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Maurice Anthony Biot was not only the scientific founder of earthquake engineering. His pioneering contributions extended well beyond, to many other fields, including mechanics of porous media, wave propagation, aerodynamics and aeronautic fluid mechanics, non-linear elasticity, theory of folding and thermodynamics. Combin- ing simplicity and breadth, his work achieved the aesthetic qualities displayed by foremost nineteenth century and turn of the century practitioners of mathematical physics like Maxwell, Rayleigh and Sommerfeld. In the following we review only Biot’s contributions to earthquake engineering, the first steps, the background, the time in which he grew and several other factors, which may have influenced him and contributed to his formulation of the response spectrum method. Today, Biot’s response spectrum method continues to be the basis for all modern seismic design work, a condicio sine qua non in all of earthquake engineering.
Suspended ceilings are among the most widely used nonstructural components. Past earthquakes have demonstrated the susceptibility of suspended ceilings to failure during seismic events. To address this vulner- ability, design codes have incorporated specific design and installation criteria for suspended ceilings. However, ceiling and grid manufacturers continue to innovate and introduce new products that are requested by engineers and architects but are not addressed in the code. Therefore, it is necessary to have the means to evaluate such prod- ucts. Because these units are difficult to analyze numerically, earthquake simulation testing can be used to assess the seismic performance of suspended ceilings. Such technique was used by one of the major manufacturers in the United States to characterize the performance of a standard code-prescribed ceiling and to use that performance as a benchmark for assessing the response of this manufacturer’s alternate installation. Testing and evaluation of data showed that the code-prescribed installation had an acceptable performance. It was also noted that the ceil- ing constructed with the proposed alternate installation performed as well as or better than the specimen installed using the code procedure. Finally, the test data revealed some of the shortcomings of the current experimental and evaluation methodology that require revisions.
Due to the high level of uncertainty characterizing existing buildings, the evaluation of the seismic behaviour of these structures must be preceded by an accurate reconstruction of their history. At this aim the present paper focuses firstly on the historical analysis and successively on the investigation of the seismic vulnerability of the “Quinto Orazio Flacco” school, built in Bari in 1933. The three-storey main masonry building has a M-shaped plan with maximum dimensions equal to 57.8 m and 82.4 m respectively in the transversal and longitudinal directions. In 1963 a new reinforced concrete building separated from the preexistent masonry one was realized along its free perimeter. By the analysis of the capacity curves obtained by suitable pushover procedures performed separately for each building, it emerges that masonry and reinforced-concrete buildings are vulnerable to earthquake-induced structural pounding in the longitudinal direction. In order to investigate this structural aspect, in this paper time history analyses are carried out, using detailed finite element three-dimensional models of the two buildings and a numerical procedure suitable elaborated by Matlab software.
For this paper is available an extended abstract after the text in Italian
The paper addresses the analysis of the seismic damage of Onna, a village near L’Aquila almost completely destructed during the 6 April event. A purposely developed data form has been used to collect the ob- servations of several surveyors. The analysis of the construction typologies, of the seismic vulnerability and of the damage lead to the conclusion that the poor characteristics of the masonry played a dramatic role in the seismic damage suffered by the buildings, despite that some typical historical seismic provisions were present (limited height of the buildings, wood ties). The low level of damage of some unreinforced masonry buildings in Onna, built following a good construction practice, indirectly confirms the heavy role played by the seismic vulnerability in the damage observed.
For this paper is available an extended abstract after the text in Italian.
Checking the seismic safety of existing structures is a complex task, mainly due to uncertainities connected with material properties, loads and structural geometry. Before O.P.C.M. 3274, with the exception of applications to masonry buildings (and after important seismic events), no italian code has defined methods specifically devoted to existing, structures considering also r.c. buildings. included. The real novelty of new code applications consists in the development of reliable and applicable produres for the analysis of existing structures, especially of the reinforced concrete ones. The more credited methods (also for practical purposes) may be divided into two classes: linear and non linear ones (among them pushover analysis). These methods may be applied either to static analysis and to dynamic analysis. Static analysis is carried out by assigning a standard distribution of lateral forces along the heigth of the considered building following the assumed shape of “first vibration mode” of regular structures. Dynamic analysis enables to analyze also geometrically articulated structures by considering modal shapes derived from eigenvectors and eigenvalues of a generalized system. The methods are shortly, with particular emphasis on the linear one, in order to estimate the ultimate PGA for the considered structure. This method represents an appropriate compromise between reliability and rapidity of calculations. By using design spectrum with behaviour factor q, it is possible to consider, for existing buildings, a minimum value of ductility.
This paper is available in Italian only