Reduction of structural vibrations is of major interest in mechanical engineering for lowering sound emission of vibrating structures, improving accuracy of machines and increasing structure durability. Besides optimization of the mechanical design or various types of passive damping treatments, active structural vibration control concepts are efficient means to reduce unwanted vibrations. In t...

The Sirri jacket offshore platform was designed and installed in Persian gulf of Iran in 1975 and has been in service since that time. The importance of offshore structure's stability and the failure of this kind of structure during an earthquake in different active zones revealed that earthquake loading has to be considered. In this paper, Magnetorheological (MR) fluid dampers have been propos...

In this paper, acoustic radiation response of thin-walled box with particle dampers is predicted. First, the effect of the collisions and friction between the granular inter-particles is interpreted as an equivalent nonlinear viscous damping based on multiphase flow theory of gas-particle. Then the contribution of particle damper is estimated as an equivalent mass-damper system. And the acousti...

Magnetorheological (MR) dampers represent one of the most promising semi-active control devices for applications aiming at the seismic risk mitigation of new or existing civil structures. Two 30 kN MR dampers were experimentally tested subjecting them to assigned conventional displacement laws at their ends. The paper describes the main results of the above experimental activity and aims at imp...

As a rule, public buildings should have higher safety level compared to residential ones. Hence, using base isolation systems is an effective and widely known way for improving dynamic response of such buildings. The idea of base isolation was known hundreds years ago, however practical implementation of base isolators started in the last few decades. The main advantage of a base isolation syst...

The paper presents a plastic analysis procedure based on the energy balance concept for performance based seismic retrofit of multi-story multi-bay masonry infilled reinforced concrete (R/C) frames with a ‘soft’ ground story using passive energy dissipation (PED) devices with the objective of achieving a target performance level of the retrofitted R/C frame for a given seismic hazard level at t...

This paper discusses a methodology of semi-active structural control using a variable friction damper. The presented algorithm is quite simple and straightforward, in which only the slip level of the friction damper is controlled in response to the interstory response velocity of the damperinstalled story so as to maintain the target constant ductility factor. In conducting control there is adv...