Elasto-plastic Dynamic Analysis Research Articles

Seismic Performance Assessment of Composite Frame–High-Strength Steel Plate Wall Core Tube Resilient Structural System

Against the backdrop of China’s continuous promotion of green and low-carbon transformation and the development of construction industrialization, high-strength composite structural systems have significant development prospects. However, their research and application in the field of construction are insufficient. In response to this issue, the study proposes a new high-performance structural system, namely the composite frame–high-strength steel plate wall core tube resilient structural system, which includes a core tube composed of double steel plate concrete composite shear walls and replaceable energy dissipation coupling beams, as well as composite frames. The highest strength grades of the steel plate and concrete used in the composite walls of the core tube are Q550 and C100, respectively. Using a 200 m building as an example, this study designs and establishes models for this high-performance structure and a conventional reinforced concrete frame–core tube structure. Subsequently, the dynamic elastoplastic time history analysis and seismic resilience assessment of structures are conducted under design basis earthquakes (DBEs), maximum considered earthquakes (MCEs), and extremely rare earthquakes (EREs). Research has shown that, compared to conventional structures, the thickness of shear walls of new high-performance structures can be effectively reduced, which helps decrease the self-weight of the structure and improve the available space in buildings. Additionally, high-performance structures exhibit a better performance in controlling the story drift ratio, lower plastic damage and overall stiffness degradation of the structure, and better seismic performance. The seismic resilience of the high-performance structure has been significantly enhanced, especially in terms of minimizing casualties, thereby better ensuring the safety of people’s lives and property.

Study on Shock-Absorbing Effect of a Double-Story Isolation Structure Considering Soil–Structure Interaction

The double-story isolation structure is a novel development based on the mid-story isolation structure. To accurately reflect the seismic response of the double-story isolation structure, this study considers a dynamic elastoplastic analysis model that incorporates soil–structure interaction (SSI). Comparative models of a base-fixed structure and a mid-story isolation structure are also established. The results indicate that the double-story isolation structure has a longer structural period compared to the mid-story isolation structure. Furthermore, the structural period increases as the soil softens and the structure becomes more flexible. When considering SSI on hard soil versus not considering SSI, the double-story isolation structure exhibits smaller base shear, story force, inter-story displacement, maximum acceleration of the top floor, and displacement of the upper isolation layer, indicating the significant shock-absorbing effect of the double-story isolation structure. However, when SSI is considered on soft soil, the shock-absorbing effect of the isolation structure diminishes, and the effectiveness of the double-story isolation structure may not necessarily surpass that of the mid-story isolation structure. In all three soil conditions, the compressive stresses of the isolation bearings in the upper isolation layer of the double-story isolation structure were lower than those in the isolation bearings of the base isolation layer. Additionally, the double-story isolation structure demonstrates reduced compressive stress in the isolation bearings, fewer plastic hinges in the frame, and less stress damage compared to the mid-story isolation structure. Consequently, the risk of overturning damage in the double-story isolation structure is significantly reduced compared to the mid-story isolation structure. The effect of soft ground on structures can be highly detrimental, which should be paid more attention to during the design process. This study offers valuable insights for future research on double-story isolation systems and serves as a reference for the development of high-performance building structures in the future.

Seismic Mitigation Effect of Lever-Type Lead Viscoelastic Node Dampers

Energy dissipation damping technology is usually used for infrastructure construction in seismic regions. In this study, a lever-type lead viscoelastic node damper (LTLVND), which can capture small rotational displacements of the infrastructure under seismic excitation, is innovatively proposed based on the leverage effect. The characteristics of energy-absorbing capacity of the LTLVND and its mitigation effect on the dynamics of the structure under seismic excitation are studied. Testing and modelling results show that a satisfactory energy dissipation effect can be observed for the innovative lead viscoelastic damper (LTLVND). Finally, a seismic analysis of a concrete frame structure with LTLVNDs is carried out. Pushover analysis and dynamic elastoplastic analysis are included. It is shown that a significant improvement in structural performance under seismic conditions can be achieved with the addition of LTLVNDs at appropriate locations.

Simple and Unified Way of Elasto-Plastic Dynamic Analysis

Simple and Unified Way of Elasto-Plastic Dynamic Analysis

Structural Design and Analysis of a Super-High Building in Nanjing, China

This study analyzes a high-rise building with B-level height (i.e., a total height of 146.5 m) and a shear wall structure. Since the project contains many plane irregularities (including 1a torsional irregularity, 1b eccentric arrangement, and 2a plane convex irregularity), it should be treated as a super high-rise building. This study introduces the main characteristics and overrun conditions of the project and describes the structural design of the foundation and the basement, upper structural layout, force conditions under frequent, fortified, and rare earthquake actions, and structural performance-based objectives in detail. The following measures can be adopted to address the overrun problem. First, the floor at the thin waist of the structure was thickened to 150 mm and reinforced in the bilayer and bidirectional patterns, with a reinforcement ratio of no less than 0.25%. The damage condition on the floors under a great earthquake was analyzed. The vertical components at the waist were reinforced to constrain the extension of the edge components toward the top. Second, the structure’s peripheral stiffness was strengthened to enhance the anti-torsional performance and minimize the adverse effects on torsional irregularities. Third, using two software programs, the performance-based envelope design under medium earthquake action and dynamic elastoplastic analysis under great earthquake action were analyzed to ensure structural safety. Fourth, the edge components were constrained for the shear wall columns with axial-to-compressive stress strength ratios exceeding 0.3. For the overall structure and critical parts, force conditions under frequent, fortified, and rare earthquake conditions were calculated and examined with the SATWE, MIDAS GEN, and SAUSAGE software packages. The calculation results revealed that the structure shows favorable anti-seismic performance, with an overall anti-seismic C-level and a safe and reliable structure. The structural design method introduced in this article can promote the sustainable development of structural design.

Analysis and Calculation of Large Span Dry-Coal Shed

The project of Wuhan Group Kunming Iron and Steel Co., Ltd., Promote the supply side structural reform and implement the special upgrading project of environment comprehensive raw material yard project ore yard (A to B) reticulated shell structure Located in Kunming Steel New Area, Cao pu Town, Anning City, Kunming City, Yunnan Province, 780m long, 50m high, the span is 147m (more than 120m), According to «Code for Seismic Design of Buildings» and «Technical points of special review on seismic fortification of high-rise buildings beyond the limit», it belongs to the out of gauge large-span space structure, Special review of engineering seismic fortification is required. The structural analysis of the project adopts SAP2000, MST2020, MIDAS Gen three kinds of software for calculation and analysis, And the individual model and the whole model are established respectively, Envelope analysis is carried out for two cases. Through linear elastic analysis, response spectrum small earthquake analysis, Medium earthquake analysis of response spectrum, elastic time-history analysis of small earthquakes, dynamic elastoplastic analysis of large earthquakes to analyze and calculate the deformation of latticed shells and the stress of membersl. Through a series of structural analysis and structural measures, To ensure that the reticulated shell and the lower part are coagulated on the short column and all performance indicators can meet the specification requirements. Through the structural analysis of two calculation models, ensure that all performance indicators can meet the specification requirements.

Performance-Based seismic design and evaluation of out-of-code structure on Nanjing Financial City

The main scope of performance-based seismic design and evaluation study focuses more on the seismic performance of the simple structure or the regular structure, instead of out-of-code structure. The C1 tower in Nanjing Financial City is taken as an engineering case study. Many design indexes of the original design scheme of the structure exceed the requirements of the existing Chinese specifications, such as the height exceed the limits, the torsional irregularity, the partial floor slab discontinuity etc., which are summarized in detail in this paper. Then, several special structural design strategies are adopted to improve the overall seismic performance of this out-of-code structure. For example, multiple lines of seismic defences are set and the outrigger trusses are strengthened to solve the height overrun. For torsion irregularity, the influence of the bidirectional seismic torsion effect is considered in the calculation. Finally, according to the results of dynamic elastoplastic time history analysis under rare earthquakes, the seismic performances of the out-of-code structure are evaluated in detail. The analysis results show that the overall seismic performances of the structure are all within a reasonable range, and the seismic performance of the main components in the structure all meet the specification requirements.

Inelastic Dynamic Time-history Analysis of a Frame-wall Structrue

The teaching building of QiaoTou School is a frame-wall structure, which has 14 storeys. In this paper, the elastoplastic model of the structure is studied. On this basis, the dynamic elastoplastic analysis of the structure is carried out by using YJK software, and the nonlinear dynamic responses of the structure, including structural deformation, component damage, are investigated under the action of rare earthquake. The results show that the buckling meets the target of "no collapse under strong earthquake".

Seismic performance enhancing of novel self-centering precast concrete frame using replaceable hysteretic dampers

To break through the design criteria of “equivalent cast-in-place” for “wet connection”, a new self-centering precast concrete (SCPC) frame with replaceable hysteretic dampers is proposed to provide sufficient energy dissipation damping, vertical shear, and self-recovering capacities. This paper focuses on the seismic behaviors enhancing of the novel SCPC frame joint compared with traditional cast-in-place reinforced concrete (RC) frame joint. The working principle of the novel hybrid joint is illustrated, and seven cyclic loading tests with different test parameters were conducted on the three full-sized novel SCPC joints and one full-sized RC joint. The hysteresis behavior, skeleton curves, stiffness degradation, energy dissipation characteristics, and reinforcement strain of these test results were discussed. Performance-based design targets under the Design Basis Earthquake (DBE) and the Maximum Credible Earthquake (MCE) levels are defined, the design procedure of the novel SCPC frame has been developed. Furthermore, a novel SCPC frame located in the high-intensity area in China is designed based on the design procedure, elastoplastic dynamic analyses of the novel SCPC frame and RC frame are performed subjected to the DBE and MCE levels. The global and local responses illustrate the seismic behaviors and structural reliability of the novel hybrid SCPC frame with replaceable hysteretic dampers have been significantly enhanced.

Nonlinear transient response of elastoplastic sandwich beam

This paper aims to propose a new theory on the elastoplastic transient response of sandwich beams under large displacement with moderate rotation, including an analysis strategy for multi-dimensional elastoplasticity and the corresponding numerical solving technique. The material behaviors follow the bilinear proportional hardening rule. According to the classifications of stress statuses, the updated structural stiffness of the sandwich beam in time history is acquired and a systematic procedure for the multi-dimensional elastoplastic dynamic analysis is subsequently developed. The dynamic governing equations involving geometric and material nonlinearities are solved by a modified Ritz-based approach, in association with the Newmark-beta technique. The closed linear solution and the finite element simulation validate the accuracy of the proposed nonlinear theory. Case study reveals that the strain hardening has significant effects on the dynamic response of sandwich beams. The application to the blast-resisting study of sandwich beams as sacrificial coatings on ship hulls further proves the effectiveness of the current theory.

Seismic Performance Analysis of Tuned Mass Rocking Wall (TMRW)-Frame Building Structures

A tuned mass rocking wall (TMRW) is a passive control device that combines the merits of a traditional tuned mass damper (TMD) and a traditional rocking wall (RW). TMRWs not only help avoid weak story failure of the host structure but can also be regarded as a largely tuned mass substructure in the building structure. Through the appropriate design of the frequency ratio, the host structure can dissipate much more energy under earthquake excitations. In this paper, the basic equations of motion for the mechanical model of an SDOF structure-rigid rocking wall are established, and the optimization formulas of frequency ratio and damping ratio of TMRW are derived. Through the dynamic elastoplastic analysis of a six-story TMRW-frame model, the applicability of the derived parameter optimization formulas and the effectiveness of the TMRW in seismic performance control are investigated. The results demonstrate that the TMRW can coordinate the uneven displacement angle between stories of the host structure. Additionally, the TMRW is found to possess the merit of reducing both the peak and root-mean-square (RMS) structural responses when subjected to different types of earthquake excitations.

Analytical treatment on singularities for 2-D elastoplastic dynamics by time domain boundary element method using Hadamard principle integral

A fully analytical method by adopting the concept of the finite part of an integral, Hadamard principle integral, is proposed to treat the singularities in both time and space in the plastic strain-related coefficients matrices Q and F in the TD-BEM formulation for elastoplastic analysis. Comparing with the treatment on singularity by using the method of rigid body displacement, the novel analytical treatment on the singularity is from the viewpoint of dynamics, without any numerical component of the elastostatic concept, meaning that the treatment is theoretically suitable for elastoplastic analysis. Meanwhile, comparing with the treatment on singularity by the initial stress expansion technique and the method of the constant strain fields, the novel analytical treatment on the singularity retains all of the inherent advantages of the TD-BEM formulation for elastoplastic analysis, restricting the discretization on boundary and in the potential plastic region and allowing models with infinite or semi-infinite geometry extension without artificial boundaries. Finally, the novel analytical treatment on the singularity is strictly mathematically tenable, without any computational error. The proposed treatment on singularity for dynamic elastoplastic analysis in TD-BEM formulation is verified by three examples.

Parametric Study on Self-centering Precast Concrete Frames with Hysteretic Dampers

The self-centering precast concrete frame structure combines the advantages of industrialization and low earthquake damage, and its energy dissipation capacity and seismic performance have always been the focus of research. This paper proposed a kind of self-centering precast concrete frame with hysteretic dampers (SCPCHD). Its modular design makes the energy dissipation device and components easy to repair and replace. In order to obtain the optimal design, the finite element models of SCPCHD frames with different layout types of post-tensioned (PT) tendons and different shapes of hysteretic dampers are established, and the elastoplastic dynamic time-history analyses are carried out. The results show that the layout types and vertical margin of PT tendons have little effect on the displacement response of the frame structure. Compared to linear PT tendons, polygonal PT tendons can better bear the bending moment of the beam and reduce the stress of longitudinal reinforcements in the beam. The reduce effect of shortening the vertical margin on the tensile damage of beam concrete is obvious in the frame with polygonal PT tendons, but not obvious in the frame with linear PT tendons. Rational design of the prestressing force also plays a crucial role in the energy dissipation capacity of SCPCHD frames.

Seismic Energy Response of SDOF Systems Subjected to Long-Period Ground Motion Records

To provide an important reference for the energy-based seismic design of long-period structures, the elastoplastic dynamic analysis program is employed to study the seismic energy response of single-degree-of-freedom (SDOF) systems under two types of typical long-period ground motions. Then, the influencing relationships of external and internal factors on the energy response spectra under near-fault pulse-like and far-field harmonic ground motions are analyzed one by one. Study results are obtained as follows: within the whole period, all the input energy, hysteretic energy and damping energy spectra of SDOF systems under near-fault pulse-like and far-field harmonic ground motions, are larger than those under common ground motions, even the seismic energy response under far-field harmonic ground motions is larger than that under near-fault pulse-like ground motions. From the aspect of energy concept, the energy response spectra and energy distribution rule of SDOF systems are evaluated based on the intensity and spectral distribution under near-fault pulse-like and far-field harmonic ground motions. If the ratio of hysteretic energy to input energy (RHEIE) is determined, the hysteretic energy which must be dissipated by a structure would be derived by the method of energy-based design. The input energy and hysteretic energy are mainly influenced by damping ratio and ductility coefficient, while the yield stiffness ratio exerts minor effects. It indicates that reasonable structural design parameters would contribute to the hysteretic energy of a structure itself.

A study on boundary integral equations for dynamic elastoplastic analysis for the plane problem by TD-BEM

The equivalent stress fundamental solution for the elastoplastic dynamic plane strain problem is proposed to transform the virtual work in the third direction to the plane. Subsequently, based on Betti reciprocal theorem, by adopting the time dependent fundamental solutions in terms of displacement, traction and equivalent stress, the boundary integral equations for dynamic elastoplastic analysis for the plane strain problem are established. The establishment procedures for the displacement and the stress boundary integral equations, together with the stress equation at boundary points, are presented in details, while the standard discretization both in time and space under the frame of time domain boundary element method (TD-BEM) and the solution of the algebraic equations are also briefly stated. Two verification examples are presented from different viewpoints, for elastic and elastoplastic analysis, for 1-D and 2-D geometries, and for finite and infinite domains. The TD-BEM formulation for dynamic elastoplastic analysis is presented for the plane strain problem as an example, where the formulation is also applicable for the plane stress problem by properly transforming the elastic constants and adopting the corresponding fundamental solutions. The equivalent stress fundamental solution for the elastoplastic dynamic plane strain problem is proposed to transform the virtual work in the third direction to the plane. Subsequently, the equivalent stress and the boundary integral equations for dynamic elastoplastic analysis for the plane strain problem, where a cavity under an uniformly distributed impact in an infinite medium, are established in the frame of the time domain boundary element method (TD-BEM).

Seismic Risk Assessment of a Novel Self-Centering Precast Concrete Frame under Near-Fault Ground Motions

The damage to structures caused by the velocity pulse effect of near-fault earthquake waves cannot be ignored, yet there are few studies on the risk assessment of seismic performance for precast concrete frame under near-fault earthquake waves. A novel self-centering precast concrete (SCPC) frame with hysteretic dampers is proposed to obtain great self-recovering and energy consumption characteristics. To accurately assess the seismic behaviors of the novel SCPC frame under the near-fault earthquake waves, a prototype structure is modelled and elastoplastic dynamic analysis is conducted at the design basis earthquake (DBE) and the maximum considered earthquake (MCE) seismic levels. Incremental dynamic analysis and the vulnerability analysis are performed. Annual and 50-year exceeding probabilities of the novel SCPC frame are calculated afterwards. In addition, the reinforced concrete (RC)frame and the traditional SCPC frame are also modelled, whose section sizes, reinforcements arrangement and seismic intensity are consistent with the novel SCPC frame. The dynamic time-history analysis at the two seismic levels are also carried out for two types of frames. The analysis results demonstrate that the novel SCPC frame has great seismic performance and low seismic risk possibility under the near-fault earthquakes loading.

Finite element approach of the buried pipeline on tensionless foundation under random ground excitation

This work presents an investigation in the numerical performance of finite element approach in the dynamic elastoplastic analysis of buried pipeline, which is subjected to random ground motion. The surrounding soil is modeled by Winkler and Pasternak type foundation, while the random ground motion is generated synthetically by generalized nonstationary Kanai–Tajimi model. The governing equation is formulated by Euler–Bernoulli beam theory and discretized by beam-pipe element. Moreover, the von Mises isotropic hardening model is employed for material behavior modeling. The Hilber–Hughes–Taylor (HHT) method and the Newton–Raphson method are adopted as the time incremental iterative algorithm to solve the global equilibrium equation. Several applications are carried out to investigate the numerical performance of the present numerical model in dealing with the dynamic elastoplastic analysis of buried pipe. The norm L2 of stress and displacement error are determined for different time intervals and the factors that contribute to the error reduction are investigated in present work.

Dynamic Elasto-Plastic Analysis of a Hybrid Coupled Wall System

In a hybrid coupled wall (HCW), a steel coupling beam with a good shear performance can replace a concrete coupling beam. This is especially applicable for locations in which height restrictions do not permit the use of deep reinforced concrete beams or in which it is not possible to economically develop required capacity, stiffness, or deformation demands with concrete beams. In this study, a new type of connection design with a steel boundary element of hybrid coupled wall (SBE-HCW) was proposed, and a 23-story SBE-HCW structure was analyzed under both gravity and seismic load to examine the seismic performance using ABAQUS. The structural failure process, base shear force, vertex displacement, and damage distribution of core tube were investigated. The analysis results confirmed that the response of specimen exhibited good plastic deformation behavior under seismic, thereby satisfying the demands of seismic ductility design. The connection between the steel coupling beams and the shear walls in the specimen appeared to be intact. The analysis evidence indicated that the proposed connection detailing appeared to be effective.

A scaled boundary finite element formulation for dynamic elastoplastic analysis

SummaryThis study presents the development of the scaled boundary finite element method (SBFEM) to simulate elastoplastic stress wave propagation problems subjected to transient dynamic loadings. Material nonlinearity is considered by first reformulating the SBFEM to obtain an explicit form of shape functions for polygons with an arbitrary number of sides. The material constitutive matrix and the residual stress fields are then determined as analytical polynomial functions in the scaled boundary coordinates through a local least squares fit to evaluate the elastoplastic stiffness matrix and the residual load vector semianalytically. The treatment of the inertial force within the solution of the nonlinear system of equations is also presented within the SBFEM framework. The nonlinear equation system is solved using the unconditionally stable Newmark time integration algorithm. The proposed formulation is validated using several benchmark numerical examples.

Study on seismic performance of steel frame with archaized-style under pseudo-dynamic loading

This paper presents an experimental study on a 1/2 scale steel frame with archaized-style under the pseudo-dynamic loading. Four seismic waves, including El Centro wave, Taft wave, Lanzhou wave and Wenchuan wave, were input during the test. The hysteresis characteristic, energy dissipation acceleration response, displacement response, strength, stiffness and strain were analyzed. Based on the experiment, the elastoplastic dynamic time-history analysis was carried out with the software ABAQUS. The stress distribution and failure mode were obtained. The results indicate that the steel frame with archaized-style was in elastic stage when the peak acceleration of input wave was no more than 400 gal. Under Wenchuan wave with peak acceleration of 620 gal, the steel frame enters into the elastoplastic stage, the maximum inter-story drift was 1/203 and the bearing capacity still tended to increase. During the loading process, Dou-Gong yielded first and played the role of the first seismic fortification line, and then beam ends and column bottom ends yielded in turn. The steel frame with archaized-style has good seismic performance and meets the seismic design requirement of Chinese code.