Fulvio Parisi

In-Plane Lateral Response of a Full-Scale Masonry Subassemblage with and without an Inorganic Matrix-Grid Strengthening System

A full-scale unreinforced masonry (URM) wall with an opening was tested under in-plane lateral loading. The wall was first subjected to monotonically increasing displacements until a moderate damage level was reached. The damaged specimen was then cyclically tested up to almost the same maximum drift attained during the monotonic test to investigate the effects of previous damage on its nonlinear response. Finally, the masonry wall was repaired with inorganic matrix-grid (IMG) composites and subjected to a cyclic displacement-controlled test up to a near-collapse state. Most of the observed damage developed in the spandrel panel affecting both lateral resistance and strength degradation. Rocking of piers governed lateral stiffness and hysteretic response, which was characterized by low residual displacements and recentering behavior. The comparison between the experimental force-displacement curves demonstrated that the IMG strengthening system was able to provide energy dissipation capacity to the spandr...

Nonlinear Behavior of a Masonry Subassemblage Before and After Strengthening with Inorganic Matrix-Grid Composites

Past experimental tests on a full-scale masonry wall with an opening evidenced the key role of the spandrel panel in the in-plane nonlinear response of the system. Recent seismic codes do not provide specific criteria to assess and to strengthen existing masonry spandrel panels with inorganic matrix-grid (IMG) composites. Numerical finite-element (FE) analyses are used to deepen the knowledge about the nonlinear response of masonry walls and the role of the IMG strengthening system. The comparison of experimental and numerical results contributes to the development of a simplified analytical model to assess the influence of the external reinforcement system on the in-plane seismic response of masonry wall systems. Some hints about the strengthening design that could change the failure mode from brittle shear to ductile flexure are given. Finally, a further enhancement of the IMG strengthening system is proposed to avoid the undesirable splitting phenomena attributable to compression forces and to exploit ...

Risk-targeted safety distance of reinforced concrete buildings from natural-gas transmission pipelines

Abstract Natural-gas pipeline accidents mostly result in major damage even to buildings located far away. Therefore, proper safety distances should be observed in land use planning to ensure target safety levels for both existing and new buildings. In this paper, a quantitative risk assessment procedure is presented for the estimation of the annual probability of direct structural damage to reinforced concrete buildings associated with high-pressure natural-gas pipeline explosions. The procedure is based on Monte Carlo simulation and takes into account physical features of blast generation and propagation, as well as damage to reinforced concrete columns. The natural-gas jet release process and the flammable cloud size are estimated through SLAB one-dimensional integral model incorporating a release rate model. The explosion effects are evaluated by a Multi-Energy Method. Damage to reinforced concrete columns is predicted by means of pressure–impulse diagrams. The conditional probability of damage was estimated at multiple pressure–impulse levels, allowing blast fragility surfaces to be derived at different performance limit states. Finally, blast risk was evaluated and allowed the estimation of minimum pipeline-to-building safety distances for risk-informed urban planning. The probabilistic procedure presented herein may be used for performance-based design/assessment of buildings and to define the path of new natural-gas pipeline networks.

A compendium of existing vulnerability and fragility relationships for flood : preliminary results

In the last decade, probabilistic approaches for flood risk assessment have emerged, often as an extension of more consolidated methods used in probabilistic seismic risk assessment. Nonetheless, only a few studies deal with best-practice methodologies for flood vulnerability assessment and existing approaches lack of an appropriate guidance for their selection. These concerns underline the need for a rational, integrated and complete compendium of all the existing flood-related vulnerability and fragility relationships to be used in a comprehensive probabilistic flood risk assessment framework. Following the same approach used in the guidelines recently developed by the Global Earthquake Model (GEM) Project, this paper presents a preliminary review of the state-of-art regarding existing empirical vulnerability and fragility curves in the context of flood risk. In particular, a worldwide overview is intended in terms of data sources, assets features and also statistical techniques employed for data collection and fitting. The research aims at providing a complete and flexible guide for selection of vulnerability and fragility curves for building structures. A discussion on data sources, building classification and considered features, and damage scales is presented, in order to evaluate the reliability, and at the same time the limitations, of different approaches and provide recommendation for future studies.

Alternative Resilience Indices for City Ecosystems Subjected to Natural Hazards

Prompt and efficient responses against natural hazards are needed to build cities capable of withstanding disasters, namely resilient cities. This study aims at presenting and testing synthetic resilience indices over a real urban center threatened by multiple hazards, for which a global overview of city performance is requested. An integrated framework is proposed for quantitative resilience assessment by way of time-independent synthetic indices. The approach proposed is in accordance to the complex network theory and uses a global indicator of the system connectivity to assess the city functioning also in case of network disruption. Resilience is evaluated as a proxy for systemic urban damage by modeling a city ecosystem as a hybrid social–physical network. Seismic and landslide scenario analyses are performed for the city of Sarno, Italy. A probability-based approach is used to compute urban vulnerability. Subsequently, to highlight changes in results according to the type of disaster, a recovery strategy is simulated to assess efficiency and damage states in each recovery stage, and urban resilience.

Derivation of risk areas associated with high-pressure natural-gas pipelines explosions including effects on structural components

Derivation of Risk Areas Associated with High-Pressure Natural-Gas Pipelines Explosions Including Effects on Structural Components Paola Russo*, Fulvio Parisi, Nicola Augenti, Gennaro Russo Dipartimento di Ingegneria Chimica Materiali Ambiente, Sapienza Università di Roma, Roma, Italia Dipartimento di Strutture per l’Ingegneria e l’Architettura, Università degli Studi di Napoli Federico II, Napoli, Italia Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione industriale, Università degli Studi di Napoli Federico II, Napoli, Italia paola.russo@uniroma1.it

Fragility of reinforced concrete framed structures to flow-type landslides

Flow-type landslides are typically triggered by heavy rainfalls and may cause large losses. Landslide risk may be rationally evaluated and mitigated with probabilistic approaches. In this paper, physical vulnerability of reinforced concrete buildings to landslides is assessed. Fragility analysis was carried out by assuming flow velocity as intensity measure, several damage states, and different mechanical models for beams, columns and masonry infill walls. Uncertainties in landslide impact loading, material properties, members geometry, and capacity models were taken into account. Both earthquake-resistant and gravity-load designed buildings were assessed as being representative of two low-rise building subclasses. Analysis results show that landslide fragility significantly depends on the presence and type of infill walls, which influence both out-of-plane and in-plane failure modes as well as yielding and failure of plastic hinges in columns.

PROGRESSIVE COLLAPSE FRAGILITY MODELS OF RC FRAMED BUILDINGS BASED ON PUSHDOWN ANALYSIS

Partial or total progressive collapse under abnormal loading conditions (e.g. deliberate terrorist attacks, uncontrolled gas releases, and vehicle or aircraft impacts) is one of the most vivid examples of low probability-high consequence (LPHC) event that may occur in the lifetime of a structure. Despite this, structural safety for extreme loads that may lead to disproportionate (or progressive) collapse has been probabilistically assessed and controlled in a few cases, thus neglecting uncertainties in loads and system capacity. As such, this paper moves from a deterministic to a probabilistic framework, proposing fragility models at multiple damage states for low-rise reinforced concrete (RC) framed bare structures which may be applied for progressive collapse risk assessment and management. Two building classes representative of structures designed for either gravity loads or earthquake resistance in accordance with current European rules were investigated. Monte Carlo (MC) simulation was used to generate random realizations of two-dimensional (2D) and three-dimensional (3D) structural models. Their fiber-based finite element (FE) representations were developed within an open source platform for nonlinear static pushdown analysis. The output consisted of fragility functions for each damage state of interest. Such fragility models were then compared to those derived through incremental dynamic analysis (IDA) in a previous study. IDAbased and pushdown-based capacities were additionally used to propose regression models for quick estimation of dynamic amplification factor (DAF) at a given displacement/drift target. The analysis results show a significant influence of both seismic design/detailing and secondary beams on robustness of the case-study building classes.

Fabric-Reinforced Cementitious Matrix (FRCM) composites

Abstract An innovative class of fiber-reinforced composites is represented by Fabric-Reinforced Cementitious Matrix (FRCM) systems, which are becoming broadly used as externally bonded strengthening of both concrete and masonry constructions. The key feature of FRCM systems is the replacement of a classical polymeric matrix with an inorganic matrix, making them particularly effective in retrofitting of masonry structures given their chemical, physical, and mechanical compatibility to the substrate. Several experimental investigations have been carried out so far, both at the scale of the composite material and of structural components, reaching an adequate level of knowledge for structural engineering applications. In this chapter, we provide a comprehensive review on the mechanical behavior of FRCM composites and their beneficial effects on the performance of retrofitted masonry walls subjected to gravity loads and earthquake actions. Important issues related to the experimental material characterization, mechanical modeling, and effectiveness of FRCM strengthening systems are highlighted.

Role of Urban Interactions and Damage in Seismic Resilience of Historical Centers.

Historical centers are places where local identity principles and contemporary dynamics of urbanization coexist. They conserve cultural heritage, hence the presence of many historical assets makes these places highly vulnerable and exposed.