scholarly journals Reduction of Maximum and Residual Drifts on Posttensioned Steel Frames with Semirigid Connections

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Arturo López-Barraza ◽  
Edén Bojórquez ◽  
Sonia E. Ruiz ◽  
Alfredo Reyes-Salazar
Keyword(s):  
Seismic Performance ◽  
Ground Motions ◽  
Soft Soil ◽  
Steel Frames ◽  
Time History ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Steel Buildings ◽  
Earthquake Ground Motions ◽  
Semirigid Connections

The aim of this paper is to study the seismic performance of self-centering moment-resisting steel frames with posttensioned connections taking into account nonlinear material behavior, for better understanding of the advantages of this type of structural system. Further, the seismic performance of traditional structures with rigid connections is compared with the corresponding equivalent posttensioned structures with semirigid connections. Nonlinear time history analyses are developed for both types of structural systems to obtain the maximum and the residual interstory drifts. Thirty long-duration narrow-banded earthquake ground motions recorded on soft soil sites of Mexico City are used for the analyses. It is concluded that the structural response of steel buildings with posttensioned connections subjected to intense earthquake ground motions is reduced compared with the seismic response of traditional buildings with welded connections. Moreover, residual interstory drift demands are considerably reduced for the system with posttensioned connections, which is important to avoid the demolition of the buildings after an earthquake.

Seismic evaluation of single-storey steel buildings

1999 ◽  
Vol 26 (4) ◽  
pp. 379-394 ◽  
Author(s):  
M S Medhekar ◽  
DJL Kennedy
Keyword(s):  
Seismic Performance ◽  
Response Spectrum ◽  
Time History ◽  
Analytical Models ◽  
Steel Buildings ◽  
Concentrically Braced Frames ◽  
Braced Frame ◽  
Seismic Zones ◽  
Concentrically Braced Frame ◽  
Concentrically Braced

The seismic performance of single-storey steel buildings, with concentrically braced frames and a roof diaphragm that acts structurally, is evaluated. The buildings are designed in accordance with the National Building Code of Canada 1995 and CSA Standard S16.1-94 for five seismic zones in western Canada with seismicities ranging from low to high. Only frames designed with a force modification factor of 1.5 are considered. Analytical models of the building are developed, which consider the nonlinear seismic behaviour of the concentrically braced frame, the strength and stiffness contributions of the cladding, and the flexibility, strength, and distributed mass of the roof diaphragm. The seismic response of the models is assessed by means of a linear static analysis, a response spectrum analysis, a nonlinear static or "pushover" analysis, and nonlinear dynamic time history analyses. The results indicate that current design procedures provide a reasonable estimate of the drift and brace ductility demand, but do not ensure that yielding is restricted to the braces. Moreover, in moderate and high seismic zones, the roof diaphragm responds inelastically and brace connections are overloaded. Recommendations are made to improve the seismic performance of such buildings.Key words: analyses, concentrically braced frame, dynamic, earthquake, flexible diaphragm, low-rise, nonlinear, seismic design, steel.

A Seismic Effective Method for Double-Layer Reticulated Shell Using Buckling-Restrained Braces

2010 ◽  
Vol 163-167 ◽  
pp. 2852-2856
Author(s):  
Chang Wu ◽  
Xiu Li Wang
Keyword(s):  
Double Layer ◽  
Seismic Performance ◽  
Linear Time ◽  
Ground Motions ◽  
Equations Of Motion ◽  
Time History ◽  
Original Structure ◽  
Loading Test ◽  
Strong Earthquakes ◽  
Buckling Restrained Braces

In this study a kind of buckling-restrained braces (BRBs) as energy dissipation dampers is attempted for seismic performance of large span double-layer reticulated shell and the effectiveness of BRBs to protect structures against strong earthquakes is numerically studied. The hysteretic curve of such members is obtained through the simulation of the cyclic-loading test, and the equations of motion of the system under earthquake excitations are established. BRBs are then placed at certain locations on the example reticulated shell to replace some normal members, and the damping effect of the two installation schemes of BRBs is investigated by non-linear time-history analyses under various ground motions representing major earthquake events. Compared with the seismic behavior of the original structure without BRBs, satisfactory seismic performance is seen in the upgraded models, which clarifies the BRBs can reduce the vibration response of spatial reticulated structure effectively and the new system has wide space to develop double layer reticulated shell.

Power Analysis of Sdof Structures with Tuned Inerter Dampers Subjected to Earthquake Ground Motions

2020 ◽  
Author(s):  
Wenai Shen ◽  
Zhentao Long ◽  
Heng Wang ◽  
Hongping Zhu
Keyword(s):  
Seismic Response ◽  
Output Power ◽  
Analytical Solutions ◽  
Ground Motions ◽  
Soft Soil ◽  
Response Control ◽  
Seismic Response Control ◽  
Earthquake Ground Motions ◽  
Short Period ◽  
Soil Site

Abstract Tuned inerter dampers (TID) have been demonstrated as efficient energy dissipation devices for seismic response control. However, its potential capability for energy harvesting remains largely unexplored. Here, we present a theoretical analysis of the power of a structure-TID system subjected to earthquake ground motions. The analytical solutions of the average damping power of the system are derived for considering white noise base excitations and the Kanai-Tajimi earthquake model, respectively. Comparisons of the numerical results of a Monte Carlo simulation and the theoretical predictions verify the accuracy of the analytical solutions. Besides, we uncover the influence of the TID parameters on the damping power and output power of the system. The optimal frequency ratio of the TID for maximizing its output power slightly differs from that for seismic response control, and the former varies with site conditions. In contrast, both the damping power and output power are not sensitive to the damping ratio of the TID. For short-period structures, a small inertance-to-mass ratio (µ) of the TID is beneficial to maximize its output power, while seismic response control requires a large µ. For long-period structures, the damping power and output power are not sensitive to the µ. Generally, a structure-TID system on a soft soil site absorbs more energy from a given earthquake and is capable of harvesting more energy than that on a hard soil site. This study may help develop new strategies for self-powered control and monitoring in civil structures.

scholarly journals The Effect of Long Duration Earthquakes on the Overall Seismic Behavior of Steel Structures Designed According to Eurocode 8 Provisions

Vibration ◽  
2020 ◽  
Vol 3 (4) ◽  
pp. 464-477
Author(s):  
Panagiota Katsimpini ◽  
Foteini Konstandakopoulou ◽  
George A. Papagiannopoulos ◽  
Nikos Pnevmatikos ◽  
George D. Hatzigeorgiou
Keyword(s):  
Seismic Performance ◽  
Time History ◽  
Steel Structures ◽  
Eurocode 8 ◽  
Steel Buildings ◽  
Long Duration ◽  
Base Steel ◽  
Fixed Base ◽  
Permanent Settlement ◽  
Nonlinear Time History

Premature and simultaneous buckling of several steel braces in steel structures due to the prolonged duration of a seismic motion is one of the issues that must be addressed in the next version of Eurocode 8. In an effort to contribute towards the improvement of the seismic design provisions of Eurocode 8, an evaluation of the overall behavior of some steel building-foundation systems under the action of long duration seismic motions is performed herein by means of nonlinear time-history seismic analyses, taking into account soil–structure interaction (SSI) effects. In particular, the maximum seismic response results—in terms of permanent interstorey drifts, overturning moments and base shears of the steel buildings as well as of the permanent settlement and tilting of their foundations—are computed. It is found that the seismic performance of steel buildings when subjected to long duration seismic motions is: (i) acceptable for the two and five-storey fixed base steel buildings and for the two-storey steel buildings with SSI effects included; (ii) unacceptable for the eight-storey fixed base steel buildings and for the five and eight-storey steel buildings with SSI effects included. In all cases of steel buildings with SSI effects included, the seismic performance of the mat foundation, as expressed by the computed values of residual settlement and tilting, is always acceptable.

DAMAGE EVOLUTION SPECTRA FOR SEISMIC ANALYSIS OF HIGH-RISE BUILDINGS

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.

scholarly journals Effects of Soil-Structure Interaction on Torsionally Coupled Base Isolated Machine Foundation under Earthquake Load

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Karmegam Rajkumar ◽  
Ramanathan Ayothiraman ◽  
Vasant A. Matsagar
Keyword(s):  
Soil Structure ◽  
Natural Frequencies ◽  
Ground Motions ◽  
Soft Soil ◽  
Soil Structure Interaction ◽  
Structure Interaction ◽  
Machine Foundation ◽  
Earthquake Ground Motions ◽  
Torsional Coupling ◽  
Base Isolators

In this paper, the influence of soil-structure interaction (SSI) on a torsionally coupled turbo-generator (TG) machine foundation is studied under earthquake ground motions. The beneficial effects of base isolators in the TG foundation under earthquake ground motions are also studied duly, considering the effects of SSI. A typical TG foundation is analyzed using a three-dimensional finite element (FE) model. Two superstructure eccentricity ratios are considered to represent the torsional coupling. Soft soil properties are considered to study the effects of SSI. This research concludes that the effects of torsional coupling alter the natural frequencies, if ignored, could lead to unsafe design. The deck accelerations and displacements are increased with an increase in superstructure eccentricity. On the other hand, the deck accelerations and displacements are greatly reduced with the help of base isolators, thus confirming the beneficial use of base isolators in machine foundations to protect the sensitive equipment from the strong earthquake ground motions. However, the effects of SSI reduce the natural frequencies of the TG foundation resting on soft soil conditions and activate the higher mode participation, resulting in amplifying the response.

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