Search Results (27)

The mutual interaction between base isolation (BI) and soil–structure interaction (SSI) needs to be considered in design applications. In the literature, the key parameters that may affect such interaction have been rarely considered. Closed formulations for the assessment of the mutual role of BI and SSI have not been proposed yet. The paper aims to cover this gap by considering a 3DOF model to propose closed relationships with the most significant parameters (structural period, isolation ratio and shear wave velocity). The outcomes show that there are two different interactions. When soil deformability and structural stiffness are not significant, the isolation ratio may be used as a main parameter. However, when the foundation soil is particularly deformable and structures are significantly rigid, a more complex relationship needs to be considered. Parametric case studies have been performed with different structures, three isolation ratios and several soil conditions (soil A, B, C and D). Full article

This paper proposes a method to investigate the design properties of geotechnical seismic isolation (GSI). This technique has been the object of many research contributions, both experimental and numerical. However, methods that may be used by practitioners for design procedures are still unavailable. The formulation presented herein may be used for preliminary assessments of two important properties: the thickness and the shear wave velocity. Three-dimensional advanced numerical simulations were performed with the state-of-the-art platform OpenSees in order to verify the analytical formulation on a benchmark case study. The elongation ratio has been taken as the relevant parameter to discuss the efficiency of GSI in decoupling the soil from the structure. The main findings consist of assessing the dependency of the elongation ratio on two parameters: the thickness and the shear velocity of the GSI layer. In this regard, a novel formulation was proposed in order to make preliminary design assessments that can be used by practitioners for practical applications. Full article

The seismic resilience of bridges has become an important concept in civil engineering since these systems need to remain operative during and after earthquakes. In this regard, the definition of recovery needs to consider the delay time (named as the time between an event and the beginning of the recovery process). The original concept of seismic resilience has been expanded herein in order to account for the delay time of bridge configurations. Its role in the quantification of seismic resilience has been investigated by performing a case study of a Californian highway bridge subjected to an ensemble of 100 input motions. The results demonstrate that the delay time may significantly reduce the seismic resilience of bridges. Full article

Resilience of systems to natural hazards has become an interesting concept in civil engineering and it is based on the determination of the losses due to the impacts of natural hazards. In the last decades, many contributions have focused on the assessment of losses that may occur at the time of the event, as generally assumed for earthquakes. However, this assumption may be incorrect when the interval between the time of occurrence and the time when the system functionality reaches the minimum value needs to be considered. This paper aims to propose a novel method to quantify this interval, which is called disruption time, by proposing a novel formulation of the loss model based on infrastructure redundancy. The proposed method was herein applied to a case study that considers landslides in Sri Lanka. The main goal of the paper is to propose a formulation that can be implemented in a more comprehensive framework to calculate more realistically the resilience of systems to natural hazards. Full article

Infrastructures are fundamental links in sustainable communities, and they need to remain at a level of functionality during and after natural events. In particular, assessing the seismic resilience of infrastructures has become an interesting topic in earthquake engineering. The estimation of indirect losses due to seismic events is still a topic under discussion, especially for infrastructures. In this regard, the paper focused on including the level of redundancy inside an analytical formulation of the seismic resilience (SR). The main idea is to explore the possibility of alternative infrastructures that allow the circulation of services and people when the flow on the original infrastructure is interrupted or reduced. This goal is fundamental for preserving the resilience for sustainable communities. Therefore, the proposed formulation consists of considering the reduction in losses when the infrastructure is redundant by introducing the concept of the level of redundancy. In particular, indirect costs were herein defined with a new formulation that includes the level of redundancy inside the calculation of SR. The paper presented a case study that implements the formulation with the aim to demonstrate the efficiency of the proposed methodology. Several levels of infrastructural redundancy have been applied in the calculation of the SR of an infrastructure subjected to an ensemble of 100 seismic motions in order to scope the role of redundancy in improving the SR of the system. Full article

Tire-derived aggregate (TDA) has been proposed in recent studies to be considered as part of backfill soil to reduce stress and strain developed in buried pipes. However, little attention is paid to checking the influence of TDA on the behavior of concrete pipes buried under trafficked roads. This research studies this topic using a verified numerical model that considers the three-dimensional nature of traffic load effects. Different road sections were considered in the analyses to cover the effect of the presence of the pavement layer and the effect of the thickness of the base and subbase materials. The results revealed that the presence of TDA decreases the bending moment induced in the pipe wall. However, the TDA performance was found to be remarkably influenced by burial depth, and it increases as the burial depth decreases. Furthermore, the TDA influence for pipes with outer diameters of 1.49 m and 2.89 m is much lower than that of 0.41 m and 0.79 m. Importantly, it was found that the highest reduction in the bending moment was achieved for the 1.0 m burial depth. The results of this research provide insight into the performance of TDA and, thus, will help practitioners make a decision regarding the use of TDA in the routine design of buried concrete pipes. Full article

Communities and ecosystems may be particularly vulnerable to fire hazard. In addition, modern societies are connected with interdependent infrastructures, and the assessment of their resilience to fire may be extremely challenging. In this regard, fire resilience may be described as the ability to maintain the functionality of infrastructures to deliver services during and after hazard events. This paper considers several typologies of interdependency in order to propose several models that may quantify fire resilience. These models are based on the previous literature and the applications recently proposed for earthquakes. Fire resilience is herein calculated by considering a multi-dimensional formulation of the repair function that depends on time and the different components of the systems. The formulations that are described may be applied for preliminary studies aimed at pre- and post-fire assessments. Many stakeholders may take advantages of such formulations to consider the interconnections between the different infrastructures, their components, and subcomponents subjected to fire hazard. Full article

The concept of seismic resilience has been introduced in the design of buildings in the last decade. In this regard, the delay time may be defined as the time that occurs between the event and the moment the repair process begins. In the literature, only a few contributions have considered delay time, and even its definition is still under discussion. However, it is a key parameter in the assessment of resilience after earthquakes since it may significantly increase the total time after which a structure may be considered recovered. The principle at the base of the paper is that seismic structural health monitoring (S2HM) may play a significant role in reducing the delay time. Therefore, delay time needs to be considered since it may significantly reduce the seismic resilience of structural systems. The paper aims to consider this important issue demonstrating the relationship between S2HM and the assessment of the seismic resilience of buildings. In particular, the assumption herein is that the accuracy of the S2HM may be described with different levels, and in correspondence with these levels, certain values of the delay time may be considered. In addition, the delay time is considered as a percentage of the total repair time. A multidimensional definition that includes the accuracy of S2HM in the description of the delay time is herein proposed to be included in methodologies that aim to assess seismic resilience. Full article

Modern and smart cities are significantly vulnerable to natural hazard, and their functionality is based on resilient infrastructure systems. In particular, seismic resilience may be considered the ability to deliver services during and after hazard events. Therefore, it is fundamental to identify the most critical components within a system, especially when multiple infrastructure systems are interdependent. The paper aims to propose a novel methodology that consider interconnected infrastructures to assess seismic resilience that may be defined as a function that depends on time, and the different components are considered the functional dimensions. The proposed methodology may be applied for several typologies of infrastructures, specifically looking at the seismic resilience analyses related to transportation systems. A case study has been considered in order to apply the proposed formulation and to demonstrate the importance of considering interdependency in the assessment of the seismic resilience. Many stakeholders (infrastructure owners, public administrations, decision makers) may be interested in applying the methodology that could be used to study several applications. Full article

Resilience has become an interesting parameter to assess the seismic risk connected with functionality of structures. In this regard, losses due to earthquakes may be significantly reduced by applying isolation at the base of the structures. However, design of isolation needs to consider the effects of soil deformability and all the connected effects of Soil Structure Interaction (SSI). In particular, soil deformability may reduce significantly the benefit of base isolation and thus the computation of resilience needs to consider such conditions. This paper aims to consider the issue by considering several isolated configurations on different soil conditions and for each of them, the seismic resilience has been computed. Numerical simulations have been performed in order to calculate the resilience of the various configurations and then this parameter was chosen a reference for comparing the isolation models on different soil conditions. Full article

The assessment of the seismic risk connected with the functionality of infrastructure has become an important issue in civil engineering, and consists of estimating costs due to earthquakes. In this regard, bridges are the most vulnerable systems among the various components of road infrastructure and the assessment of their resilience has recently been proposed. However, the development of methodologies that can assess the resilience of the full road infrastructure still constitutes a gap in the literature. This paper aims to fill this gap by proposing a novel methodology to include direct and indirect losses using a probability-based approach. A case study was carried out to investigate a road network consisting of two interdependent infrastructures. Full article

The role of abutments on the seismic vulnerability of bridges has been relatively little studied in geotechnical literature. To cover this gap, 3D numerical simulations were herein performed, by studying the seismic performance of three single-span bridge configurations. The numerical models used OpenSees to account the effects due to soil structure interaction between the deck and the abutments. In particular, advanced materials were implemented to model the non-linear hysteresis and plasticity that are responsible for soil deformations and, thus, structural damage. A probabilistic-based approach was considered and analytical fragility curves were developed to account modeling uncertainties. The role of bridge deformability was investigated by considering several limit states based on the calculation of the longitudinal displacements of the deck. Full article

The assessment of resilience of health infrastructures during an epidemic crisis is a fundamental issue in civil engineering, as shown by the recent COVID-19 crisis. During epidemic crises, health services and infrastructures need to maintain a level of functionality and avoid failures. In addition, it is important to evaluate post-hazard procedures, such as emergency and recovery actions. In this regard, the paper applied resilience as a parameter to assess investments, countermeasures and mitigations. The Resilience-Based (RB) methodology herein proposed was then applied to quantify the resilience of health infrastructure systems by considering the recovery of four European Countries (Germany, France, United Kingdom and Italy) after the first wave of COVID-19. The results demonstrated that the resilience of health system infrastructures (HSI) depends significantly on the policies that every government management applied—these being ultimately responsible for the differences in respective COVID impacts. In particular, the principal advantage of using resilience lies in its readability by many stakeholders, such as health infrastructure managers, government owners and public authorities. Full article

This paper presents parametric studies that assess the role of loading factors (i.e., number of cycles, frequency, and amplitude) on liquefaction-induced failure by performing numerical simulations. Most of the existing literature considers the effects of the soil properties on the development of excess pore pressure with few research endeavours focusing on the effects of the input motion itself. Numerical simulations are performed herein, via the advanced software platform OpenSees, to generate several finite element models that consider non-linear development of pore pressure inside the soil. Several sinusoidal inputs were considered to study the effects of the various loading factors and compare the responses. The main findings arise from evaluating the effects of several input motion parameters (number of cycles, frequency, and amplitude) on soil liquefaction through numerical simulations. This research study, based on state-of-the-art knowledge, may be applied to assess future seismic events and to update or propose new code provisions for soil liquefaction. Full article

On 6 April 2021, a 200 m-long under-construction prestressed concrete bridge failed in the Chitwan District in central Nepal. Two of the four bridge spans collapsed without any notable evidence of dynamic force application. Under-construction bridge failures are sometimes reported and can have a significant impact on the future construction adjustments. Thus, a detailed study of failure mechanisms will be insightful for the structural engineering community. Aiming to document the failure modes and exemplify lessons for improvement, this paper reports the detailed component level failure mechanisms of the bridge using visual inspection, site measurements, finite element modeling, and some forms of non-destructive testing. The chronological failure mechanisms are presented based on the field evidence and juxtaposed with the results of analytical modeling. The sum of findings highlights that the dead load failure, triggered by the settlement of falseworks, is the most critically governing factor that initiated and aggravated the damage scenario. Full article