Camillo Nuti

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

SUMMARY 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 e⁄ect of di⁄erent post-earthquake emergency measures like the use of camp hospitals. The eƒciency 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.

Seismic safety of network structures and infrastructures

Realistic assessment of network structural safety requires modelling of a reasonably large part of the network itself. Although this statement may appear too demanding, both for modelling and computing reasons, there are clear motivations and technological possibilities to do complex network analyses. In this paper, the safety analyses of three infrastructures that have been shaken by an earthquake are described, modelled and computed: the electric power, water and road systems. For each network, results extracted from real networks, some of which have been studied in the past by the authors, are presented and discussed. No inter-network analysis is carried out, although it is recognised that this would be the most complete approach. The common parts in the procedure to model and analyse each network, via Monte Carlo simulations, are detailed at the beginning of the paper, thus showing the many common points that show up in any network analysis.

A simplified procedure to assess the seismic response of nonlinear structures

The paper presents an improvement of the iterative procedure proposed in the ATC 40 document to evaluate seismic response of nonlinear structures in terms of maximum displacement and acceleration, given the structural initial elastic period, the yielding acceleration and the hardening ratio in the plastic range. As a second issue the results of the procedure are compared with nonlinear step by step dynamic integration, with the bilinear and Takeda model, and with the assumptions of equal energy and equal displacement. Two case studies of existing reinforced concrete buildings are further examined. For the cases examined, the ATC 40 procedure is overall as or less precise than the simpler equal energy and equal displacement principles.

Damage patterns in the town of Amatrice after August 24th 2016 Central Italy earthquakes

The impact of the two seismic events of August 24th 2016 on the municipality of Amatrice was highly destructive. There were 298 victims, 386 injured, about 5000 homeless, and the historical center of the town suffered a great number of partial and total collapses. The 260 strong motion records obtained for the first event were analyzed and plotted in a shakemap, comparing them with the macroseismic damage surveys made in 305 localities. On the basis of an inspection survey made in September 2016, a map of the damage patterns of the buildings in the historical center was elaborated according to the EMS 98 classification. The damage level resulted very high with more than 60% of the inspected buildings showing partial or total collapse. The elevated level of destruction was mainly caused by the high vulnerability of the masonry buildings, mostly due to specific vulnerability factors such as the poor quality of masonry, the lack of connections between walls and the poor connection between external walls and floors.

A procedure for assessing the functional reliability of hospital systems

Abstract An effective reliability-based procedure is presented to assess the capability of hospitals to be functional after a seismic event of a given intensity. Every major function in a hospital depends on the joint action of various cooperating services, which in turn are made up from a certain number of sub-services. Such a complex organization is described in terms of a logical scheme and subsequently reduced to a minimal cut-set representation. For each sub-service a collapse criterion is defined, by which the strength is compared to the action load, both represented as random variables. Strengths are evaluated through assessment analyses based on design drawings. Loads are evaluated from 3-D linear dynamic analyses under seismic input. This is given by the Eurocode 8 elastic response spectrum, scaled at a given peak ground acceleration and account for the position of the sub-service within the building. By calculating the failure probability of each service by FORM (First Order Reliability Method) or SORM (Second Order Reliability Methods), the probability of functional interruption is obtained in terms of Didevsen bounds, conditional on a given earthquake intensity. The method helps to single out weak elements and potential sources of damage (structural, non-structural, equipment) within the hospital. This allows: (a) to investigate quantitatively the effectiveness of different upgrading criteria, (b) to select rationally intervention hypotheses, both in the retrofitting and rehabilitation of existing hospitals and in the design optimization of new ones, and (c) to evaluate different investment options for seismic vulnerability mitigation. As an example, an application to a case study hospital is presented.

Experimental program for pseudodynamic tests on repaired and retrofitted bridge piers

ABSTRACT This research aims to study the seismic performance of existing r.c. bridge piers specimens heavily damaged after previous pseudodynamic tests and actually repaired and upgraded by using self compacting concrete, stainless steel rebars and CFRP wrapping. Pier specimens are representative of tall and squat circular r.c. piers designed according to Eurocode 8 or Italian Code before 1986. The study comprehends preliminary tests carried out on self compacting concrete and stainless steel bars, as well as on going pseudodynamic tests in order to evaluate the effectiveness of adopted repairing and upgrading techniques to increase both ductility and shear strength.

Damage, Vulnerability and Retrofitting Strategies for the Molise Hospital System Following the 2002 Molise, Italy, Earthquake

The earthquake of October 31, 2002, inflicted moderate damage on the region of Molise in southern Italy. However, it attracted much attention because almost all the victims were children killed in the structural failure of their primary school. This paper focuses on a different, but equally important, structural type: hospitals. The earthquake left them largely untouched. In the paper we first give a detailed picture of the structural damage and of the organization of emergency operations. Then we try to give guidance about the most effective retrofitting strategies for the regional hospital system as a whole, following a methodology developed in Nuti and Vanzi (1998b), which has been adjusted for this case study. Depending on the community decision criteria, the hospitals of Campobasso and Bojano appear to have the highest priority for retrofitting, even though they were unscathed by the event.

Performance of Lifelines During the 2002 Molise, Italy, Earthquake

The Molise earthquake affected a wide rural area with sparse houses, villages and towns. The paper investigates the response of water, electric power, telecommunications, natural gas, rail and motorway systems. Despite the amount of damage to buildings, lifeline systems reported only minor damage. The damage was light not only because the event caused relatively moderate ground motion in the affected area but also because the main lifelines do not cross the epicentral region and were in a fair state of maintenance.

Generation of Non-synchronous Earthquake Signals

In this chapter, we describe two procedures to generate earthquake asynchronous signals at different space points for the same seismic event. The foundations of long structures, such as bridges, are placed at distant space points. The earthquake signals at these points have different characteristics and their correct evaluation is important to define design actions. However, design codes around the world do not consider this complex type of action in a consistent manner. The point-to-point signal variation is due both to time lag, since the seismic waves move through the soils with a finite velocity among distant points, and to a change of the signal frequency contents. This depends on physical complex soil-wave interaction phenomena during wave propagation (reflection, refraction, filtering, amplification, etc.). In this chapter, two different generation procedures (PR1 and PR2) to determine the non-synchronous actions at different surface points are shown. Both procedures have been implemented in MATLAB. PR1 generates asynchronous signals at the soil surface. It starts from recorded signals at a few surface points for the same seismic event. PR2 produces asynchronous surface signals by amplifying the bedrock signals obtained by a bedrock propagation process. The inputs for the bedrock propagation are obtained via deconvolution of the recorded surface signals. These latter are also the inputs of the PR1 procedure. Detailed knowledge of soil characteristics is required (soil layers, shear wave velocity profiles, soil density, nonlinear materials shear moduli and damping curves), which relies on in situ tests. Deconvolution and amplification processes are performed by Equivalent-Linear Earthquake Site Response (1D soil model, SHAKE91 (Schnabel et al. 1972) and EERA (Bardet et al. 2000)). PR1 and PR2 are then applied to an example case. Asynchronous surface signals are generated at eight foundation points of a bridge placed in the Aterno Valley near the city of L’Aquila in Italy, where recordings are available at different recording stations (AQA and AQV) for the same earthquake. The EW component of the strong main shock of 4-6-2009 in L’Aquila is selected as input for the two procedures. Finally, the comparison between the signals resulting by PR1 and PR2 and the input signals recorded at the same points is discussed in term of effects on the structures (acceleration response spectrum) and characteristics of the generated signals (Fourier amplitude spectra, coherences for each frequency) to evaluate the differences between the two procedures and between the procedures and the actually recorded signals.

Proposal and application of the Incremental Modal Pushover Analysis (IMPA)

Existing reinforced concrete frame buildings designed for vertical load only could suffer severe damage during earthquakes. In recent years, many research activities have been paid to develop reliable and practical analysis procedure to identify the safety level of existing structures. The Incremental Dynamic Analysis (IDA) is considered to be one of the most accurate methods to estimate seismic demand and capacity of structures. But it requires the execution of many nonlinear response history analyses (NL_RHA) in order to describe the entire range of structural response. The research discussed in this paper deals with proposal of an efficient Incremental Modal Pushover Analysis (IMPA) to obtain capacity curves by replacing the NL_RHA of the IDA procedure by Modal Pushover Analysis (MPA). In this work, the basic idea of IMPA is presented and the step-by-step computational procedure is then summarized. This new procedure, accounting the higher modes effects, does not need the execution of complex NL-RHA, but only simpler nonlinear static analysis. Then, the new procedure is applied to an existing irregular building. The capacity curves obtained by different procedures (standard pushover analysis, IMPA and IDA) are presented and discussed.