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Intercity networks constitute a highly important civil infrastructure in developed countries, as they contribute to the prosperity and development of the connected communities. This was evident after recent strong earthquakes that caused extensive structural damage to key transportation components, such as bridges, overpasses, tunnels and geotechnical works, that in turn led to a significant additional loss associated with the prolonged traffic disruption. In cases of seismic events in developed societies with complex and coupled intercity transportation systems, the interdependency between citizens’ life and road functionality has further amplified the seismically-induced loss. Quantifying therefore, the resilience of road networks, defined as their ability to withstand, adapt to, and rapidly recover after a disruptive event, is a challenging issue of paramount importance towards holistic disaster risk mitigation and management. This study takes into account the above aspects of network resilience to earthquake loading and establishes a comprehensive, multi-criterion framework for mitigating the overall loss expected to be experienced by the community due to future earthquake events. The latter is decoupled into the direct structural damage-related loss and the indirect loss associated with the travel delays of the network users, as well as the wider socio-economic consequences in the affected area. In order to reflect the multi-dimensional nature of loss, a set of novel, time-variant indicators is herein introduced, while cumulative indicators are proposed for assessing the total loss incurred throughout the entire recovery period. This probabilistic risk management framework is implemented into a software to facilitate informed decisions of the stakeholders, both before and after a major earthquake event, thus prioritizing the pre-disruption strengthening schemes and accelerating the inspection and recovery measures, respectively.

It is generally known that reinforced concrete frame structures with unreinforced masonry infills frequently suffer severe damage when subjected to earthquake loading. Recent earthquakes show that the damage occurs to both older buildings and new seismically designed buildings. This is somehow surprising as this construction type has been the subject of intensive research projects for decades and simplified verification concepts are available in standards. However, these concepts are based on the separate verification of in-plane and out-of-plane loading although the importance of the design for combined loading conditions is already known. This situation was the reason to perform comprehensive investigations of the seismic behaviour of this traditional construction type for separate and combined in-plane and out-of-plane loading within the framework of the collaborative European research project INSYSME (Innovative systems for earthquake resistant masonry buildings in reinforced concrete buildings). These investigations are helpful to develop innovative approaches to improve the seismic behaviour of infilled frames. This article presents the fundamental project results of experimental investigations on reinforced concrete frames filled with high thermal insulating clay bricks under separate, sequential and combined in- and out-of-plane loading. The test results clearly illustrate that the load-bearing capacity severely depends on the boundary conditions in the connection area between the infill and the frame.

The study presented in this paper describes the coupled influence of corrosion and cross-sectional shape on failure mechanism of reinforced concrete (RC) bridge piers subject to static and dynamic earthquake loading. To this end, two RC columns varied in cross-sectional shape and corrosion degree are considered. An advanced nonlinear finite element model, which accounts for the impact of corrosion on inelastic buckling and low-cycle fatigue degradation of reinforcing bars is employed. The proposed numerical models are then subjected to a series of monotonic pushover and incremental dynamic analyses. Using the analyses results, the failure mechanisms of the columns are compared at both material and component levels. Furthermore, using an existing model in the literature for uncorroded columns, a dimensionless corrosion dependent local damage index is developed to assess the seismic performance of the examined corroded RC columns. The proposed new damage index is validated against the nonlinear analyses results. It is concluded that the combined influence of corrosion damage and cross-sectional shape result in multiple failure mechanisms in corroded RC columns.

Ultra-high-performance fiber-reinforced concrete (UHP-FRC) has a high compressive strength of 22 to 30 ksi (152 to 210 MPa) and a substantial shear strength as well as exceptional compressive ductility and confinement characteristics due to the addition of high-strength steel microfibers, which alleviate the need for excessive transverse reinforcement in high-strength concrete. The application of UHP-FRC in seismic-resistant reinforced concrete (RC) columns was investigated in this study. Two full-scale columns, one with normal strength concrete and the other with UHP-FRC in the plastic hinge region, were tested under simulated earthquake loads to evaluate their damage-resistance ability, deformation capacity, and failure mechanism. Experimental results show that the use of UHP-FRC changes the failure mode of RC columns as it improves confinement and shear capacity, as well as prevents concrete from crushing. The UHP-FRC column exhibits a higher peak strength and a greater deformation capacity before succumbing to significant strength degradation compared to the normal-strength RC column. The lateral displacements of the ACI 318-19-compliant RC column mainly result from distributed reinforcing bar yielding. Conversely, displacements of the UHP-FRC column are dominated by the slip deformation at the column-footing interface due to the strain penetration of the longitudinal reinforcing bars into the footing. Unlike the RC column, the failure of the UHP-FRC column is controlled by the low-cycle fatigue life of its longitudinal reinforcing bars. Concrete crushing in the RC column started at 1% drift ratio and became nearly unrepairable beyond 2.75% drift ratio. On the other hand, the UHP-FRC column experienced limited damage even at large drift ratios. This will result in great post-earthquake functionality and considerable cost savings in repairs for structures with UHP-FRC columns. In addition, incremental dynamic analyses of a four-story prototype RC moment frame indicate that buildings with UHP-FRC columns can sustain earthquakes with 20% higher peak ground acceleration before collapsing due to the greater deformation capacity. Keywords: buckling; column; deformation capacity; earthquake loading; seismic; ultra-high-performance concrete (UHPC); ultra-high-performance fiber-reinforced concrete (UHP-FRC).

The motivation of this study stems from a retaining wall made of waste tires. The wall did not suffer any earthquake or tsunami-induced damage during the 2011 Off the Pacific Coast of Tohoku Earthquake, Japan. This paper deals with a case study on this tire retaining wall. Results from a series of field and laboratory investigations are first described. A numerical simulation is also described in which whole tires were used as protective layers in an embankment. The results show that confining effect of each tire, friction between the tires, ductility, and damping inherent in tires contribute towards the excellent performance of the retaining wall during the earthquake loading. The case study also reveals that it is the isolation mechanism due to the vibration absorption capability of rubber particles in tires, which could protect tire retaining structure during the earthquake.

A series of experiments on 14 square cantilevered columns under constant axial load was conducted to investigate the fire resistance time and residual seismic capacity of reinforced concrete columns subjected to a post-earthquake fire. All specimens were first subjected to a reversed cyclic loading or a simulated earthquake loading, and then exposed to a simulated fire endurance test (wherein high temperature representative of fire loading was imposed on the specimens), or they were subjected to cyclic reversed loading following a post-earthquake fire. The experimental results indicate that the tested specimens satisfied the fire protection requirements of ISO 834 and the Chinese Design Code after moderate earthquake damage, represented in this study by reversed cyclic loading up to a peak drift of 2% and simulated seismic displacement history with a peak drift of 3.5%. Residual drift had a more significant impact than the maximum lateral drift for post-earthquake fire resistance. The seismic response of columns subjected to post-earthquake fire exhibited reduced lateral load capacity, effective stiffness, and ductility. Results from the present study indicate that the lateral drift should be monitored during a fire test, and that lateral drift limits be incorporated into the criteria for post-earthquake fire loading. Keywords: earthquake loading; experimental testing; fire resistance; reinforced concrete (RC) column; residual seismic performance.

Obsequent rock slopes are often thought to be more stable than consequent slopes and passive sliding is unlikely to occur under earthquake loading. However, failures in obsequent rock slopes were indeed observed in recent large earthquakes. This paper presents a time–frequency solution to the seismic stability of obsequent rock slopes fully considering the time–frequency characteristics of earthquake waves. Large-scale shaking table tests were conducted to illustrate the application of the time–frequency method to an obsequent rock slope containing multiple weak layers with a small dip angle. The seismic stability of the obsequent rock slope is analyzed combining the time–frequency method, outcomes from the shaking table test, and conventional pseudo-static and dynamic numerical analyses. The results show that passive sliding can develop in the obsequent rock slope when taking the time–frequency components of the earthquake waves and the vertical seismic force into account. The middle–upper part of the obsequent rock slope is more vulnerable to seismic damage. The slope bulges under the earthquake loading; the maximum permanent surface displacement occurs at the middle–upper part of the slope, rather than the slope crest. Additionally, the response of seismic safety factor lags behind the responses of acceleration and surface displacement.

This paper presents a three-dimensional (3D) multi-surface plasticity model to computationally simulate the behavior of coarse-grained granular soil during seismically-induced liquefaction. The model extends an existing multi-surface plasticity formulation and includes the Lade–Duncan failure criterion as the yield function to more closely capture salient characteristics of laboratory test data. Subsequently, flow rules are updated for modeling the essential shear response mechanisms associated with dilatancy, cyclic mobility, and post-liquefaction shear strain accumulation. The constitutive model is implemented into the OpenSees computational framework, and Finite Element (FE) calibrations are undertaken to match a set of laboratory test data, including drained monotonic/undrained stress-controlled cyclic triaxial tests, and a centrifuge test on a liquefiable sloping ground. It is demonstrated that the soil constitutive model and the employed computational framework can reasonably predict the seismic response of the liquefiable sloping ground under earthquake loading. On this basis, full 3D FE simulations of a typical bridge abutment seated on liquefiable sloping ground are conducted to further highlight underlying earthquake-induced liquefaction effects on the ground-structure system deformations. Overall, the developed constitutive model provides a useful tool for evaluating earthquake-induced soil liquefaction hazards and associated 3D ground seismic response scenarios.

Small dams are critical infrastructures, which provide different kinds of benefits, such as water supply, flood control, hydropower generation. Existing small dams are typically embankment structures, built without complying with the regulations of well-engineered large dams. Being often located near inhabited areas, the failure under earthquake loading of such types of structures would entail serious consequences for community safety. This paper aims at proposing a multi-scale methodology to assess the seismic risk of small dams. An application is illustrated with reference to the dams located in the Valle d’Aosta Region (Italy). State-of-the-art indices for large-scale risk-based prioritization are computed by convolving the seismic hazard with the vulnerability and the exposure. According to the methodology, for the dams to which the worst values of seismic risk indices are assigned, specific analyses based on Monte Carlo simulations are carried out to express the seismic response of embankment dams by addressing the associated uncertainties. The outcomes computed in the preparedness phase could be adopted to evaluate in near real-time the response of small dams in the immediate aftermath of an earthquake. Indeed, an algorithm was developed by using Geographic Information System for near real-time assessment of earthquake-related damage to small dams. The proposed multi-scale tool may support decision-makers, from civil protection organizations at the national level down to regional administrations, dam owners, first responders, infrastructure operators, and environmental protection agencies.

Liquefaction has been known as a phenomenon in which the shear strength and stiffness of saturated soil are reduced by the generation of pore water pressure under earthquake loading. Consequently, liquefaction-induced settlement can result in severe damage including building cracks or slope failure, which pose a threat to human lives and properties. In the current Vietnamese standard TCVN 9386:2012, liquefaction potential hazard is often evaluated using the simplified method, which solely identifies the areas with a high risk of liquefaction. Prediction of Safety Factor (FS), Settlement (S), Liquefaction Potential Index ( LPI ), and Liquefaction Severity Number ( LSN ) has not received sufficient attention to a completeness standard. This study assesses the liquefaction of the site at Ho Chi Minh City, Vietnam by using four conventional methods: the simplified procedure, linear equivalent analysis, loosely-coupled effective stress analysis, and fully-coupled effective stress analysis based on standard penetration test (SPT) data in Ho Chi Minh Metropolitan City. A class of seismic events that are compatible with the design response spectrum in the Vietnamese standard TCVN 9386:2012 is used as input ground motion at the bedrock. According to the results of different methods, maps of ground settlement, LPI , and LSN are proposed as useful references for construction works on such soils, which may have a high potential for liquefaction and subsidence.