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A dynamic analysis of the Makhool dam using Geo-studio software is presented in this paper for the purpose of investigating the seismic behavior of earth dams. With emphasis on the dam's height, soil characteristics, and input motion, this study examines the effect of earthquake excitation on the dam's behavior. With input from the SEEP/W program, the analysis was conducted using the QUAKE/W program. In this study, the horizontal component of motion was taken at three different values: 0.04g, 0.06g, and 0.08g. In addition to total stress in x-direction and y-direction, pore water pressure, and x-displacement, the results were presented in figures. Study findings showed that the horizontal displacement and shear strain of the dam increased with dam height, with the maximum displacement of the dam equal to 94 cm at the end of the earthquake. Besides the type of dam soil, the acceleration of the dam was also affected by the strength of the soil, since weaker soil reduced the acceleration of the dam. The pore-water pressure at the dam's base was the highest, with the horizontal movement increasing with depth. In earthquake zones, seismic evaluation is vital for dam construction, and the research provides valuable advice for designing and building earth dams. [ABSTRACT FROM AUTHOR]

Seismic risk is one of the biggest challenges for tunnel safety, and several mitigation techniques have been proposed to enhance the seismic performance of existing tunnels. This paper aims to investigate the effectiveness of an innovative approach for reducing the seismic risk of existing tunnels by using soft material walls (SMW) symmetrically installed in the surrounding soils. The investigation is performed with a two-dimensional numerical model and the effectiveness of SMW in mitigating the seismic-induced lining forces is quantitatively evaluated by reduction ratio. The influences of nonlinear properties of soil, SMW and tunnel lining on the isolation effectiveness are also discussed. The parametric studies show that the computed reduction ratio is strongly affected by the modulus ratio between the SMW and the soil, the wall geometric parameter, and the flexibility ratio. It is more effective for the thick and soft isolation walls that are inserted near a stiff tunnel in the soft soil. The tunnel seismic response can be reduced by up to 50% for the scenarios investigated. Notably, the parametric study identifies an optimum normalized depth of SMW and recommends a relation between the maximum isolation effect and the flexibility ratio. Finally, simple charts are suggested in this work for estimating the isolation effect in specific conditions of the soil and the tunnel. Along these lines, the results of this work may be used in the seismic retrofitting of an existing tunnel, aiding the preliminary design of the isolation walls. [ABSTRACT FROM AUTHOR]

For extended structure, the seismic load has a spatiotemporal variation that simultaneously changes with time and space. The incorporation of the seismic wave spatial random variability effect is especially important when large structures such as long bridges, dams, and large buildings are analyzed. The effect of spatially varying earthquake ground motion (SVEGM) on the seismic response of earth dams is analyzed in this paper. To this end, a parametric study is conducted to investigate the effects of length to height ratio (H L) on the 3D seismic response of the studied dams. Ground motions, consistent with the three-directional lagged coherency model, are generated at different discretized cells at the base of the dam. The dams are assumed to sit on trapezoidal and V-shaped canyons and vibrate in all three directions, upstream-downstream, vertical, and longitudinal. The average coherency of different frequencies is calculated and used for the generation of SVEGM. The time histories are simulated using a spectral representation-based method. The separation distance between the cells is determined in such a way that 90% of correlation between seismic input motions can be captured. For each case of H L ratio, a numerical model of the dam and its foundation is constructed using the finite difference numerical method. The 3D seismic behavior of the earth dams is evaluated under the artificially generated three-directional components of SVEGM. Generally, it is concluded that with increasing H L ratio, at the midpoint of the dam crest, the difference between maximum of acceleration values obtained by applying uniform and SVEGM excitations decreases. In all cases of analyses, SVEGM has decreasing effect on the vertical displacement of dam crest. [ABSTRACT FROM AUTHOR]

This paper discusses continuum models for simulating earthquake sequences on faults governed by rate-and-state dependent friction. Through detailed numerical analysis of a conventional strike-slip fault, new observations regarding the use of various continuum earthquake models are presented. We update a recently proposed plasticity-based model using a consistently linearized formulation, show its agreement with discrete fault models for fault thicknesses of hundreds of meters, and demonstrate mesh objectivity for slip-related variables. To obtain a fully regularized fault width description with an internal length scale, we study the performance and mesh convergence of a plasticity-based model complemented by a Kelvin viscosity term and the phase-field approach to cohesive fracture. The Kelvin viscoplasticity-based model can introduce an internal length scale and a mesh-objective response. However, on grid sizes down to meters, this only holds for very high Kelvin viscosities that inhibit seismic slip rates, which renders this approach impractical for simulating earthquake sequences. On the other hand, our phase-field implementation for earthquake sequences provides a numerically robust framework that agrees with a discrete reference solution, is mesh objective, and reaches seismic slip rates. The model, unsurprisingly, requires highly refined grids around the fault zones to reproduce results close to a discrete model. Following this line, the effect of an internal length scale parameter on the phase-field predictions and mesh convergence are discussed. [ABSTRACT FROM AUTHOR]

This paper introduces a new low-damage hybrid steel–timber rocking braced frame with self-centring capability and proposes a design methodology in the framework of Canadian design standards. This system consists of a gravity load-resisting timber frame and a steel concentrically braced frame acting as the lateral load-resisting system that is connected using U-shaped steel fuses. The self-centring capability is achieved by post-tensioning strands and rocking bases within the lateral load-resisting system. The system, along with its components, is first introduced. The proposed design method and system performance objectives are then presented. The seismic performance of the system and the proposed design procedure are validated through numerical analyses considering the interaction between the lateral and gravity load-resisting systems. The results of dynamic analyses confirm the enhanced seismic performance of the proposed hybrid system with almost no residual deformations after the earthquake. Moreover, the proposed design guidelines can accurately predict the system's seismic response and demands imposed on the members. [ABSTRACT FROM AUTHOR]

Seismic isolation devices, as known, are particularly efficient tools for the protection of newly designed or existing buildings and infrastructures and for the mitigation of maximum effects due to earthquakes. The highest is the vulnerability of a given existing construction, and the higher is the benefit in structural terms due to a possible retrofit intervention based on base isolation. This is especially the case of reinforced concrete (RC) building frames built in the 1960s in the Italian context and originally designed with a code of the first generation ("Regio Decreto Legge 25 Marzo 1935, n. 640") in a city characterized by a long history of severe earthquakes (as the Reggio Calabria and Messina earthquake in 1908), and thus recognized as highly seismic regions. In this paper, a case-study application is proposed for the Frangipane school constructed in Reggio Calabria (Italy) and recently subjected to a major renovation intervention for its retrofit against the high seismic hazard. [ABSTRACT FROM AUTHOR]

A large number of fires occur in offshore structures as a result of oil spill or earthquake. A potential but rarely examined risk is the sequential happening of fires and earthquakes. The high ignition temperature can have serious structural influences on the seismic behavior of dolphin-type berth structure. The fire induced structural effects on the seismic performance of Dolphin structure is not well unstated, but may be critical in the occurrence of aftershocks and/or future ground excitations. Considering the irreparable consequences of reducing the seismic performance of fixed marine structures under post-fire conditions, it is vital for engineers to better understand post-fire earthquake hazards in Dolphin structure. The current manuscript presents a numerical investigation to examine the influence of post-fire conditions on the seismic behavior of dolphintype berth structure. the main goal of this paper is to investigate the effects of fire on the seismic response of the structure. In order to better investigate the effects of temperature increase on the performance of the structure, fire is applied in the first stage near the water surface and in the second stage to the berth deck. The ABAQUS software package is utilized to model and solve the problem. [ABSTRACT FROM AUTHOR]

Tailings impoundments are often prone to failure due to various causes related to complex loading conditions. For instance, tailings impoundments can fail during or after a seismic event, mainly because of the liquefaction of loose, cohesionless tailings. To improve the seismic stability of impoundments, the density of the tailings can be increased or waste rock inclusions (WRI) can be added in the impoundment. This paper presents the results of numerical analyses of the impoundments loaded with a variety of ground motions with different frequencies, scaled at two different levels of intensity representative of two mining regions of Eastern Canada. The results show that the conventional impoundments are subjected to medium to high displacements at the end of shaking; these show a high probability of rupture during the earthquake or in the post-seismic phase. Tailings densification can decrease the volume of liquefied tailings and displacements during the seismic phase but does not significantly reduce the probability of post-seismic failure. WRI can slightly reduce the volume of liquefied tailings, depending on the intensity of the motions, but the reinforcement reduces significantly the lateral displacements; impoundments with WRI show even better performances during the post-seismic phase. The use of WRI is deemed a good approach to ensure the seismic stability of tailings impoundments and reduce the risk of seismically induced failure. [ABSTRACT FROM AUTHOR]

This paper represents the analysis and interpretation of the airborne magnetic data of central and northern Egypt to delineate the subsurface faults and other structures and also the tectonic framework of the area. First, the total observed magnetic field data was reduced to the north magnetic pole (RTP) and using the power spectrum, the regional and residual magnetic fields were separated using the Butterworth filter to isolate the anomalies caused by each of them. Then, the airborne magnetic data was subjected to several filters to enhance the signals from the different magnetic sources for better delineation and edge detection. Additionally, Euler deconvolution was applied to estimate the depth of the different magnetic sources. The final outputs show a wide variety of magnetic anomalies reflecting different magnetic sources and subsurface features. The main subsurface structures are the linear NNW-SSE parallel to the Red Sea trend and the Gulf of Suez and the NE-SW faults and lineaments surrounding the basins in the northern and western area, the deeply rooted basic intrusions, and the depo-centers (basins) in the western and central parts of the area. Moreover, the area shows several basement uplifts and consequently faulted basins of different directions and displacements. [ABSTRACT FROM AUTHOR]

This paper presents a hybrid-triggered catastrophe bond (CAT bond) pricing model. We take earthquake CAT bonds as an example for model construction and numerical analysis. According to the characteristics of earthquake disasters, we choose direct economic loss and magnitude as trigger indicators. The marginal distributions of the two trigger indicators are depicted using extreme value theory, and the joint distribution is established by using a copula function. Furthermore, we derive a multi-year hybrid-triggered CAT bond pricing formula under stochastic interest rates. The numerical experiments show that the bond price is negatively correlated with maturity, market interest rate and dependence of trigger indicators, and positively correlated with trigger level and coupon rate. This study can be used as a reference for formulating reasonable CAT bond pricing strategies. [ABSTRACT FROM AUTHOR]

Due to its location in one of the most seismically active regions in the world, Iran has witnessed many devastating earthquakes through history. To finance a part of these losses and reconstruction expenses, earthquake insurance has been offered as a rider of fire policy by the Iranian insurers. This mechanism, if well operated, can substantially contribute to disaster risk management. On the other hand, if the pricing and management of catastrophe risk lack a sound, risk-based practice, it might add to the problems and act to the detriment of disaster risk management. In this paper, we first compare the current earthquake insurance pricing and risk management in the Iranian insurance industry with a state-of-the-art insurance regulation in the European Union (Solvency-II). Then, we examine the consequence of following each approach in terms of business profitability and viability by conducting a numerical analysis on a hypothetical portfolio of property risks in Iran. The results suggest that maintaining the current insurance pricing and risk management techniques in Iran will probably lead to a substantial accumulation of earthquake risk for domestic firms and eventually endanger the solvency of these companies in the event of large- scale earthquake losses in future. [ABSTRACT FROM AUTHOR]

The paper illustrates the construction of abacuses for the semi-quantitative assessment of stratigraphic seismic amplification phenomena, applicable in the eastern Abruzzo region (central Italy). The abacuses provide three expected Amplification Factors (Fas): Fa0.1-0.5, Fa0.4-0.8, Fa0.7-1.1, performed as the ratio between the integral of output and input, in the mentioned time intervals, considering the acceleration response spectra. The choice derives from the fact that these parameters are better correlated to the response of the buildings, characterised by their own different periods. To prepare the abacuses, a procedure was adopted that took into consideration the geological analysis of the area, the collection of all the available geophysical and geotechnical data, the choice of the seismic inputs representative of the seismic hazard, the identification of the main seismic stratigraphic sequences and the numerical analysis aimed at evaluating the Fa. The abacus consists of a series of tables prepared in order to take account of the stratigraphic variability in the area, as a function of the basic seismic hazard level and the vibration period interval to calculate the Fa. By knowing the stratigraphic and mechanical characteristics of the site and using the abacuses, the values of the Fa are obtained. [ABSTRACT FROM AUTHOR]

The review focuses on three main essentials of numerical analyses, namely soil behavior and constitutive model, pile and pile-soil interface modeling and computational framework. This paper presents a critical review of the current challenges in analyzing large, realistic pile groups in soft clay soil under earthquake shaking. [Extracted from the article]

The present manuscript deals with the seismic vulnerability assessment of existing masonry churches, which is a fundamental process for risk and consequent prioritization analyses, as well as application of effective retrofitting strategies. In the past, different approaches with various levels of accuracy and application ranges have been developed to assess the vulnerability to damage of such structures in case of seismic events. Based on the classification provided in the Italian Guidelines for the Cultural Heritage, in this paper a review of seismic vulnerability assessment methodologies for existing masonry churches is presented. The main goal of the current study is to provide a critical comparative overview about these procedures, highlighting the main issues related to the application of each detail level. Moreover, particular attention is focused on the applications present in literature, allowing for the definition of a potential systematic procedure for smart management policy aimed at preserving cultural, architectural and historical heritage. [ABSTRACT FROM AUTHOR]

Geotechnical seismic isolation (GSI) consists of an innovative technique to mitigate the effects of earthquakes based on interposing a superficial soil layer to filter the seismic energy from the soil to the structure. This approach is particularly applied in developing countries due to low-cost applications. In order to account the uncertainties, the presented paper aimed to develop fragility curves of 3D configurations performed by numerical finite element models. The mail goal is to assess and discuss the potentialities of GSI as a mitigation technique for several configurations. Opensees PL has been applied to perform the numerical analyses and to realistically reproduce the behaviour of GSI. [ABSTRACT FROM AUTHOR]

In this study, a hybrid countermeasure for river embankments is proposed consisting of a wall of sheet-piles installed on one side of the toe of embankment and partial floating sheet-piles (PFS) installed on the other. Previous studies show that the PFS method is effective against embankment settlement caused by liquefaction of loose sand and consolidation of soft clay. However, such previous studies were carried out on simple model cases, and hybrid countermeasures on actual embankments have not been thoroughly studied. Therefore, the authors have performed numerical analyses to verify the effectiveness of the hybrid countermeasure applied to actual field conditions with an earthquake motion occurred in the past. It was concluded that the settlement of embankment was reduced by the hybrid countermeasure even in the actual field case. Additionally, authors obtained fundamental data for making a design method, that is the maximum bending stress among the different lengths of the sheet-piles after consolidation. [ABSTRACT FROM AUTHOR]

Underground structures are susceptible to float and move upward during earthquakes when located in a liquefiable soil deposit. There are examples of this phenomenon in past major earthquake events. In this study, the uplift of circular tunnels in a liquefiable sand layer was investigated with a series of shaking table tests. The research has focused on the buried depth of the tunnel, tunnel diameter, tunnel weight, liquefaction extent, uplift mechanism, and factor of safety against liquefaction-induced uplift. According to the test results, the shallow buried depth, larger diameter, and lower weight can intensify the tunnel uplift, so the displacement in post-liquefaction time continues at the same rate as during the shaking time. Due to the shear-induced dilation, pore water pressure generation around the tunnel was reduced compared with that of the free field. The excess pore water pressure dissipation in the soil overlying the uplifted tunnel was significant, which leads to suction in the soil deposit. Furthermore, the acceleration response of overlying soil with the uplifted tunnel was similar to that of the free field. However, the soil acceleration response around the tunnel without uplift was similar to the base motion. [ABSTRACT FROM AUTHOR]

During the past years, different control devices have been introduced and used to reduce the response of structures. This article presents the performance of active-passive tuned mass dampers (AP-TMDs) in the reduction of structural responses and a comparison between the uses of different controllers, including tuned mass damper (TMD), active tuned mass damper (ATMD), and multituned mass damper (MTMD). Analyzing and modeling the structure under four near- and far-field earthquakes are performed in MATLAB and SIMULINK. Finally, the responses of controlled and uncontrolled structures equipped with these controllers are investigated. Fuzzy and genetic-based fuzzy logic controllers are used to determine the control force of ATMD and AP-TMD, respectively. In order to compare the performance of the dampers, the mass ratio of TMDs is fixed in all cases and is taken to be 5%. Damping of the structure is considered equal to 5%. The frequency and damping ratio of TMDs with maximum and RMS displacement optimization criteria are obtained. The mass ratio of TMDs in controlled structures with MTMD and AP-TMD is calculated by numerical analysis. It can be inferred that using control force affects response reduction in both ATMD and AP-TMD controllers significantly. In addition, using AP-TMD can bring the merits of both passive and active systems by providing active control and reducing power requirements for control forces. All controllers are recommended for structural control although AP-TMD reduced maximum and RMS displacement by about 50% in the best case, which has better performance than others. On the other hand, ATMD decreased RMS acceleration by 37.5% on average in four earthquakes compared to the uncontrolled structure. [ABSTRACT FROM AUTHOR]

This paper presents details of numerical investigations on exterior beam-column joint sub-assemblages with a novel fuse link beam-to-column connection. The connection is designed to protect the connected beams and columns of moment frame buildings during strong earthquake shaking by confining the inelasticity within the connection elements. The connection consists of two fuse links and one standard shear tab. Detailed numerical analyses are performed to study the behaviour of the connection including the level of plastic strain distribution around the connection region. First, the results of numerical analyses are validated using experimental results of full-scale experimental investigations on exterior beam-column joint sub-assemblages, which demonstrated the good performance and replaceability of the connection. Then, parametric studies are carried out to identify and investigate the effect of major parameters on the connection behaviour - the key parameters being the geometric parameters of fuse link and the beam depth. Finally, it is shown that the results of the numerical study are in good agreement with those of an analytical model that can be used for proportioning of the fuse link connection at the design stage. Also, the results of the analytical model can be used in global analysis of moment frames using the developed fuse link connection. [Display omitted] • A new partial-strength strong-axis steel beam-to-column moment connection is developed. • A methodology is proposed to design the fuse link beam-to-column connection • Detailed numerical analyses is carried out to verify the proposed design methodology • Numerical results clearly depicts concentration of inelasticity within the fuse link keeping the primary members elastic • The proposed design methodology is simple and efficient. [ABSTRACT FROM AUTHOR]

On 4 March 2021, two tsunamigenic earthquakes (Mw 7.4 and Mw 8.1) occurred successively within 2 h in the Kermadec Islands, offshore New Zealand. We examined sea level records at tide gauges located at ∼100 to ∼2000 km from the epicenters, conducted Fourier and wavelet analyses as well as numerical modeling of both tsunamis. Fourier analyses indicated that the energy of the first tsunami is mainly distributed over the period range of 5–17 min, whereas it is 8–32 min for the second tsunami. Wavelet plots showed that the oscillations of the first tsunami continued even after the arrival of the second tsunami. As the epicenters of two earthquakes are close to each other (∼55 km), we reconstructed the source spectrum of the second tsunami by using the first tsunami as the empirical Green's function. The main spectral peaks are 25.6, 16.0, and 9.8 min. The results are similar to those calculated using tsunami-to-background ratio method and are also consistent with the source models. [ABSTRACT FROM AUTHOR]

Following the Cephalonia, Greece, 2014 earthquake sequence (Mw=6.1 and Mw=6.0), liquefaction of gravelly earthfill materials at the ports of Lixouri and Argostoli resulted in the manifestation of ground cracking and coarse-grained soil ejecta, and the quay walls in these ports exhibited lateral ground displacements ranging from 0.1 to 1.5 m. To evaluate the seismic performance of the port quay walls, numerical analyses using the finite-difference method were performed, and the results compared with the observed response. Three commonly used constitutive models (PM4Sand, UBCSand, and URS/ROTH) calibrated based on in situ site investigation data were considered in modeling the liquefiable earthfills. The results of the numerical analyses at both ports using the best-estimate parameters indicate that taller walls exhibit smaller lateral ground displacements than shorter walls, something that is in line with field observations. For the shorter walls, liquefaction-induced lateral spreading played an important role in the observed response, whereas for the taller walls, the seismic behavior is dominated predominantly by the dynamic response of the structural system. PM4Sand and UBCSand models seem to yield very similar deformational results, but the URS/ROTH model, which assigns residual shear strength parameters once liquefaction is triggered, resulted in horizontal displacements that are closer to the observations for short-wall geometries but overpredict the response when the effect of liquefaction on the overall displacements is small. Finally, the numerical analyses demonstrate the strong influence of the pulselike characteristics, as well as the polarization of the input motion on the seismic response of the Lixouri quay walls, indicating that forward directivity contributed significantly to the observed quay wall deformations. [ABSTRACT FROM AUTHOR]

The present manuscript deals with the seismic vulnerability assessment of existing masonry churches, which is a fundamental process for risk and consequent prioritization analyses, as well as application of effective retrofitting strategies. In the past, different approaches with various levels of accuracy and application ranges have been developed to assess the vulnerability to damage of such structures in case of seismic events. Based on the classification provided in the Italian Guidelines for the Cultural Heritage, in this paper a review of seismic vulnerability assessment methodologies for existing masonry churches is presented. The main goal of the current study is to provide a critical comparative overview about these procedures, highlighting the main issues related to the application of each detail level. Moreover, particular attention is focused on the applications present in literature, allowing for the definition of a potential systematic procedure for smart management policy aimed at preserving cultural, architectural and historical heritage.