PRESSAFE-Disp: A Method For The Fast Seismic Assessment of Existing Precast RC Buildings After The Emilia Earthquake Of May 2012

The existing precast reinforced concrete structures, especially those not specifically designed against the earthquakes, have proved to be inadequate to withstand the remarkable seismic demands related to the presence of heavy roof elements. In fact, the cantilever columns entailing large top displacements and the poor devices adopted to connect different precast elements have shown high sensitivity to seismic actions. After the lesson learned from the recent Emilia earthquake of May 2012, causing many collapses and severe damage, reliable seismic design criteria have been established for the design of new precast structures and for the strengthening of the existing ones. Despite this, a large percentage of the existing precast buildings in the Italian territories actually has not been object of interventions and remains in an unsafe condition with regards to the seismic actions. In this context, the methods for a rapid seismic assessment can be very helpful both to estimate the current safety level of large building stocks and to plan the necessary strengthening interventions, possibly at the wide scale of an industrial area. To this aim, the paper proposes a new method, named PRESSAFE-disp (PRecast Existing Structure Seismic Assessment by Fast Evaluation-displacements), for the fast evaluation of the fragility curves of precast structures. The method follows the approach of the PRESSAFE method, but different damage criteria have been introduced in order to take into account the relative displacements and the sliding between different precast elements. The damage criteria considered, applicable to both structural elements and perimeter cladding elements conceived as non-structural elements, have been properly selected in order to capture the damage mechanisms observed during the several building inspections conducted by the authors in the aftermath of the 2012 Emilia earthquakes. In the present configuration, the method allows a comprehensive explanation of the seismic behaviour of the existing precast buildings and could be effectively adopted, for example, in earthquake loss estimations and seismic risk assessments of large Italian industrial areas, as well as of wide seismic-prone territories of the Mediterranean area.

Latest Findings on the Behaviour Factor q for the Seismic Design of URM Buildings

Recent earthquakes as the 2012 Emilia earthquake sequence showed that recently built unreinforced masonry (URM) buildings behaved much better than expected and sustained, despite the maximum PGA values ranged between 0.20 - 0.30g, either minor damage or structural damage that is deemed repairable. Especially low-rise residential and commercial masonry buildings with a code-conforming seismic design and detailing behaved in general very well without substantial damages. The low damage grades of modern masonry buildings that was observed during this earthquake series highlighted again that codified design procedures based on linear analysis can be rather conservative. Although advances in simulation tools make nonlinear calculation methods more readily accessible to designers, linear analyses will still be the standard design method for years to come. The present paper aims to improve the linear seismic design method by providing a proper definition of the q-factor of URM buildings. These q-factors are derived for low-rise URM buildings with rigid diaphragms which represent recent construction practise in low to moderate seismic areas of Italy and Germany. The behaviour factor components for deformation and energy dissipation capacity and for overstrength due to the redistribution of forces are derived by means of pushover analyses. Furthermore, considerations on the behaviour factor component due to other sources of overstrength in masonry buildings are presented. As a result of the investigations, rationally based values of the behaviour factor q to be used in linear analyses in the range of 2.0 to 3.0 are proposed.

Pullout tests on the connection to an existing foundation of a steel warehouse rebuilt after the 2012 Emilia (Italy) earthquakes

The tests described in this paper were aimed at evaluating the tensile capacity of the anchorages connecting an automated pallet warehouse with an existing RC foundation. The warehouse is a new steel structure erected in the place of a previous warehouse collapsed due to the Emilia earthquake, but whose foundation remained undamaged. The investigated fastening consists of 10 post-installed, bonded threaded rods with diameter (d) and embedment depth (hef) of 20 and 500 mm, respectively. Neither anchor arrangement nor embedment depth (hef > 20d) was covered by current standards for fastening design. To reproduce the in-situ actual conditions of the fastening, an unconfined test configuration was used. The maximum loads achieved were more than 3 times greater than the seismic demand for the fastening. The tests highlighted the crucial role played by the reinforcing steel which was present in the foundation. Concrete-related failure mechanisms, such as the combined pullout and concrete cone failure mechanism typical of bonded anchors, were not activated. The observed crack patterns rather suggest the onset of a flexural failure mechanism of the concrete slab. This feature is confirmed by analytical calculations showing that, at the maximum loads achieved in the tests, the top reinforcement was likely to be yielded. In six preliminary unconfined tension tests on single anchors, steel rod failure was achieved, associated with limited cracking of the concrete surface in proximity of the anchor.

Empirical damage and liquefaction fragility curves from 2012 Emilia earthquake data

The study focuses on the effects of liquefaction on structures taken from data on about 1000 private residential masonry buildings located in several municipalities struck by the 2012 Emilia earthquake. Survey data were collected by teams of experts coordinated by the Italian Department of Civil Protection in the immediate post-earthquake emergency phase. They included information on building characteristics and the level and extent of the damage to structural and non-structural components. Furthermore, according to data related to the reconstruction process, information on the liquefaction-induced type and extent of the damage was also collected. Through a comparative analysis of the empirical damage, it was found that liquefaction strongly affected the buildings, confirming its relevance in the damage scenario under specific subsoil conditions. Based on this evidence, the article proposes a correlation between structural damage and liquefaction when it comes to deriving proper preliminary empirical fragility curves. A suitable parameter to define liquefaction effects at ground level is introduced and correlated to damage grades defined according to the European Macroseismic Scale: EMS-98.

The resilient retail entrepreneur: dynamic capabilities for facing natural disasters

Purpose The purpose of this paper is to investigate the formative dimensions of organizational resilience – namely dynamic capabilities (DCs) and social capital – displayed by retail entrepreneurs in the face of natural disasters (i.e. the 2012 Emilia earthquake). The paper evaluates social capital and the various types of DCs that support small entrepreneurs’ resilience during three temporal units of analysis: before the earthquake, during the emergency period, and during the recovery process. Design/methodology/approach The study was performed by applying a qualitative approach based on two focus groups and a double set of semi-structured interviews administered to a sample of eight small retail entrepreneurs hit by the 2012 Emilia earthquake. Content analysis was then applied. Findings The findings show that DCs and social capital are instrumental to enhancing organizational resilience; moreover the contribution of each category of DCs (reconfiguration, leveraging, sensing and interpreting, learning and knowledge integration) and social capital to entrepreneurs’ resilience changes according to the temporal phase of the natural disaster under analysis. Research limitations/implications This study will provide small retailer entrepreneurs and public authorities with useful insights on how DCs and social capital can practically support recovery paths at different times in the occurrence of a natural disaster. Originality/value This study contributes to the scientific debate on organizational resilience in disaster management, studying it through the lens of DCs and social capital, and analyzing the role of different types of DCs in developing entrepreneurs’ resilience during the various periods of a natural disaster. Moreover, it contributes by applying the concepts of resilience and DCs to a poorly investigated entrepreneurial context such as the retail one.

Geophysical Monitoring of Blast-induced Liquefaction at the Mirabello (NE Italy) Test Site

A blast-induced liquefaction test was conducted in the surroundings of Mirabello (NE Italy), where extensive liquefaction phenomena were observed after the 2012 Emilia earthquake. This experiment is the first blast-induced liquefaction test carried out in Italy. Several geophysical investigations were performed at the site to define initial soil condition and to evaluate the variations of the geophysical parameters over time. Specifically compressional ( V P ) and shear ( V S ) wave velocities were measured using both invasive (down-hole) and non-invasive (surface wave) tests. Electric Resistivity Tomography (ERT) tests were also carried out. Tests results before and after the blast-induced liquefaction are here presented and discussed with respect to the observed liquefaction effects. The evolution of measured geophysical parameters suggests that the soil modifications due to blasting ( i.e., changes in porosity and soil structure) can be imaged with the adopted approaches.