scholarly journals Effect Mechanism of Connection Joints in Fabricated Station Structures

2021 ◽  
Vol 11 (24) ◽  
pp. 11927
Author(s):  
Huafei He ◽  
Zhaoping Li
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Joint Distribution ◽  
Damage Index ◽  
Time History ◽  
Subway Station ◽  
Bottom Plate ◽  
Relative Deformation ◽  
Damage Degree ◽  
Station Structure

The seismic response of a fabricated subway station is a complex structural connection problem that depends on the mechanical properties of the joints. In order to obtain the optimal joint distribution of a fabricated station structure under earthquake action, three finite element models of a single ring structure of fabricated subway stations assembled with seven, five, and four prefabricated components were proposed. Seismic wave characteristics, peak acceleration, and coupled horizontal and vertical seismic components were considered to study the seismic response of the fabricated subway station structure with different forms of the joint distribution. The dynamic time history method was used to analyze the seismic response in three aspects: structure plastic strain, interlayer relative deformation, and internal force. The damage indexes and residual strength indexes of the joints were offered based on the concrete damage index to evaluate the joints’ damage degree. The results showed that the joints of the vault or bottom plate had little influence on the seismic response of the fabricated station structure. The sidewall joints had the obvious seismic response and the most severe damage under horizontal ground motion or coupled ground motion, which were the weak joints of the fabricated station structure. The existence of vertical ground motion aggravated the damage degree of sidewall joints, making the damage occurrence time of sidewall joints earlier and the damage end time extended. On the premise of meeting the mechanical load and site requirements, an assembly scheme with fewer prefabricated components can be selected.

Confirmation of Reduction Effect Due to Tank’s Rocking Behavior and Proposal for a Simplified Evaluation Method of Nonlinear Seismic Response

2003 ◽  
Author(s):  
Satoru Yamaguchi ◽  
Hideyuki Tazuke ◽  
Kazuo Ishida
Keyword(s):  
Nonlinear Analysis ◽  
Seismic Response ◽  
Evaluation Method ◽  
Time History ◽  
Bottom Plate ◽  
Response Factor ◽  
Mass System ◽  
Nonlinear Seismic Response ◽  
Reduction Effect ◽  
Rocking Behavior

Aboveground LNG storage tank consists of inner and outer cylindrical containers. LNG is stored in the inner container made by 9%Ni steel. Anchorages are attached to some tanks in order to prevent bottom plate from excessive uplifting by seismic overturning moment. However tanks without anchorages have some probability that the seismic response factor decreases since the resonance period of tank is lengthened by nonlinear behaviors, for example uplifting of bottom plate (rocking behavior). In this paper, the reduction effect of response factor due to rocking behavior was quantitatively confirmed by 3-dimensional FEM nonlinear analysis and time-history nonlinear analysis that was modeled with single-degree-of-freedom spring-mass system. And a simplified evaluation method that allows easily calculating the reduction effect was proposed. As the result of study, it was proved that this method gave valid and conservative results.

Exact Solution of the Base-Isolated Structure With Sliding Type Base Isolator

2004 ◽  
Author(s):  
C. S. Tsai ◽  
Tsu-Cheng Chiang ◽  
Bo-Jen Chen
Keyword(s):  
Exact Solution ◽  
Seismic Response ◽  
Earthquake Engineering ◽  
Degrees Of Freedom ◽  
Good Accuracy ◽  
Base Isolation ◽  
Time History ◽  
Relative Deformation ◽  
History Analysis ◽  
Base Isolator

The use of base isolation for enhancing the seismic resistibility has been proved as an efficiency way from experimental efforts and theoretical studies. It is usual to insert a flexible device in horizontal direction to permit the most relative deformation at this level. Because of the rigidity of the superstructure is much higher than that of the base isolator underneath the structure, therefore, the behavior of the superstructure can be idealized as a rigid body during earthquakes. In general, hundreds of degrees of freedom and a step-by-step time history analysis are the basic requisitions for calculating the seismic response of a base isolated structure under earthquakes. In order to develop a simple tool which can be easily adopted for calculating the sliding displacement and the shear force of the base isolator, an exact solution for predicting the seismic responses of base isolated structures has been derived in this study. The comparison between the experimental results conducted at National Center for Research on Earthquake Engineering (NCREE) in Taiwan and the analytical results obtained from the exact solution show that the exact formulation derived in this study can predict the seismic response of the base isolated structure with very good accuracy.

scholarly journals Modal-Based Ground Motion Selection Method for the Nonlinear Response Time History Analysis of Reinforced Concrete Shear Wall Structures

2021 ◽  
Vol 11 (17) ◽  
pp. 8230
Author(s):  
Yang Liu
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Nonlinear Response ◽  
Time History ◽  
Shear Wall ◽  
Seismic Demands ◽  
Ground Motion Selection ◽  
Wall Structures ◽  
History Analysis ◽  
Rc Shear Wall

This paper presents a modification of the modal-based ground motion selection (MGMS) method for improving the reliability of the nonlinear response time history analysis (NLRHA) of reinforced concrete (RC) shear wall structures. The original MGMS procedure quantified the impact of frequency content combinations in the time domain (FCCTD) of input ground motions (IGMs) on the seismic response of building structures using the level of interaction of the first three modes induced by IGMs. However, previous research found that the first two modes have far larger modal mass coefficients than those of higher modes and dominate the vibration of the RC shear wall structures with a symmetric plan. Therefore, the MGMS procedure should be modified by employing the interaction of the first two modes induced by IGMs to properly account for the effect of the FCCTD of IGMs on the seismic response of structures. In the MGMS procedure for RC shear wall structures, seven IGMs that caused the most significant interactions of the first two modes were selected from a suite of twenty seed IGMs, which were chosen with a conventional spectra-matching-based IGMs selection procedure for the NLRHA of the structure. A comprehensive case study involving three RC shear walls with different heights was conducted to investigate the capability of the MGMS in selecting suitable IGMs for the NLRHA of RC shear wall structures. Sets of seed IGMs were selected, adopting conditional mean spectra and design spectra as the target spectra. It was found that the seismic demands computed using MGMS selected IGMs can ensure a more reliable and reasonable computation of seismic demands compared with conventional spectra-matching-based IGMs selection methods.

scholarly journals Tying Devices to Mitigate Pounding of Adjacent Building Blocks

2020 ◽  
Vol 10 (3) ◽  
pp. 5643-5647
Author(s):  
M. S. Masmoum ◽  
M. S. A. Alama
Keyword(s):  
Seismic Response ◽  
Damage Index ◽  
Time History ◽  
Building Blocks ◽  
Elastic Model ◽  
Expansion Joints ◽  
Linear Elastic ◽  
History Analysis ◽  
Adjacent Building ◽  
Minimum Separation

Adjacent building blocks separated by thermal expansion joints are vulnerable to pounding during earthquakes. The specified Saudi building code minimum separation may be very large and does not necessarily eliminate pounding forces. This research discusses the feasibility of tying the adjacent building blocks with simple devices to mitigate structural pounding when separated by thermal joints. Six and twelve-story moment resistance frames of intermediate ductility were designed for seismic loads of moderate risk. The seismic response was studied for frames with variable separation distances in three cases related to thermal joint, code minimum separation, required separation to eliminate pounding force, and in a fourth case in which the tying device was used along with thermal separation. A linear elastic model was used to model the assigned gap links between the adjacent building blocks. The tying device was modeled with a tension-only hook element. Four normalized earthquake records were used with inelastic-time history analysis to assess the seismic response of the adjacent building blocks. The proposed tying devices reduced successfully the pounding forces by 40% to 60% for adjacent building blocks with installed thermal separations. Building damage as observed from damage index and the hysteretic response was not influenced by the pounding force, indicating that the tying may be used on existing buildings with thermal separation as a partial mitigation technique to reduce the pounding hazard in such cases. Further improvement on the tying device will increase the mitigation of the pounding hazard.

scholarly journals Effects of Burial Depth on the Seismic Response of Subway Station Structure Embedded in Saturated Soft Soil

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Xuelei Cheng ◽  
Zongguang Sun
Keyword(s):  
Seismic Response ◽  
Numerical Models ◽  
Soft Soil ◽  
Pressure Ratio ◽  
Bending Moment ◽  
Subway Station ◽  
Burial Depth ◽  
Two Phase ◽  
Crucial Effect ◽  
Station Structure

For the aim to study the effects of burial depth on seismic response in the subway station’s structure embedded in saturated soft soil, on the basis of the OpenSEES program, numerical models with four cases of burial depth for the nonlinear interaction system including subway station’s structure and saturated soft soil are developed with the u-p formulations of Biot’s theory as it seeks to describe the saturated two-phase media. The effects of burial depth on the seismic response and the failure pattern of the subway station structure are investigated. The numerical results show that (1) the burial depth has a significant effect on the nonuniform uplift of station’s structure due to the movement of soil from far field towards baseplate; (2) with the increase of burial depth, the inertial effect of overlaying soil of the subway station structure becomes more obvious, and the peak zone of the pore pressure ratio contracts from the outer area to the baseplate bottom with decreasing amplitude; (3) the dynamic index R decreases with the increasing burial depth of the station’s structure; and (4) in terms of the middle column, the burial depth of the station’s structure has the most crucial effect on the additional dynamic shear force and bending moment at the top end.

Effects of Spatial Variable Ground Motions on the Seismic Response of Base-Isolated Building

2010 ◽  
Vol 163-167 ◽  
pp. 4422-4428
Author(s):  
Yong Qin Lei ◽  
Yong Feng Du
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Ground Motions ◽  
Time History ◽  
Spatial Variable ◽  
Passage Effect ◽  
History Analysis ◽  
Large Plane ◽  
Wave Passage ◽  
Wave Passage Effect

Aimed to base-isolated building with large plane dimension, the change laws of seismic response for base-isolated building under spatial variable ground motions were researched. Firstly, the artificial spatial variable earthquake time histories were generated using spectral representation method based on code response spectrum. Then the 3-D FEM modal of one based-isolated building with large plane dimension was established and the seismic response of based-isolated building under spatially ground motion was studied by nonlinear time history analysis. The mitigation effects of based-isolated building with large plane dimension were compared each other at the cases of uniform excitation, non-uniform excitation considering only wave passage effect, non-uniform excitation considering both the wave passage effect and incoherence effect, multi-component uniform excitation, multi-component non-uniform excitation considering the wave passage effect and multi-component non-uniform excitation considering both the wave passage effect and incoherence effect. The results show that the seismic response of base-isolated structure with large plane dimension under the uniform excitation is relative safety. When the base-isolated building with large plane dimension is designed by time history analysis, the spatial variability of earthquake ground motion effects can be considered.

Seismic Response Characteristics of Subway Station Structure

2013 ◽  
Vol 838-841 ◽  
pp. 1613-1619
Author(s):  
Hong Ni ◽  
Ming Hui Li ◽  
Xi Zuo
Keyword(s):  
Dynamic Characteristics ◽  
Damage Model ◽  
Damage Index ◽  
Subway Station ◽  
Energy Response ◽  
Element Analysis ◽  
Hysteretic Energy ◽  
Response Characteristics ◽  
Seismic Motion ◽  
Station Structure

The dynamic Davidenkov model is used to model dynamic characteristics of soils, and plastic-damage model is used to model dynamic characteristics of station structure concrete. So that, considering the influence of soil-station structure interaction for 2D finite element analysis, the dynamic interaction of soil-station structure is modeled. The damage characteristics and energy response of station structure under seismic motion is analyzed. The result shows that damping energy and hysteretic energy are monotone increasing under ground motion, and the seismic characteristic has significant effect on the energy response of subway station structure. Furthermore, concentration effect of hysteretic energy of subway station structure is measured by hysteretic energy density. It is found that the hysteretic energy is the most centralized in the column, so the dynamic response of the columns is the maximum. Furthermore, the nonlinear damage evolution law of station structure is analyzed. The law of local and global damage index is consistent essentially, and the damage index is increased by the effect of accumulative deformation.

Analysis of Equivalent Static Method for Subway Station

2012 ◽  
Vol 594-597 ◽  
pp. 1382-1386
Author(s):  
Liang Chen ◽  
De Jian Yang
Keyword(s):  
Structural Integrity ◽  
Time History ◽  
Static Method ◽  
Subway Station ◽  
Seismic Load ◽  
Important Indicator ◽  
Finite Element Software ◽  
History Analysis ◽  
Equivalent Load ◽  
Station Structure

Structural integrity of Subway station is a very important indicator when the earthquake happens as it is a densely populated venue. Time-history analysis of Tianjin metro line 3 based on the theory of coupling seismic load was done with the finite-element software ANSYS. Consequently, numerical expression of the equivalent load was fixed and the procedure of seismic check of subway station structure gets further simplified and necessary theoretical basis.

scholarly journals Analysis on the Influence of Increasing Seismic Fortification Intensity on Seismic Performance of Underground Station

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Ying Zeng ◽  
Shiguang Xu ◽  
Shiqian Yin
Keyword(s):  
Ground Motion ◽  
Seismic Performance ◽  
Time History ◽  
Time History Analysis ◽  
Structural Deformation ◽  
Equivalent Linearization ◽  
History Analysis ◽  
Underground Station ◽  
The Impact ◽  
Station Structure

China Earthquake Parameter Zoning (2016) has increased the seismic fortification intensity in Chengdu from VII to VIII. It is necessary to conduct in-depth discussion on the impact of the seismic performance of the built underground station structure. In this paper, a stratum-structure finite element model is established with a Chengdu subway station as an example. The model boundary adopts viscoelastic boundary, and the ground motion is input in the form of equivalent nodal force. The equivalent linearization method is used to consider the nonlinearity of soil materials. The time-history analysis of seismic fortification intensity of VII and VIII degrees is carried out, respectively. By comparing the calculation results of the two seismic fortification intensity ground motion conditions, it is concluded that the connection between the side wall and the floor is the weakest position of the station structure under the action of the earthquake; the seismic fortification intensity is increased from VII to VIII to the internal force of the structure. It has a relatively large impact, especially the most obvious impact on the bending moment. The results of the verification of the seismic time-history analysis show that the increase of fortification intensity will have a more obvious impact on the structural deformation, and the structural design of the station can meet the safety performance requirements of VII and VIII degrees of seismic fortification. The research has certain reference significance for the seismic safety evaluation of the built underground station structure in Chengdu area.

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