Claudio Moroni

Transport infrastructure surveillance and monitoring by electromagnetic sensing: the ISTIMES project

The ISTIMES project, funded by the European Commission in the frame of a joint Call “ICT and Security” of the Seventh Framework Programme, is presented and preliminary research results are discussed. The main objective of the ISTIMES project is to design, assess and promote an Information and Communication Technologies (ICT)-based system, exploiting distributed and local sensors, for non-destructive electromagnetic monitoring of critical transport infrastructures. The integration of electromagnetic technologies with new ICT information and telecommunications systems enables remotely controlled monitoring and surveillance and real time data imaging of the critical transport infrastructures. The project exploits different non-invasive imaging technologies based on electromagnetic sensing (optic fiber sensors, Synthetic Aperture Radar satellite platform based, hyperspectral spectroscopy, Infrared thermography, Ground Penetrating Radar-, low-frequency geophysical techniques, Ground based systems for displacement monitoring). In this paper, we show the preliminary results arising from the GPR and infrared thermographic measurements carried out on the Musmeci bridge in Potenza, located in a highly seismic area of the Apennine chain (Southern Italy) and representing one of the test beds of the project.

Jet-Pacs Project: Dynamic Experimental Tests and Numerical Results Obtained for a Steel Frame Equipped with Hysteretic Damped Chevron Braces

The experimental and numerical results obtained by Research Units of the University of Basilicata and University of Calabria for a steel frame, bare or equipped with metallic yielding hysteretic dampers (HYDs), are compared. The shaking table tests were performed at the Structural Laboratory of the University of Basilicata within a wide research program, named JETPACS (“Joint Experimental Testing on Passive and semiActive Control Systems”), which involved many Research Units working for the Research Line 7 of the ReLUIS (Italian Network of University Laboratories of Earthquake Engineering) 2005–2008 project. The project was entirely founded by the Italian Department of Civil Protection. The test structure is a 1/1.5 scaled two-story, single-bay, three-dimensional steel frame. Four HYDs, two for each story, are inserted at the top of chevron braces installed within the bays of two parallel plane frames along the test direction. The HYDs, constituted of a low-carbon U-shaped steel plate, were designed with the performance objective of limiting the inter-story drifts so that the frame yielding is prevented. Two design solutions are considered, assuming the same stiffness of the chevron braces with HYDs, but different values of both ductility demand and yield strength of the HYDs. Seven recorded accelerograms matching on average the response spectrum of Eurocode 8 for a high-risk seismic region and a medium subsoil class are considered as seismic input. The experimental results are compared with the numerical ones obtained considering an elastic-linear law for the chevron braces (in tension and compression), providing that the buckling be prevented, and the Bouc-Wen model to simulate the response of HYDs.

Reconstruction process of damaged residential buildings outside historical centres after the L’Aquila earthquake: part I—"light damage" reconstruction

Assessment of the seismic damage and usability of the building stock started a few days after the L’Aquila earthquake in order to evaluate the safety conditions of the buildings concerned. Several ordinances of the Prime Minister were issued to regulate the reconstruction process. In particular, based also on damage level, the procedures for repair, strengthening or demolition/reconstruction of residential buildings were established with the definition of relevant state funding. For each damaged building, practitioners engaged by property owners designed repair and strengthening interventions and then computed the corresponding costs. These projects were the technical basis for funding applications that owners submitted to the government. Technical and financial information collected during the approval procedure of such applications allowed compilation of a database regarding 5775 residential buildings damaged by the L’Aquila earthquake. The present study examines the restoration policy and the procedures regulating the reconstruction process of residential property outside city centres. In particular, the data related to the first phase of the reconstruction process (the so-called “light damage” reconstruction) to recover the usability of slightly damaged buildings are illustrated. The discussion focuses on the time-to-approval of funding applications and on the public contributions granted for repair and local strengthening works.

Experimental and numerical behaviour of hysteretic and visco-recentring energy dissipating bracing systems

An extensive program of shaking table tests under the name Project JetPacs (Joint experimental testing on Passive and semi active control systems) has been developed with the goal of assessing the effectiveness of seven different passive and semi-active energy dissipating bracing (EDB) systems in controlling the seismic vibrations of framed buildings. The experimental program, carried out considering a 3D 1/1.5 scaled steel frame, was entirely funded by the Italian Department of Civil Protection as part of the RELUIS 2005–2008 project. The following article focuses on the experimental tests carried out considering only two EDB systems, based on hysteretic dampers (HD) and visco-recentring devices (SMA + VD) respectively. Specially shaped low carbon steel plates were used to provide hysteresis in the HD based devices, while the innovative SMA + VD visco-recentring system was made up of a combination of viscous dampers (VD) and shape memory alloy (SMA) wires. In this paper a displacement focused design procedure based on non linear static analysis has been proposed in order to evaluate the mechanical characteristics of both types of energy dissipating device. The aim of this design procedure is to limit inter-storey drifts after frame yielding. In order to assess the robustness of the design procedure and to evaluate the effects of the viscous and recentring components, two different sets of HD and SMA + VD devices characterized by slight alterations in the mechanical properties have been tested and compared. Finally, the experimental seismic response of the structure equipped with and without the HD and SMA + VD elements is reported and compared with numerical results obtained using non linear time history analysis.

Remarks on damage and response of school buildings after the Central Italy earthquake sequence

The seismic assessment of the vulnerability of existing public structures, especially school buildings, is a crucial issue in seismic prone countries. Recently, several national and regional programs and activities have focussed on the mitigation of Italian public buildings. They promote the scheduling of public buildings’ structural safety assessment and, when needed, the design and execution of strengthening interventions. Nevertheless, the three strong earthquakes that occurred in the last decade in Italy, Abruzzo (2009), Emilia (2012), and Central Italy (2016), confirmed the vulnerability of school buildings and the social importance of their quick re-opening after a damaging earthquake. In the present paper, the activities carried out on 1514 school building structures in the aftermath of the 2016 Central Italy earthquake sequence are reported and analysed. According to survey data collected by post-earthquake usability inspections, the paper analyses the school buildings characteristics, damage level and extent to structural and non-structural components as well as the correlation between seismic intensity and observed damage.

Estimation of repair costs for RC and masonry residential buildings based on damage data collected by post-earthquake visual inspection

In the immediate post-earthquake, the safety conditions of buildings are commonly evaluated by field visual inspections. Then, a second phase involves the design of repair interventions and the relevant funding requests to the government or to insurance companies. The paper discusses the data related to the 2009 L’Aquila earthquake, focusing on the empirical damage and relevant Actual Repair Costs (ARC) of damaged residential buildings derived from requests for funding presented by practitioners engaged by owners in the reconstruction process. In particular, the data collected from a set of 2500 residential Reinforced Concrete (RC) and masonry buildings are presented focussing on the construction age, number of storeys, damage extent on structural components and ARC. A damage index for each building component has been computed according to data collected by field inspections and the relationship between damage index and different classes of buildings is herein outlined. Then, a correlation between the empirical damage and ARC is determined by means of a regression analysis. The proposed relationship between empirical damage and ARC may drive decision makers, in the immediate post-earthquake, to make preliminary estimates of the repair costs, only based on quick surveys on residential buildings. The relationship may also be used as a tool to figure out repair costs based on damage scenarios.

FRP Local Retrofit of Non-Conforming RC Beam-Column Joints

Recent seismic events have clearly confirmed the vulnerability of existing reinforced concrete (RC) structures. In particular, field observation of structures damaged by L’Aquila earthquake strongly confirmed that premature failure of partially confined (i.e. exterior) beam-column joints was one of the main causes limiting the global structural seismic capacity. Poor attention to details and a lack of adequate transverse reinforcement typically lead to premature brittle shear failure of joints. To provide support to practitioners involved in the L’Aquila reconstruction process, a proper guideline which illustrates the design of local retrofit interventions on structural and non structural elements has been edited by the Italian Civil Protection Department (DPC) and the Laboratories University Network of Seismic Engineering (ReLUIS). In particular, a viable FRP strengthening strategy to increase the seismic performances of partially confined joints (design procedure and installation steps) is widely discussed and presented in the document. To validate the strengthening system recommended in this guideline, an experimental program has been carried out on as-built and FRP strengthened full scale corner RC joints (T shaped joints). After presenting the main guideline recommendations for local strengthening of existing structures, the paper focuses on the experimental program activity; in particular, the specimen design strategy and test setup definition as well as the comparative analysis of the behavior of tested joints.

The Italian guidelines for seismic risk classification of constructions: technical principles and validation

The Italian “Guidelines for the seismic risk classification of constructions” approved in February 2017 define the technical principles for exploiting tax deductions with respect to seismic strengthening interventions on existing buildings (Sismabonus). Tax deductions represent a unique opportunity to improve the seismic safety of the existing Italian building stock. The guidelines are very simple and allow practitioners to deal with the sophisticated concepts behind modern seismic design, such as expected annual losses (EAL) and repair costs (expressed as a fraction of the Reconstruction Cost: %RC). The seismic risk classes of buildings and the class upgrade due to strengthening interventions can be assessed using the principles included in the guidelines. The seismic risk class is the minimum between the class defined by the building safety index at the ultimate limit state and the one related to the EAL. The latter class depends on the area under the curve of the expected losses, which is easily obtained by computing the safety index converted in the return period (annual frequency) at different limit states and the relevant %RC. This paper illustrates the technical principles at the base of the guidelines and the procedure used to calibrate the repair costs associated with the different limit states using the actual repair costs monitored in the reconstruction process following recent Italian earthquakes. Finally, simple tools to estimate the cost of the strengthening interventions to improve the seismic capacity at the life-safety limit states are provided.

EMPIRICAL DAMAGE AND ACTUAL REPAIR COSTS ON MASONRY PRIVATE BUILDINGS AFTER L’AQUILA EARTHQUAKE

In the first phase of the emergency management after the April 6, 2009, L’Aquila earthquake, field inspections were carried out through the AeDES form, a first level survey form for post-earthquake damage and usability assessment, to evaluate the usability conditions of buildings. Once the damage and usability assessment was completed, the reconstruction process of residential buildings outside the historical centre of L’Aquila and surrounding municipalities was regulated by several Ordinances of the Prime Minister. The public grant was released according to funding requests made by practitioners and checked by a proper commission entrusted by the Government. The data collected on a set of about 1,000 residential masonry buildings in terms of vulnerability class, construction age, number of storyes, empirical damage, as well as of Actual Repair Costs (ARCs) are herein discussed and presented. Building Damage Factor, DF has been computed based on the damage data of structural and non-structural component collected with the AeDES forms. A calibration of different parameters, as the damage extent and severity on each structural and non-structural component and the weight of the damage on a single component on the total repair costs of the building, was carried out. The calibration allow us to determine the best correlation between the empirical damage and ARC. The proposed relationship between empirical damage and ARC may drive decision makers, in the immediate post-earthquake, to make preliminary estimates of the repair costs, only based on quick surveys on residential buildings. The relationship may also be used as a tool to figure out repair costs based on damage scenarios. 2765 Available online at www.eccomasproceedia.org Eccomas Proceedia COMPDYN (2017) 2765-2776