Andrea Dall'Asta

University of Camerino | UNICAM · Scuola di Architettura e Design

This paper deals with the seismic protection of building frames by means of external dissipative systems. Dampers and external framing system can be arranged in several configurations, involving different kinematic behaviours and seismic performances. This study analyses a recently-developed solution called "dissipative tower", which exploits the r...

Current practical approaches for probabilistic seismic performance assessment of structures rely on the concept of intensity measure (IM), which is used to decompose the problem into hazard analysis and conditional seismic demand analysis. These approaches are potentially more efficient than traditional Monte-Carlo based ones, but the performance e...

Recent works on seismic hazard have introduced the concept of time-dependent seismic hazard and different models have been proposed to predict the inter-arrival time between consecutive events. Currently, the reliability assessment of structures and relevant design rules proposed by the codes are based on the Poisson recursive model, for which the...

Anti-seismic devices should be designed with proper safety margins against their failure, because the reliability of the structural system where they are installed is strongly influenced by their reliability. Seismic Standards generally prescribe safety factors (reliability factors) amplifying the device responses at the design condition, in order...

Experimental testing of a two-storey 5875 square meters steel braced-frame structure resting on a reinforced concrete slab isolated from the foundations through a hybrid system (28 high-damping rubber bearings and 36 low-friction sliding bearings) is presented. The building incorporates a push-and-release device to evaluate its actual global dynami...

Scour constitutes a significant treat to bridges. When it is not directly measured, it can be very difficult to detect and may go unnoticed until it produces catastrophic effects. Thus, understanding the effects of scour on bridge structures is of paramount importance for the development of effective scour monitoring strategies and early warning sc...

The λ-factors for stiffness and damping of rubber bearings should be experimentally assessed during the qualification process or deduced from tests performed on material specimens. Moreover, the λ-factors suggested in the informative annexes of EN 15129 and of EC8-part 2 can be also used as reference values. However, they are derived from outdated...

Video processing for structural monitoring has attracted much attention in recent years thanks to the possibility of measuring displacement time histories in the absence of stationary points close to the structure, using hardware that is simple to operate and with accessible costs. Experimental studies show a unanimous consensus on the potentialiti...

The question of maintenance and monitoring of bridges gained attention during the last decade, especially in Italy, after some serious collapses. The first emergency phase was the census and the visual evaluation of the state of maintenance and preservation of existing heritage to highlight the critical conditions for security. For this reason, in...

This paper presents the structure of new collaborative research project entitled SAFOTEB “A reviewed SAfety FOrmat for structural reliability assessment of post‐TEnsioned concrete Bridges”. The research aims at assessing the reliability of the current safety format and developing specific suggestions for existing concrete bridges with post‐tensione...

The structural reliability of existing post‐tensioned concrete bridges is a non‐trivial topic because of uncertainties affecting many parameters involved in their assessment process. This last is performed according to the current Codes specification through the partial factor method. Such method can be applied considering realistic material proper...

The Italian infrastructural asset, mainly consisting of RC bridges, is affected by significant obsolescence: many bridges overpassed their theoretical nominal life and did not experience any maintenance intervention. Such a critical scenario is even worse if it is additionally considered the increase of vehicular traffic that occurred in the last d...

The seismic performance of hybrid coupled walls (HCWs) made of a single reinforced concrete (RC) wall connected to two steel side columns by means of steel links is studied in this article. Steel links are designed as dissipative elements while the RC wall and the steel side columns should remain elastic. Given that previous studies highlighted the...

Recent seismic events occurred in Central Italy drew the attention towards the resilience of the Italian road network, which is characterised by a significant number of old reinforced concrete bridges and viaducts. In this context, the fragility assessment of existing bridges is crucial, since their collapse or loss in functionality after earthquak...

Seismic reliability assessment of selected bridge structures code-conforming with respect to the current Italian practice is carried out. Two viaducts, tall and shallow, and two highway overpasses, with traditional seat-type or integral abutments, are considered. Each structure is ideally placed at three reference sites, that is, Milan, Naples and...

Final report of the research project: Seismic reliability of representative Italian code-conforming highway bridges, ReLUIS-DPC 2019-2021

Designing a structure to resist earthquakes by targeting an explicit failure risk has been a key research topic over the past two decades. In this article, a risk-targeted design approach is developed for circular reinforced concrete bridge piers, based on a probabilistic optimization procedure aimed at minimising the design resisting moment at the...

The seismic response of base-isolated structures is notably influenced by mechanical properties of isolation devices due to their essential role in structural behavior. Consequently, the variability of such properties should be accounted for in the design process. The current seismic codes prescribe a simplified approach based on structural analyse...

Schools should be safe places where children and young people are hosted during their training years to develop their abilities and skills and to receive an education that makes them prepared to become the future of the nations where they live. Even though these aspects are of paramount importance and widespread recognized, the same importance does...

Rubber compounds are extensively used for manufacturing rubber bearings for seismic isolation. Current seismic codes prescribe the use of design properties of seismic isolators derived from experimental evaluations to account for the effects of strain rate representative of the design seismic condition, cyclic degradation, frequency and environment...

Most of the current seismic codes on seismic isolation prescribe upper and lower bound analyses to account for the variability of mechanical properties of seismic isolators. This procedure should be based on experimental data provided by manufacturers during qualification tests. When such data are not available, codes provide the so-called property...

Recent years have seen an increasing demand in the use of glass partition walls in office buildings, with major concerns regarding their behaviour and safety in case of strong seismic events. This study illustrates the development of an innovative solution for aluminium-glass partition walls that can resist, without any damage, horizontal accelerat...

Damper failures are generally brittle mechanisms, which can compromise the capacity of the structure to withstand the seismic action, leading to a lack of robustness of the overall system. The brittle failure is due to the attainment of the maximum force capacity, because of end-stroke impacts, which causes an arising of the forces, or to an excess...

This study illustrates the development of innovative solutions for school furniture designed to protect children and teachers in school buildings that cannot guarantee sufficient level of safety in case of seismic events. Attention is given to school desks and shelving units, the former having as objective the protection against falling debris from...

Fragility curves are one of the substantial means required for seismic risk assessment of buildings in the framework of performance-based earthquake engineering (PBEE). Obtaining fragility curves, however, needs an extensive analytical analysis which makes it time-consuming and sometimes inaccurate due to errors. In this study, hence, machine learn...

The seismic assessment of existing bridges is of the utmost importance to characterise the main structural deficiencies, estimate the risk, prioritise retrofit interventions, or estimate losses and repair costs in case of earthquakes. The above tasks require information on the damage mechanisms likely to occur as well as on the damage extent over t...

Seismic isolation is considered an effective solution to protect buildings and related content from earthquakes, and consequently reduce seismic losses. However, the overall reliability levels achieved on these systems by following the design rules suggested by codes are not uniform and they may be strongly influenced by some choices made in the st...

The seismic performance of existing RC frame buildings seismically retro-fitted by base isolation is examined. Two different types of isolation systems are considered, i.e.: rubber-based and friction-based isolation systems, respectively. Two different performance levels are examined, namely: Global collapse prevention and Usability preventing dama...

Bar splice methods have always been studied and discussed by structural engineers due to their crucial influence on the seismic performance of RC elements and structures. In the recent decades, extensive researches have been conducted on the investigation of different splice methods such as lap, mechanical and welded splices incorporated in structu...

This work focuses on the fragility assessment of reinforced concrete multi-span continuous bridges, which is a widespread structural typology in Italy, with the aim of investigating the peculiar vulnerabilities of the bridge class under investigation, the reinforced concrete link slab jointless bridges. The need for a deeper study on the topic deri...

p>Structural design in seismic areas could be based on either dissipative or non-dissipative concepts, as for example allowed in European and Italian codes. In the first case, capacity design is the basis of structural dimensioning; both strength and ductility verifications are required. In the second case, structural elements are designed to remai...

A technological system capable of automatically producing damage scenarios at an urban scale, as soon as an earthquake occurs, can help the decision-makers in planning the first post-disaster response, i.e., to prioritize the field activities for checking damage, making a building safe, and supporting rescue and recovery. This system can be even mo...

Tall piers are essential components of the earthquake resisting system of bridges. The dynamic behaviour of tall piers differs significantly from that of short piers due to a number of factors, such as their high flexibility and inertia. This paper aims to quantify the influence of axial loads and higher order modes on the seismic response of bridg...

This correction is published as author name typo was found in the original article and should be read as Michele Morici instead of Michele Morci.

Hybrid steel and concrete seismic-resistant systems made by steel frames with reinforced con-crete infill walls (SRCWs) have potential advantages over structural solutions made only by steel or reinforced concrete (RC). In fact, the high initial stiffness of concrete is useful to minimize the damage of non-structural elements under frequent (low to...

Hybrid steel and concrete seismic-resistant systems made by steel frames with reinforced concrete infill walls (SRCWs) have potential advantages over structural solutions made only by steel or reinforced concrete (RC). In fact, the high initial stiffness of concrete is useful to minimize the damage of non-structural elements under frequent (low to...

This paper presents an insight on the seismic response and seismic risk of base-isolated structures performed within the RINTC project, considering different configurations of rubber-based isolation systems. This represents an in-depth revision of past works due to the adoption of more robust and accurate isolator model. Four archetype 6-storeys RC...

The Sendai Framework for Disaster Risk Reduction 2015-2030 (SFDRR) highlights the importance of scientific research, supporting the ‘availability and application of science and technology to decision making’ in disaster risk reduction (DRR). Science and technology can play a crucial role in the world’s ability to reduce casualties, physical damage,...

Generally, strong seismic events cause serious damage to cultural heritage, especially in ancient churches characterized by a high vulnerability due to the intrinsic peculiarities of their structural systems which are not able to develop efficient resisting mechanisms. Starting from observed damage of churches and recorded ground motions, it is pos...

Buckling‐restrained braces (BRBs) have proven to be very effective in improving the seismic performance of existing and new structures. They provide strength, stiffness and add energy dissipation to the structure. However, being BRBs characterized by a low post‐elastic stiffness, their use may lead to residual deformations hindering the building's...

High-Damping Natural Rubber (HDNR) bearings are widely employed for seismic isolation. These bearings are characterized by a remarkable nonlinear behaviour and often by a degrading cyclic response, induced by the addition of filler to enhance its dissipation capacity. This latter phenomenon, denoted as stress-softening or Mullins effect, can signif...

This paper presents results of an extensive experimental campaign carried out during the construction phases of a base-isolated bridge across the Potenza river in central Italy. The structure is constituted by a half-through steel arch bridge composed by two coupled weathering steel tubular arches sustained by thirty couples of hangers and by two a...

This paper analyses the new Research Centre designed for the University of Camerino and entirely financed by the national Civil Protection Department (DPC), following the seismic events in Central Italy in 2016. The building has been designed to guarantee speed of execution as well as a high level of safety, especially regarding seismic actions. Th...

Some short remarks on Risk Assessment

This paper investigates the seismic design of fluid viscous dampers connecting adjacent structural systems. A simplified dampers design strategy is proposed, which relies on a linearized reduced order model of the coupled system. A stochastic linearization technique is adopted with the aim of extending the design method to non-linear viscous damper...

Risk assessment basis on a prediction of possible hazardous events, in terms of recurrence in time, and is oriented to the estimation of potential consequences, considering potential sources of uncertainty. In this paper, attention is focused on the probability of construction failure (consequence) due to a strong earthquake (event). Generally this...

Steel frames with reinforced concrete infill walls (SRCWs) are an interesting structural solution for applications in seismic areas if designed to exploit the stiffness of reinforced concrete (RC) and the ductility and dissipative capacity of steel. Three horizontal resisting mechanisms can be identified in SRCW: 1) contribution of the steel frame;...

Steel frames with reinforced concrete infill walls (SRCWs) are an interesting structural solution for applications in seismic areas if designed to exploit the stiffness of reinforced concrete (RC) and the ductility and dissipative capacity of steel. Three horizontal resisting mechanisms can be identified in SRCW: 1) contribution of the steel frame;...

Recent works on seismic hazard have introduced the concept of time-dependent seismic hazard and different models have been proposed to predict the inter-arrival time between consecutive events. Currently, the reliability assessment of structures and relevant design rules proposed by the codes are based on the Poisson recursive model, for which the...

Steel frames with reinforced concrete infill walls (SRCWs) have potential advantages as seismic-resistant systems. However, the review of the state of the art highlighted how the behaviour of hybrid shear walls is rather difficult to be controlled due to ambiguities in the definition of the resisting mechanism and lack of capacity design rules. Whi...

The optimum combination of steel and concrete elements to constitute hybrid steelconcrete seismic-resistant structural systems should exploit the stiffness of concrete and the ductility and dissipative capacity of steel. If the seismic damage is limited to some, easy to replace, steel components only and the residual deformations are limited, the s...

Buckling-restrained braces (BRBs) have proven to be very effective devices improving the seismic performance of existing and new building frames. They provide strength, stiffness and added damping to the structure, however, due to their low lateral post-elastic stiffness, their use may lead to excessive residual deformations which may hinder the bu...

This paper analyses the observational damage from post-earthquake investigations carried out on churches of the Marche Region struck by the 2016 Central Italy seismic sequence. Such seismic activity seriously damaged many historical buildings and particularly churches, due to their intrinsic inability to develop an efficient box-like resisting mech...

This paper applies the Performance-Base Earthquake Engineering (PBEE) framework to estimate the risk of a urban district recently hit by a earthquake, in order to compare model prediction with effective damage observed after the event. For this purpose, the reinforced concrete buildings of the Vallicelle district of Camerino, are considered. This d...

The post-earthquake inspections for the assessment of buildings’ usability have a key role in the post-earthquake emergency phases. In particular, a primary importance is given to the damage and usability assessment of public buildings, which is crucial for a quick recovery of the social activity. A significant contribution in the usability evaluat...

The seismic sequence that struck central Italy from August to October 2016 caused severe damage to many historical and artistic buildings. In particular, churches were widely affected due to the intrinsic peculiarities of their structural system, unable to develop an efficient box-like resisting mechanism. After the seismic events, teams of experts...

Damping and isolation devices are often employed to control and enhance the seismic performance of structural systems. However, the effectiveness of these devices in mitigating the seismic risk may be significantly affected by manufacturing tolerances, and systems equipped with devices whose properties deviate from the nominal ones may exhibit a pe...

This article describes the structural design, nonlinear modeling, and seismic analysis of prototype single-storey non-residential steel buildings made of moment-resisting portal frames in the transverse direction and concentric braces in the longitudinal direction. Various design parameters (building geometry, seismic hazard, foundation soil catego...