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This study delves into the intricate interplay of reservoir–foundation interaction on the structural comportment exhibited by concrete gravity dams, employing the Pine Flat dam as a representative case study. In the context of seismic excitation sourced from established FEMA standards, a comprehensive investigation was conducted, encompassing both linear and nonlinear mass concrete behaviors. The coupled problem of fluid–structure interaction was solved simultaneously using implicit finite element technique. The findings of this research show the significant augmentation of tensile strength, moderation of compressive stress, and the introduction of precarious failure mechanisms within the dam structure when the reservoir–foundation interaction is considered. These observations underscore the necessity of accounting for this interaction in dam engineering, whereas disregard for this interaction in dam design culminates in inherently unsafe and unreliable results. [ABSTRACT FROM AUTHOR]

This study investigated the hydrodynamic characteristics associated with the shape and descent height of falling objects, focusing on the generation, propagation, and deformation of landslide-generated tsunamis (LGTs). It also examined the run-up, wave pressure, and wave force against a simplified dam model through numerical analysis using LS-DYNA based on fluid–structure interactions. The initial wave is characterized by a drastic increase in the water-surface elevation owing to the falling impact, followed by a secondary wave induced by the ascent of the displaced air mass. Objects with a low shape ratio produce a concentrated impact load that generates LGT waves with high amplitudes, strong nonlinearity, and asymmetry. These highly nonlinear waves gradually transform into stable waveforms, balancing the dispersion and nonlinearity as they propagate. When the shape ratio of the falling object reaches 2.04, the run-up height at the vertical wall peaks, and the hydrodynamic pressure distributed over higher positions increases, which shifts the fluid force application point and significantly increases the moment. Consequently, for gravity dam designs accounting for the LGT wave pressure, a trapezoidal cross-section with a wider base is essential to enhance structural stability, considering that the dam must withstand shear forces and moments that exceed those generated under hydrostatic pressure. This study identifies the critical conditions under which LGTs pose the greatest risk and emphasizes the need to consider nonlinear wave interactions in engineering calculations for dam design and reinforcement strategies. [ABSTRACT FROM AUTHOR]

The failure mechanism of a gravity dam under blast loading is much more complex than failure under other dynamic loads such as earthquakes. It is therefore important to evaluate the safety performance of these structures under blast load. The structural dynamic behaviour of Koyna dam, India, subjected to underwater explosion (UndEx) was investigated. The Johnson–Holmquist 2 model was used to capture the non-linear response of concrete. The dam–reservoir interaction was modelled using the coupled acoustic–structural technique, which employs a total wave formulation to incorporate the propagation of spherical shock waves. Dynamic responses such as displacement, damage profiles and principal stresses under various detonation depths, weights and reservoir levels were examined. The findings indicated that areas facing the explosion experience the most damage, while local damage occurred at the dam's heel as the explosion depth increased. Additionally, displacement decreased notably as the TNT depth increased for a consistent explosive amount. The damage distribution in the dam was found to depend on both TNT depth and weight. Damage accumulation in the dam was substantially reduced by lowering the reservoir height (five different levels were assessed). The results provide valuable insights into the Koyna gravity dam's response to UndEx under varying conditions. [ABSTRACT FROM AUTHOR]

This study aims at seismic fragility assessment of concrete gravity dams under synthetic near source ground motions. The numerical modelling of the dam-reservoir-foundation coupled system and the nonlinear time history analysis are carried out in ABAQUS. Two sets of synthetic near source records characterized by forward-directivity and fling-step effects are generated using an empirical stochastic approach. Maximum value of the seismic response quantities of the coupled system are obtained as engineering demand parameters (EDP) and various ground motions parameters are selected as intensity measurement (IM). Fragility functions are generated from the cloud response data (EDP-IM pairs) using a Probabilistic Seismic Demand Model (PSDM). [ABSTRACT FROM AUTHOR]

Seismic isolation and damping technologies, though extensively used in buildings, are less common in large hydraulic structures, underscoring the importance of researching seismic mitigation methods for these constructions. This research first establishes that saturated sandy soil can act as a damping material through experimental and theoretical analysis. Subsequently, a novel hollow concrete gravity dam containing saturated sandy soil is proposed, utilizing the EOS (equation of state) subroutine for viscous fluids to model the liquefied sand. The findings indicate that the new-type dam exhibits a reduction in displacement of approximately 20% along the flow direction under an 8-degree seismic event compared to conventional gravity dams. This decrease correlates inversely with the characteristic wave speed of the saturated sandy soil, while the energy dissipation capacity of the saturated sandy soil is directly proportional to the soil layer's thickness. Finally, a small-scale shaking table test revealed that saturated sandy soil effectively reduces displacement and acceleration at the dam crest. These findings were corroborated by numerical simulations, which further substantiated the reliability of both the experimental and simulated data. Utilizing saturated sandy soil for energy dissipation and seismic damping in dams offers cost benefits, high durability, and significant effectiveness, representing a promising direction for the advancement of seismic mitigation in concrete gravity dams. [ABSTRACT FROM AUTHOR]

Seismic damage assessment of concrete gravity dams is a challenging task due to the difficulty in establishing the damage states in relation to target performance levels. Post-seismic loading and uplift in cracking is generally not considered in this complex assessment and the effects are not clear. A quantitative damage estimation approach considering post-earthquake effects is proposed in this work to investigate this issue. A novel procedure to include post-earthquake effects on the monolith cracking was proposed in which demands from the aftershocks and uplift are assessed on the cracked state after the main event. Damage state was quantified in terms of the extent of crack propagation on the dam monolith. Categorising performance as such, the effects of post-earthquake factors were investigated on three representative systems in two steps. First, over 2000 nonlinear time history analyses were conducted to obtain damage states for the main shaking event. Then, the change in these states due to the effect of post-earthquake factors, including water pressure penetrating the cracks and aftershocks, were quantified. The results, as well as the methodology proposed, can serve organisations managing dam stock risk in re-assessment of seismic analysis results considering post-earthquake effects. [ABSTRACT FROM AUTHOR]

Copyright of Water Conservancy Science & Techonlogy & Economy is the property of Water Conservancy Science & Technology & Economy Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To improve the calculation accuracy of the Monte Carlo (MC) method and reduce the calculation time. Firstly, CNN and LSTM deep learning networks are introduced for designing nonlinear dynamic systems simulating dam stress. Then, spatial feature mining and sequence information extraction of nonlinear data of dam stress are carried out respectively, and a combined prediction model of dam stress depth (DS-FEM-CNN-LSTM) is proposed. Secondly, to solve the problem of a long time and heavy workload for the MC method to calculate a single sample point, the DOE test method is used to design the sample points. The weight factor and the distance to the failure surface are used as screening criteria. The reliability calculation method of the gravity dam (DS-FEM-CNN-LSTM-MC) is established. Finally, numerical results show that the proposed DS-FEM-CNN-LSTM-MC method performs better than the existing methods in terms of computational time consumption and accuracy. [ABSTRACT FROM AUTHOR]

A scaled model of a concrete gravity dam was designed, and nine tests were conducted to investigate the dynamic response characteristics of the dam subjected to underwater explosions. The pressure time histories in the water, and the velocity and acceleration time histories of the dam during various explosions were recorded. The acceleration signal was processed by the Fast Fourier Transform (FFT) to perform time–frequency conversion. The energy migration law of the acceleration signal along the dam elevation was explored based on the theory of wavelet packets. Furthermore, the effects of charge weight, explosion distance, and explosion depth on the dynamic response of the dam were comprehensively investigated. The results show that the distribution of peak acceleration along the dam elevation closely relates to the explosion distance, but the global response of the dam tends to weaken as the explosion distance increases. Increasing the charge weight causes an enhancement in the dam response. Compared with an explosion suspended in water, the bottom explosion causes a weaker response to the dam. With the increase of the dam elevation, the energy of the acceleration signal gradually shifts from low frequency to high frequency. The bubble curtain has a significant mitigation effect against underwater explosions. [ABSTRACT FROM AUTHOR]

Purpose: The dams with unconventional cross-sections are vulnerable to strong earthquakes, with most of the damages occurring at the neck region where there is a change in the slope of the cross-section at the downstream side. In the event of a sequence of mainshock and aftershocks, complete failure of the neck region is anticipated. With this background in view, two such dams, Koyna and Pine Flat dams, are taken as illustrative examples and are analyzed under a sequence of mainshock and aftershocks. Methods: A nonlinear time history analysis of a 2D cross-section of the tallest non-overflow monolith is performed for near and far field station earthquake records. The cross-section is analyzed for the mainshock and aftershock effects by joining the segments of the earthquake with an adequate time gap created by zero excitations. The time gap is decided such that the free vibration of the dam under the influence of one earthquake shock comes to rest with any possible residual displacement. The analysis considers the inelastic effect of the damage plasticity model available in ABAQUS. Results and Conclusion: The results of the numerical study indicate that some portions of the dam included in the neck region may be severely damaged if the effect of aftershocks is considered in the analysis, even at a PGA level of 0.4g. The extent of the damage depends on the type of earthquake and the geometry of the dam cross-section. [ABSTRACT FROM AUTHOR]

The original single component of seismic data served as the foundation for the majority of previous investigations on the impact of pulse-like ground motion on the dynamic response of structures. The seismic responses of significant infrastructure are less studied when multicomponent motion is taken into account as seismic excitation. As velocity pulses may cause considerable damage to long-period structures, it is of great significance to understand the seismic responses of gravity dams under near-fault pulse-like ground motions for mitigating structural damage. In this study, a unique evaluation approach is suggested for examining the dynamic responses of gravity dams using the combined ground motion of the horizontal and vertical components. Furthermore, the seismic responses of the dam body under rotated and scaled multipulse excitations are investigated. We employed continuous wavelet transform to choose 16 near-fault pulse-like ground motions from actual seismic events with similar amplitude as seismic excitation signals in order to simulate the earthquake damage to the Koyna Dam using the finite-element approach. The displacement, principal stress, and damage fractures of the gravity dam are used to quantify the impact of the pulse intensity variation. The analysis results demonstrate that the structure has remarkable seismic response owing to the presence of large pulse records. The large residual and peak displacements are mainly caused by the velocity pulses and the sensitivity of the upper part of the dam neck to the horizontal relative displacement is significantly higher than that of the lower part. Although the mean intensity parameter of the rotated records with velocity pulse is smaller than that of the Koyna nonpulse, the former increases the mean damage to the dam by 41%. Compared with the rotated records, the scaled records may overestimate the damage of pulse-like motions to the structure, and the stronger pulses are likely to cause severe penetration cracks around the dam neck. The seismic response spectra reveal the potential effects of multicomponent pulse-like motions on the gravity dam and emphasize the significance of considering the combined motion for seismic design. [ABSTRACT FROM AUTHOR]

The scaled boundary finite element method (SBFEM) is implemented in ABAQUS through the user subroutine interface. The accuracy of the proposed method and computer program are verified by using two benchmark examples. With the coupled SBFEM and standard finite element method (FEM), the dynamic interaction model of concrete dam – reservoir – foundation considering the geometrical nonlinearity of transverse joints is established using the viscous-spring absorbing boundary conditions. The overlaying element technique is applied to define the contact interface of transverse joints. The dynamic characteristics and linear seismic response of the Koyna gravity dam have been analyzed using polyhedral elements. Finally, nonlinear seismic analysis of the NG5 arch dam has been conducted. The calculated results are in good agreement with those of ABAQUS built-in elements. Moreover, numerical examples demonstrate that proposed method has high computational accuracy and can be applied to the dynamic analysis of complex engineering structures. [ABSTRACT FROM AUTHOR]

An accurate prediction model for dam deformation is crucial for ensuring the safety and operational integrity of dam structures. This study introduces a hybrid modeling approach that integrates long short-term memory (LSTM) networks with Kolmogorov–Arnold networks (KANs). Additionally, the model incorporates a dual-stage attention mechanism (DA) that includes both factor and temporal attention components, enhancing the model's precision and interpretability. The effectiveness of the DA-LSTM-KAN model was validated through a case study involving a concrete gravity dam. A comparative analysis with traditional models, including multiple linear regression and various LSTM variants, demonstrated that the DA-LSTM-KAN model significantly outperformed these alternatives in predicting dam deformation. An interpretability analysis further revealed that the seasonal and hydrostatic components contributed significantly to the horizontal displacement, while the irreversible component had the least impact. This importance ranking was qualitatively consistent with the results obtained from the Shapley Additive Explanations (SHAP) method and the relative weight method. The enhancement of the model's predictive and explanatory capabilities underscores the hybrid model's utility in providing detailed and actionable intelligence for dam safety monitoring. [ABSTRACT FROM AUTHOR]

This research proposes simplified methods for response spectrum and modal dynamic analyses of gravity dams using time-history and spectral seismic accelerations modified to directly account for hydrodynamic effects. The developed methods waive the need for specialized fluid-structure interaction software. They also lead to more accurate assessment of coupled structural flexibility and hydrodynamic effects due to each vibration mode than the static correction method commonly used in traditional simplified methods. The methodology utilizes analytical formulations of hydrodynamic pressure or simplified added masses to obtain the contributions of the selected vibration modes to the total seismic response. A hydrodynamic modification factor characterizing the amplification/de-amplification of acceleration seismic demands due to earthquake-induced hydrodynamic effects is also introduced. The application of the proposed methods is illustrated numerically through examples of two typical gravity dam-reservoir systems subjected to four earthquakes. The obtained results are in excellent agreement with the classical reference solutions. Time-history and spectral seismic acceleration demands modified by hydrodynamic effects as well as selected key response indicators, such as relative displacements and stresses within the studied gravity dams, are discussed. [ABSTRACT FROM AUTHOR]

The geomechanical model test (GMT), a means of intuitively exploring the model's failure modes and revealing failure mechanisms, is considered an effective approach for studying the structural characteristics of dams under complex geological conditions. However, during the overloading process of the model, the catastrophe trends of monitoring data are unclear, and catastrophe points differ at different monitoring sites. These factors have led to large errors in the judgment of researchers regarding the model's state and misperception of the structural properties during the damage process. In this study, a comprehensive evaluation method for the model's state intervals in the damage process is proposed. The criterion employed an interval analysis hierarchy process that considered the differences, consistency, and credibility (CDC‐IAHP) among multiple decision‐makers (DMs), effectively reducing the subjectivity of their judgments. Additionally, this process was combined with cusp catastrophe theory (CCT) to determine whether the model underwent an abrupt change at various overload factors comprehensively. This is the first time that CDC‐IAHP and CCT have been combined as criterion for a comprehensive method on the damage process of concrete dams in GMTs, and was applied to the Wudu gravity dam, indicating its applicability is very good. Compared to the researcher's judgment, this approach is used to analyze and judge the structural state more accurately and scientifically while reducing subjectivity, which can help to better understand the structural characteristics and bearing capacity of actual engineering projects. [ABSTRACT FROM AUTHOR]

Integrating long-term observational data analysis with numerical simulations of dam operations provides an effective approach to dam safety evaluation. However, analytical results are often subject to errors due to challenges in accurately surveying and modeling the foundation, as well as temporal changes in foundation properties. This paper proposes a concrete dam displacement separation model that distinguishes between deformation caused by foundation restraint and that induced by external loads. By combining this model with intelligent optimization techniques and long-term observational data, we can identify the actual mechanical parameters of the dam and conduct structural health assessments. The proposed model accommodates multiple degrees of freedom and is applicable to both two- and three-dimensional dam modeling. Consequently, it is well-suited for parameter identification and health diagnosis of concrete gravity and arch dams with extensive observational data. The efficacy of this diagnostic model has been validated through computational case studies and practical engineering applications. [ABSTRACT FROM AUTHOR]

In this research, the coupled fluid-structure forced vibrations (harmonic load) of the Koyna gravity dam are studied. Using the finite element method (FEM), the influence of structural damping and fluid compressibility are studied for different reservoir dimensions of the dam. The numerical approach is done through the U-P formulation (structure displacement and pressure for fluid). Thus, the spectral response of structural displacements and of hydrodynamic pressures were investigated with different structural damping rates, both considering incompressible and compressible fluids. With analyses, the greater the effect of the structure's damping, the lower the displacement and the hydrodynamic pressure amplitudes. The structural damping has the same effect tendency in both incompressible and compressible fluids. Furthermore, for the incompressible fluid, the coupled modes are not influenced by the length of the reservoir, there are no acoustic modes identified and the mass modes are predominantly identified. With the compressible fluid, the analysis of the dominant modes showed that the fundamental mode is not altered by the length of the reservoir, but from the second mode onwards, each cavity geometry predominates in the vibration, and it is necessary to evaluate the frequency range of the structure and the fluid separately. Therefore, the harmonic numerical analysis of the present study contributes with innovative results of the Koyna dam and in the analysis of the effects involved in Fluid-Structure Interaction (FSI) simulations of other problems related to Dam-Reservoir Interaction (DRI). [ABSTRACT FROM AUTHOR]

Purpose: Concrete gravity dams are important structures for flood control and hydraulic power generation, but they can be vulnerable to seismic activity due to ground movements that trigger crack propagation. Design/methodology/approach: To better understand the factors that affect the stability of concrete gravity dams against concrete fracture during earthquakes, a concrete plastic damage model has been utilized with two new expressions to simulate compressive and tensile damage variables. Findings: The findings showed that the crack patterns were strongly influenced by the concrete's strength. The simulation results led to the proposal of appropriate concrete properties aimed at minimizing damage. These findings, together with the proposed model, offer significant insights that can enhance the safety and stability of concrete gravity dam structures. Originality/value: This study offers a comprehensive analysis of concrete behavior under varying grades and introduces simple and robust expressions for evaluating concrete parameters in plastic damage models. The versatility of these expressions enables accurate simulation of stress-strain curves for different grades, resulting in excellent agreement between model results and experimental findings. The simulation of the Koyna Dam case study demonstrates a similarity in crack patterns with previous simulations and field observations. [ABSTRACT FROM AUTHOR]

Dams have been structures that have served to meet humanity's water needs for centuries. Because they are large structures, critical investigations must be made before they are built. However, these investigations and scaled or one-to-one modeling of dams have become costly today. At this point, package programs working with finite elements are used functionally. ANSYS package program is also a frequently preferred package program that provides results close to reality. In this study, a 3D dam body modeled with ANSYS was examined. While modeling, the water load acting outside the dam's own weight and the material properties of the dam body were taken into account and analyzed. The dam was modeled in accordance with its exact dimensions without any scaling. This study examines the stress and displacement of a concrete gravity dam under half-filled and fully filled conditions, highlighting significant differences in structural behavior. It was determined that the displacement and stress values found for the full state were higher than the half-full state. [ABSTRACT FROM AUTHOR]

Effective temperature control measures are crucial for achieving temperature regulation and preventing cracking in the dam body during the construction of large-volume concrete gravity dams. Due to the low ambient temperatures in winter, it is especially important to focus on temperature control measures for concrete dam construction in cold regions. This paper employs a numerical simulation method that takes into account dam temperature control measures to simulate and predict the overall temperature and stress fields of the Guanmenzuizi Reservoir Dam, and validates these simulations with field monitoring results. This study finds that the ambient temperature significantly impacts the temperature and stress of the dam body's concrete. The internal temperature of the dam reaches its highest value approximately 7 days after pouring, followed by periodic fluctuations, with the dam body's temperature changes exhibiting a certain lag compared to the ambient temperature. The interior of the dam is under compression, while the upstream and downstream surfaces experience significant tensile stress. This project adopts targeted temperature control measures for the cold environmental conditions of the region, which are reasonably implemented and effectively reduce the temperature rise of the concrete during construction, achieving the temperature control objectives. This study also explores the impact of the cooling water pipe density on the dam body. The research results offer valuable references for the implementation of temperature control measures and the establishment of temperature control standards for concrete gravity dams in cold regions. [ABSTRACT FROM AUTHOR]

The overtopping process, resulting from landslide-induced waves, has the potential to cause significant damage to downstream infrastructures. To minimize the associated losses, it is essential to study the overtopping phenomenon. Limited research has been conducted on physical modeling and volumetric calculation of wave overtopping in reservoirs with arch dams. The study designed a physical model experiment at a geometric scale of 1∶70 to investigate the occurrence of wave overtopping caused by landslides in arch dam reservoir areas at the maximum water depth scenario. Equations developed for straight dams, such as gravity dams, overestimate the volume of overtopping caused by landslides in arch dam reservoirs due to structural dissimilarities. Two volumetric overtopping equations specifically applicable to arch dams were derived through regression analysis. Additionally, the analysis of model experimental data unveiled the distribution pattern of the initial wave amplitude along the dam face, the overtopping duration characteristics, as well as the factors influencing the volume of overtopping. The underlying causes of these phenomena are explained in this paper. This study offers valuable insights into comprehending the intricate process of wave overtopping generated by landslides. These insights encompass the estimation of overtopping volume, as well as the safety assessment of downstream. [ABSTRACT FROM AUTHOR]

The seismic assessment of concrete gravity dams is a problem of prediction of cracking and the corresponding consequences. With the widespread use of general-purpose finite element programs, the work in the field has shifted towards quantifying the behaviour in a framework for assessment. The nonlinear analysis and coupling with foundation–reservoir interaction, conversely, is still a challenging task. The modelling approach has significant effects on the analysis results and the assessment framework. The field remains an active area for research with many outstanding issues regarding damage quantification and assessment compared to any other major infrastructure component. A comprehensive overview of the seismic assessment of gravity dams is presented in this work with the goal to outline the issues in the field. Different models and modelling choices are compared in the context of damaged state assessment of gravity dams. The links between practical difficulties and theoretical issues are critically discussed. The aleatoric and epistemic uncertainties in the field, and their sources, are presented. Areas of future work are identified for improvement in seismic assessment as well as reducing and quantifying the uncertainties in the prediction of damaged states for concrete gravity dams. [ABSTRACT FROM AUTHOR]

Recent studies in dam displacement monitoring primarily focus on single‐response monitoring or model updating using advanced techniques. Few studies involve the combination analysis of displacement with other synchronized responses utilizing their monitoring characteristics. In situ strain data provide a strength‐safety perspective for dam displacement monitoring. The challenge lies in that estimating displacement directly using limited discrete strain data may be misleading. This paper analyzes the relationship between displacement and global, and multipoint local strains from the perspective of the differences in load effects of gravity dams, and indicates that introducing appropriate state factors improves the estimation. A displacement estimation model driven by strain data and state factors is developed using stacked convolutional neural network, and the variable relationships within the model are interpretated via accumulated local effects. Incorporating specific strength criteria, a novel displacement monitoring indicator based on the tensile safety of the dam heel is proposed. A case study of a gravity dam showcases the effectiveness of the proposed approach in comparison with the solely strain‐based model and the traditional hydrostatic‐seasonal‐time factors‐based model. [ABSTRACT FROM AUTHOR]

Copyright of Water Conservancy Science & Techonlogy & Economy is the property of Water Conservancy Science & Technology & Economy Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: In the present study, the application of a recent damage plasticity model is presented for nonlinear dynamic analysis of the Koyna gravity dam. This is a single surface isotropic damage plasticity concrete model, which is based on the decomposition of stresses and was proposed in a previous study. The theoretical aspects of the model are initially reviewed, and a few preliminary verification examples are illustrated. Thereafter, the HHT-α (i.e. Hilber–Hughes–Taylor) algorithm is presented for nonlinear dynamic analysis of concrete gravity dams. Design/methodology/approach: Based on the prepared tools, nonlinear behavior of the Koyna Dam is studied by applying the invoked damage plasticity model. For this purpose, three cases are considered for the present study. Case A, which is based on the linear model, is mainly used for comparative purposes. The other two cases (B and C) correspond to the nonlinear (i.e. damage plasticity) model. The basic data for these two cases are similar. However, the employed damping algorithms are different and correspond to constant and variable damping algorithms, respectively. This means that the damping matrix is either kept constant or updated for all iterations of different time increments through the course of analysis. Findings: The time histories of horizontal displacement at the dam crest were initially compared for the three cases: the linear Case A, and two nonlinear Cases B and C. It was observed that nonlinear cases' responses begin to deviate from the corresponding linear case after the time of about 4.3 s. However, the amount of change for Case C (i.e. variable damping) was much greater than for Case B (i.e. constant damping). This was manifested initially in the peaks of response. It was also noticed that the period of response changed slightly for Case B in comparison with the linear Case A, while this change was significant for Case C. The obtained tensile and compressive damages were subsequently compared for the two nonlinear cases. For constant damping Case B, it was noticed that tensile damage occurred in the D/S face kink and on the U/S face slightly at a lower elevation. Moreover, it had a scattered nature. However, in variable damping Case C, it was noticed that tensile damage was much more localized and acted similar to a discrete crack. Of course, both cases also show tensile damages at the dam's heel. In regard to compressive damages, it is observed that low values are occurring for both nonlinear cases as expected. Originality/value: The application of a recent single surface isotropic damage plasticity concrete model is presented for nonlinear dynamic analysis of the Koyna gravity dam. The nonlinear response of the dam is investigated for two different damping algorithms. Moreover, the influence of variable characteristic length is also investigated in the latter part of this study. [ABSTRACT FROM AUTHOR]

Anti-sliding stability safety is a critical issue that must be given sufficient and widespread attention during the entire lifecycle of gravity dams. The calculated anti-sliding stability safety factor (ASS-SF) is usually compared with the allowable value required by the standards in the traditional method, which ignores the influence of material parameter uncertainties and leads to unreasonable safety evaluation results. Therefore, the nonlinear functional relationship between the stability safety factor (SF) and the random variable parameters is constructed based on the response surface equations, and the distribution types of SF sequences calculated by the Monte Carlo sampling are determined, then a probabilistic stability evaluation method for concrete gravity dams is proposed. Engineering application shows that the calculated SF obeys the normal distribution; the minimum guaranteed rate of different sliding paths in a gravity dam is 86.66%, and the guaranteed rate for the overload safety factor (OSF) is 36.00%. The results imply that a guaranteed rate for the allowable value of the ASS-SF should be provided when making the stability safety evaluation of the dams, especially the OSF. The outcome of this research will advance the understanding of stability evaluation of concrete dams, and reduce the potential risk of sliding instability of concrete dams. [ABSTRACT FROM AUTHOR]

Concrete gravity dams are constructed for holding big volume of water for various uses, and their stability is vital to ensure its benefits. Rabigh dam (RD) is the third important dam in Saudi Arabi, located in the eastern side of the Red Sea, and intended to protect Rabigh city and the adjacent industrial complex and recharging the groundwater. Its length is 380 m, 71 m high with a huge reservoir of 220 million m3. A gravity dam is subjected to two external hydraulic forces in addition to the force of the submerge silt. Those external forces are opposed by the dam self-weight (Wt). The acting forces introduce compressive and tensile stresses on dam body that need to be checked for the concrete limits for those stresses. The main objective of this study is to reevaluate the dam stability in static and pseudo-static conditions in view of global warming. Several recent research warned of an expected increase of rainwater and flood frequency due to global warming, which will raise the destabilizing forces while the dam weight (Wt.) is the same. The stability was tested for three types of failure: overturning, sliding and the induced stresses in the dam body. It turns out that the obtained factor of safety (Fs) is within expectable values for all tested conditions. [ABSTRACT FROM AUTHOR]

Parwan Gravity Dam is under construction stage in the Jhalawar district of Rajasthan, India. A thin sub-vertical surficial fracture trending N 75°W to S 75°E has been observed in the foundation area of the dam. Geophysical techniques such as electrical resistivity tomography (ERT), seismic refraction tomography (SRT), and multichannel analysis of surface waves (MASW) are utilized extensively in the field of civil engineering, exploration geophysics for the assessment and construction of large-scale infrastructures such as dams. These methods provide critical information about the subsurface conditions without the need of extensive drilling and excavation. The combination of electrical resistivity tomography (ERT), seismic refraction (SR), and multichannel analysis of surface waves (MASW) techniques with the different acquisition parameters have been used to image the extent of shallow subsurface geological structures. Various geophysical Surveys have been carried out along several profiles in the longitudinal direction and along the transverse direction to the fault axis. A total of 13 refraction and resistivity profiles were conducted of which 9 were transverse profiles and 4 were longitudinal profiles. A total of nine MASW profiles were conducted of which 8 are transverse profiles and 1 is a longitudinal profile. In this paper, the subsurface distribution of seismic wave velocity and electrical resistivity have been studied to identify any possible anomalous zone in bedrock and to detect the downward extension of surface fracture of brittle fault using the afore mentioned methods. The vertical and lateral extent of the surface fracture of the fault has been investigated by the analysis of these survey results. The analysis of the results indicates that a very tight and narrow fracture is present in the shallow subsurface. [ABSTRACT FROM AUTHOR]

Cracks are always a serious concern in the stability analysis of gravity dams. One of the main reasons for the initiation of cracks is overflow. In most previous crack propagation analyses, the presence of water and different configuration of the materials is not considered. In this study, to adequately evaluate the crack development in gravity dams subjected to overflow, a polygonal grain-based model (P-GBM), enriched in considering the influence of joint roughness through the Barton–Bandis (B-B) model, is employed in a distinct element framework. To take into account the effect of joint softening on the tensile strength of cracks, the B-B model is improved by a polynomial tensile law. Then, the model is verified by Brazilian and Uniaxial tests containing various combinations of rock and mortar. The numerical results demonstrated a good agreement by the experiments in terms of the strength characteristics and fracture phenomenon. Then, failure analysis for two heterogeneous gravity dams with various complexities under the reservoir overflow is investigated. Performing the risk analysis with different flood scenarios revealed that because of considering the joint–water interactions, the P-GBM suitably predicts the crack propagation. The crack path begins nearly horizontal and then turns downwards toward the dam's toe. Once cracks form, they act as conduits for water movement and allow more water to penetrate, which increases the pore water pressure and accelerates the propagation of cracks. Also, the critical dam displacements in terms of cracking (initiation, horizontal, and inclined parts) are investigated with different approaches, such as the tangent intersection method, the external second-order work, and the broken joint index. The results revealed that all three techniques determine suitably the critical heights and horizontal displacements in various flood scenarios. Highlights: The polygonal grain-based technique simulates the rock and mortar combinations in good agreement with experimental tests. The improved Barton–Bandis joint model for softening can reasonably predict the tension behavior of materials. The impact of water on the dam structure and inside the cracks during an overflow is assessed for two case studies by a distinct element method. For a 6 m overtopping, the cracks develop inside the dam body horizontally parallel to the crest. For a 12 m overtopping, the cracks extend to the downstream direction of the dam, and the dam body is severely damaged. [ABSTRACT FROM AUTHOR]

Current engineering practice in dam maintenance and safety evaluation generally neglects the contribution of three-dimensional (3D) roughness along a gravity dam's base to its sliding stability. This important question is addressed in this article through the development and stability analysis of nonlinear finite element (FE) models of dam-rock foundation systems. These models implement realistic large-scale 3D dam-rock joints based on topographic data extracted from existing dam sites. Detailed analyses of the stability response of the studied dam-rock interfaces are presented in terms of limit friction angles, sliding safety factors, aperture and interface roughness coefficients (IRC). The effects of 3D roughness on the distribution of apertures and shearing stresses are discussed. It is shown that the location of asperities within a dam-rock interface may greatly affect the sliding stability. It is also found that 3D roughness may significantly increase the shear strength of dam-rock joints and that bidimensional (2D) sliding stability analyses may over-estimate the shear strength of natural shear keys. However, the asperities along 3D dam-rock interfaces are found to increase the global shear strength in comparison to 2D stability analyses. Limitations of currently available roughness parameters and shear strength criteria are also discussed. [ABSTRACT FROM AUTHOR]

The widespread adoption of high concrete gravity dams in China and globally underscores the necessity for enhancing design processes to address potential risks, notably hydraulic fracture. This study delves into this urgency by scrutinizing common design regulations and investigating the impact of hydraulic fracture on high concrete gravity dams. A comparative analysis of design specifications from China, the USA, and Switzerland, employing the gravity method, elucidates distinctions, focusing on the Guxian dam. In addition, evaluation of standards with higher resistance to hydraulic fracture was conducted using the Finite Element Method (FEM) with XFEM (eXtended Finite Element Method), employing initial cracks with different depths at the dam heel ranging from 0.2 to 2 m. The vulnerability of the Guxian dam's cross-section to safety risks prompts further inquiry into the dam's resistance to hydraulic fracture. Therefore, high-pressure water splitting risks to the ultimate bearing capacity were examined through FEM simulation and theoretical calculations. FEM simulations assessed the dam's ultimate bearing capacity with and without automatic crack propagation combining the XFEM and overloading methods, particularly considering weak layers in the RCC (Roller-Compacted Concrete) dams. Theoretical calculations utilized a fracture mechanical evaluation model. This model derived mechanism formulas to assess the dam's resistance to hydraulic fracture. Additionally, the investigation explored the effect of the uplift pressure on the ultimate overload coefficient. Findings indicated that the Guxian dam's current cross-sectional area was insufficiently safe against hydraulic fracture, necessitating an increase to its cross-sectional area to 18,888.1 m2. Notably, the USA's and Switzerland's criteria exhibited greater resistance to hydraulic fracture than the Chinese criteria, especially without considering uplift pressure. Also, the Chinese regulations tended to calculate a lower dam cross-sectional area compared with the other regulations. Numerical calculations revealed a substantial decrease in overall dam safety (up to 48%) when considering automatic crack propagation and the dam's weak layers. The fracture mechanical evaluation model showed that the Guxian dam had the lowest resistance, with an overloading coefficient of 1.05 considering the uplift pressure. In the case of not considering the uplift pressure, the dam resistance to hydraulic fracture increased and the overloading coefficient rose to 1.27. The results highlighted the risk of hydraulic fracture in concrete dams. Hence, it is recommended that design specifications of high concrete gravity dams incorporate safety analyses of hydraulic fracture in the design process. Reducing uplift pressure plays a crucial role in enhancing the dam's resistance to hydraulic fractures, emphasizing the need for this consideration in safety evaluations. The differences between the three design specifications were particularly pronounced for dams higher than 200 m. In contrast, dams of 50 m yielded similar results across these regulations. [ABSTRACT FROM AUTHOR]

Since ancient times, dams have been built to store water, control rivers, and irrigate agricultural land to meet human needs. By the end of the 19th century, hydroelectric power stations arose and extended the purposes of dams. Today, dams can be seen as part of the renewable energy supply infrastructure. The word dam comes from French and is defined in dictionaries using words like strange, dike, and obstacle. In other words, a dam is a structure that stores water and directs it to the desired location, with a dam being built in front of river valleys. Dams built on rivers serve various purposes such as the supply of drinking water, agricultural irrigation, flood control, the supply of industrial water, power generation, recreation, the movement control of solids, and fisheries. Dams can also be built in a catchment area to capture and store the rainwater in arid and semi-arid areas. Dams can be built from concrete or natural materials such as earth and rock. There are various types of dams: embankment dams (earth-fill dams, rock-fill dams, and rock-fill dams with concrete faces) and rigid dams (gravity dams, rolled compacted concrete dams, arch dams, and buttress dams). A gravity dam is a straight wall of stone masonry or earthen material that can withstand the full force of the water pressure. In other words, the pressure of the water transfers the vertical compressive forces and horizontal shear forces to the foundations beneath the dam. The strength of a gravity dam ultimately depends on its weight and the strength of its foundations. Most dams built in ancient times were constructed as gravity dams. An arch dam, on the other hand, has a convex curved surface that faces the water. The forces generated by the water pressure are transferred to the sides of the structure by horizontal lines. The horizontal, normal, and shear forces resist the weight at the edges. When viewed in a horizontal section, an arch dam has a curved shape. This type of dam can also resist water pressure due to its particular shape that allows the transfer of the forces generated by the stored water to the rock foundations. This article takes a detailed look at hydraulic engineering in dams over the millennia. Lessons should be learned from the successful and unsuccessful applications and operations of dams. Water resource managers, policymakers, and stakeholders can use these lessons to achieve sustainable development goals in times of climate change and water crisis. [ABSTRACT FROM AUTHOR]

The safety condition of concrete gravity dams is influenced by multiple factors, and assessing their safety solely based on a single factor is difficult to comprehensively evaluate. Therefore, this paper proposes a comprehensive modeling and analysis approach to assess dam safety by considering long-term temperature, stress, and strain monitoring data of actual concrete gravity dams. Firstly, the K-means clustering algorithm is utilized to classify the data. Then, the study area of the dam is meshed and three indicator evaluation values for all the elements are calculated. The other elements' evaluation values can be obtained by the Inverse Distance Weighting (IDW) method. Finally, the analytic hierarchy process extended by the D numbers preference relation (D-AHP) method is applied to compute the weights of temperature, stress, and strain and evaluate the dam's safety comprehensively. The effectiveness of this method is validated through application to specific engineering cases. The results demonstrate that compared to assessing methods considering only single factors, the comprehensive evaluation method proposed in this paper can more comprehensively and accurately reflect the actual safety condition of concrete gravity dams, providing important references for engineering decision-making. [ABSTRACT FROM AUTHOR]

The bearing capacity of large rectangular foundations on soil subjected to combined loading [simultaneously subjected to vertical load (V), overturning moment (M), and horizontal or lateral load (H)] is one of the central topics of interest to geotechnical engineers as it relates to the design of foundations such as ground anchorages of bridges, offshore structures, and gravity dams. To solve this problem, a combination of numerical simulation and theoretical research was used, and a stability evaluation model of large rectangular foundations on soil subjected to combined loading was established. First, an empirical equation for the failure envelope in the V‒M‒H loading space of rectangular foundations was developed. Second, the safety factor for load-path dependency (LPD) was established by considering the combined effects of V, M, and H, the stability evaluation model for large rectangular foundations on soil subjected to combined loading was constructed by proposing a method for calculating the LPD safety factor based on the V‒M‒H failure envelope. Last, the accuracy and effectiveness of the stability evaluation model proposed was verified. The proposed model provides a convenient means of calculating the stability of large rectangular foundations on soil under combined loading. The model was applied to the optimal design of a gravity anchorage project of a suspension bridge, which proves that the proposed model is rational and efficient. [ABSTRACT FROM AUTHOR]

For the last five decades, a number of overflow stepped chutes were built because the staircase shape is conducive to reduced construction costs and increased rate of energy dissipation. The stepped chute operations are characterised by air‐water flows that are highly turbulent flows with a large rate of energy dissipation, in comparison to smooth chutes. Herein, physical measurements were performed in a large‐size 1 V: 0.80H stepped chute model, with a steep slope typical of modern concrete gravity dams. The results are compared to visual observations of prototype spillway operation under Froude similar conditions. The detailed two‐phase flow measurements were conducted to characterise finely the self‐aeration and air diffusion process downstream of the inception region of free‐surface aeration. The bubble count rate profiles scaled with the instantaneous void fraction variance, and the relationship was biased close to the stepped invert under the influence of large‐scale vortical structures. The rate of energy dissipation was carefully estimated based upon the two‐phase flow measurements and the results are compared to earlier results on similar steep invert slopes and prototype data estimates. At the downstream end of the stepped chute, the rate of energy dissipation ranged from 43 to 46%, i.e. more than twice that on a smooth-invert chute for a similar chute length and discharge range. Characteristics of self-aerated stepped chute flows for dc/h = 1.3—(I) Prototype flow at Hinze Dam (Re = 4.0 × 107); (II) Air-water flow properties in the large-size laboratory model (1:15) stepped spillway (Re = 6.1 × 105) Article Highlights: Air-water measurements were performed in a large‐size 1V:0.8H stepped chute model. The results are compared to visual observations of prototype stepped chute operation under Froude similar conditions. The energy dissipation was estimated, taking into account the air-water flow properties inclusive of air-water pressure and velocity correction coefficients. The rate of energy dissipation ranged from 43 to 46%, i.e. more than double that on a smooth-invert chute. The contribution paves the way for future research to close the knowledge gap on self-aerated chute flows in full-scale structures. [ABSTRACT FROM AUTHOR]

The parameters of gravity dams and foundation materials objectively exhibit spatial variability due to environmental and load influences, which significantly affect the safety status of dam structures. Therefore, a safety risk analysis method for a gravity dam–foundation system based on random field theory is proposed in this paper. Spatial variabilities in materials are particularly considered by using the finite element method. Then, composite response surface equations for the performance function (PF) of strength and stability failure are established, and then, the system failure risk is obtained using the Monte Carlo method. The proposed method solves the problem wherein the effect of spatial variability on failure risk cannot be reflected accurately by the performance function of multi-element sliding paths, and the difficulties in solving the failure risk of the series–parallel system due to multiple failure paths and their complex correlations. The application of a gravity dam shows that the developed method overcomes the disadvantages of the traditional method, such as the homogenization of the spatially random characteristics of parameters and the overestimation of failure risk in the system due to large variance estimation. [ABSTRACT FROM AUTHOR]

Highlights: A block limit equilibrium analysis method is proposed based on the respective advantages of block theory and three-dimensional rigid limit equilibrium method. This method perfectly explains the continuous transformation from double-plane sliding to single-plane sliding. The proposed method was successfully applied in the anti-slip stability analysis of a gravity dam foundation optimal design. [ABSTRACT FROM AUTHOR]

This paper examines the influence of monolith length on the temperature field of concrete gravity dams built using the block method. The developed 3D model is capable of conducting a thermal analysis of a 95.0 m high concrete gravity dam built using the block method, where each newly cast block represents a new analysis phase. The calculation accounts for the period of construction, the filling of the reservoir, and the service for a total duration of about 5 years. The thermal properties of the material, the influence of cement hydration heat, the temperature of the surrounding rock mass, the temperature of the fresh concrete mixture, and the corresponding boundary conditions defining a heat transfer were taken into account. The height and width of the blocks, as well as the sequence of concreting, were considered invariable, while the length of the blocks (dimension in the direction of the dam's axis equal to the monolith length) varied, with values of 10.0, 12.5, 15.0, and 20.0 m. The obtained calculation results for the control nodes showed that the maximum reduction in the monolith length (from 20.0 m to 10.0 m) caused a decrease in the maximum temperature values of the concrete (from 1.6 to 3.4 °C, depending on the control node). Also, the results showed that, by reducing the length of the monolith, there was a delay in the moment at which the maximum temperature values of the concrete appeared in the selected control node. The delay in reaching the maximum, in relation to the 10.0 m long monolith, was from 7 days (for points on the crest dam) to 49 days (for points in the central zone of the monolith) for the other considered monolith lengths. The above indicates the importance of concrete temperature control for longer monoliths, especially during construction in extreme air temperatures. The main contribution of the conducted analysis is the development of insight into temperature field changes depending on monolith length, which can help engineers during the design and construction of new, as well as the maintenance of existing, dams. [ABSTRACT FROM AUTHOR]

Dams are among the most important civil engineering structures, but they are also susceptible to damage that can endanger their stability and functionality. It is therefore crucial to detect any damage in dams to ensure their long-term integrity and overall safety. In light of this, the present study proposes a new two-stage method for identifying damage in concrete gravity dams. In the first stage, a modal curvature-based damage index (MCBDI) is presented to detect the location of suspected damaged zones along the height of the dam. The mode shape data collected from some measurement points on the downstream side of the dam is used to accomplish this task. In the second stage, the pathfinder algorithm (PFA) as a powerful meta-heuristic optimization technique is applied to determine the severity of potentially damaged zones by minimizing an objective function specified in terms of natural frequencies and mode shapes. The capability and effectiveness of the proposed method are evaluated by implementing two numerical simulation examples of concrete gravity dams under both noise-free and noisy conditions. The results obtained suggest that the proposed two-stage method, comprising the MCBDI indicator and the PFA algorithm, represents an accurate and efficient approach for localizing and quantifying damage in concrete gravity dams. [ABSTRACT FROM AUTHOR]

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Investigating the dynamic response patterns and failure modes of concrete gravity dams subjected to strong earthquakes is a pivotal area of research for addressing seismic safety concerns associated with gravity dam structures. Dynamic shaking table testing has proven to be a robust methodology for exploring the dynamic characteristics and failure modes of gravity dams. This paper details the dynamic test conducted on a gravity dam model on a shaking table. The emulation concrete material, featuring high density, low dynamic elastic modulus, and appropriate strength, was meticulously designed and fabricated. Integrating the shaking table conditions with the model material, a comprehensive gravity dam shaking table model test was devised to capture the dynamic response of the model under various dynamic loads. Multiple operational conditions were carefully selected for in-depth analysis. Leveraging the dynamic strain responses, the progression of damage in the gravity dam model under these diverse conditions was thoroughly examined. Subsequently, the recorded acceleration responses were utilized for identifying dynamic characteristic parameters, including the acceleration amplification factor in the time domain, acceleration response spectrum characteristics in the frequency domain, and modal parameters reflecting the inherent characteristics of the structure. To gain a comprehensive understanding, a comparative analysis was performed by aligning the observed damage development with the identified dynamic characteristic parameters, and the sensitivity of these identified parameters to different levels of damage was discussed. The findings of this study not only offer valuable insights for conducting and scrutinizing shaking table experiments on gravity dams but also serve as crucial supporting material for identifying structural dynamic characteristic parameters and validating damage diagnosis methods for gravity dam structures. [ABSTRACT FROM AUTHOR]

Seismic assessment of plain concrete structures like gravity dams is generally conducted based on cracking. The responses of two types of gravity dams, i.e. the conventional and roller compacted concrete (RCC), were investigated in this study using a discrete element tool coupled with special reservoir elements. Using incremental dynamic analysis, the relationship between the seismic intensity measures and crack widths on the U/S face of the monolith was obtained. The damage accumulation on conventional and RCC dams was different: The cumulative cracking on the upstream face of the monolith correlated well to a seismic intensity measure representing base shear. [ABSTRACT FROM AUTHOR]

Advances in nonlinear dynamic analysis of dams have not completely resolved concerns over modeling confidence and analysis accuracy. Verification and validation offer accuracy assessment, but uncertainties persist during performance evaluation due to both epistemic (modeling) and aleatory (parametric) sources. Epistemic uncertainties arise from simplifications and modeling techniques. This paper addresses epistemic uncertainties in a gravity dam seismic analysis using data from the International Comnission on Large Dams (ICOLD) benchmark study. While the benchmark formulation included the finite element model of the dam, mechanical material properties, and dynamic loads, participants retained the flexibility to opt for best‐practice modeling assumptions, simplifications, and other specifics. Notable response variability emerged, particularly in crack profiles and damage predictions. This study examines sources of variability, quantifying modeling uncertainty for the benchmark problem. More specifically, the modeling variability is quantified using the logarithmic standard deviation, also known as dispersion. This metric enables its incorporation into other seismic risk assessment and fragility studies. Under relatively low‐intensity motion (peak ground acceleration [PGA] of 0.18 g in this case), modeling dispersion of 0.45, 0.30, 0.32, and 0.30 were calculated for the maximum dynamic crest displacement, maximum hydrodynamic pressure at the heel, heel and crest maximum acceleration, respectively. Additionally, the dispersion of the failure PGA was determined to be 0.7. Findings underscore the need for systematic seismic response modeling in dam engineering to enhance prediction accuracy. A better understanding of the sources and magnitudes of modeling uncertainties can help improve the reliability of dam seismic analysis and contribute to the development of more effective risk assessment and mitigation strategies. [ABSTRACT FROM AUTHOR]

Assessment of flood damage caused by dam failures is typically performed deterministically on the basis of a single preselected scenario, neglecting uncertainties in dam-break parameters, exposure information, and vulnerability model. This paper proposes a probabilistic flood damage model for the estimation of life loss due to dam-break flooding with the aim of overcoming this limitation and performing a more comprehensive and informative evaluation of flood risk. The significant novelty lies in the fact that the model combines uncertainties associated with all three components of risk: hazard, exposure, and vulnerability. Uncertainty in flood hazard is introduced by considering a set of dam-break scenarios, each characterized by different breach widths and reservoir levels. Each scenario is linked to a probability, which is assumed conditional on the dam-break event. Uncertainty in exposure is accounted for using dasymetric maps of the population at risk for two socio-economic states (representing business and non-business hours of a typical week), along with associated likelihood. Vulnerability to flooding is described through a well-established empirical hazard-loss function relating the fatality rate of the population at risk to the flood hazard, the flood severity understanding, and the warning time; a confidence band provides quantitative information about the associated uncertainty. The probabilistic damage model was applied to the case study of the hypothetical collapse of Mignano concrete gravity dam (northern Italy). The main outcome is represented by probabilistic flood damage maps, which show the spatial distribution of selected percentiles of a loss-of-life risk index coupled with the corresponding uncertainty bounds. [ABSTRACT FROM AUTHOR]

This discussion is based on the paper by Chen et al. in 2023 (hereafter referred to as "the original paper/authors"). In their study, the original authors conducted a series of analyses using nonpulse, single‐pulse, and multipulse ground motion records, evaluating their impact on a frame structure, a slope, and a gravity dam. Their key finding suggests that multipulse ground motion leads to more severe structural damage compared to nonpulse and single‐pulse ground motions. However, it is important to note that the seismic damage analysis of the gravity dam in this paper does not adhere to state‐of‐the‐practice recommendations. Consequently, drawing a definitive conclusion regarding the influence and importance of multipulse ground motion records on the seismic response of concrete dams requires further justification. This necessitates the incorporation of high‐fidelity numerical models and probabilistic performance evaluation. We will discuss the significance of modeling assumptions, specifically addressing the dam–rock dynamic interaction in crack propagation and failure in dams. [ABSTRACT FROM AUTHOR]

Purpose: The effective numerical model that examines the seismic behavior of concrete gravity dams in the Laplace domain-Finite Element (FE) approach is presented. Further research on seismic performance of the dam body is done considering the simultaneous effect of horizontal (H) and vertical (V) components of six different earthquake loads. The time durations of the selected earthquakes vary from 10 to 80 s with the magnitude range from 6.5 to 7.62 Mw. Methods: The Lagrangian fluid finite elements are utilized to model the near-field water domain, while the fluid infinite elements are utilized to model the far-field water domain. The two-dimensional (2D) FE model is developed in FORTRAN 90 and MATLAB programming languages. Results: The obtained results revealed that the longer length of significant earthquake duration leads to the high deformations, high stress excursions and high probability of damages in the dam body. 20.9% and 18.8% of the selected dam cross section experienced overstress condition under the H and H + V components of the Chi-Chi earthquake loads, respectively; this indicate the severe damages and even the dam failure. Conclusion: This study concludes that the seismic behavior of concrete gravity dam affects not only with the seismic severity; the length and significant time duration of the earthquake are also important factors should be considered in the seismic analysis and design of dams. [ABSTRACT FROM AUTHOR]

A rock-filled concrete (RFC) dam is an original dam construction technology invented in China nearly 20 years ago. The technology has been continuously improved and innovated upon, and the accumulated rich practical experience gradually formed a complete dam design and construction technology. Seismic design is a key design area for RFC dams that still requires more investigation; therefore, this article attempts to address some questions in this area. In the article, the seismic design for a curved gravity dam, currently under construction, is compared for RFC and conventional vibrating concrete (CVC) dam alternatives based on American design documents. The conclusions drawn from investigations include the following: The displacement and stress distributions in both the CVC and RFC alternatives are similar, but the maximum computed values for the RFC dam model are slightly smaller than those for the CVC one, while the sliding resistance of both dam alternatives can meet the requirements of the specifications. Regarding the nonlinear seismic analysis results, the extent of damage in the RFC dam model is significantly reduced when compared with the CVC model, which can be explained by the higher cracking resistance of RFC. In general, the seismic performance of the investigated dam made of RFC appears to be better than that of CVC. [ABSTRACT FROM AUTHOR]