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The problem is the scattering of a plane sound wave at a rough water-air interface. The purpose of this paper is to describe in detail the method and demonstrate its work with simple examples. The main advantage of this approach is that there are no limits on the relation between the shape of the surface and the incident wave, so we can consider large Rayleigh parameter, shading, multiple scattering. The solution of the Helmholtz equation in the form of an integral over the boundary is used only in the inner domain, in the outer domain the separation of variables is used to obtain a nonlocal integral boundary condition on the artificial boundary. [ABSTRACT FROM AUTHOR]

In this paper, the axial behaviour of boundary elements of rectangular ductile reinforced concrete (RC) walls is investigated. For this purpose, axial tests on rectangular RC prisms representing the boundary zones of ductile RC walls are carried out. Critical design parameters influencing the local compression response of ductile wall boundaries are identified and the effect of these parameters on the axial response of RC prisms is experimentally investigated. Key parameters investigated in this study include loading history, transverse reinforcement detailing (arrangement, spacing and diameter), longitudinal reinforcement detailing (yield strength and area) and cover concrete. The influence of these parameters on the performance of RC wall boundary zones is discussed in light of the experimental observations of the prisms tested in this study. The experimental test results reaffirm the susceptibility of isolated wall boundary elements to the progression of large out-of-plane deformations and subsequent instability. The experiment test results show that loading history and transverse reinforcement detailing are the critical parameters that influence the failure modes of boundary zone prisms. [ABSTRACT FROM AUTHOR]

Understanding the deformation of arterial walls under loading is essential for the definition of some new therapeutic protocols. This requires the modeling of the mechanical behavior of the artery wall. In this work, in order to account for the microstructure, each of the conventional three layers of the artery is assumed to behave like a dilatation elastic solid. The resulting compound is then submitted to various loads and the response analyzed in order to highlight the contribution of the microstructure. Finally, the impact of a localized zone of microstructure modification on the overall deformation is investigated. [ABSTRACT FROM AUTHOR]

Laboratory tests demonstrated that reinforced masonry shear walls (RMSWs) can provide sufficient strength and ductility to be considered an efficient seismic force resisting system (SFRS) for mid-rise buildings. The ductility and overall seismic performance of shear walls were increased by providing confinement to the end zones of the walls to form boundary elements (BEs)., which enhanced the ultimate masonry compressive strain and curvature ductility of the walls. Regular stretcher blocks are commonly used in the construction of masonry boundary elements; however, they impose some constraints due to their geometrical characteristics. This study investigated the construction and testing of three half scale specimens of reinforced masonry shear walls with boundary elements (RMSWs+BEs) that were characterized by flexural dominance under reversed cyclic moment and lateral loading. In the lower story panel of a 12-story RMSW building, these walls constitute the plastic hinge zone, which is represented by a plastic hinge wall. In this study, C-shaped masonry units were used instead of stretcher units to construct BEs with different sizes and vertical reinforcement ratios. The findings of this work revealed that employing C-shaped masonry units to construct the BEs was effective in overcoming the construction limits imposed by stretcher units. Additionally, the results of this study demonstrated that when RMSWs+BEs are subjected to quasi-static reversed cyclic loading, they are capable of providing a high level of ductility with minimal loss of strength. • C-shape boundary element blocks were utilized to form the boundary elements. • Specimens were slender walls that represented the plastic hinge of high-rise wall. • Testing of reinforced masonry walls with high aspect ratio. • overcome the constructability limits imposed by using stretcher units • The boundary elements of the walls are different in size and vertical reinforcement. [ABSTRACT FROM AUTHOR]

A symmetric coupling of methods of finite and boundary elements for numerical solution of transient eddy current problems is described. This is an essential step in modelling of electromagnetic forming of metalic sheets. The finite element method is employed in the conducting region of the metalic sheet. The boundary element method relies on the Stratton-Chu representation formula and it models the electromagnetic field in the air including its decay at infinity. We impose external currents by the Biot-Savart law.

The earthquakes in Chile 2010 and New Zealand 2011 demonstrated the significance of the out-of-plane buckling failure of reinforced concrete structural walls. Past studies have demonstrated that when the out-of-plane deformation is enough to cause instability, loss of vertical load carrying capacity occurs. This paper proposes improvements to an existing wall instability model that estimates the onset of buckling instability. In order to accomplish that objective, a fiber-based computational model is developed to capture the experimental response of twelve reinforced concrete prisms representative of the boundary elements of special planar structural walls with two-layers of reinforcement. The computational model is then employed in a parametric study that aims to improve on an existing out-of-plane buckling instability approach. The computational model is capable of relating the tensile strain developed by in-plane loading to the critical out-of-plane deformation as a function of the prism geometry, the longitudinal and transverse steel contents, and the mechanical properties of materials in the potential buckling region. The proposed approach allows engineers a more accurate means of assessing the parameters that impact the onset of buckling instability. [ABSTRACT FROM AUTHOR]

Sometimes boundary value problems have isolated regions where the solution changes rapidly. Therefore, when solving numerically, one needs a fine grid to capture the high activity. The fine grid can be implemented as a composite coarse-fine grid or as a global fine grid. One cheaper way of obtaining the composite grid solution is the use of the local defect correction technique. The technique is an algorithm that combines a global coarse grid solution and a local fine grid solution in an iterative way to estimate the solution on the corresponding composite grid. The algorithm is relatively new and its convergence properties have not been studied for the boundary element method. In this paper the objective is to determine convergence properties of the algorithm for the boundary element method. First, we formulate the algorithm as a fixed point iterative scheme, which has also not been done before for the boundary element method, and then study the properties of the iteration matrix. Results show that we can always expect convergence. Therefore, the algorithm opens up a real alternative for application in the boundary element method for problems with localised regions of high activity. [ABSTRACT FROM AUTHOR]

• This paper investigates the seismic collapse capacity of buildings with ductile RM shear walls with boundary elements. • The study provides practical design recommendations to enhance overall structural performance. • Simple and efficient nonlinear numerical macro-model for RM shear walls is proposed. • Results demonstrate the potential of ductile RM shear walls with boundary elements as a SFRS in high-rise buildings. • It is concluded that the building height limits of NBCC 2015 can be relaxed for ductile RM shear walls. The National Building Code of Canada, NBCC-15 has recently added a new Seismic Force Resisting System (SFRS) category, ductile shear walls, for Reinforced Masonry (RM) buildings. Although it was assigned a higher ductility-related force modification factor compared to that of moderately ductile walls, NBCC-15 assigned the same building height limits for the ductile and moderately ductile RM walls. This study aims to assess (i.e. numerically) the seismic performance and collapse capacity of ductile RM buildings, having heights exceeding the code limit, built using ductile RM shear walls with boundary elements as the SFRS. The main objective is to propose height limits based on solid and objective seismic performance acceptance criteria. In this regard, six archetype buildings with varying heights are designed according to CSA S304-14 with ductile RM structural walls having confined boundary elements. The reference buildings are located in two regions representing the high and moderate seismicity levels of NBCC-15. The seismic performance is evaluated using nonlinear pseudo-static pushover and Incremental Dynamic Analyses (IDA). The quantification of seismic performance and collapse capacity is executed using the procedure outlined in FEMA P695. This research study contributes to the understanding of the seismic performance and collapse capacity of ductile RM shear wall buildings with boundary elements. It provides practical design recommendations to enhance the overall system performance. In addition, the study proposes a simple, yet efficient nonlinear numerical macro-modeling approach for RM shear walls. Finally, based on the findings of this study, it is suggested to assign a 70 m limit for the height of buildings in moderate seismicity regions and a 50 m limit for the buildings in regions with high seismic hazard. [ABSTRACT FROM AUTHOR]

The detection of damages inside structures is of great importance because damages may be critical for serviceability and safety of structural elements. Only two reliable techniques for nondestructive examination of structures, ultrasonic and x-ray may be applied in practice for the precise location of subsurface damages. However, such techniques are expensive, time consuming, and require special procedures for their application. Current researches point toward the possible use of numerical-computational methods in assisting the detection of damages inside structures. In general, numerical methods for detecting damages, like cracks are based on Finite Element modeling and comparisons between the structures´ signatures or responses before and after damage has occurred. In this paper, the Boundary Element Method is associated with Wavelet Transform to detect damages in structures. With this association, numerical modeling of structures is more precise, simpler, and does not require the structure signature before the occurrence of the crack. After presenting the proposed numerical technique, the paper shows applications concerning the detection of subsurface cracks in structures subjected to static loads. Single and multi-cracks with different orientations inside two-dimensional structures with different support conditions are investigated. The results show the proposed numerical procedure is effective in indicating the location of damages. [ABSTRACT FROM AUTHOR]

Highlights • Reinforced Masonry Boundary Elements (RMBEs) are a kind of column added to wall ends. • Axial stress-strain response of 17 RMBEs with various aspect ratios (AR) is studied. • Stress-strain empirical model is proposed capable of predicting RMBEs axial response. • The model is calibrated using the experimental data of 33 RMBE specimens. • Model considers RMBE confinement and vertical reinf. ratios, grout strength, and ARs. Abstract Reinforced masonry (RM) shear walls with boundary elements have been recently presented as a more ductile alternative to RM rectangular shear walls. Evaluating the complete (i.e. including the post-peak branch) compression stress-strain behavior of the confined and unconfined masonry is essential for predicting the seismic response of the RM walls with boundary elements. Recently, the authors investigated the effect of various volumetric ratios of transverse reinforcement, vertical reinforcement ratios, and grout strength on the axial stress-strain behavior of reinforced masonry boundary elements (RMBEs). However, all the specimens had a specific height to thickness ratio (i.e., AR = 5). This study presents the observed stress-strain relationship of seventeen half-scale fully grouted unreinforced and RMBE specimens, built using C-shape blocks, tested under concentric compression loading up to failure. Thus, quantifying the effect of various aspect (height to thickness) and confinement ratios on the RMBEs peak stress, strain corresponding to peak, and post-peak behavior. The results indicate that, as the hoop spacings and/or aspect ratio decreases, the peak stress and post-peak strains increase. Moreover, this study presents a stress-strain empirical model capable of predicting the RMBE stress-strain response by computing the confined and unconfined masonry stress-strain behavior. The model is calibrated using the experimental data of thirty-three RMBE specimens, tested in this study and literature. The proposed model presents an efficient tool that can be implemented in different analytical/numerical packages. [ABSTRACT FROM AUTHOR]

Abstract A coordinate change of conjugation twin boundaries in Ni-Mn-Sn single crystals is studied with scanning electron microscopy. During mechanical training, the so-called orthogonal shear process initiates variant reorientation leading to the replacement of the main with conjugation type I twin boundaries. The experimental data demonstrate that highly organized redistribution of adjacent variants, in the neighboring areas, is then critical for the removal of conjugation boundaries by coordinated secondary twinning. In addition, a more complex variant reorientation mechanism is uncovered and it is found to allow for transitioning between non-conjugate twin systems. The proposed mechanism appears consistent with the orientation relationship between austenite and martensite, which is controlled by a shear deformation and martensite crystallography leading to an equal distribution of martensitic variants. This contribution complements the existing theory of martensite crystallography providing direct evidence for the general nature of the orthogonal shear process as a first step in variant reorganization during mechanical training of martensite. Highlights • Removal of type II twins and type II inter-plate boundaries by a coordinate change of conjugate twin planes. • Orthogonal shear process affects the neighboring colonies allowing transition between non-conjugated twin systems. • Coordinated secondary twinning generates shear-induced rotation reducing the number of orientations from 24 to 12. • All rotations during training procedure are symmetric with respect to austenite orientation. [ABSTRACT FROM AUTHOR]

The numerical stability of different formulas for the correction term of the half-space Green's function is investigated. The formula with complex monopoles is taken as a reference. The expressions of Koh and Yook, tested in a previous publication [R. Piscoya and M. Ochmann, Acoustical Green's function and boundary element techniques for 3D half-space problems, J. Comput. Acoust. (2017), https://doi.org/10.1142/S0218396X17300018 ], are rewritten to improve their range of application. The formulas of Sommerfeld and Thomasson are analyzed and its suitability for a BEM implementation is evaluated by comparing their accuracy against our reference. For the sake of completeness, the first and second derivatives of the formulas are explicitly written. [ABSTRACT FROM AUTHOR]

Abstract The hydrodynamic interactions between successive two-dimensional (2D) solitons and structures have been investigated based on velocity potential theory. Successive solitons are generated by a moving horizontal elliptic cylinder at critical speed in shallow water. As a submerged cylinder or a rectangular floating barge encounters the solitons, it drifts with the wave induced flow. The interactions of solitons and structures are simulated using the mixed Euler-Lagrangian method (MEL) through a time stepping scheme. The auxiliary functions are introduced to analyse the coupled motions. The responses of structures have been analyzed and the velocity fields have been examined. Highlights • The reflection of solitons on a wall is the propogation of energy and the transformation of kinetic and potential energy. • The motion of submerged cylinder resembles the wave induced flow and drifts with the solitons. • The barge experiences large translational motion and the heave and roll motions decline as the breath increases. [ABSTRACT FROM AUTHOR]

To ensure the mechanical property of lapped spliced reinforcement and concrete confinement of boundary elements for precast concrete shears, two kinds of constraints, local constraint by additional spiral stirrups placed around each reinforcement splicing and overall constraint by lapped welding closed stirrups replacing traditional stirrups and ties, were proposed in this paper. Low-cyclic reversed loading tests were conducted on three full scale specimens, including one reference cast-in-situ specimen, one precast concrete specimen with local constraint and one precast concrete specimen with overall constraint. By comparing the aspects of strength, stiffness, ductility and energy-dissipation capacity with that of cast-in-situ specimen, it is found that local constraint and overall constraint can be considered equivalent. However, due to the over restraint by local constraint detail, the specimen with local constraint exhibited earlier yielding, poorer energy-dissipation capacity and better ductility than that with overall constraint. Coupled with the consideration of steel usage and construction simplicity, overall constraint detail should be preferred in practical engineering. [ABSTRACT FROM AUTHOR]

A circular perfectly conducting disk is one of only a few 3-D geometries amenable to exact electromagnetic analysis. In this communication, the currents induced on the disk by an incident plane wave are used to study the accuracy and convergence of numerical boundary element techniques that incorporate singular basis functions. It is shown that the use of singular basis functions improves the accuracy of the results compared to a conventional polynomial expansion. [ABSTRACT FROM AUTHOR]

Highlights • Existing model for confined concrete does not capture compressive behavior. • Crossties must be fully developed to provide effective restraint of longitudinal bars. • Unrestrained longitudinal bars do not contribute to arching of the confined core. • Proposed confined concrete model effectively simulates prism and wall tests. Abstract Reinforced concrete (RC) structural walls can provide superior stiffness in tall buildings while maintaining notable ductility when subjected to seismic demands. In flexure-dominated walls, this ductility is based on the ability of the end regions (also known as boundary elements) to maintain load carrying capacity through increasing tension and compression cycles. In order to achieve this behavior, modern design practice aims to force substantial yielding in tension prior to loss of compressive strength. As such, a sound understanding of the compressive behavior of wall end regions is paramount to understanding RC wall ductility. A database of both rectangular RC prism (axial) and RC wall tests was assembled, and the results were compared with a popular analytical constitutive model for confined concrete. The existing model assumes that compressive behavior is based on fracture of the transverse reinforcement, however the data indicates that bar buckling and/or crushing of the core can occur well before transverse bar fracture. Therefore, the existing model significantly overestimates both compressive strength and strain capacity in many conditions consistent with modern design. Formulations for compressive strength and strain capacity, as well as a monotonic constitutive model, are proposed to capture the compressive behavior observed in the data. Both the number of longitudinal bars and the use of crossties in place of closed hoops were found to have a significant impact on the compressive behavior of confined concrete, and are therefore integral to the proposed model. The model was developed based on tests performed by the authors, and then validated using the aforementioned database. [ABSTRACT FROM AUTHOR]

• The AEM method was utilized to capture the dynamic and quasi-static response of RMSW + BEs. • IDA was performed on the RMSW + BEs using Eastern Canada earthquake excitations. • Various design parameters of RMSW + BEs had different effect on wall response under dynamic and static loadings. • Mathematical correlations between the dynamic and quasi-static wall response parameters were proposed. • RMSW + BEs exhibited more stiffness, strength and energy dissipation from dynamic loading than their quasi-static counterparts. Reinforced masonry shear walls with boundary elements (RMSW + BEs) have enhanced curvature and displacement ductility and more energy dissipation than their rectangular counterparts when subjected to quasistatic cyclic loading. However, the behavior of walls tested under quasistatic cyclic loading is different from that under dynamic loading. Although there are many studies in the literature regarding the seismic response of RMSW + BEs, there is a gap in understanding the seismic performance parameters of RMSW + BEs when subjected to dynamic loading. Therefore, in this study, a numerical investigation of the seismic behavior of twelve previously tested half-scaled fully grouted RMSW + BEs was performed to quantify the seismic performance parameters of the walls under quasistatic cyclic loading and incremental dynamic loading. The studied walls have different design parameters that cover different aspect ratios, applied axial stress, horizontal and vertical reinforcement ratios, confinement type in boundary elements (BEs), discontinuity in BEs at upper floors and the presence of interstory slabs. A 2D numerical macromodel was developed using the Extreme Loading for Structures (ELS) software to validate and simulate the nonlinear lateral cyclic response of the studied walls. A nonlinear time-history analysis (NLTHA) was carried out using seven pairs of simulated ground motion records developed by Atkinson to represent Eastern Canada earthquake regions (i.e., Montreal, Quebec). The results showed good agreement between the walls' results among the two loading protocols to better estimate and correlate the walls' dynamic performance from quasistatic cyclic testing. The quasistatic loading results showed conservative lateral performance compared to dynamic loading in terms of stiffnesses, lateral capacity and energy dissipation. Moreover, the effect of different design parameters has been inspected on the dynamic performance of RMSW + BEs. Increasing the wall aspect ratio led to lower wall stiffnesses and lateral capacities at different loading stages. More energy dissipation and lateral capacity levels were observed when utilizing higher axial stresses on the walls. This study's findings will help better predict and estimate the lateral behavior of RMSW + BEs to help develop subsequent editions of the North American design standards for masonry structures. [ABSTRACT FROM AUTHOR]

Finite-element techniques in geomechanic calculations to assess strain-stress state in rock have shown insufficient flexibility towards varying geometry of computational schemes and necessity to set a large number of the unknown in solving space problems. Numeric calculation of stress intensity factor at the fracture tip by finite element analysis is a very demanding task in dimensional geomechanic simulation. Domain partition by irregular grid significantly expands the length of rigidity matrix bandwidth, which also largely depends on element enumeration approach. When computational scheme geometry considerably exceeds the size of the area of the detailed exploration of strain-stress state application of traditional methods of finite elements and geometric immersion is not feasible. The paper suggests to apply a potentially more accurate computational scheme for assessing strain-stress state of three-dimensional piecewise-homogeneous elastic environment on the basis of indirect method of boundary elements. In developing potassium beds by pillar system displacement discontinuity method as a variation of boundary element method appears to be a convenient tool to compute strain-stress state, which allows taking account of relation between the top and soil of the longwall space. Based on the indirect method of boundary elements, a software package was developed that offers a computational scheme to solve the problem of evaluating strain-stress state of piecewise-homogeneous linear-elastic environment. The results of solving test problems are given that prove adequacy of the computational scheme to evaluate strain-stress state of rock.

Tall towers and multi-storey buildings have fascinated mankind from the beginning of civilization, their construction being initially for defense and subsequently for ecclesiastical purposes. These tall buildings because of its height, is affected by lateral forces due to wind or earthquake actions tends to snap the building in shear and push it over in bending. In general, the rigidity (i.e. Resistance to lateral deflection) and stability (i.e. Resistance to overturning moments) requirement become more important. Shear walls (Structural walls) contribute significant lateral stiffness, strength, and overall ductility and energy dissipation capacity. In many structural walls a regular pattern of openings has to be provided due to various functional requirements such as to accommodate doors, windows and service ducts. Such type of openings reduces the stiffness of the shear wall to some extent depending on the shape and size of the opening. In the present parametric study, efforts are made to investigate and critically assess the effects of various size of openings in shear walls on the responses and behaviors of multi-storey buildings. The 30 storey Prototype buildings with different types of openings in shear wall with and without incorporating the volume of shear wall reduced in the boundary elements are analyzed using software E-TABS using Response spectrum method (1893(Part-1)-2002) and Time history method.

This work investigates the optimization of elasticity problems using the boundary element method (BEM) as a numerical solver. A topological shape sensitivity approach is used to select the points showing the lowest sensitivities. As the iterative process evolves, the original domain has portions of material progressively removed in the less efficient areas until a given stop criterion is achieved. Two benchmark tests are investigated to demonstrate the influence of the boundary conditions on the final topology. Following this, a suspension trailing arm is optimized and a new design is proposed as an alternative to commercially available methods. A postprocedure of smoothing using Bézier curves was employed for the final topology of the trailing arm. This process allowed the external irregular shapes to be overcome. The BEM coupled with the topological derivative was shown to be an alternative to traditional optimization techniques using the finite element method. The present methodology was shown to be efficient for delivering optimal topologies with few iterations. All routines used were written in open code. [ABSTRACT FROM AUTHOR]

Abstract: We consider the elastic wave equation in three dimensions with transparent boundary conditions on a bounded, not necessarily convex domain. This leads to a coupling of the elastic wave equation in the interior domain with time‐dependent boundary integral equations. This coupled system is to be solved numerically. The major theoretical result of this paper shows a coercivity property of a Calderón operator for the elastic Helmholtz equation, which is valid for all complex frequencies in a half‐plane. Combining Laplace transform and energy techniques, this coercivity in the frequency domain is used to prove the stability of the fully discrete numerical method in the time domain. The considered numerical method couples finite elements and explicit leapfrog time‐stepping in the interior with boundary elements and convolution quadrature on the boundary. We present convergent error bounds for the semi‐ and full discretization. [ABSTRACT FROM AUTHOR]

Reinforced concrete structural walls are one of the most commonly used lateral force-resisting systems for buildings located in regions of high seismicity. Structural walls are expected to provide significant strength and ductility under cyclic earthquake loading. However, compression failures observed following recent earthquakes and in laboratory testing have resulted in concern by the structural engineering community that wall boundary elements may not be able to sustain significant cyclic demands without significant damage. An experimental research program was undertaken to investigate the response of structural wall boundary elements, with a specific focus on boundary element detailing. The test program was developed as multiple series of tests of rectangular prisms that were intended to simulate the effects of geometry, confining reinforcement, and axial loading on the compressive strength and deformability of boundary elements. Each test series studied key confinement detailing parameters, such as vertical spacing of transverse steel, pattern of bar restraint, and the use of crossties in place of continuous hoops. In addition, impact of loading protocol was also studied. These test results were combined with data from existing test programs to form an extensive database, which was used to evaluate impact of such parameters on the distribution of plasticity and strength loss with respect to various ACI 318-14 detailing requirements. Results indicate that boundary elements tested in axial compression just meeting the minimum ACI 318 requirements exhibit strength and strain capacities that are, on average, 20% and 10% larger than unconfined concrete, respectively. The database was also used to develop new detailing recommendations for the spacing and pattern of confinement needed to achieve larger levels of confined response and deformability. [ABSTRACT FROM AUTHOR]

An accurate complex variable boundary element method is proposed for the numerical solution of two-dimensional boundary value problems governed by a steady-state advection–diffusion–reaction equation. With the aid of the Cauchy integral formulae, the task of constructing a complex function which gives the solution of the boundary value problem under consideration is reduced to solving a system of linear algebraic equations. The method is applied to solve several specific problems which have exact solutions in closed form and a problem of practical interest in engineering. [ABSTRACT FROM AUTHOR]

This work presents the analysis of three-dimensional polycrystals in the microscale with different lattice structures, hexagonal closed package (HCP) and face centered cubic (FCC). In these materials, the grained medium is considered as a continuum elastic body. An artificial polycrystalline structure is modeled using the Voronoi tessellation to generate random morphological microstructures. To reproduce the stochastic effects, arbitrary crystalline orientations are distributed over the structure. The boundary element method (BEM) is used to obtain the static displacement and traction fields, with a fundamental solution for 3D general anisotropic materials based on double Fourier's series. The macroscopic effective elastic properties are evaluated using the average homogenization technique and compared to the reference values through convergence statistical analysis. Explicit schemes are presented in order to improve the computational load and decrease the time required by the main BEM application implemented on distributed memory architectures. Numerical examples are presented showing the convergence of the results and comparisons of anisotropy level between these FCC and HCP materials using a recently proposed anisotropy factor. [ABSTRACT FROM AUTHOR]

In this paper, a comprehensive study on the seismic behavior of fractured concrete gravity dams during ground shakings is carried out considering dam-reservoir interaction effects. To gain the seismic behavior of the whole system, finite and boundary elements are employed to model the liquid region and the cracked structure, respectively. Formulation and different computational aspects of the suggested staggered hybrid approach are thoroughly argued. A computer code was developed in order to discuss the presented hybrid BE-DE technique and comparisons are made between the obtained results and those reported in the literature. To gain this goal, several problems of seismic excitations in frequency- and time-domains are presented employing the proposed approach, showing that the present results agree well with the results from other numerical procedures. The cracked Koyna Dam is scrutinized, considering the dynamic interaction between dam and reservoir with focus on the nonlinear behavior due to its top profile crack. The developed numerical model is rigorously validated by extensive comparisons with available results in the literature in which the dam-reservoir interaction were simplified by added masses. It can be concluded that there is significant disparity between the overturning and sliding response schemes of the nonlinear analysis and those of added mass technique. [ABSTRACT FROM AUTHOR]

In the present study, steel reinforcement details for slender structural walls were developed, which were lighter than those required by current design codes. In the developed details, transverse re-bars at wall boundaries with a relatively wide spacing and amorphous metallic fibers (AMFs) were used. Five slender wall specimens with an aspect ratio of 2.7 were constructed and tested under cyclic lateral and constant axial loads: one of these specimens was a control specimen, which was designed in accordance with the Korean concrete design code (KCI 2012), and the other four specimens were reinforced with AMFs. Two primary parameters are the fiber volume fraction of AMFs and the spacing between the transverse re-bars; three different fiber volume fractions of 0%, 0.3%, and 0.6% and three different spacing of transverse re-bars of 60 mm, 90 mm, and 120 mm were used. The test results showed that thin slender walls reinforced with AMFs exhibited inelastic behaviors and performances similar to those of the control specimen in terms of flexural strength, drift capacity, energy dissipation, equivalent damping ratio, and strain distribution along the wall height. In particular, the walls reinforced with AMFs satisfied the drift level required for collapse prevention performance specified in ASCE 41-13. In addition, a practical analysis method evaluating the drift capacity of slender structural walls reinforced with AMFs was developed and verified by comparing its prediction with the test results. [ABSTRACT FROM AUTHOR]

This paper presents a review of basic concepts of the boundary element method (BEM) for solving 3D half-space problems in a homogeneous medium and in frequency domain. The usual BEM for exterior problems can be extended easily for half-space problems only if the infinite plane is either rigid or soft, since the necessary tailored Green's function is available. The difficulties arise when the infinite plane has finite impedance. Numerous expressions for the Green's function have been found which need to be computed numerically. The practical implementation of some of these formulas shows that their application depends on the type of impedance of the plane. In this work, several formulas in frequency domain are discussed. Some of them have been implemented in a BEM formulation and results of their application in specific numerical examples are summarized. As a complement, two formulas of the Green's function in time domain are presented. These formulas have been computed numerically and after the application of the Fourier Transformation compared with the frequency domain formulas and with a FEM calculation. [ABSTRACT FROM AUTHOR]

We propose and analyze a new coupling procedure for the Hybridizable Discontinuous Galerkin Method with Galerkin Boundary Element Methods based on a double layer potential representation of the exterior component of the solution of a transmission problem. We show a discrete uniform coercivity estimate for the non-symmetric bilinear form and prove optimal convergence estimates for all the variables, as well as superconvergence for some of the discrete fields. Some numerical experiments support the theoretical findings. [ABSTRACT FROM AUTHOR]