Earthquake-Induced Pounding of Medium-to-High-Rise Base-Isolated Buildings

During earthquakes, out-of-phase vibrations in adjacent buildings with limited distance may cause pounding between them. In recent years, the use of seismic isolation has expanded considerably as an effective approach to reduce seismic damage. However, the isolated building experiences large displacements during earthquakes, and there is a possibility of collisions with adjacent structures. The research on earthquake-induced pounding of base-isolated buildings has been mainly focused on interactions between low structures. In this paper, the influence of structural pounding on the response of medium-to-high-rise base-isolated buildings is investigated under different ground motions. The analysis has been focused on collisions between two insufficiently separated five-story and eight-story base-isolated and fixed base buildings aligned in three different configurations. The results of the study indicate that structural pounding may significantly increase the response of medium-to-high-rise base-isolated buildings during earthquakes. Moreover, substantial dependence of the structural behavior on the gap size between structures has been observed. The general trend shows the reduction in the pounding-involved response with the increase in the gap size value. The results indicate that the increase in the response of the base-isolated building is larger when the height of the structure is bigger. They also show that larger amplifications of peak accelerations of the upper stories can be expected due to collisions. On the other hand, the amplifications of the story shears have not shown any specific trend for different stories of the analyzed base-isolated building.

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DAMAGE EVOLUTION SPECTRA FOR SEISMIC ANALYSIS OF HIGH-RISE BUILDINGS

Journal of Earthquake and Tsunami ◽

10.1142/s1793431112500212 ◽

2012 ◽

Vol 06 (03) ◽

pp. 1250021

Author(s):

Y. B. HO ◽

J. S. KUANG

Keyword(s):

Damage Evolution ◽

Seismic Analysis ◽

Ground Motions ◽

Time History ◽

Tall Buildings ◽

Response Spectra ◽

Seismic Damage ◽

Analysis And Design ◽

High Rise ◽

Earthquake Ground Motions

Seismic response spectra are amongst one of the most important tools for characterizing earthquake ground motions. In design practice, the response spectra are presented without including any load history, hence the nonlinear analysis of structures based solely on conventional earthquake response spectra is theoretically unsound, particularly for long-period or vertically irregular high-rise buildings. In this paper, a concept of seismic damage evolution is introduced and the method of analysis for characterizing the process of seismic damage to structures under earthquakes is presented. Seismic damage evolution spectra for analysis and design of high-rise buildings are then developed as an effective means of describing and simplifying earthquake ground motions. These spectra are shown to be very useful in selecting the ground motion-time history and, particularly, validating the equivalent static-load analysis and design of high-rise buildings under near-fault pulse-like ground motions. Case studies of the seismic inelastic performance of two vertically irregular, tall buildings are presented considering the seismic damage evolution spectra.

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VISCOELASTIC DAMPER CONNECTED TO ADJACENT STRUCTURES INVOLVING SEISMIC ISOLATION

Journal of Civil Engineering and Management ◽

10.3846/13923730.2005.9636362 ◽

2005 ◽

Vol 11 (4) ◽

pp. 309-322 ◽

Cited By ~ 4

Author(s):

Vasant Annasaheb Matsagar ◽

Radhey Shyam Jangid

Keyword(s):

Seismic Isolation ◽

Equations Of Motion ◽

Viscoelastic Damper ◽

Step Method ◽

Viscoelastic Dampers ◽

Adjacent Structures ◽

Fixed Base ◽

Real Earthquake ◽

Isolation Systems ◽

Incremental Form

The seismic response of multi‐storied base‐isolated structure to various types of isolation systems connected using viscoelastic dampers to the adjacent dissimilar base‐isolated or fixed‐base structure is investigated. The multi‐storied structures are modelled as a shear type structures with lateral degree‐of‐freedom at each floor, which are connected at different floor levels by viscoelastic dampers. The performance of this combination is studied by deriving the governing equations of motion and solving it in the incremental form using Newmark's step‐by‐step method of integration. The variation of top floor absolute acceleration of both the buildings and bearing displacement under different real earthquake ground motions is computed to study the behaviour and effectiveness of resulting connected system. It is concluded that connecting the two adjacent base‐isolated buildings with the viscoelastic dampers is useful in controlling large bearing displacements in the base‐isolated structures thereby eliminating the isolator damages arising due to instability at these large displacements or pounding with adjacent ground structures during earthquakes. The viscoelastic damper connection between adjacent structures is found to be most effective when the adjacent base‐isolated and fixed‐base buildings are connected. Such scheme is hence useful in upgrading the seismic performance of existing fixed‐base structures adjacent to a base‐isolated structure.

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Effects of a Group of High-Rise Structures on Ground Motions under Seismic Excitation

Shock and Vibration ◽

10.1155/2015/821750 ◽

2015 ◽

Vol 2015 ◽

pp. 1-25 ◽

Cited By ~ 2

Author(s):

Qing-jun Chen ◽

Wen-ting Li

Keyword(s):

Ground Motions ◽

Three Dimensional ◽

Time Domain Analysis ◽

Coupled Systems ◽

Structural Group ◽

High Rise ◽

Adjacent Structures ◽

Single Structure ◽

Structural Responses ◽

Dimensional Simulation

A three-dimensional simulation was created to determine the seismic performance of coupled systems with a group of up to 100 pile-high-rise structures resting on soil layers using system modal, harmonic, and time domain analysis. The results demonstrated that the existence of a structural group mitigates the structural responses with respect to the single-structure-soil interaction (SSI) and results in significantly nonuniform ground seismic motions. Due to the influence of a structural group, adjacent structures can exhibit fully alternating mechanical behavior, and buildings in the urban fringe are subjected to stronger shaking than downtown buildings. The overall trend of the influence of structural groups is that ground motions are lessened inside an urban area, and ground motions at the locations between structures differ from those at the locations of the structures. Moreover, the effective distance of a structural group on ground motions is associated with the urban width. Less distance between structures enhances the interaction effect. In addition, the soil properties can greatly influence the system’s seismic responses and can even completely change the effect trends. The results in our paper are consistent with the phenomena observed in the Mexico City earthquake and the 1976 earthquake in Friuli, Italy.

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Advantages and Limitations of Seismic Isolation

Earthquake Spectra ◽

10.1193/1.1585630 ◽

1991 ◽

Vol 7 (2) ◽

pp. 301-324 ◽

Cited By ~ 9

Author(s):

John Stanton ◽

Charles Roeder

Keyword(s):

Seismic Isolation ◽

Ground Motions ◽

Large Displacements ◽

Conventional Analysis ◽

Equivalent Linear ◽

Methods Of Analysis ◽

Dynamic Forces ◽

The Impact

Under many circumstances, seismic isolation is an effective way of reducing the impact of earthquakes on structures. Dynamic forces in the structure itself are reduced at the expense of relatively large displacements in the isolators. These displacements can generally be predicted adequately by simple methods and accommodated without difficulty. However, some circumstances appear to exist where the isolator displacements might be significantly larger than conventional analysis would suggest, or where simplified methods of analysis may prove inadequate and fail to predict the response properly. The paper explores the limits of the applicability of equivalent linear analyses and the response to ground motions which might lead to large displacements isolation that can be achieved.

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