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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.

A wharf is typically constructed as an engineering structure for loading and unloading goods. This structure may be built on weak layers of sand and gravel, depending on the beach conditions. In this way, if a wharf is poorly designed or experiences a rupture, all activities at the site might be halted for a significant period, potentially causing damage to nearby facilities. For this reason, it is of great importance to evaluate the behavior of coastal structures against rupture factors, such as earthquakes and their liquefaction effects. Generally, numerical methods are used to analyze the performance of wharves against liquefaction. This article aims to simulate liquefaction in the soil around the wharf by applying the capabilities of FLAC3D software to analyze nonlinear effective stress and generate excess pore water pressure in a continuous soil environment. The simulation was conducted using the P2PSand behavioral model, a multi-directional model, under bidirectional earthquake loading. Subsequently, the effect of various earthquake parameters on wharf behavior was investigated to extract results for excess pore water pressure, horizontal displacement, soil settlement, and bending moments of piles. Further, an attempt was made to assess the correlation of these parameters with different earthquake factors. Earthquake intensity measures are crucial in the probabilistic seismic demand assessment of various structures. Thus, this study seeks to investigate determinant indicators such as efficiency, practicality, proficiency, and sufficiency in relation to earthquake magnitude and the distance from the center of earthquake propagation to evaluate the quality of earthquake intensity measures. The results indicated good agreement between earthquake CAV parameters and response parameters.

Seismic performance of a flexurally-dominated reinforced concrete wall is dependent on the response of its end boundary zones. In order to evaluate the performance of structural walls, a common practice adopted in laboratories is to test reinforced concrete columns representing the corresponding wall boundaries under uniaxial cyclic loading. This paper presents a numerical investigation leading to the development of a quasi-static uniaxial cyclic loading protocol based on the inelastic strain demands at the wall boundaries, when the corresponding structural wall is subjected to earthquake ground motions of various characteristics. With an increasing emphasis on performance-based design, the proposed loading protocol is structured around inelastic strain demands generated at the performance-based drift limits of structural walls. Non-linear time history analyses are carried out on a numerical wall model to obtain the average strain histories at the wall boundaries. A statistical evaluation of the number of inelastic cycles and the corresponding strain ranges forms the main basis for deriving the loading protocol. As damage is predominantly caused due to repeated large inelastic strain excursions, the rain flow cycle counting method is utilized for counting and sorting of the inelastic cycles. The proposed uniaxial cyclic strain histories are more representative of the cumulative demands imposed by moderate-to-large magnitude earthquakes, and their application would facilitate a more rational assessment of the seismic performance of flexurally-dominated RC walls than the current approach of testing boundary zones under arbitrarily decided tension-compression cycles.

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.

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).

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.

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.

In the early hours of June 24, 2017, a major landslide event occurred in Xinmo Village, Sichuan Province, China. The landslide instantly devastated the whole village. Ten people died and 73 were missing in this major landslide event. The study area has suffered from several strong earthquakes in the past 100 y. Present studies have reported that the cumulative damage effect of the Xinmo landslide induced by earthquake is obvious. In this study, we conducted a shaking table test based on the detailed geological survey, historical seismic data, satellite optical image, unmanned aerial vehicle photography. The test result presents the characteristics of multistage seismic damage and progressive deformation process of the Xinmo landslide model, and shows that the historical earthquakes have caused serious damage to the interior of rock mass in the source area. The test also shows that the cumulative damage of the model increases with an increase in duration of earthquake loading. When the excitation intensity increases to a certain value, the damage accumulation velocity of the model suddenly increases. It reveals that frequent historical earthquake loads can be regarded as a main reason for the damage and deterioration of landslide rock mass. Damage accumulation and superposition occur in the slope. Under a long-term gravity, deformation of the slope gradually increases until catastrophic failure is triggered. The progressive deformation process of slope is summarized. Firstly, under strong earthquakes loading, a tensile fracture surface forms at the rear edge of the wavy deformation high and steep bedding slope. It reaches a certain critical depth and expands along the interlayer structural plane. Meantime, damaged fissures perpendicular to the structural plane also appear in the steep-gentle turning area of the slope. Secondly, under a coupling action of seismic loading and gravity, the interlaminar tensile crack surface at the rear edge of the slope extends to depth continuously. Meanwhile, rock fracture occurs in the steep-gentle turning area. The “two-way damage propagation” mode of the inter-layer tensile crack surface occurs until the sliding surface is connected. However, due to the “locking section” effect of rock mass at the slope foot, it can still maintain a short-term stability. Thirdly, under the influences of the heavy rainfall before a landslide and the long-term gravity of the upper sliding mass, rock mass in the steep section at the slope foot breaks outward. Finally, a catastrophic landslide occurs.