Dynamic Elastic-plastic Analysis Research Articles

Study on the Seismic Optimization Scheme of Steel Bundled-Tube Structure with Vertical Setback

In order to improve the seismic performance of vertical setback steel bundled-tube structure and meet the dynamic multi-objective requirements of seismic performance-based design, the optimization effects under rare earthquakes on the zone of fortification intensity 7 and 8 in China are researched by improving members stiffness and adding dampers in the weak parts of structure, based on dynamic elastic-plastic analysis. The results show that: 1) Under rare earthquakes on the zone of fortification intensity 7, increasing the stiffness of weak skirt beam can improve the seismic performance of spiral and symmetrical setback structure; 2) For the spiral setback structure, under rare earthquakes on the zone of fortification intensity 7, the damper can only be arranged at the junction of the first layer of the setback frame unit and the frame unit without setback. However, under rare earthquakes on the zone of fortification intensity 8, it is not advisable to install dampers at the weak areas; 3) After incorporating dampers at the weak areas of symmetrical setback structure, the optimized members experienced a reduction in stress levels, significantly decreased the inter-layer displacement angles with a maximum reduction of 43%, and the optimization effect is significant.

Ultimate Strength of a Thin Wall Tee for Sodium Cooled Fast Reactors Under Seismic Loads

Abstract It is a key issue to clarify failure mode of piping in nuclear power plants and its safety margin included in the design practice. In this study, a series of dynamic failure tests of a thin wall tee for sodium-cooled fast reactors was conducted. Some discussions related to the thin wall tee are provided on the failure mode under seismic load, dynamic response behavior, accuracy of fatigue prediction by dynamic elastic-plastic analysis, and a safety margin of fatigue evaluation which is included in conventional design rule.

Seismic performance of prefabricated semi-rigid RCS structures

To study the seismic behavior of prefabricated reinforced concrete column-steel beam (RCS) hybrid structures, a cyclic loading test on a novel RCS joint was conducted to investigate the failure modes, ductility, and energy dissipation. The moment-rotation relationship model of the joint was proposed according to the test. Furthermore, the model of a 3-bay, 5-story semi-rigid prefabricated RCS frame was established in SAP2000 software. The modal analysis and dynamic elastic–plastic analysis were carried out on the semi-rigid and rigid RCS frames respectively to study the effect of semi-rigid connections on the seismic performance of RCS structures. Analysis results show that the failure mode of the prefabricated RCS joint meets the strong column-weak beam requirement. The ‘bow’-shaped hysteretic curve indicates the joint has good seismic performance with good ductility and energy dissipation capacity. Compared to rigid RCS structures, semi-rigid connections lead to a reduction in the overall stiffness and an increase in the natural vibration periods of the structure. Under the action of the earthquake, the base shear force of the semi-rigid RCS structure is smaller than that of the rigid RCS structure. The maximum inter-story drift angles and top displacement of semi-rigid RCS structures will increase, but still meet the requirements of the seismic standard.

Global damage model for the seismic reliability analysis of a base‐isolated structure

A method for seismic reliability analysis based on a global damage model is proposed for a base-isolated structure. A sample space is created using the Latin Hypercube Sampling method, in which the randomness of structure and seismic ground motions is considered, and then dynamic elastic–plastic analysis is carried out for each sample. The cumulative damage factors of the upper structure and the isolated story are calculated using a global damage model of an isolated structure. The probability of progressive sideway collapse for base-isolated structure under earthquake action is obtained using the quadratic fourth-moment method, and this method is also used to analyze the evolution of the probability density of cumulative damage for structure. From aforementioned analysis, the change tendency of damage factor over time can be obtained using the global seismic damage model based on the quadratic fourth-moment method. Due to the introduction of the quadratic fourth-moment method in this paper, the impacts of skewness coefficient and kurtosis coefficient on the failure probability of structure can be taken into account, if the scheme of a structural parameter cannot be confirmed. The method provides results that are more accurate than those of the classical first-order second-moment method. A method for the seismic reliability analysis of an isolated structure from the component to the global structure is also established, in which the failure probabilities of the upper structure and the isolated story are considered with a global seismic damage model.

Research on Hysteretic Models for Prestressed and Non-Prestressed Steel Reinforced Concrete Frames

The beam-column fibre model is used to simulate the entire hysteretic process of the prestressed and non-prestressed steel reinforced concrete frame, and the results are compared with the test results. Based on the analysis of a large number of parameters, the hysteretic curve characteristics of this kind of composite frame are discussed, and the load-displacement hysteretic models of single-storey and single-span composite frame are established. The models can comprehensively consider the influence of axial compression ratio and column slenderness ratio and can predict the hysteretic behaviour of this kind of composite frame under horizontal loads. The load-displacement hysteretic models are consistent with the numerical simulation results. Relevant research can provide reference for simplifying the elastic-plastic dynamic analysis of structures.

Analysis and Computer Dynamic Three-Dimensional Model of Seismic Measures for High Rise Steel Frame Structure Using Finite Element Software

The newly-built 20-story hospital building is located in the seismic fortification 8 degree area, and its independent steel corridor is a steel frame structure. In order to analyze the performance of the structure under strong earthquake, the static and dynamic elastoplastic three-dimensional finite element model of the structure is established by using the finite element software PERFORM-3D. In this paper, buckling restrained braces are used for energy dissipation. Through the dynamic elastic-plastic analysis of the steel frame buckling restrained brace structure, the structural response under strong earthquake input is analyzed, and the structural reliability is checked.

The dynamic elastic-plastic analysis of frame- shear wall structure of a power plant main building

The main machine hall has the characteristics of the uneven distribution of mass and stiffness. It is important to research the structural seismic performance to ensure the normal operation of power plant, prevent serious damage to important equipment and personnel. This paper uses the general finite element software ABAQUS to investigate seismic performance of structures under strong earthquakes, the various parts of the inelastic phase sequence, damage degree and distribution, and on this basis puts forward opinions and suggestions on structure scheme. The analysis results show that the structural maximum interlayer displacement Angle can meet the demands of 1/100 limit, the seismic fortification standard of “no collapse under strong earthquake” can be achieved and the results can provide important basis for design.

Failure analysis of steel open dam against an extreme boulder debris flow

This paper presents a failure analysis for a steel open-type Sabo dam (hereafter, steel open dam) against an extreme boulder debris flow load (hereafter, level II load) by a two-step analysis. The first step analysis is to estimate the level II load against the rigid wall by using the revised distinct element method (DEM). In the second step, the failure mechanism of a steel open dam is examined by using a dynamic elastic plastic analysis, in which the level II load-time relations obtained by the first analysis are multiplied by a reduction factor and then used. For the second step, the effects of the flange joint and dent deformation of the connection between column and beam are considered. Finally, a simple entire uniform load onto the steel open dam is proposed as a level II load model for the safety assessment.

Optimal design of a large-span spatial structure based on dynamic elastic-plastic analysis

With the expansion of the urban areas and the rapid growth of the urban population, the disposal of large amounts of domestic waste has become a problem faced by large cities. To solve this problem, many MSW incineration power plants have been continuously built. As a typical large-span spatial structure of waste incineration power plant, how to achieve economic, beautiful, and environmentally friendly design goals under the premise of meeting the requirements of the production process is an important problem currently facing. In this paper, a structural design optimization method based on damage index is proposed. Taking a large-span mixed structure of a MSW incineration power plant as an example, the paper firstly uses the dynamic elastic-plastic time history analysis method to evaluate its seismic performance, and then optimizes the structure according to the damage degree of the structure under small and large earthquakes design. The results show that under the premise of meeting the requirements of the code, this method can ensure that the degree of structural damage under the earthquake remains almost unchanged, while significantly reducing the amount of building materials and reducing the cost. At the same time, this method is more direct, simple, and effective than optimization design methods based on experience and internal forces of structural members.

Numerical Analysis on the Seismic Performance of Plane Irregular Structure Based on ABAQUS

Rod element and shell element were used in finite element software ABAQUS to establish dynamic elastic-plastic analysis model of the structure, the seismic performance of an irregular plane complex overrun structure numerical simulation, the structure was calculated under different input level and displacement response of the acceleration response, and analyses the force of the wear layer column and the floor of the open hole stress level. The results were compared with the shaking table test to verify the accuracy of the numerical simulation results. The results of numerical calculation were basically consistent with the experimental results, and the finite element model basically reflected the response of the structure under the simulated earthquake.

Seismic Behavior of Low-rise Concrete Shear Wall with Single Layer of Web Reinforcement and Inclined Rebars: Restoring Force Model

In order to study the restoring force model of low-rise concrete shear wall with single layer of web reinforcement and inclined rebars, a series of specimens were investigated by quasi-static tests. Based on the fitting of experimental data and theoretical analysis, the restoring force model considering four characteristic points (crack point, yield point, peak point and failure point) and degradation of unloading stiffness was established. The hysteretic rule of restoring force model was determined by analyzing characteristic of hysteresis curve for cyclic loading tests. The results show that skeleton curves and hysteresis curves calculated by the restoring force model are in good agreement with the test curves, which can provide reference for the elastic-plastic dynamic analysis of low-rise concrete shear walls with single layer of web reinforcements and inclined rebars. Shaking table tests of two low-rise concrete shear walls were also conducted to investigate dynamic performance and the seismic damage mechanism of low-rise concrete shear wall with single layer of web reinforcement and inclined rebars. Research on dynamic nonlinear simplified model of SAP2000 shows that the proposed restoring force model can be used to analyze the elastic and elastic-plastic dynamic response for the low-rise concrete shear wall with single layer of web reinforcement and inclined rebars.

Static and Dynamic Elastic-Plastic Analysis of a Storey-Adding Structure

With the rapid economic development of our country and the improvement of housing function requirement and the lack of land for construction, adding layer structure has become a trend in the development of construction industry. Now a lot of adding layer buildings have sprung up both at home and abroad. Adding layer structure needs to undertake seismic calculation to ensure the reliability under the earthquake effect. At present, many researchers’ studies of the adding layer structure only stay in elastic stage, and there are only very little researches about the static and dynamic elastic-plastic of the structure. Based on the literature and art center of Changzhi city as the background, it is introduced the calculation process, which adopted the EPDA& PUSH software for the static and dynamic elastic-plastic analysis of reinforced concrete structure, obtained the carrying capacity and the deformation under the rare earthquake, and analyzed the results. By comparison, the results of the static and dynamic elastic-plastic analysis are similar.

Study on Design Measure of Seismic Capacity Design in R.C. Mega-Frame Structures

This paper explores the design method of several typical mega plane frames, with the variables being the combination of varying amplification coefficient of moment at bottom sections of ground floor columns of the secondary frame on the main beams. The elastic-plastic dynamic analysis program Drain-2d+ of the plane structure is used to carry out the elastic-plastic time-history analysis for each typical mega-frame under the earthquake action. Based on the analysis, the deformation characteristics of the mega-frame, the emerging of the plastic hinge and the weak point of the overall structure under the earthquake action is developed, from which the correct method of obtaining the design value of amplification coefficient of moments at bottom sections of ground floor columns of the secondary frame on the main beams is concluded. The reasonable design values are recommended as the basis to provide some suggestions for the design of the reinforced concrete mega-frame structure.

Overall Dynamic Analysis of K-Reticulated Shell Structure with BRB in Severe Earthquakes

The overall K6 reticulated shell structure's dynamic elastic-plastic analysis in 9 degrees area under earthquake was researched under different places of Buckling Restrained Braces (BRB) on the shell. The elastic effects of supporting structure and BRB were two key factors. Analysis result shows that it has good performance for energy dissipation on K6 reticulated shell with BRB on both upper and supporting structures together.

Seismic Response of Baihua Viaduct during the Wenchuan Earthquake and Methods of Reducing Seismic Damage

Baihua Viaduct which is an important transportation project of 213 National Highway was severely destroyed during the 512 Wenchuan earthquake. The fifth segment of the bridge suffered the most severe unrepairable damage, such as the rupture of the piers and falling of beams. It is worth to study the performance through the FEM dynamical analysis to explain the damage performance of Baihua Viaduct in the earthquake. The dynamical FE model of the Baihua Viaduct is established considering the non-liner properties of piers and bearings. Further the earthquake records of the nearest Wolong station is chosen to be as the earthquake excitation input to conduct the seismic analysis. The analysis shows that the results of damage position and damage degree of components of the bridge calculated by elastic-plastic dynamic analysis are close to the actual damage of Baihua Viaduct. The reinforcement ratio of piers is low, while there is not any shear failure on piers. The damage degree of elastic hinge is related with the arrangement of bearings. The girders’ displacement is much larger because there are not any anti-dropping devices on the bridge. Damage of the fifth segment of bridge may be caused by plasticity destroy of some piers.

Seismic Response of Baihua Viaduct during the Wenchuan Earthquake and Methods of Reducing Seismic Damage

Baihua Viaduct which is an important transportation project of 213 National Highway was severely destroyed during the 512 Wenchuan earthquake. The fifth segment of the bridge suffered the most severe unrepairable damage, such as the rupture of the piers and falling of beams. It is worth to study the performance through the FEM dynamical analysis to explain the damage performance of Baihua Viaduct in the earthquake. The dynamical FE model of the Baihua Viaduct is established considering the non-liner properties of piers and bearings. Further the earthquake records of the nearest Wolong station is chosen to be as the earthquake excitation input to conduct the seismic analysis. The analysis shows that the results of damage position and damage degree of components of the bridge calculated by elastic-plastic dynamic analysis are close to the actual damage of Baihua Viaduct. The reinforcement ratio of piers is low, while there is not any shear failure on piers. The damage degree of elastic hinge is related with the arrangement of bearings. The girders’ displacement is much larger because there are not any anti-dropping devices on the bridge. Damage of the fifth segment of bridge may be caused by plasticity destroy of some piers.

Dynamic Elastic-Plastic Analysis of Reinforcement Geogrids Applied in High Earth-Rockfilled Dam Slope

Considering the dynamic response of high earth-rockfilled dam, dynamic elasto-plastic analysis method for dam slope reinforcement with geogrids was set up. Based on this model, the paper analyzed the deformation and failure mechanism of dam slope, as well as the effect of connection, the length, the spacing and the stiffness of geogrid on dam with deformation. The results show that geogrids with high elastic modulus and proper extensibility will apparently reduce the deformation and imporve the stability of the dam slope. In the case of high dam slope, the reinforcement length of geogrids is supposed to be 2a (a is the slip surface length), and the spacing is 2m.

Development of a particle method for dynamic elastic-plastic analysis

Development of a particle method for dynamic elastic-plastic analysis

Incremental impact test and simulation of prestressed concrete beam

This paper presents both experimental and analytical approaches on the dynamic behavior of a prestressed concrete (PC) beam under incremental impact loading. First, the weight-dropping test was performed in order to investigate the impact behavior of a PC beam under the condition that the weight is constant and the dropping-height increases. Second, the incremental impact analysis was developed in order to simulate the incremental impact test results by using an elastic-plastic dynamic analysis method based on a beam element model, Finally, the computational results are compared with the experimental ones.

Elastic-Plastic Model of Pinned Beams Subjected to Impulsive Loading

An elastic-plastic dynamic analysis of simply supported beams with end membrane restraints subjected to impulsive loading is developed. The beam is elastically curved. The model takes into account elastic and plastic deformations and their effect on the stretch force and the distribution of inertia forces. Instantaneous plastification of the midspan zone caused by bending and axial actions is considered. The effect of the length of the plastic zone is discussed. Equations of motion are derived by virtual work. Using the yield condition, the number of these equations is reduced by relating the variations of the displacement variables. This analysis is compared with the standard form of Lagrange's equation of motion showing that the latter is not energy conservative for this case where the deflection shape is nonlinearly dependent on the generalized displacements. Test results using a spring-powered apparatus are presented. Strain rate sensitivity is accounted for as plastic damping. The model's results are compared with test and rigid-segment model results. The comparison shows that the tests are sensitive to the curvature of the axis.