---

Abstract: No dam could be safely designed without functionality dependence on reliable performance of a number of appurtenant structures. Gates are the main appurtenant structures responsible for controlling  water flow from the reservoir. Earthquakes induce acoustic and surface waves in the reservoir and cause hydrodynamic pressure on the adjacent gates. Hydrodynamic pressures might surpass hydrostatic pressure on some locations of the dam upstream face. Some engineers use the hydrodynamic pressure solution concerning  to  axi-symmetric offshore and coastal structures for  the design of such hydro-mechanical  gates. Flexibility  of these gates may magnify the hydrodynamic pressure due to severe generation  of vibrations separate from the dam body itself even for those installed within the dam bodies. This statement reflects the design philosophy of secondary structures. Fundamental frequency of such gates are usually reduced due to  the presence of infinite fluid in their vicinity. Therefore the  study of their behavior is somehow complicated during the earthquake. Design regulations of hydraulic structures, demand the hydrodynamic pressure as a design action and usually admits its simple calculation from the Westergaard formula. In this article, by using floor response spectrum in gate level which is used to design the secondary systems and also the spectral acceleration parameter in gate level which is used based on predominant frequency of gate-reservoir, the common relation of gate design against hydrodynamic pressure has been corrected. Then a new non-dimension factor is suggested for sliding rectangular gates in different levels of dam body that is related to the performed analyses and log-normal distribution of data.. In general for various conditions the dimensionless coefficient of Westergaard formula changes  from 0.875 to widely varying values between 0.25 to 2.5 when using the base acceleration. However when the spectral acceleration of the floor response spectrum is used for the fundamental frequency of gate-reservoir, this coefficient is more precisely determined for vertical rectangular gates.

---

Failure of a concrete gravity dam will cause unavoidable human loss and financial damages. In this study SARIYAR concrete gravity dam, located in turkey was chosen as a case study and its probability of sliding failure in various condition was studied. The most important reason in sliding failure of a concrete dam was lateral and uplift loads, caused by increase in the level of reservoir water. Different scenarios were considered in which might happen for a dam, all the possible height of reservoir water simulated. Afterward, Probability of failure and reliability index was calculated with Monte Carlo simulation and FORM method in all conditions and comparison with each other. The influence of the Number of Simulations (NOS) in the Monte Carlo method was also discussed. Results showed that, in some cases, the resistance of the system was much more than the loads and limit state function had a significant distance from samples. In such states, Monte Carlo was unable to calculate the probability of failure with each NOS but FORM method obtained the Reliability Index (β) in these situations. It became clear that these values were far from reality. With increase in the forces, responses from Monte Carlo had a high degree of precision. The probability of failure generated by FORM method was less than a reality. Failure of a concrete gravity dam will cause unavoidable human loss and financial damages. In this study SARIYAR concrete gravity dam, located in turkey was chosen as a case study and its probability of sliding failure in various condition was studied. The most important reason in sliding failure of a concrete dam was lateral and uplift loads, caused by increase in the level of reservoir water. Different scenarios were considered in which might happen for a dam, all the possible height of reservoir water simulated. Afterward, Probability of failure and reliability index was calculated with Monte Carlo simulation and FORM method in all conditions and comparison with each other. The influence of the Number of Simulations (NOS) in the Monte Carlo method was also discussed. Results showed that, in some cases, the resistance of the system was much more than the loads and limit state function had a significant distance from samples. In such states, Monte Carlo was unable to calculate the probability of failure with each NOS but FORM method obtained the Reliability Index (β) in these situations. It became clear that these values were far from reality. With increase in the forces, responses from Monte Carlo had a high degree of precision. The probability of failure generated by FORM method was less than a reality. Failure of a concrete gravity dam will cause unavoidable human loss and financial damages. In this study SARIYAR concrete gravity dam, located in turkey was chosen as a case study and its probability of sliding failure in various condition was studied. The most important reason in sliding failure of a concrete dam was lateral and uplift loads, caused by increase in the level of reservoir water.

---

In the current study, seismic cracking identification of concrete dams is conducted based on extended finite element method (XFEM) and Wavelet (WT) transform. First, the dam is numerically modeled and analyzed using the finite element method (FEM). Then cracking capability to the dam structure is added by applying the XFEM without introducing the initial crack, and the dam is analyzed under the seismic excitation. In fact, the whole dam structure is potentially under damage risk, and any zone reaching the fracture limit, begins to crack, which grows in the structure. This crack is usually unpredictable and is not easy to detect, therefore the structural modal parameters and their variation should be investigated based on structure response by using time-frequency transform. Results show that, investigating time-frequency window of the structure response and model parameters obtained from the numerical model, the history of physical changes occurred in the structure, cracking initiation time and damage localization is performed from comparing the intact and damaged vibration modes. Moreover, investigating the first natural modal indices of the intact and damaged structure, damage initiation and its location on Koyna dam height is easily detected, while for the second indices it is not performable.

---

Abstract:
Composite construction in steel and concrete offers significant advantages for use as the primary lateral resistance systems in building structures subjected to seismic loading. While composite construction has been common for over half a century through the use of composite beam and joist floor systems, over the past decade a substantial amount of research has been conducted worldwide on a wide range of composite lateral resistance systems. These systems include unbraced moment frames consisting of steel girders with concrete-filled steel tube (CFT) or steel reinforced concrete (i.e., encased steel sections, or SRC) beam-columns; braced frames having concrete-filled steel tube columns; and a variety of composite and hybrid wall systems.
Structural walls are widely used in building structures as the major structural members to provide substantial lateral strength, stiffness, and the inelastic deformation capacity needed to withstand earthquake ground motions. In recent years, steel reinforced concrete (SRC) walls have gained popularity for use in high-rise buildings in regions of high seismicity. SRC walls have additional structural steel embedded in the boundary elements of the reinforced concrete (RC) walls. Walls with additional shapes referred as composite steel-concrete shear walls, contain one or more encased steel shapes, usually located at the ends of the wall.
Composite shear walls with steel boundary element are known as the structural members able to withstand high in-plane lateral forces at low displacement levels. Reinforced concrete shear walls with steel boundary element being performed in Iran are joined to the foundation, in boundary element section, usually through bolts and base plates. Most reliable codes of the world have nothing to say about the behavior of this type of shear walls, and no experimental studies or analyses have been conducted on the behavior of this type of shear walls. In the past decade, great effort has been devoted to the study of seismic behavior of SRC walls, for Design provisions for SRC walls have also been included in some leading design codes and specifications, for example, AISC 341-10 , Eurocode 8, and JGJ 3-2010
Exposed baseplates together with anchor bolts are the customary method of connection of steel structures to the concrete footings . In this paper, the influence of cross section of base plate’s joint bolts to the foundation and the wall’s longitudinal bars embedding within the area of boundary element in the foundation, on the behavior of this type of shear walls have been investigated. The finite element software is first calibrated and the accuracy of its results is validated through modeling the experimental samples. In this research, the concrete’s nonlinear finite element analysis method and concrete damage plasticity model have been used for the concrete’s behavior modeling. The results show that increasing in the level of bolt’s cross section and also the embedding of longitudinal bars of boundary element in the foundation cause an improvement of the capacity of these walls. However, these walls’ resistance against the normal axial loads is considered to be less than reinforced concrete shear wall.

Keywords: Reinforced concrete shear wall, Steel boundary element, Concrete damage plasticity model, Finite element model.

---

In the present paper a new numerical simulation method based on finite volume is developed for calculating hydrodynamic pressure distribution in the reservoir of dams during earthquake excitation. An explicit finite volume scheme is applied for discretization of dynamic governs equation. In the proposed method the asymmetry effect of reservoir shape on hydrodynamic pressure distribution can be considered. In the simulation quadrilateral elements with center cell algorithm is used. Because of the negligible changing of hydrodynamic pressure in the cross direction with averaging, the average differential partial equation in central vertical plan of reservoir is solved. The absorption effects of bottom sediment and lateral wall are included in the analysis and an exact far end boundary condition is applied in the truncation boundary. Different approaches to the solution of the coupled field problems exist solution of the entire set of equations as one discretized system, referred to as the monolithic approach. This approach is often inefficient due to its attempt to capture with one discretization methodology the completely different spatial and temporal characteristics of fluid and the structure. The second approach often mentioned is the notion of strong coupling, referring to solvers which might use different discretizations for the fluid and the structure but which employ sub-iteration in each time step to enforce coupling between the fluid and the structure. In these methods, the governing equations for fluid and structure are discretized separately in each of the sub-domains and coupled using a synchronization procedure both in time and in space without sub-iteration. Weakly –coupled schemes have been extensively applied to a variety of different fluid-structure interaction problems of engineering interest in past ten years. wo vital issues when coupling two domains are: the method of data transformation between domains and what information must be transferred. The property of fluid adjacent of a structure such as density and viscosity are also key parameters in the efficiency of a numerical scheme.A dense fluid coupled with a structure cause a strong coupling and required some special technique to overcome corresponding difficulties. Key questions with this approach include properly enforcing boundary conditions at the solid-fluid interface, and accurately transmitting tractions between the solid and fluid. The biggest complaint about the explicit staggered partitioned solution procedure is the typical instability associated with the method,that is generally caused by the time lag between the integration of the fluid and structure equations. In the typical partitioned method, the fluid and the structure equations are integrated in time, and the interface conditions are enforced asynchronously. In the solution of coupled problems using partitioned methods, it is necessary to find a cost-minimization (optimization) compromise between a few passes solution with small time steps and a more iterated solution with larger time steps. This compromise may depend, among other things, in the degree of nonlinearity of the structural problem, which may require equilibrium iterations independently of the interaction effects. From the computational point of view, a one–pass solution with no iteration would be optimal, but stability consideration may prove this impractical.

---

Structural damages in arch dams, are often of major concern and should inevitably be evaluated for probable rehabilitation to ensure safe regular normal operation and safe behavior in future under unusual loading. These are crucial to prevent any catastrophic or failure consequences for the life time of the dam. If there is a specific major infection such as a large crack in the dam body, the assessments will be necessary to determine the current level of safety and predict the resistance of the structure to various future loading, such as earthquakes, etc. In this research, Morrowpoint dam is selected as a case study to assess the dam performance and its safety level, at the presence of an actual crack with almost known geometry created in the dam body during the sequence of its reservoir first impounding. Three-dimensional modeling of the dam and its foundation is constructed for several different crack types with specific geometry and different mechanical properties. For modeling of both the existing cracks, and the vertical contraction joints of the arch dam, no-tension, zero-thickness joint elements with variable compression-shear behavior are used. The applied loads include normal or service loads (weight and hydrostatic water pressure) as well as abnormal load of water penetration into the crack surface. In the first set of analyses, concrete material is assumed as linear. By observing the high tensile stresses, non-linear concrete materials with plastic damage model is introduced for selected cases although the foundation materials remain as linear. Safety factors of shear and compressive tractions are calculated at the surfaces of the contraction joints and the cracks. For the safety factor of the dam body mass concrete surfaces, a 2-D failure criterion is employed. In applying the weight load, the construction sequence of 3D blocks of the dam, and the stages of grouting the contraction joints have been fully accounted for. The results indicate that for cracking with an extension depth of half the thickness of the dam body, for both cases of penetration and non-penetration of water load into the cracks, safety factors are only slightly reduced and thus the dam safety in normal loading condition remains acceptable. However, in the case of increasing the depth of crack extension into the entire thickness of the dam body, the friction angle of the cracked surface is crucial, and if reduced, the normal loading safety factors of stresses and joints tractions are reduced significantly even when neglecting water penetration effects in cracks. When water penetration into the cracks is added during normal loading case, the situation is of much concern and great damages are expected. Simultaneously, it is observed that, the foundation interface also suffers of much shear safety loss. 

---

---

Dams are structures whose continuous evaluation is of great importance. Due to their large scale, experimental study of concrete dams is difficult and therefore, the numerical simulation is used in the dynamic analysis of such dams more effectively. Despite the widespread use of concrete, our knowledge on its exact properties and physical behavior under different conditions is still limited, and many assumptions and simplifications are made to study the concrete behavior in most studies. This is especially complicated in mass concrete structures such as concrete dams. The presence of joints in most concrete structures is common and inevitable. Lift joints in dams cause different characteristics in vertical and horizontal planes. In fact, this is a special type of anisotropy that follows axial symmetry with respect to any vertical axis, which means that the mechanical behavior is the same in all horizontal planes. The mechanical behavior in all vertical planes passing through the axis of symmetry is also the same, however, it is different from the behavior of horizontal planes. Since the lift joints are usually ignored in the numerical analyzes of concrete dams, in the present paper, taking into account the orthotropic behavior of concrete, the concreting joints that cause weakness in specific positions and directions of the dam body are included. First, non-linear seismic analyzes were performed using FEAP finite element software, then a Fortran program was coded to predict the time history of displacement. The proposed method draws upon evolutionary algorithms inspired by Darwinian biology, which are increasingly utilized as surrogate models for various analyses. This approach relies on data-driven learning, wherein algorithms, based on training or sample data, generate a mathematical model for making predictions.  The Pine Flat dam was modeled and analyzed under the Taft earthquake loading over a 20 second time interval with 0.02 second time steps. After successful training and learning, the model was compared and tested for other anisotropy ratios. The purpose of developing the program was to reduce the time required for analyzes so that by analyzing the initial seconds of seismic loading, by importing training inputs to the program, a proper prediction of the response process for the rest of the loading time could be obtained. In addition, by training the program for the isotropic and orthotropic modes, time history diagrams could be extracted for other orthotropic modes in different anisotropy ratios. According to the obtained results, the program is acceptably able to predict the graphs in a very short time. In addition, an equation for predicting the displacements in the orthotropic mode is presented. The maximum displacement of the orthotropic analysis was more than the isotropic one, and the use of isotropic material and homogeneous modeling of the dam body caused errors in the results. Therefore, considering the orthotropic properties of concrete can lead to more realistic results. The results reveal that time history plots derived from the implemented program closely resemble those from finite element analyses. The output results are remarkable, given the significantly reduced time required for predictions generated by the implemented program.