Giacomo Buffarini

Experimental Seismic Analysis of a Historical Building

This article discusses seismic analysis of a historical building to predict the state of damage in case of earthquakes. A temporary array is first used to have a first glance at the dynamic properties of the building. Then a permanent array is installed and several events are recorded. The experimental results are compared with those obtained by means of a simplified finite element model that reproduces the complex nature of the building. The results obtained are very useful to predict where stresses could be concentrated and where cracks or damage could start under seismic actions. Such an analysis is very important both to identify areas in the structure particularly vulnerable to earthquakes and to plan an effective building retrofit program to resist seismic actions.

Experimental analysis of base isolated buildings under low magnitude vibrations

The effects of low magnitude vibrations on the base isolated building are analysed and discussed with reference to two particular structures. The first one is a complex structure, composed by two blocks of three floors, rising up from a common base deck, which is supported by the foundation beams by means of isolation devices. During a moderate intensity earthquake, higher modes were excited, pointing out their very irregular behaviour. In the second case, which regards a building having a hemispherical shape, with three floors plus an underground one, the data recorded under ambient vibrations revealed the significant contribution of the isolation system. In both cases, the experimental behaviour was quite different from the expected one and this should be accounted for when designing base isolation systems.

Dynamic Behavior of a Historical Building

Given the particular difficulty in classifying and defining the characteristics of the structural systems of historical buildings, especially when they are part of complex historical constructions, the vulnerability study efforts becomes significantly more difficult than the study of regular modern structural systems. Furthermore, old buildings may have been altered repeatedly over time, may be founded on older buildings that got buried over and could be connected one to the others. This will cause dynamic interactions with other buildings or sub-structures during an earthquake. Therefore, the particular architectural and structural history of each structure adds uncertainties in the assessment of its seismic vulnerability. In this paper the dynamic response of CEDRAV building, part of the historical centre of Cerreto di Spoleto (Italy), is analyzed, by means of the data recorded by several temporary deployments of velocimeters. The complexity in assessing seismic behavior of the historical built environments is pointed out and so the dynamic interaction with adjacent buildings.

Optimization Criteria In Design Of Seismic Isolated Building

Use of new anti‐seismic techniques is certainly suitable for buildings of strategic importance and, in general, in the case of very high risk. For ordinary buildings, instead, the cost of base isolation system should be balanced by an equivalent saving in the structure. The comparison criteria have been first defined, then a large numerical investigation has been carried out to analyze the effectiveness and the economic suitability of seismic isolation in concrete buildings.

Base Isolation of Buildings with Curved Surface Sliders: Basic Design Criteria and Critical Issues

Curved surface sliders are being used more and more in the seismic isolation of buildings. They are preferred not only because of their lower cost with respect to elastomeric isolators but also of their technical characteristics, such as the fact that the value of the period of vibration is independent of the mass and the automatic coincidence between the gravity mass center of the superstructure and the stiffness center of the isolation system. In this paper, these features are analysed with reference to simple structures, pointing out the possibility of rotations of the superstructure and the loss of contact in some devices. Finally, the importance of the static friction is also emphasized showing the experimental seismic response of an isolation system under a low-energy earthquake. For all these reasons, the use of nonlinear analysis, revised and detailed in this paper, is advisable for the isolation system made of curved surface sliders.

Vulnerability Analysis and Seismic Retrofit of a Strategic Building

AbstractThe seismic vulnerability analysis of a strategic building is presented in this paper. A refined finite-element model was set up on the basis of available experimental results, and updated on the basis of new experimental analyses on materials and structure. As demonstrated by an experimental vibration analysis, the structural behavior is influenced very much by the irregularity of the building and the presence of an adjacent building with no seismic joint. The results indicate a high vulnerability of the building to seismic actions, and the inadequacy of the pile foundation—for which a specific nonlinear analysis was performed—to support horizontal seismic loads. A retrofit intervention, based on the insertion of a seismic isolation system and the realization of a seismic joint with the adjacent building, was proposed, which allows the reduction of horizontal forces in the piles and the torsional movements of the structure.

Seismic analysis and retrofit of a mid-rise building

5th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering, COMPDYN 2015