The earthquake design and analysis of equipment isolation systems

This paper investigates the effects of the nonlinear behaviour of isolation pads on the seismic capacity of bridges to identify the parameters of base isolation systems that can be used to improve seismic performance of bridges. A parametric study was conducted by designing a set of bridges for three different soil types and varying the number of spans, span lengths, and pier heights. The seismic responses (acceleration, displacement and pier seismic forces) were evaluated for two structural models. The first model corresponded to the bridges supported on elastomeric bearings with linear elastic behaviour and the second model simulated a base isolated bridge that accounts for the nonlinear behaviour of the system. The seismic demand was represented with a group of twelve real accelerograms recorded on the subduction zone on the Pacific Coast of Mexico. The nonlinear responses under different damage scenarios for the bridges included in the presented study were estimated. These results allow determining the seismic capacity of the bridges with and without base isolation. Results show clearly the importance of considering the nonlinear behaviour on the seismic performance of bridges and the influence of base isolation on the seismic vulnerability of medium size bridges.

Download Full-text

Building analysis for inelastic earthquake design of regular moment frames and dual systems addressing moment redistribution

Engineering Structures ◽

10.1016/j.engstruct.2011.08.034 ◽

2012 ◽

Vol 34 ◽

pp. 147-154

Author(s):

Tae-Sung Eom ◽

Jae-Yo Kim ◽

Hong-Gun Park

Keyword(s):

Moment Frames ◽

Dual Systems ◽

Moment Redistribution ◽

Earthquake Design

Download Full-text

Design and analysis of a vibration isolation system with cam–roller–spring–rod mechanism

Journal of Vibration and Control ◽

10.1177/10775463211000516 ◽

2021 ◽

pp. 107754632110005

Author(s):

Yonglei Zhang ◽

Guo Wei ◽

Hao Wen ◽

Dongping Jin ◽

Haiyan Hu

Keyword(s):

Vibration Isolation ◽

Dynamic Stiffness ◽

Experimental Studies ◽

Excitation Amplitude ◽

Isolation System ◽

Vibration Isolation System ◽

Stiffness Characteristic ◽

Negative Stiffness Mechanism ◽

Isolation Systems ◽

Vibration Isolation Performance

The vibration isolation system using a pair of oblique springs or a spring-rod mechanism as a negative stiffness mechanism exhibits a high-static low-dynamic stiffness characteristic and a nonlinear jump phenomenon when the system damping is light and the excitation amplitude is large. It is possible to remove the jump via adjusting the end trajectories of the above springs or rods. To realize this idea, the article presents a vibration isolation system with a cam–roller–spring–rod mechanism and gives the detailed numerical and experimental studies on the effects of the above mechanism on the vibration isolation performance. The comparative studies demonstrate that the vibration isolation system proposed works well and outperforms some other vibration isolation systems.

Download Full-text

Analytical Evaluation of MCE Collapse Performance of Seismically Base Isolated Buildings Located at Low-to-Moderate Seismicity Regions

Applied Sciences ◽

10.3390/app10249150 ◽

2020 ◽

Vol 10 (24) ◽

pp. 9150

Author(s):

Hyung-Joon Kim ◽

Dong-Hyeon Shin

Keyword(s):

Base Isolation ◽

Numerical Models ◽

Influential Factors ◽

Collapse Mechanism ◽

Total System ◽

Practical Applications ◽

Seismic Design Code ◽

Moderate Seismicity ◽

Design Requirements ◽

Isolation Systems

The promising seismic response emerged by the concept of base isolation leads to increasing practical applications into buildings located at low-to-moderate seismicity regions. However, it is questionable that their collapse capacities can be ensured with reasonable reliability, although they would be designed according to a current seismic design code. This paper aims to investigate the collapse capacities of isolated buildings governed by the prescribed design criteria on the displacement and strength capacities of the employed isolation systems. In order to evaluate their collapse capacity under maximum considered earthquakes (MCEs), simplified numerical models are constructed for a larger number of nonlinear incremental dynamic analyses. The influential factors on the collapse probabilities of the prototype buildings are found out to specifically suggest the potential modifications of the design requirements. Although the MCE collapse probabilities of all isolated buildings are smaller than those expected for typical non-isolated buildings, these values are significantly different according to the degree of seismicity. The MCE collapse probabilities are dependent upon the governing collapse mechanism and the total system uncertainty. For the prototype buildings located at low-to-moderate seismicity regions, this study proposed the acceptable uncertainty to achieve a similar collapse performance to the corresponding buildings built at high seismicity regions.

Download Full-text