the parts vibrate at high speed under the action of the electromagnetic force and the rebound force of the elastic pad. The state of the elastic parts inside the workpiece is changed into plastic state, and then, springback is eliminated through vibration. A common spiral coil is used to generate the magnetic field. A finite element model has been developed to analyze the effects of coil structure and coil discharge position on the stress, strain, and surface quality of the parts. It is found that a 1.5-mm bump is generated on the sheet surface, which corresponds to the middle of the coil. This is because this sheet region corresponds to the coil edges moving towards each other in opposite directions. Subsequently, the electromagnetic shielding method is used to isolate half of the spiral coil. Both the simulation and experiment demonstrated that no bulge was produced on the sheet surface. Moreover, the internal stress and springback of the parts are significantly reduced due to that the sheet vibrates at high speed. Large-scale skin was obtained after the coil was discharged multiple times in six different positions. Compared to traditional stretching, the springback of the parts is significantly reduced and the plate surface is smooth after electromagnetic forming. Consequently, the high-speed vibration induced by electromagnetic forming can reduce springback and enables the manufacturing of large size parts with smooth surface.

ABOUT THE YIELD PLATEAU UNDER SIGN-VARIABLE LOADING

During tension of samples of low-carbon steels and some other plastic materials, the sharp yield point and the yield plateau are fixed on the deformation diagram. In this case, Chernov-Luders bands appear on the surface of the sample in the local section, which then propagate along the tension axis. The physical nature of the sharp yield point is established: the drop in the load after reaching the (upper) yield limit occurs as a result of dislocations being an extraction out of the cloud of the embedded atoms and vacancies (Cottrell's cloud). At the occurrence of the sharp yield point , the plastic strain is limited to a small area. When the sample deformation increases, the plasticity zone (the yield plateau is marked on the diagram at this time) expands, and the stress-strain state in this zone becomes almost homogeneous, if we do not consider its boundary with the elastic region. At the end of the yield plateau, the entire sample experiences a uniform plastic deformation, excluding its ends (galtels). From this point on, the strain diagram shows the of material hardening; presumably, this hardening occurred from the very beginning, but was hidden under the yield plateau. This is evidenced by the resulting strain-induced anisotropy. After unloading the sample, when the plastic strain front (in the form of Chernov-Luders bands) has not yet passed through the entire sample, and the Bauschinger's effect is observed with the subsequent change in the stress sign. The fact that after the occurrence of the sharp yield point , the plastic strain is not localized in a certain volume, similar to what occurs during the neck formation, but spreads along the sample, serves as proof of the material hardening due to plastic deformation immediately after the load falls. Therefore, if the plastically deformable part of the sample did not have a hardening of the material due to the plastic strain growth, it would not be able to spread to the elastic part of the sample. This paper presents the experimental data of the sign-variable torsion of the thin-walled tubular samples of steel 45 in the annealed state. The deformation atdiagram of the occurrence and development of the yield plateau in distinct sections along the length of the test sample is obtained. The material hardening diagram hidden under the yield plateau is reconstructed using the well-known Masing's principle.

Cyclic Behavior of Simple Models in Hypoplasticity and Plasticity with Nonlinear Kinematic Hardening

The paper gives insights into modeling and well-posedness analysis driven by cyclic behavior of particular rate-independent constitutive equations based on the framework of hypoplasticity and on the elastoplastic concept with nonlinear kinematic hardening. Compared to the classical concept of elastoplasticity, in hypoplasticity there is no need to decompose the deformation into elastic and plastic parts. The two different types of nonlinear approaches show some similarities in the structure of the constitutive relations, which are relevant for describing irreversible material properties. These models exhibit unlimited ratchetting under cyclic loading. In numerical simulation it will be demonstrated, how a shakedown behavior under cyclic loading can be achieved with a slightly enhanced simple hypoplastic equations proposed by Bauer

Coupling Stokes Flow with Inhomogeneous Poroelasticity

Summary We investigate the behaviour of flux-driven flow through a single-phase fluid domain coupled to a biphasic poroelastic domain. The fluid domain consists of an incompressible Newtonian viscous fluid while the poroelastic domain consists of a linearly elastic solid filled with the same viscous fluid. The material properties of the poroelastic domain, that is permeability and elastic parameters, depend on the inhomogeneous initial porosity field. We identify the dimensionless parameters governing the behaviour of the coupled problem: the ratio between the magnitudes of the driving velocity and the Darcy flows in the poroelastic domain, and the ratio between the viscous pressure scale and the size of the elastic stresses in the poroelastic domain. We consider a perfusion system, where flow is forced to pass from the single-phase fluid to the biphasic poroelastic domain. We focus on a simplified two-dimensional geometry with small aspect ratio and perform an asymptotic analysis to derive analytical solutions. The slender geometry is divided in four regions, two outer domains that describe the regions away from the interface and two inner domains that are the regions across the interface. Our analysis advances the quantitative understanding of the role of heterogeneous material properties of a poroelastic domain on its mechanical response when coupled with a fluid domain. The analysis reveals that, in the interfacial zone, the fluid and the elastic behaviours of this coupled Stokes—poroelastic problem can be treated separately via (i) a Stokes–Darcy coupling and (ii) the solid skeleton being stress free. This latter finding is crucial to derive the coupling condition across the outer domains for both the elastic part of the poroelastic domain and the fluid flow. Via specification of heterogeneous material properties distribution, we reveal the effects of heterogeneity and deformability on the mechanics of the poroelastic domain.

Pseudoelastic PP and PSSP modeling in stratified media

Many modeling techniques have been developed to find the acoustic and elastic responses of a stack of plane layers to a plane spectral wave. For an elastic medium bounded above by an acoustic half-space, the acoustic wave propagator matrix modeling method can be modified to model pseudoelastic PP arrivals and PSSP arrivals. PP arrivals propagate as pure longitudinal (P) waves in the layers, whereas PSSP arrivals propagate as shear (S) waves in the elastic part of the model. A simple modification of the pseudoelastic PP response modeling scheme allows modeling of primary P reflections. A primary reflection event involves just one reflection in the plane stratified model and thus excludes internal multiples. The propagator modeling scheme is formulated in the frequency-horizontal slowness domain. By applying inverse Fourier transforms over the frequency and horizontal wavenumbers, where the wavenumber is the horizontal slowness divided by the frequency, modeled seismograms are computed and displayed in the time-space domain. By applying an inverse Fourier transform over the frequency for selected horizontal slowness components, the computed seismograms can be shown in the intercept time-horizontal slowness ([Formula: see text]) domain. When the source wavelet is unity for frequencies of interest, the [Formula: see text] domain seismograms become plane-wave Green’s function seismograms. The [Formula: see text]-traces of the Green’s function primary P-wave seismograms accumulate with increasing time band-limited step functions weighted by reflection strengths.

Strain gradient elasto-plasticity model: 3D isogeometric implementation and applications to cellular structures

In the present work, we combine Mindlin’s strain gradient elasticity theory and Gudmundson–Gurtin–Anand strain gradient plasticity theory to form a unified framework. The gradient plasticity model is enriched by including the gradient of elastic strains into the expression of the internal virtual work and free energy. This augments the modelling capabilities by incorporating elasticity-related length scales along with plasticity-related energetic and dissipative ones. The strong form governing equations are derived via the principle of virtual work addressing a complete set of boundary conditions. The fourth-order boundary value problem of the gradient elasto-plasticity model is then formulated in a variational form within an H2 Sobolev space setting. Conforming Galerkin discretizations for numerical results are obtained utilizing an isogeometric approach with NURBS basis functions of degree p≥2 providing Cp−1-continuity. The implementation follows a viscoplastic constitutive framework and adopts the backward Euler time integration scheme. A set of benchmark examples is considered to illustrate convergence properties and to accomplish parameter studies. It is shown that the elastic length scale parameter controls the slope of the elastic part and causes an additional hardening in the plastic part of the material response curves. Finally, an illustrative example is considered in order to demonstrate the applicability of both the continuum model and the numerical method in capturing the size-dependent torsion response of cellular structures.

Effect of Compliance on Residual Stresses in Manufacturing With Moving Heat Sources

Abstract Manufacturing processes involving moving heat sources include additive manufacturing, welding, laser processing (cladding and heat treatment), machining, and grinding. These processes involve high local thermal stresses that induce plasticity and result in permanent residual stress and distortion. The residual stresses are typically calculated numerically at great computational expense despite the fact that the inelastic fraction of the domain is very small. Efforts to decouple the small plastic part from the large elastic part have led to the development of the tendon force concept. The tendon force can be predicted analytically for the case of infinitely rigid components; however, this limitation has prevented the broader use of the concept in practical applications. This work presents a rigorous mathematical treatment using dimensional analysis, asymptotics, and blending which demonstrates that the effect of geometric compliance depends on a single dimensionless group, the Okerblom number. Closed-form expressions are derived to predict the effect of compliance without the need for empirical ad-hoc fitting or calibration. The proposed expressions require input of only material properties and tabulated process parameters and are thus ideally suited for use in metamodels and design calculations, as well as incorporation into engineering codes and standards.

Optimization and fast prototyping of polymer parts exposed to cyclic loading

Many mechatronic systems operate with parts made of polymers. This cost-effective solution is also easy to design. Manufacturing is trivial for producers who produce millions of parts. The solution is more complicated when the fatigue and loading is a significant factor. The paper describes the development of polymer parts that are loaded by cyclic operation. The number of cycles in a specific application can be around 1 million. The specific case also deals with a corrosion environment around these components. Gasses in the environment cause degradation of material and failure of parts made of specific polymers. This interaction limits the choice of suitable materials. The mechanism operates in two directions which define the opening of a valve and free turn. Two variants of elastic valves were analysed. Loading states were simulated by final element methods. Internal stresses and contact stresses were analysed. Results were compared with long-term test results. The material creep and other material properties define the function of elastic parts after thousands of cycles. The technology of mould fabrication was analysed considering simplification and general effectivity of production. Prototype valves were printed by FDM 3D printer and tested. Prototype moulds were printed by SLA 3D printer, which produces high-temperature stable polymer. This procedure shows cost-effective prototype development and test procedures.

Wave propagation in porous thermoelasticity with two delay times

Plane time‐harmonic waves with assigned wavelength are supposed to propagate in an infinite linear thermoelastic space: The thermodynamic response is framed into the time differential dual‐phase‐lag model, while the Cowin–Nunziato theory is used to depict the effect of porosity for the elastic part. We are able to show that it is possible to identify two shear waves, undamped in time and not affected by porosity and/or temperature, as well as four longitudinal waves (a quasi‐elastic wave, a quasi‐pore wave, a quasi‐thermal mode, and a quasi‐phase‐lag thermal wave); the corresponding dispersion relation is presented like a seventh‐degree algebraic equation. The numerical simulations and the graphs presented show the effects of the various elasto‐porous‐thermal couplings on the characteristics of the four longitudinal waves. The work has to be intended as evolution and, at the same time, as a point of synthesis with respect to similar previous studies which took into account, exclusively, or the double delay time or the presence of voids.

Single-Molecule Force Spectroscopy Studies of Missense Titin Mutations That Are Likely Causing Cardiomyopathy.

The giant muscle protein titin plays important roles in heart function. Mutations in titin have emerged as a major cause of familial cardiomyopathy. Missense mutations have been identified in cardiomyopathy patients; however, it is challenging to distinguish disease-causing mutations from benign ones. Given the importance of titin mechanics in heart function, it is critically important to elucidate the mechano-phenotypes of cardiomyopathy-causing mutations found in the elastic I-band part of cardiac titin. Using single-molecule atomic force microscopy (AFM) and equilibrium chemical denaturation, we investigated the mechanical and thermodynamic effects of two missense mutations, R57C-I94 and S22P-I84, found in the elastic I-band part of cardiac titin that were predicted to be likely causing cardiomyopathy by bioinformatics analysis. Our AFM results showed that mutation R57C had a significant destabilization effect on the I94 module. R57C reduced the mechanical unfolding force of I94 by ∼30–40 pN, accelerated the unfolding kinetics, and decelerated the folding. These effects collectively increased the unfolding propensity of I94, likely resulting in altered titin elasticity. In comparison, S22P led to only modest destabilization of I84, with a decrease in unfolding force by ∼10 pN. It is unlikely that such a modest destabilization would lead to a change in titin elasticity. These results will serve as the first step toward elucidating mechano-phenotypes of cardiomyopathy-causing mutations in the elastic I-band.

A finite-deformation constitutive model of particle-binder composites incorporating yield-surface-free plasticity

Abstract We present a constitutive model for particle-binder composites that accounts for finite-deformation kinematics, nonlinear elasto-plasticity without apparent yield, cyclic hysteresis, and progressive stress-softening before the attainment of stable cyclic response. The model is based on deformation mechanisms experimentally observed during quasi-static monotonic and cyclic compression of mock Plastic-Bonded Explosives (PBX) at large strain. An additive decomposition of strain energy into elastic and inelastic parts is assumed, where the elastic response is modeled using Ogden hyperelasticity while the inelastic response is described using yield-surface-free endochronic plasticity based on the concepts of internal variables and of evolution or rate equations. Stress-softening is modeled using two approaches; a discontinuous isotropic damage model to appropriately describe the softening in the overall loading-unloading response, and a material scale function to describe the progressive cyclic softening until cyclic stabilization. A nonlinear multivariate optimization procedure is developed to estimate the elasto-plastic model parameters from nominal stress-strain experimental compression data. Finally, a correlation between model parameters and the unique stress-strain response of mock PBX specimens with differing concentrations of aluminum is identified, thus establishing a relationship between model parameters and material composition.

Elastic and Viscoelastic Models of Crust Deformation in Strike-slip Fault

The crust, when viewed over a long period, moves towards one another. Crusts might experience sudden slip on a fault plane and caused fractures or cracks. There are three different types of faults, normal, reverse, and strike-slip faults. Induced stress due to sudden rupture on fault planes capable of creating stress and need to be measured quantitatively to comprehend the earthquake process. To understand the stress that occurs in strike-slip faults in the earth’s crust, the previous researchers study the use of elastic materials as the material of the earth’s crust, so that the earth crust’s deformation is elastic. However, elastic material has linear stress and strain relationship that results in reversible deformations or returns to their original shape. This material is not suitable for modeling the earth’s crust’s long-term deformation, where the deformation of the earth’s crust can be permanent, so a model is needed to solve this problem. In this study, we will compare the stress in the strike-slip fault in the upper crust with elastic materials, while the lower crust and upper mantle have viscoelastic materials compared to purely elastic materials through numerical simulations. This comparison is made to see the comparison between the two approaches with the earth’s layers’ actual state. The two models is chosen to represent the different failure processes of the earth crust, i.e. the elastic deformation part describes the response to stress in a short period, and the viscous deformation can explain the response over a more extended period. The study of both materials above is based on plate tectonic theory, in which the lithosphere plates will relatively move to each other because the layer material underneath is solid but can flow like a liquid for a long period.

Seismic waves in medium with poroelastic/elastic interfaces: a two-dimensionalP-SVfinite-difference modelling

SUMMARYWe present a new methodology of the finite-difference (FD) modelling of seismic wave propagation in a strongly heterogeneous medium composed of poroelastic (P) and (strictly) elastic (E) parts. The medium can include P/P, P/E and E/E material interfaces of arbitrary shapes. The poroelastic part can be with (i) zero resistive friction, (ii) non-zero constant resistive friction or (iii) JKD model of the frequency-dependent permeability and resistive friction. Our FD scheme is capable of subcell resolution: a material interface can have an arbitrary position in the spatial grid. The scheme keeps computational efficiency of the scheme for a smoothly and weakly heterogeneous medium (medium without material interfaces). Numerical tests against independent analytical, semi-analytical and spectral-element methods prove the efficiency and accuracy of our FD modelling. In numerical examples, we indicate effect of the P/E interfaces for the poroelastic medium with a constant resistive friction and medium with the JKD model of the frequency-dependent permeability and resistive friction. We address the 2-D P-SV problem. The approach can be readily extended to the 3-D problem.

High Strength Steel and Fuse Dissipative Solutions for Seismic Resistant Building Structures

AbstractThe robustness of structures against severe seismic action is ensured by their global performance, in terms of ductility stiffness and strength, properly calibrated. The “plastic“ members of ductile Mild Carbon Steel ‐ MCS – (S235 to S355) will dissipate the seismic energy, acting as “structural fuses“, while the “elastic“ members, must be provided of adequate overstrength, to have the capacity to carry the supplementary stresses after the plastic hinges have been formed and the redistribution forces were occurred. For these elastic members, High Strength Steels (HSS), such as S460 to S690, might be used, provide them the necessary overstrength, without enhancing the stiffness, because that could unbalance the structural system. These structures, which combine HSS with MCS, are termed Dual‐Steel (DS). The braced frames can be equipped with detachable dissipative MCS members, which are acting as seismic fuses. In case of CBF, the fuses might be the Buckling Restrained Braces (BRB), while for EBF, the links could take this role. In case of MRF, Steel Plate Shear Walls (SW) can be used as fuses. To make possibly to replace the used fuses, the HSS elastic part of the structure, has the mission to re‐centring the structure after the earthquake. This is the subject of present paper.