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Seismic losses due to earthquakes have been shown to have significant economic, social and environmental consequences. Over recent years, research to predict potential economic and social impact due to seismic risk has been increasing. Recognizing that the traditional philosophy of life safety design can lead to extensive damage and demolition which has a large environmental cost, incorporating environmental impacts associated with the expected seismic damage over a building's life is a key step as the building industry moves towards both sustainable and seismically resilient design. This paper introduces a framework that uses environmental indicators quantifying losses from seismic response that can then be used to advocate for a change in seismic performance objectives. First, existing literature and previously developed approaches for quantifying potential environmental impact due to seismic damage are summarized. Next, performance based earthquake engineering concepts are used to demonstrate a probabilistic approach to quantify potential environmental impacts using a range of environmental and resource use indicators over the life span of a case study building. In addition, a case study is presented to compare different environmental indicators between a Code Minimum building and the same building redesigned for a higher seismic performance. The majority of the composition of the environmental indicator values are from the inclusion of the non-repairable scenario, and from the repair activities, the majority of the impacts are from damage to drift sensitive components including curtains walls, partitions and elevators. For the Code Minimum building the non-repairable scenario contributes to between 8 to 11% the total seismic cost. For the Stronger Stiffer building, the non-repairable scenario contributes around 3% of the initial impact. Neglecting non-repairable scenarios does significantly reduce the potential environmental impacts when analyzing buildings designed for current code minimum structural standards. [ABSTRACT FROM AUTHOR]

In May 2012, two strong earthquakes hit the northern Italy revealing the significant seismic vulnerability of precast reinforced concrete structures and causing severe damage and many collapses, and high economic losses. After the lesson learnt from these events, more reliable seismic design criteria have been established for the design of new structures and different approaches have been proposed for the seismic assessment of the existing structures. In this context, the paper presents the results of a first application of the PRESSAFE-disp method, recently proposed by the authors, allowing to define the fragility curves of precast RC buildings at various limit states, including collapse. A stock of 91 precast buildings in the industrial area of San Felice sul Panaro (Modena) was selected as a benchmark case study to verify the reliability of the method in assessing seismic damage scenarios. In particular, with reference to the 2012 seismic ground-motion, two large-scale stochastic models are outlined to predict the number of the buildings collapsed in the area. The first one is based on a Monte Carlo simulation which incorporates the evaluation of the uncertainties, while the second one is a direct simplified calculation. Comparative considerations on the outcomes of the two methods for different seismic intensities are discussed, including the directionality effect of the ground-motion. To test the soundness of the simulations, the results of the two methods are compared with the real data collected through in-situ surveys. The procedures proposed here result, on average, in good agreement with the observed damage scenario. It is worth noting that, due to the inherent simplicity of the methods, they could be implemented to perform scenario-based seismic loss assessments to estimate the financial consequences of an earthquake affecting one or more industrial areas, and to drive the decision-making process for the seismic retrofit of existing precast RC buildings. [ABSTRACT FROM AUTHOR]

The study of the seismic response of long bridges under non-uniform seismic excitation date back to the early 80 s. So far, many methods have been developed to estimate the bridge responses under such excitation. Eurocode-8 is considered the first seismic design code that provided a simplified method for linear seismic analysis of long bridges under non-uniform seismic excitation. In this method, earthquake ground motion at each bridge support is decomposed into uniform and relative excitations. Any desired elastic response quantity of bridge for each input is obtained and results are combined using the SRSS combination rule. In this paper, it is shown that the SRSS method leads to very conservative and unrealistic responses. An alternative combination rule is then recommended for response estimation, and random vibration analysis is used to calculate the correlation coefficient between the two mentioned responses. Efficiency evaluation of the proposed method is investigated by Monte Carlo simulation results of nine long bridges with different geometrical and dynamic characteristics. Two simplified mathematical bridge models for longitudinal and transverse directions are developed. Then, a simple mathematical formula for the correlation coefficient is extracted, and its accuracy and performance are evaluated. Finally, it is concluded that the proposed formula is relatively accurate and appears in acceptable results. [ABSTRACT FROM AUTHOR]

The influence of distanced uniform strip load on the design of cantilever sheet pile walls under static as well as seismic condition is sudied in this paper. A simplified theoretical solution based on limit equilibrium approach is proposed to design the cantilever sheet pile walls having a distanced strip load in cohesionless soil. By considering the rigid rotation about pivot point and the displacement pattern, the active and passive earth pressure are assumed fully mobilise. To completely define the earth pressure distribution, horizontal force and moment equilibrium are considered to calculate the embedded depth. The influence of distanced uniform strip load has been observed by emplying Coulomb earth pressure theory. Expressions are given to calculate bending moment and shear force at any depth of the cantilever sheet pile walls. Some aspects to design the cantilever sheet pile walls with distanced strip load are also highlighted in terms of maximum bending moment, embedded depth and depth of pivot point from dredge level. Design charts in non-dimensional form are also given as a ready reference. [ABSTRACT FROM AUTHOR]

An investigation on seismic response characteristics and modal parameters of a cable-stayed bridge with movable bearings using vibration records obtained from a seismic monitoring system is presented in this paper. The object of this study is the Tokachi cable-stayed bridge, a single plane prestressed cable-stayed bridge that is equipped with moveable spherical frictional plate (SFP). The bridge seismic responses subjected to various levels of earthquake including the 2003 Tokachi Great earthquake were obtained from a permanent seismic monitoring system. The bridge dynamic characteristics that include frequency and damping were estimated by both the time-invariant and time-variant recursive subspace identification methods. The identification results reveal that damping ratios of the low order modes estimated during the largest earthquake can reach more than 10% of the critical damping, which is higher than what usually assumed in the seismic design code. Supplementary damping caused by friction force at the movable SFP bearings was identified as the main source of the large damping, and it was quantified by a modal-based inverse analysis using the sparse regularization method. Results of the analyses confirm the influence of moveable SFP bearings performance with its Coulomb-friction type stick–slip behavior on the dynamic characteristics of the bridge. The bearings remain stuck at smaller excitation causing higher stiffness of the structure and slip during a larger excitation resulting in stiffness reduction. The sliding process induces friction force between contacting surfaces of the SFP bearings which results in the increase of damping as the excitation level increases. The damping, however, does not increase continuously, but becomes steadier after a certain level of excitation. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive geological and geotechnical study of the whole area affected by liquefaction following the 2012 Emilia earthquakes, including all the available information from the field reconnaissance surveys, in situ tests, and laboratory analyses. The compilation was performed at 120 liquefied sites to verify and validate the reliability of liquefaction charts in alluvial sediments, and to assess liquefaction induced by the 2012 seismic sequence in the Emilia plain. The results reveal a wide range of grain sizes (from clean sands to sandy silts) and compositional characteristics (quartz-rich to litharenitic) in the 2012 ejecta, and show a strong relationship between the liquefaction and stratigraphic architecture of the subsurface. The availability of in situ tests at the liquefied sites makes it possible to verify and validate the reliability of the liquefaction charts in alluvial sediments with respect to the real observations. For the analyzed Emilia case studies, the use of non-liquefiable crust provides better estimations of the liquefaction manifestations when coupled with the thickness of the liquefiable layer rather than with the liquefaction potential index. Altogether, this work makes available to the international scientific community a consistent liquefaction database for in-depth earthquake studies. [ABSTRACT FROM AUTHOR]

Seismic hazard maps from probabilistic seismic hazard analysis or PSHA collect, at different sites, the values of the (site-specific) ground motion intensity measures of interest that, taken individually, have the same exceedance return period. For large-scale analyses, a widely used intensity measure is the macroseismic (MS) intensity, that provides an assessment of the earthquake effect based on the observed consequences in the hit area. Hazard maps can be developed in terms of MS intensity, and some examples exist in this respect. In the case of Italy, the last MS hazard map is based on the same seismic source model (known as MPS04) adopted to derive the design seismic actions of the current building code, a study dating more than ten years ago. It provides results in terms of countrywide Mercalli–Cancani–Sieberg (MCS) intensity level with 475 years return period. This short paper presents and discusses MCS probabilistic seismic hazard maps for Italy based on a recent grid-seismicity source model, herein named MPS19, synthetizing the large effort of a wide scientific community. The results, which are obtained by means of classical PSHA, are given in the form of maps referring to the 475 years return period, and also others of earthquake engineering interest. Moreover, it is discussed that the return period does not univocally identifies the MS intensity because, although MS is, by definition, a discrete random variable, it is modelled, in a given earthquake, by means of a normal distribution, that is, treated as continuous. Thus, the maps of the minimum return period causing the occurrence or exceedance of different MCS intensities are also provided. Finally, the comparison between the 475 years return period hazard map presented and the one which is currently the point of reference in Italy, that is, computed using MPS04, is briefly discussed. All the computed maps are made available to the reader as supplemental material. [ABSTRACT FROM AUTHOR]

The existing precast reinforced concrete structures not specifically designed against earthquakes have proved to be very sensitive to seismic demands. After the lesson learnt from the 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 regard 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 large scale of an industrial area. To this aim, the paper proposes the PRESSAFE-disp (PRecast Existing Structure Seismic Assessment by Fast Evaluation-displacements) method, useful for the fast evaluation of the fragility curves of precast structures. The damage criteria, applicable both to structural elements and non-structural cladding elements on the perimeter, have been selected in order to capture the damage mechanisms observed during the building inspections conducted by the authors in the aftermath of the 2012 Emilia earthquakes. The method allows a comprehensive explanation of the seismic in-plane behaviour of existing precast RC 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. [ABSTRACT FROM AUTHOR]

The Eurocode 8—Part 4 approaches, per their December 2022 update, are presented for the design of acceleration-sensitive industrial ancillary components. The seismic performance of such nested and/or supported ancillary elements, namely mechanical and electrical equipment, machinery, vessels, etc. is critical for the safety and operability of an industrial facility in the aftermath of an earthquake. Of primary importance are the structural characteristics of the supporting structure and the supported component, pertaining to resonance, strength, and ductility, and whether these are known (and to what degree) during initial design and/or subsequent modifications and upgrades. Depending on the availability and reliability of information on the overall system, the Eurocode methods comprise (a) a detailed component/structure-specific design accounting for all pertinent component and building characteristics, equivalent to typical building design per Eurocode 8—Part 1–2, (b) a conservative approach where a blanket safety factor is applied when little or no such data is available, and (c) a ductile design founded on the novel concept of inserting a fuse of verified ductility and strength in the load path between the supporting structure and the ancillary element. All three methods are evaluated and compared on the basis of a case-study industrial structure, showing how an engineer can achieve economy without compromising safety under different levels of uncertainty. [ABSTRACT FROM AUTHOR]

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 pier base. In order to reduce the computational effort, a surrogate model is developed to describe the influence of two key design parameter (i.e., the pier diameter and the longitudinal reinforcement ratio) on the structural behaviour and performance. The proposed approach is applied in a case study for Italy for target mean annual frequencies of failure selected according to European codes using a probabilistic seismic hazard assessment for average spectral acceleration across a wide range of structural periods. The variation in the design parameters across Italy is considerable because of the large variation in seismic hazard. It is found that in areas of low seismic hazard the level of seismic design required is near the minimum allowed by Eurocode 8 in terms of reinforcement ratio. In areas of the highest seismic hazard much higher reinforcement ratios and pier diameters are required to meet the risk targets. If both pier diameter and longitudinal reinforcement ratios are considered as design parameters then the optimisation procedure may mean adjacent sites have significant different pairs of these parameters as the target can be reached in multiple ways. This problem can be solved by fixing one parameter and optimising the other. [ABSTRACT FROM AUTHOR]

Dynamic interaction between soil and structure group (SSGI) is of great significance to the seismic design and evaluation of structures in densely built areas. However, detailed three-dimensional parametric analysis of the SSGI effect using realistic modeling on both the superstructure and soil is still limited. This study develops a three-dimensional numerical method to account for the SSGI effect and validates it against the shaking table test result. Subsequently, parametric analyses are conducted to investigate the SSGI effect for a three-dimensional soil and structure group, where key parameters include the structure height, number, and spacing, material properties of the soil, and spectrum distributions of seismic records. Compared with the dynamic interaction between soil and a single structure, the SSGI can reduce the structural base shear and story drift (up to 17% and 24%, respectively) in most cases. However, the level of reduction is below 5% when (1) structure spacing is greater than 2.0 times the width of the structure foundation or (2) the shear wave velocity of soil is no less than 300 m/s. Essentially, the SSGI changes the seismic demand of the concerned structure mainly by altering its local ground acceleration input at the base. The SSGI effect is more significant when structure spacing is reduced, structure number is increased, or the height of the central structure equals those of the surrounding structures. In contrast, the influence of soil property on the SSGI effect is minor under medium-level earthquakes. [ABSTRACT FROM AUTHOR]