$4.00Add to Cart
Conventional probabilistic seismic hazard assessments (PSHA) are complex and frequently lead to different results because of the interpretations and approximations used by different experts. Simple PSHA is based on deterministically defined peak ground accelerations (PGA) with additional definition of probabilities of their exceedences. This way there is no duality between deterministic and probabilistic approaches used. The use of the simple PSHA is demonstrated for Abu Dhabi and the results are compared with a conventional PSHA. One comparative case is not sufficient to decide about the correlation between the conventional and the simple method of PSHA. It is obvious, however, that the simple method is more transparent and easy to use then more complex conventional method of PSHA. The simple procedure can be used for response spectra and other ground motion parameters with defined attenuation relationships.
Linear static analysis is the easiest method for the seismic design of unreinforced masonry buildings. What makes this method particularly convenient to apply is that the fundamental vibration period of the structure may be obtained conventionally from a formula given by the codes of practice, rather than being calculated rigorously. Usually, the code-based formula overestimates – sometimes significantly – the rigorous value of the fundamental period of vibration of masonry structures. By referring to a series of unreinforced masonry buildings, the paper shows that the conventional period may be even 4-9 times greater than the rigorous one. However, overestimating the fundamental period may lead to a reduction of the design loads to be applied in the static method. This occurs, in particular, when the design response spectrum decreases in the short-period range, where natural periods of masonry buildings typically fall. Some codes do not allow design spectra to be negatively sloped in the short-period range. While others, such as the Italian code of practice, do allow it, and in so doing, they make the linear static method non-conservative (in the given examples the shear at the base of masonry buildings may be underestimated by even as much as 35% when compared to the values obtained from the more precise linear dynamic method). The paper gives some hints towards making the code-based static method for seismic design of masonry buildings safe.
The strategic paths, clearly identified in an emergency plan, are a part of the ordinary roads network, that after an seismic event has to be ensured to enable the arrival at the strategic elements, the possibility of ap- proaching each urbanized area of the municipality, and, more in general, a minimum service mobility to the resident population. This paper proposes a quick methodology, subject of a first trial, with proper Survey form, that analyzes a few in- dicators, considered highly significant, and allows the evaluation of critical situations of the various links in which can be broken down the entire emergency road system of the Plan. The methodology is intended to provide an application that, in case of earthquake, allows to focus attention primarily on a few well-defined critical points of the emergency paths system, to determine the final scheme for the event occurred, by replacing any of the links, no longer functional, with others that are already contemplated as alternative in the plan. This analysis is also functional to the scheduling of any preventive actions required to reduce or eliminate the critical problems.
The New Auditorium of the Castle in l’Aquila, designed by Architect Renzo Piano, financed by the Province of Trento, temporarily relieves the Concert Hall of the 16th century Spanish fort, unfitted for use by the earthquake of April 6, 2009. The new hall is an oblique cube with 18m-long edges.The principles upon which the overall design is based are seismic action drop and building mass reduction. The choice of using wood comes from both architectural and structural reasons. Wood is a lightweight but very strong material. Little mass reduces the danger in case of earthquake. The Hall has a limited dissipative behaviour, because of its shape and of the chosen structural technology. There- fore we have adopted a base isolation system, composed by sixteen elastomeric isolators that reduce the seismic force by about 80%. The two additional buildings are used by the audience and the orchestra and are designed with the standard cross- lam panels building method, as an example of the application of lightweight and innovative earthquake-resistant techniques that can be used for the safe reconstruction of the Town too.