Elastic-plastic Time-history Analysis Research Articles

The Rigid Frame-Whole Bracing Model of Eco-Composotie Wall Structure

The eco-composite wall structure consists of concrete blocks，concrete frame grids , concealed frame and so on. When entering, the obvious damage phenomena appears on the eco-composite wall, the deformation coordination between the block and the frame grid, compound wall and the outer framework is broken, which brings relatively large-difficulty to establish the elasto-plastic model of structure. The rigid frame - whole bracing model of the eco-composite wall structure in elastic-plastic stage is presented based on previous study. The correctness of models is verified by experiments. Theoretical analysis and experimental results show that the rigid frame-whole bracing model giving consideration to accuracy and efficiency is applicable to structural elastic-plastic time-history analysis under strong seismic action.

Coincident Work between Upper Steel Structure and Lower Concrete Structure of Ningxia Flower Art Center

In order to investigate the joint work pattern of upper steel part and lower supporting concrete part，the example of Ningxia flower art center was adopted to create finite element models for upper steel structure only and steel-concrete structure. And a further analysis for the models was done in terms of statistic analysis、elastic analysis under frequently occurred earthquake and dynamic elastic-plastic time-history analysis under seldom occurred earthquake. Besides, the influence of concrete structure’s elastic-plastic property to the whole structure under seldom occurred earthquake was discussed. The results show that structure response such as displacement and internal force increase considerably under joint work pattern. Moreover，the magnification effect of the lower structure about seismic load can not be ignored when designing and analyzing. And the structure’s seismic response will decline if we take into account the lower concrete's elastoplasticity under seldom occurred earthquake.

Research on Elastic-Plastic Seismic Response of Inclined Mega-Structures

With a special structure system and architectural shape, Kelamayi Exhibition Building has a quite complicated seismic response and dynamic behavior. Based on performance-based seismic design method, vibration characteristics and seismic response under different earthquakes are researched in this paper. Elastic-plastic model is made, and elastic-plastic time history analysis of structure subjected to strong earthquake is carried out, to verify the bearing capacity of the structure according to aseismic behavior indexes. The results of static analysis and elastic-plastic time history analysis show that, the maximum storey drift angle is less than the limit value 1/100. Parts of the structure is in plastic, but not deep, and can be put into use after some repairment. In a word, Kelamayi Exhibition Building can meet the requirement of seismic fortification and fixed aseismic behavior indexed, and have enough seismic bearing capacity.

The Seismic Behavior Analysis of the Light-Duty Steel Structure Residence System

The light-duty steel structure residential demonstration project is analyzed by mode-superposition response spectrum method, the elastic and elastic-plastic time-history analysis, push-over analysis, which used the finite element software ETABS and PKPM. The safety is assessed. The seismic behavior of this structural system is analyzed under different site classification, design characteristic and seismic intensity, and is compared with the ordinary steel structure, concrete structure, masonry structure. The results show that, this structural system can meet the current codes under frequent and rare earthquake action. But the column has a surplus stable stress values. And it is suitable for application in large areas in China. In high intensity areas and compared with the different structure system, it shows that the lateral has the main effect on this structure.

Discussion on the Method of Pushover with Cyclic Loading

The cyclic loading pushover method which can simulate the real ground motion are suggested, and the target displacements of cyclic loading are discussed to overcome the drawbacks of traditional Pushover method which cannot consider the important seismic response of plane frames under earthquake, such as cyclic loading history, duration of strong motion, and the cumulative damage of structures. Through the comparison analysis of the story drift and hysteretic energy of plane framed structures gotten by adopting cyclic loading pushover method, traditional pushover method, and dynamic elastic-plastic time-history analysis method respectively, the conclusion that cyclic loading pushover method can better reflect the loading process with ground motion and the cumulative disruptive effect caused by hysteretic energy of structure can be obtained ,which provides some references for performance evaluation of elastic-plastic analysis of seismic structures.

Study on Effects of Infill Walls on Seismic Performance of RC Slab-Column Structure

The research focused on the effects of infill walls on the RC slab-column structural system. In order to accomplish this, the elastic-plastic time-history analysis of RC slab-column structure was performed. Based on the test results of a full-scale three-story RC structure repaired and strength with masonry infill walls, the four optional analysis models were analyzed. The first was the pure RC slab-column structure without infill walls, the second was the RC slab-column structure added with half-height infill walls, which was equivalent to open holes inside infill walls, the third was the RC slab-column structure added with infill walls arranged symmetrically along the plane symmetric axis, and the fourth was the RC slab-column structure added with infill walls arranged around the plane geometry center. Analysis results indicated that addition of infill walls could increase the seismic performance of the structural system, configurations and amounts of infill walls, and the hole positions and sizes inside infill walls had effects on the structural system.

Fiber Element Based Elastic-Plastic Analysis Procedure and Engineering Application

Elastic-plastic time history analysis of super high-rise building is accomplished by the program PERFORM-3D to evaluate the global response and component deformation of structure based on fiber element theory. Direct modeling of a tall building in PERFORM-3D is complicated; hence a pre-process program ETP is established for a more effective and accurate modeling. Analysis improves that fiber element-based nonlinear analysis of the overall structure reveals the macro properties of the structure as well as the force-deformation relationship for the component and stress-strain relationship for the fiber in the micro scope. Finally, the global response, component deformation and energy dissipation of the complicated tall building designed by the current codes subjected to severe ground motions are studied in one engineering practices.

Time History Analysis of the Non-Symmetrical Special-Shaped Column Structure on Multi-Dimensional Seismic

In this paper, the spatial analysis model of non-symmetrical special-shaped column is established in ANSYS, and then, the translational and rotational component of the seismic wave was input to the frame structural model, taking account of stiffness enhancement of the floor on the beam, and carried out the elastic-plastic time-history analysis. Simulations show that the trend of development of displacement basically the same way on two horizontal components and torsional acceleration component, and the displacement on two horizontal components and torsional acceleration component increases significantly compared with one horizontal component; because of the presence of the floor, the intensity of beam is enhanced, leading to some columns more strain than the beam, so the floor should be fully considered in the design of the beam.

Research on Application of BRBs in Steel Frame Structures

This paper presents an analysis on the seismic behavior of buckling-restrained brace frames（BRBFs）with different rigidity ratios by the finite element analysis software ANSYS. Based on the elastic-plastic time-history analysis, the relationships of maximum story drift ratio and the uniformity of maximum story drift ratio with different rigidity ratios are established for BRBFs subjected to large earthquakes, a reasonable range of rigidity ratio is recommended, which is the reference for the design of BRBFs.

Elastic-Plastic Time History Analysis of Self-Anchored Cable-Stayed Suspension Bridge

Base on the elastic-plastic analytical theory, an elastic-plastic time-history analysis of self-anchored cable-stayed suspension bridge, which engineering background is Dalian Gulf Cross-sea Bridge program, is performed by using general finite element software Midas/Civil. The material nonlinearity of structure is considered with reinforcement concrete fiber model, and distributed hinge type is adopted to simulate for plastic hinge. Compared with the results of an elastic time-history analysis, it is shown that for the structure into the elastic-plastic stage, because of the production of plastic hinge, the input seismic energy is dissipated partially, and the internal forces of structural elements are reduced. The bending moments and axial forces occur mainly in the main tower root. Furthermore, the rotation properties of the plastic hinge causes displacement increasing of certain parts of the structure, which assumes mainly the vertical displacement present on the top of main tower and the main beam. In conclusion, it is proposed that caging devices are set in the design.

Research on Seismic Performance Objectives of High-Rise Diagrid Tube Structures

Diagrid tube structures have advantages on constructing high-rise buildings for its great lateral stiffness, but its seismic design methodology researches are limited. The two-stage design method in Chinese code is not specific enough for the seismic fortification objectives of this kind of structures. It is necessary to propose some specific seismic performance objectives for the key components. Typical CFST diagrid tube-concrete core tube structures are studied by dynamic elastic-plastic time-history analysis using Perform-3D program. The structure plasticity developing process is summarized and the distribution characteristics of seismic fortification lines between tubes are discussed. The influences of main structure lateral stiffness related factors on the plasticity developing process are researched. The key components of structure lateral stiffness and plastic energy dissipation are studied. The seismic performance objectives of the key components are proposed for the three-level seismic fortification objectives.

Seismic elastic-plastic time history analysis and reliability study of quayside container crane

Quayside container crane is a kind of huge dimension steel structure, which is the major equipment used for handling container at modern ports. With the aim to validate the safety and reliability of the crane under seismic loads, besides conventional analysis, elastic-plastic time history analysis under rare seismic intensity is carried out. An ideal finite element (FEM) elastic-plastic mechanical model of the quayside container crane is presented by using ANSYS codes. Furthermore, according to elastic-plastic time history analysis theory, deformation, stress and damage pattern of the structure under rare seismic intensity are investigated. Based on the above analysis, the established reliability model according to the reliability theory, together with seismic reliability analysis based on Monte-Carlo simulation is applied to practical analysis. The results show that the overall structure of the quayside container crane is generally unstable under rare seismic intensity, and the structure needs to be reinforced.

Inelastic Displacement Amplification Factor for Ductile Structures with Constant Strength Reduction Factor

Based on elastic-plastic time-history earthquake analysis of the single degree of freedom (SDOF) system, the inelastic displacement amplification factor Cd2 of the elastic-perfectly plastic (EPP) model with the same yield strength reduction was investigated for different normalized periods T/TgR, site types, strength reduction factors R, damping ratios, post yield stiffness ratios and second order ( P-Δ) effects. The factor Cd2 can be used to estimate the maximum inelastic response displacement from the elastic displacement under the design seismic conditions. It is found that the probability distribution of Cd2 satisfies the lognormal distribution approximately. The factor Cd2 decreases with decreasing damping (in the medium-long period range) and with increasing post yield stiffness. The existence of the P-Δ effect will increase Cd2 significantly and needs to be considered in future seismic design. Three other hysteretic models: the modified-Clough (MC), shear-slipped (SSP) and bilinear elastic (BIL) models, were analyzed to check the effect of the hysteretic model on Cd2 spectra The results were compared to those of the EPP model and it was found that the Cd2 of the EPP model is the smallest among the four hysteretic models.

P-Δ Effects on Seismic Force Modification Factors for Modified-Clough and EPP Hysteretic Models

Based on the elastic-plastic time-history analysis of SDOF(single degree of freedom) systems for the Modified-Clough(MC) model and the elastic perfectly-plastic (EPP) model, this paper carried out a study of the seismic force modification factors Rμ (SFMF) both when the P-Δ effects are not allowed for ( Rμ) and when they are allowed for ( R'μ). 370 earthquake records from 4 site & soil conditions, 74 to 106 records for each site, were used to calculate the structural response. The structural periods varied from 0.1 to 6sec and the ductilities were taken to be 2,3,4,5 and 6. The stability index θ were varied from 0.025 to 0.1. The ratio spectra S of Rμ to R'μ were constructed to analyze the influence of P-Δ effects on the SFMF. It is found that the spectral values of S depend on the ductility, the stability index and the normalized period T / TgR. The results indicate that the influence of P-Δ effect is different for the two hysteretic models. The increase in strength demand to maintain constant ductility in the presence of P-Δ effects using the EPP model is greater than that given by the modified- Clough model.

Seismic force modification factor for ductile structures

The earthquake forces used in design codes of buildings should be theoretical determinable. This work examines the seismic force modification factorR based on elastic-plastic time-history earthquake analysis of SDOF systems, wherein the hysteresis models are elastic-perfectly-plastic (EPP), elastic-linearly-hardening (ELH), shear-slipped and bilinear-elastic. The latter two models are analysed for separating the effect of the ductility and the energy-dissipating capacity. Three-hundred eighty-eight earthquake records from different site conditions are used in analysis. The ductility is taken to be 2, 3, 4, 5 and 6, with the damping ratio being 0.02, 0.035 and 0.05 respectively. The post-yield stiffness ratios 0.0, 0.1 and 0.2 are used in the analysis. TheR spectra are standardized by the characteristic period of the earthquake records, which leads to a much smaller scatter in averaged numerical results. It was found that the most important factor determiningR is the ductility.R increases more than linearly with ductility. The energy-dissipating capacity, damping and the post-yield stiffness are the less important factors. The energy dissipating capacity is important only for structures with short period and moderate period (0.3≤T/T g <5.0). For EPP and ELH models,R for 0.05 damping is 10% to 15% smaller than for 0.02 damping. For EPP and ELH models, greater post-yield stiffness leads to greaterR, but the influence of post-yield stiffness is obvious only when the post-yield stiffness is less than 10% of the initial stiffness. By means of statistical regression analysis the relation of the seismic force modification factorR with the natural period of the system and ductility for EPP and ELH models were established for each site and soil condition.

Equivalent linear ductility design of soil-structure interaction systems

The purpose of this paper is to propose a new semi-explicit ductility design method for a shear building model taking into account dynamic soil-structure interaction. The shear building model is supported by swaying and rocking springs and by the corresponding dashpots. Design earthquakes are defined as a set of spectrum-compatible earthquakes at the ground surface level. The normal bilinear rule is adopted as the story shear force-interstory drift relationship. It is shown that the introduction of an equivalent linear model and application of the hybrid inverse eigenmode problem, due to the present author, to this equivalent linear model enable one to construct a new efficient ductility design method for an elastically supported shear building model. This design method, although approximate, does neither require any eigenvalue analysis nor any repetitive procedure including elastic-plastic time-history response analysis. The validity and accuracy of this design method is demonstrated by elastic-plastic time-history response analysis.