Journal of Earthquake Engineering

This study was started in the frame of an assessment of the completeness of parametric earthquake catalogues. Its primary aim was to check whether early journalistic sources can yield "new" earthquake data, i.e. data on previously unknown damaging earthquakes and previously unknown data on such already known events. Another aim was to assess the quality of the resulting information, an important matter given the widespread opinion that early journalistic sources are highly unreliable. A large sample of monographical (pamphlets) and serial (gazettes) early journalistic sources was systematically searched for "new" earthquake data. The results show them to have a high informative content, while being no more unreliable than most historical sources. It is safe to assume that a large-scale combined effort to put this informative potential within general reach would give a great impetus towards increasing the completeness of the parametric earthquake catalogues of most European (and also non-European) countries.

An extensive program of shaking table tests on 1/4-scale three-dimensional R/C frames was jointly carried out by the Department of Structure, Soil Mechanics and Engineering Geology (DiSGG) of the University of Basilicata, Italy, and the National Laboratory of Civil Engineering (LNEC), Portugal. It was aimed at evaluating the effectiveness of passive control bracing systems for the seismic retrofit of R/C frames designed for gravity loads only. Two different types of braces were considered, one based on the hysteretic behaviour of steel elements, the other on the superelastic properties of Shape Memory Alloys (SMA). Different protection strategies were pursued, in order to fully exploit the high energy dissipation capacity of steel-based devices, on one hand, and the supplemental re-centring capacity of SMA-based devices, on the other hand. The experimental results confirmed the great potentials of both strategies and of the associated devices in limiting structural damage. The retrofitted model was subjected to table accelerations as high as three times the acceleration leading the unprotected model to collapse, with no significant damage to structural elements. Moreover, the re-centring capability of the SMA-based bracing system was able to recover the undeformed shape of the frame, when it was in a near-collapse condition. In this paper the experimental behaviour of the non protected and of the protected structural models are described and compared.

If RC structural walls are properly designed and proportioned, these walls can behave in a ductile manner. To achieve this goal, the designer should provide adequate strength and deformation capacity of structural walls corresponding to each performance level (e.g. immediate occupancy, life safety and collapse prevention). This study investigates the drift and ductility capacities of T-shaped structural walls on the basis of results from experimental tests and sectional analyses. To determine proper deformation capacities for T-shaped structural walls, structural performances of T-shaped walls were evaluated with several parameters such as longitudinal reinforcement ratio, distribution of longitudinal reinforcement, lateral confinement ratio, and axial load ratio. Based on these results, the level of deformation capacity specified in current design provisions (ICBO, UBC 1997), which were expressed as both strain-based damage limit and interstorey drift ratio, were evaluated.

Shape memory alloys (SMAs) are a class of materials that have unique properties, including Young's modulus-temperature relations, shape memory effects, superelastic effects, and high damping characteristics. These unique properties, which have led to numerous applications in the biomedical and aerospace industries, are currently being evaluated for applications in the area of seismic resistant design and retrofit. This paper provides a critical review of the state-of-the-art in the use of shape memory alloys for applications in seismic resistant design. The paper reviews the general characteristics of shape memory alloys and highlights the factors affecting their properties. A review of current studies show that the superelastic and high-damping characteristics of SMAs result in applications in bridges and buildings that show significant promise. The barriers to the expanded use of SMAs include the high cost, lack of clear understanding of thermo-mechanical processing, dependency of properties on temperature, and difficulty in machining.

Is it really plausible that earthquakes break speleothems? May unbroken speleothems prove that no strong earthquake has ever occurred during a certain period of time? The mechanical behaviour of speleothems has been investigated through static bending tests performed on stalactites and soda straws. These tests give an indication not only of the mean tensile resistance, but also — more importantly — of its variation. In fact, it is this variation that makes it difficult to estimate the acceleration necessary to break an individual speleothem. That is why a statistical approach is mandatory. The potentially most vulnerable unbroken as well as broken stalactites were measured in a pilot cave (Milandre, Switzerland). Four classes of stalactites were defined, according to their shapes. For each of these classes, a vulnerability curve (probability of breaking as a function of peak ground acceleration) was obtained by means of a Monte Carlo simulation. Dynamic amplification as well as heterogeneity of bending resistance within each speleothem were taken into account. Finally, an original statistical approach, valid for incomplete and imprecise data, was developed. This approach allowed to estimate the probability that at least one moderate earthquake has occurred in the past.

The present study deals with the seismic performance of partial perimeter and spatial moment resisting frames (MRFs) for low-to-medium rise buildings. It seeks to establish perimeter configuration systems and hence the lack of redundancy can detrimentally affect the seismic response of framed buildings. The paper tackles this key issue by comparing the performance of a set of perimeter and spatial MRFs, which were "consistently designed". The starting point is the set of low- (three-storey) and medium-rise (nine-storey) perimeter frames designed within the SAC Steel Project for the Los Angeles, Seattle and Boston seismic zones. Extensive design analyses (static and multi-modal) of the perimeter frame buildings and consistent design of spatial frame systems, as an alternative to the perimeter configuration, were conducted within this analytical study. The objectives of the consistent design are two-fold, i.e. obtaining fundamental periods similar to those of the perimeter frames, i.e. same lateral stiffness under design horizontal loads, and supplying similar yield strength. The seismic behaviour of perimeter and spatial configuration structures was evaluated by means of push-over non-linear static analyses and inelastic dynamic analyses (non linear time histories). Comparisons between analysis results were developed in a well defined framework since a clear scheme to define and evaluate relevant limit states is suggested. The failure modes, either local or global, were computed and correlated to design choices, particularly those concerning the strength requirements (column overstrength factors) and stiffness (elastic stability indexes). The inelastic response exhibited by the sample MRFs under severe ground motions was assessed in a detailed fashion. Conclusions are drawn in terms of local and global performance, namely global and inter-storey drifts, beam and column plastic rotations, hysteretic energy. The finding is that the seismic response of perimeter and spatial MRFs is fairly similar. Therefore, an equivalent behaviour between the two configurations can be obtained if the design is "consistent".