Journal of Earthquake Engineering

The attenuation of the maximum shear wave for strong ground displacements in large earthquakes (5.4 < M_w < 7.2) in California was studied from a seismological viewpoint. Smooth regression curves of attenuation were statistically fitted to measurements made personally on each seismogram. The curves were computed for two different geological classifications of the recording location (rock or soil), and two different fault mechanisms of the seismic source (strike-slip or reverse-fault). The sample consisted of eight strike-slip and four reverse-fault mechanism earthquakes with 237 soil and 92 rock peak ground displacement measurements.

The peak ground-motion displacements were measured from the S body-wave portion of the seismograms (frequencies between 0.2 and 1 Hz) after discrimination of the seismic wave types. The peak displacement from any surface wave train was not considered in this analysis. An attenuation distance H_slip was used as the distance from the recording station to the location on the fault plane of largest slip. Two sub-samples were formed consisting of the transverse (SH) and vertical (SV) measurements.

The set of ground-displacement attenuation curves predict greater amplitudes at sites classified as soil sites compared to rock sites, and for SH versus SV motion for both types of seismic source mechanisms.

The Krasnovodsk earthquake of 8 July 1895 occurred on the extension of the Kopet Dagh fault zone, which is on the border of Iran at the edge of the Turan plate, locally the north-eastern limit of the Alpine-Himalayan mountain belt. This is a major basement structure that separates the stable Turan plate from the Kopet Dagh mountain range, and has a relatively low level of seismicity compared to the Kopet Dagh folded zone. However, it is capable of generating infrequent large earthquakes. Until recently, the Krasnovodsk earthquake of 1895 was considered to be a large sub-crustal event with a magnitude of 8.2.

We re-examine this earthquake using additional macroseismic and early instrumental data and conclude that this was a crustal event of magnitude not exceeding Ms 7.4. We find that in the near-field, much of the destruction it caused was due to ground liquefaction, and that the very strong asymmetry in the distribution of intensity displayed in the far-field between the north and south parts of the felt area is consistent with the slow and fast attenuation associated with the stable continental region of Russia and the deformed crust of Iran, respectively.

A non-parametric multidimensional regression method is proposed for the prediction of seismic ground motion parameters. The main features which distinguish the method from standard regression procedures are: (1) The relationship between the input and output variables is not selected a priori by a prediction law, (2) an arbitrary number of input variables can be taken into account, provided that an appropriate data base exists, and (3) the computational procedure is very simple. The results can be easily updated when new information becomes available. The method has been applied for the derivation of attenuation relations by using a combination of databases compiled by other researchers. In the majority of the cases discussed in this paper, the method was used for the prediction of horizontal peak ground acceleration as a function of magnitude and distance. In some cases, ground conditions were also taken into account. Some results on the attenuation relations of peak ground velocity and displacement, as well as Arias intensity, are also presented.

This paper aims at assessing the influence of the design procedure followed in designing the columns of a reinforced concrete (R/C) building on the performance of the columns, as well as of the structure as a whole, when subjected to seismic loading; to identify potential weaknesses in currently adopted procedures; and to present a new procedure which is based on currently-available, powerful analytical tools, and results in increased reliability with regard to seismic loading. Two case studies are presented, involving multi-storey reinforced concrete buildings with frame and dual structural systems subjected to various appropriately-scaled input accelerograms. The results obtained indicate that capacity design of columns results in adequate safety margins against failure, even when the adopted overstrength factors are quite low, but hinging in columns is not avoided unless very high overstrength factors are used. The suggested novel technique of capacity design led to very satisfactory seismic performance, and offers the possibility of cost reduction by achieving an appropriate balance between provided flexural strength and corresponding confinement.

The economy and reliability of steel-framed buildings in seismic areas depend basically on the hysteretic behaviour of its individual components, such as members and joints. With reference to the latter, despite the recent semi-continuous frame approach (which appears generally very convenient for the design of low- and medium-rise steel buildings), the present state of knowledge does not allow for a complete understanding of the behaviour and the low-cycle fatigue life of beam-to-column connections under dynamic loads.

This paper presents a criterion for the definition of the low-cycle fatigue strength of steel connections, and proposes two approaches for the design of steel frames in seismic zones via the assessment of the fatigue damage, which is evaluated alternatively on the basis of either the ductility or of the load carrying capacity.