Papers by Keyword: Seismic Response

Abstract: The dynamic characteristics of 80 m single-layer spherical lattice shell structure are analyzed to control its vibration under seismic load. Through the response spectrum curve of current design specification, the analyses for the vertical and horizontal seismic responses of the single-layer spherical lattice shell structure are made by CQC, and the displacement response of the nodes and internal force of the rods unit are calculated respectively. The calculation results show that the vertical and horizontal seismic responses of the long-span lattice shell structure are in great difference, and should be performed in vibration control at the same time, which could provide certain references for the seismic design and vibration control of single-layer spherical lattice shell structure.

Abstract: In this thesis, based on the design of a 140+90m span unusual single tower and single cable plane cable-stayed bridge, free vibration characteristics and seismic response are investigated; three dimensional finite element models of a single tower cable-stayed bridge with and without the pile-soil-structure interaction are established respectively by utilizing finite element software MIDAS/CIVIL, seismic response of Response spectrum and Earthquake schedule are analyzed respectively and compared. By the comparison of the data analysis, for small stiffness span cable-stayed bridge, the pile-soil-structure interaction can not be ignored with calculation and analysis of seismic response.

Abstract: The seismic response analysis of project soil site is important to obtain the ground motion parameters for seismic design of upper structures. First, a simplified solving method is introduced, in which, the horizontal seismic loadings are expanded into Fourier series in the circumferential direction, using the orthogonality between the normal and tangential direction on the circumference, the three-dimensional problem is reduced to a series of two-dimensional problems. Then, the simplified method is used for seismic response analysis of a practical large-scale soil site with large diameter circular diaphragm wall. The influence of wall to the site is obtained through two field conditions, which are wall field and free field (without wall). Compare with the results of the site without wall, the peak acceleration of the pit bottom is increased owing to the confinement effect of wall, and the influence to ground surface far from the wall is very little.

Abstract: Based on properties of high-speed railway bridge and rail system restraints, the rail-bridge model is established by considering CRTS II unballasted track and bridge structure. The results show that the effect of CRTS II system restraints on seismic response for multi-span simply supported girder bridge is greater so the rail-bridge model should be adopted in earthquake response analysis. Due to the effect of longitudinal stiffness of the railway and bridge transitional section such as terminal spine, the more significant is unloading for seismic response of the side piers if the fewer is the number for the rear-structure spans.

Abstract: Taking an engineering design case about a three-span uniform section continuous curved box-girders bridge of city viaduct,this paper sets up a finite element calculating model for the curved box-girders bridge by means of finite element analysis program ANSYS and researchs the influence of dynamic characteristic and seismic response on curved box-girders bridge with the different curvature radius under the same span. The analysis results show that in the same span of curved beam , the low-level frequency impact of changes in different curvature radius of the curved beam bridge is larger,the curvature radius is an importance parameter which influence on dynamic characteristic, and have significant influence on tangential stiffness、radial stiffness and seismic response of curved box-girders bridge.

Abstract: A radius of curvature 20 times greater than the deck width of the bridge (R≥20b) is required as a specification in the regular bridge simplification conditions of the seismic response of curved girder bridges. Selecting benchmark bridges and employing parameter analysis method, this article studies on the effect of R/B value of the curved girder bridge on the response ratio of the seismic response calculated using the finite element model and that using a regular girder bridge. This study shows that on conditions that the deck width of the bridge is constant, the smaller the radius of curvature and the larger the B/R value (i.e., the smaller the R/B value) of the curved girder bridge are, the greater the difference between the seismic response of the curved girder bridge and the result calculated with a regular girder bridge is, and the difference is more significant under traverse seismic effect than that of longitudinal seismic effect. On conditions that the radius of curvature is constant, the impact of the change of B/R value due to the deck width change of the bridge on the difference between the seismic response of the curved girder bridge and the result calculated with a regular girder bridge is insignificant. Compared with the deck width of the bridge, the difference between the seismic response of the curved girder bridge and the result calculated with a regular girder bridge is more sensitive to the radius of curvature.

Abstract: Submarine pipelines are described as the lifeblood of offshore oil and it is crucial to ensure the seismic safety of the submarine pipelines. Based on the fluid-structure interaction numerical analysis method and by using finite element software ADINA, the analysis models of the free long-span submarine flexible pipelines under earthquakes were established. By employing dynamic time-history method, the influences of fluid-structure interaction on the seismic response of the submarine pipelines were researched. The results showed that the peak normal stress and the peak displacement of submarine pipelines’ mid-span considering the influences of the fluid-structure interaction are greater than those without considering the influences, and the influences of the fluid-structure interaction on the seismic response of the submarine pipelines will increase with the increase of the submarine pipelines‘ diameter.

Abstract: The seismic response of the base-isolated structure can be reduced significantly in the far-field region compared to the conventional seismic structure. However, near-fault ground motions with velocity pulse may cause the adverse influence on the seismic performance of the base-isolation building, which needs to be investigated deeply. In this paper 6 ground motions with velocity pulse are selected as the input, and the seismic response of a 9 layers conventional seismic RC frame building and comparative base-isolation building with lead-core rubber bearings are obtained by nonlinear time history analysis. The result indicates that base-isolation building with lead-core rubber bearings are of good aseismic performance under the near-fault ground motions with velocity pulse.

Abstract: The seismic response of step-terrace frame structure is affected by the slope. Considered soil parameters of slope, the floor numbers and span numbers of layers below the scarp, 45 step-terrace frame example structures were designed, and three excitations at bedrock were selected to analyze the example structures response with dynamic time-history analysis method. The research indicates that when the other conditions are the same, the soil becomes softer, or structure's span numbers on the slope becomes larger or the slope becomes higher, the dynamic interaction between slope and step-terrace frame structure becomes more obvious. When the inputted ground motion at slope foot is adopted and the slope soil is soft, the seismic response of structure without soil-structure interaction is smaller than that of with soil-structure interaction.

Abstract: As a general-purpose finite element program, ABAQUS’s strong non-linear calculation capacity make it especially suitable for elasto-plastic time-history analysis, in this paper, with a super high-rise project, the experience of elasto-plastic time-history analysis using ABAQUS is described, include the modeling process, material constitutive model, numerical integral method and evaluation of analysis results, some reference will be provided to the other engineering practices.