Class Of Ground Motions Research Articles

Dual hysteretic damper system effective for broader class of earthquake ground motions

This paper aims to develop a dual hysteretic damper (DHD) effective for a broader class of ground motions, which includes two level-oriented hysteretic dampers and a gap element. To reveal the influence of DHD parameters on the earthquake structure response, a closed-form solution is used for the maximum response of a single-degree-of-freedom system with DHD under the critical double impulse. An energy balance approach plays a central role in the derivation of such closed-form solution. A design process of DHD in a multi-degree-of-freedom system is proposed which is based on the sensitivity analysis. The transformation of earthquake ground motions into the double impulse overcomes the difficulty in the emergence of sensitive response variation to design parameters. It is demonstrated that DHD is effective for both small and large-amplitude input motions and the proposed system is applicable to recorded ground motions approximately. It is also verified through the comparison with the designs obtained by the Monte Carlo simulation and the genetic algorithm (GA) that the proposed design method is more effective and efficient than conventional methods.

Smart passive damper control for greater building earthquake resilience in sustainable cities

Abstract Passive dampers are used recently in many mid and high-rise buildings. This trend is accelerated by the increased demand and desire for safer, more reliable and more comfortable buildings under uncertain external loading and environment. Viscous, visco-elastic, hysteretic and friction dampers are representatives of passive dampers. Such passive dampers also play a key role in the implementation of structural rehabilitation which is essential for the realization and promotion of sustainable buildings. The technique of structural health monitoring is inevitable for the reliable and effective installation of passive dampers during the structural rehabilitation or retrofit. The design earthquake ground motions change from time to time when a new class of ground motions (e.g. long-period ground motions due to surface waves) is observed or a new type of damage appears during severe earthquakes. The concept of critical excitation is useful in responding to this change together with the usage of passive dampers from the viewpoint of sustainable buildings and cities. In this paper, a historical review is made on the development of smart or optimal building structural control with passive dampers and some possibilities of structural rehabilitation by use of passive dampers are discussed.

Vector-valued intensity measures for pulse-like near-fault ground motions

A vector-valued intensity measure (IM) is shown to account for the effects of pulse-like near-fault ground motions. This class of ground motions, which are indicated by the presence of a velocity pulse, can cause large responses in structures and their effects are not well described by traditional intensity measures such as spectral acceleration at the structure’s first-mode period, S a ( T 1 ) . It is seen that the period of the velocity pulse is an important parameter affecting structural response, and a vector intensity measure which combines S a ( T 1 ) with a measure of spectral shape is much more effective at accounting for the effects of this pulse period. By performing probabilistic seismic hazard analysis for this IM and combining the results with predictions of structural response as a function of the IM, it is possible to account for near-fault effects when assessing the reliability of structures located at sites where pulse-like ground motions may occur.