Luigi Petti

Robust Design of a Single Tuned Mass Damper for Controlling Torsional Response of Asymmetric-Plan Systems

A new robust design methodology to control the seismic performance of asymmetric structures equipped with a Single Tuned Mass Damper (STMD) is presented in this article. This design approach aims to control the seismic response of such systems by reducing both flexible-and stiff-edge maximum displacement. The dynamic problem has been investigated in the state space representation showing that the TMD works as a closed-loop feedback control action. A synthetic index to estimate the seismic performance of the main system has been defined by using H∞ norm. Wide-ranging parametric numerical experimentation has been carried out to obtain design formulae for the STMD in order to minimize such a performance index. These formulae allow for a simple design of STMD position and stiffness to optimally control both translational and rotational motion components, whereas two mass devices are generally considered to improve the seismic performance of asymmetric structural systems The effectiveness and efficiency of the obtained design formulae have been tested by investigating the dynamic behavior of the asymmetric structure after being subjected to different recorded seismic inputs.

Stochastic Response Comparison between Base Isolated and Fixed‐Base Structures

Random response of linear Base Isolated Systems, mounted on elastomeric bearings, subject to horizontal random excitations, is analyzed in comparison with the one of the fixed-base structures. Considering the superstructure motion described by its first modal contribution, a two-degree-of-freedom equivalent linear model, under stationary Gaussian excitations modelled by the modified Kanai-Tajimi power density spectrum, has been used in the analysis. The response sensitivity to design parameters for the superstructure and the isolators have been evaluated for a wide range of parameters. Optimum viscous damping and isolation degree values which minimize structural response are also obtained. Some implications of these results for the design and code requirements are discussed.

Heritage and Reconstruction: Different Perspectives

Heritage is the physical expression of the cultural identity of local communities and in most cases it is a key factor supporting the development of the local economy. Due to its own nature, heritage is a non-renewable patrimony to protect for the future generations. The purpose of this paper is to describe reconstruction issues for urban conservation in historic cities, which have been led to destruction by accident, because of flooding, earthquakes, storm, fires, and also war, pointing out the association between conservation and development. In so doing, the paper will focus on the case study of a city listed in the World Heritage List, Kathmandu. A further matter concerns the controversial approach of reconstruction: while restoration aims to bring a monument back to its original state or preserve from further damage, reconstruction instead is accomplished on buildings that are destroyed or constituted of just limited ruins, sometimes even requiring the construction of a new building. After the Second World War the patrimony of the European historic cities was severely damaged, making the population aware of their loss of cultural and national identity and opening the international debate on the proper techniques and theories that should be applied. When it comes to historical cities, rather than a single monument, it does not involve just the physical appearance and the historical value but might allow to reinstate the socio-economic condition and the cultural identity of a place after a period of decline.

A Model Flexible Design for Pediatric Hospital

The main objective of this research is the identification of a pediatric hospital contemporary design model, developing, at the same time, a prefabricated construction technology able to meet today’s health from building flexibility characteristics. Therefore, starting from the analysis of the evolution of architecture and health care facilities, in history, and the main aggregation methodologies used, the basic parameters have been identified on which is based the design of the pediatric ward: flexibility, modularity, environmental quality and humanization. Based on these parameters was developed a contemporary children’s hospital model that, in addition to responding to the initial requirements, could lend itself to multiple aggregation solutions. The finalization of the architectural model has determined, in addition, the need to develop a suitable construction technology, able to adapt to the requirements of flexibility on which is based the entire study: from such reflections was, therefore, experienced a basic module which is based on the design principles of precast lightweight.