N. Ranieri

Shaking Table Tests on a Passive Equipment Isolation System for Earthquake Protection

The present work refers to steel frame structures in industrial plants. A passive isolation system for seismic protection of a considerable equipment, already present on a frame support structure and rigidly constrained to it, is investigated through both numerical simulations (1+1 DOF system) and shaking table tests on a 1:5 scale two-story steel frame structure. The equipment (e.g. a pipeline, a compressor unit, ...) is modelled as a rigid mass. The optimal design is determined by minimizing the dynamic response of the isolated mass. In order to ensure strenght and serviceability, the response of the frame is also monitored.Copyright

Numerical analysis of a MDOF structure protected with TMD techniques

In the present paper a complete numerical study of a 1:5 scaled four-storey steel-frame structure with the application of Tuned Mass Dampers (TMD) is reported. In particular, Passive Tuned Mass Dampers (PTMD), Semi-Active Tuned Mass Dampers (SATMD), and Hybrid Tuned Mass Dampers (HTMD) were considered and compared. The initial aim of this work was to define a Simplified Equivalent Model to be conveniently utilized for simulations instead of a realistic Prototype Numerical Model in order to estimate the designing parameters of the devices with good approximation and sensible time calculation saving. Subsequently, the feasibility, the reliability and the effectiveness of the considered seismic control techniques were also assessed. The results of the numerical analysis showed how the use of a simplified model allows to estimate the designing parameters with accuracy. More importantly, the numerical results showed to what extent the several TMD techniques revealed to be effective for the seismic response reduction.Copyright

Shaking Table Tests on Innovative Anti-Seismic Systems Developed in the Framework of the LESSLOSS European Integrated Project

The Integrated Project LESSLOSS (Risk Mitigation for Earthquakes and Landslides), partially funded by the European Commission within the 6th Framework Programme, started on September 2004 and was concluded in August 2007. Activities were carried out by 46 European partners, with a total budget of 9.4 ME. The Project was divided into 11 Sub-Projects. This paper describes the activities performed in the framework of Sub-Project 6 (Development and Manufacturing of Energy Dissipation Devices and Seismic Isolators), which was coordinated by ENEA and whose partnership included two manufacturers of antiseismic devices (ALGA, Milan, Italy and MAURER SHONE, Munich, Germany) and two consulting and construction companies (STAP, Lisbon, Portugal and VINCI, Paris-Rueil, France). Aim of Sub-Project 6 was the development and validation of two innovative antiseismic devices (a low stiffness isolator and an electroinductive damper), the improvement of the performances of a slider with curved surface and the evaluation of benefits and limits of isolation systems based on steel hysteretic dissipaters coupled with flat sliders. The Low Stiffness Isolator (LSI) was developed by ALGA; it is a natural rubber seismic isolator particularly addressed to light structures like family houses. The Electroinductive Damper (DECS), developed by ALGA, is an energy dissipater based on the interaction of a diamagnetic material, like aluminium, with an electric field generated by permanent magnets. The Sliding Isolation Pendulum (SIP) developed by MAURER is an improved curved surface slider, capable of withstanding high weights for long periods without creep effects and high velocity deformations without damages due to friction. Finally, several types of Steel Hysteretic (SH) elements of different geometries and materials have been analyzed and tested in order of evaluating the benefits and the limits of such devices, with particular regard to the re-centering capabilities. All the abovementioned devices have been tested on the ENEA shaking table of the Casaccia labs (near Rome), with a suitable mock-up capable of providing a 300 kN force on the devices in the acceleration and frequency ranges of interest, using several natural and artificial acceleration time histories purposely developed by ENEA. The paper describes the main features of the devices, the numerical activity aimed at the optimization of their behavior and the results of the four shaking table campaigns carried out on each device.Copyright