Assessment of post-earthquake availability of hospital system and upgrading strategies

A model for the regional hospitals system behaviour in case of a seismic event is developed. The aim is the evaluation of the vulnerability of the system as well as the selection of the best intervention strategy for the retrofitting of the hospitals so as to minimize the cost benefit ratio and to evaluate the effect of different post-earthquake emergency measures like the use of camp hospitals. The efficiency of the system is measured in terms of the mean distance to be cured for persons injured by the earthquake and by damages to the system. Some simplifying assumptions are used and discussed; these can be easily removed if necessary. Results allow to clearly indicate the most convenient interventions. © 1998 John Wiley & Sons, Ltd.     

Strain-dependent slope stability

Acta Geotechnica - The state of equilibrium of a slope is usually interpreted and expressed by safety factors based on calculations with limit equilibrium methods. Different stress states, failure...     

Seismicity in the block mountains between Halle and Leipzig,Central Germany: centroid moment tensors,ground motion simulation,and felt intensities of two <Emphasis Type="Italic">M</Emphasis> ≈ 3 earthquakes in 2015 and 2017

On April 29, 2017 at 0:56 UTC (2:56 local time), an M_W =?2.8 earthquake struck the metropolitan area between Leipzig and Halle, Germany, near the small town of Markranstädt. The earthquake was felt within 50 km from the epicenter and reached a local intensity of I₀ = IV. Already in 2015 and only 15 km northwest of the epicenter, a M_W =?3.2 earthquake struck the area with a similar large felt radius and I₀ = IV. More than 1.1 million people live in the region, and the unusual occurrence of the two earthquakes led to public attention, because the tectonic activity is unclear and induced earthquakes have occurred in neighboring regions. Historical earthquakes south of Leipzig had estimated magnitudes up to M_W ≈?5 and coincide with NW-SE striking crustal basement faults. We use different seismological methods to analyze the two recent earthquakes and discuss them in the context of the known tectonic structures and historical seismicity. Novel stochastic full waveform simulation and inversion approaches are adapted for the application to weak, local earthquakes, to analyze mechanisms and ground motions and their relation to observed intensities. We find NW-SE striking normal faulting mechanisms for both earthquakes and centroid depths of 26 and 29 km. The earthquakes are located where faults with large vertical offsets of several hundred meters and Hercynian strike have developed since the Mesozoic. We use a stochastic full waveform simulation to explain the local peak ground velocities and calibrate the method to simulate intensities. Since the area is densely populated and has sensitive infrastructure, we simulate scenarios assuming that a 12-km long fault segment between the two recent earthquakes is ruptured and study the impact of rupture parameters on ground motions and expected damage.     

Precast industrial buildings in Southern Europe: loss of support at frictional beam-to-column connections under seismic actions

This paper presents the evaluation of the loss-of-support conditions in frictional beam-to-column connections of industrial precast concrete buildings under seismic actions. This type of connection is widespread throughout Southern Europe in non-seismically designed industrial precast buildings. First, geometric properties of industrial precast buildings and of the frictional beam-to-column connections, together with reference values for the friction coefficient, are reviewed. Then, earthquake time histories taken from the European Strong-Motion sets and recordings of the two major shocks of the 2012 Emilia-Romagna events are presented and discussed showing the importance of the vertical component. Two dynamic models of increasing complexity are used to ascertain loss-of-support conditions under seismic action. The first model is an elastic one, representing a single frame of the industrial buildings. Results are obtained according to: (1) 2D analyses, disregarding the time correlation between the response peaks along the horizontal and vertical directions, (2) 2D analyses taking into account time correlation, and (3) 3D analyses to evaluate also directionality effects. The second model is a 2D non-linear planar frame developed within the OpenSees framework. Results show that simplified (linear) models are a good proxy to more refined (non-linear) ones. However, one must resort to non-linear models if differential displacements between beam and column are of interest. The non-linear numerical investigations show that friction coefficient, horizontal and vertical periods and damping, and column reinforcement ratio are the key variables in estimating the loss-of-support conditions.     

Assessment of the dynamic response of unreinforced masonry structures using a macroelement modeling approach

The seismic performance of unreinforced masonry structures is strongly associated with the interaction between in‐plane and out‐of‐plane mechanisms. The seismic response of these structures has been thoroughly investigated by means of experimental testing, analytical procedures, and computational approaches. Within the framework of the numerical simulations, models based on the finite element method provide a good prediction of the seismic performance of unreinforced masonry structures. However, they usually require a high computational cost and advanced user expertise to define appropriate mechanical properties and to interpret the numerical results. Because of these limitations, simplified models for practical applications have been developed during the last decades. Despite this, a great number of these models focus mostly on the evaluation of the in‐plane response, assuming box (or integral) behavior of the structure. In this paper, a simplified macroelement modeling approach is used to simulate the seismic response of 2 masonry prototypes taking into consideration the combined in‐plane and out‐of‐plane action. The numerical investigations were performed in the static and dynamic fields by using pushover analyses and nonlinear dynamic analyses respectively. The latter is a novel implementation of a model previously developed for static analysis. The results obtained from this study are in good agreement with those provided by a detailed nonlinear continuum FE approach, demonstrating the applicability of this macroelement model with a significant reduction of the computational cost.     

HVSR of ambient noise in Ston (Croatia): comparison with theoretical spectra and with the damage distribution after the 1996 Ston-Slano earthquake

Horizontal-to-vertical spectral ratios (HVSR) of ambient vibrations measured in the ancient town of Ston (Croatia) on 99 locations, are shown to be well matched to the theoretical ones computed for body-waves as well as for the surface waves. This match is poorer for sites on the slopes of nearby hills. The ratios of measured peak horizontal ground acceleration during the damaging earthquake in 1996 (M _L = 6.0) and the ones obtained using empirical attenuation laws is approximately equal to the mapped value of the dynamic amplification factor determined on the basis of observed HVSR in the vicinity of the accelerometric station. The HVSR of the accelerogram is very similar to the HVSR of the ambient noise. The damage to the building stock in the old town centre caused by the earthquake series of 1996 is closely related to the estimated soil amplification and its fundamental frequency. More measurements in buildings are needed to arrive at confident conclusions about possible soil-structure resonance.     

Some connections between aerosols,atmospheric transport,and relative humidity at peak Musala

Some connections between aerosols, atmospheric transport, and relative humidity are investigated based on measurements at Basic Environmental Observatory (BEO) station, peak Musala (2,925 masl) for the period January 2009–January 2010. Data are chosen at 0:00 and 12:00 GMT every day. Main methods employed in this research are statistical—nonparametric tests of Mann–Whitney and Spearman. The main conclusion is that greater aerosol load at peak Musala is connected with transport of air masses from north to east horizon quarters. Bigger particles with longer lifetimes come from there. Air coming from the south horizon quarter is aerosol clearer. Relative humidity shows opposite distribution—higher values for transport from south horizon quarter. Correlation between this parameter and aerosols is negative with significant but small value. Distribution of blue, green, and red scattering and backscattering coefficients is similar to distribution of total aerosol concentration. Correlations between scattering and backscattering coefficients and total aerosol concentration are significant and positive. Courses of total aerosol concentration; diameter of particles with maximum concentration; and blue, green, and red scattering and backscattering coefficients have summer maximum and winter minimum. Diurnal course of total aerosol concentration in the two main seasons, winter (January) and summer (July), has day maximum and night minimum. Aerosols at peak Musala are predominantly of transparent or translucent type. The calculation of Ångström exponent α is more precise by using scattering coefficients. The nephelometers data could successfully characterize the haziness of the atmosphere above peak Musala.     

Magnification of undamped seismographs and the analysis of the 1906 San Francisco earthquake record obtained on the Vicentini seismograph in Zagreb (Croatia)

A method to estimate the dynamic magnification of nonlinear seismographs is presented. The method was tested by applying it to the record of the 1906 San Francisco earthquake seismogram obtained on the Vicentini seismograph in Zagreb, in order to reconstruct the ground motion amplitudes. The magnitudes inferred from the corrected Vicentini recording of P- and surface waves are internally consistent ( m _b= 7.74, M _s= 8.48) and agree with the values published in various catalogues, within the error limits of magnitude determination for individual events. The corrected P-waveform is compatible with a rupture slip profile exhibiting several distinct maxima along the 300 km-long section of the San Andreas fault, in accordance with recent studies and contemporary geodetic measurements.     

Investigation of ship hydroelasticity

The importance of hydroelastic analysis of large and flexible container ships of today is pointed out. A methodology for investigation of this challenging phenomenon is drawn up and a mathematical model is worked out. It includes definition of ship geometry, mass distribution, structure stiffness, and combines ship hydrostatics, hydrodynamics, wave load, ship motion and vibrations. Based on the presented theory, a computer program is developed and applied for hydroelastic analysis of a flexible segmented barge for which model test results of motion and distortion in waves have been available. A correlation analysis of numerical simulation and measured response shows quite good agreement of the transfer functions for heave, pitch, roll, vertical and horizontal bending and torsion. The tool checked in such a way can be further used for reliable hydroelastic analysis of ship-like structures.     

Slow growth and early sexual maturity: Bane and boon for the red coral Corallium rubrum

This study investigates the size, age and growth of Corallium rubrum which is a key species of the only large reef-like structure in the Mediterranean Sea, the coralligéne. Two populations were studied in the Ligurian Sea at a depth between 36 and 42 m. Basal diameter, colony height and numbers of branches of 230 colonies were measured, and age and growth rates were assessed from 25 colonies. Mean growth rate was 0.2 mm yr⁻¹ of basal diameter growth, corresponding to a mean annual total branch length increase of 5 mm. These results point to a coral growth much slower than assumed in many earlier studies. Additionally, age and size at first reproduction were analysed. Male colonies were shown to become sexually mature at a minimum age of six years (1.2 mm of basal diameter), while female colonies reached maturity when at least 10 years old (2 mm of basal diameter). We further discuss the implications of slow growth and early sexual maturity for red coral management and conservation.