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Seawalls are commonly constructed to prevent landward erosion of the shoreline and to maintain the configuration of the area behind them against wave action. In order to consider the effect of seawalls on surf zone hydrodynamics, experiments have been performed at laboratory model scale on partially reflective seawalls located in the surf zone. The main objectives of these experiments were to undertake a quantitative comparison of near-bed velocities in two cases (i.e. with and without the reflective structure). The presence of a reflective structure and the influence of reflected waves result in significant changes in the mean flow and the near-bed horizontal velocities in the surf zone. The latter is illustrated by comparing the probabilistic properties of velocities measured with and without a reflective structure. In this paper, a semi-empirical approach based on the measured probability density functions of near-bed horizontal velocities, is presented to predict the short-term response of a partially reflective seawall to random wave attack. The results obtained from the model and comparison with the experimental results, which have been reported previously are promising and encouraging for further developments of the preliminary model.

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A two-dimensional numerical model has been developed to study wave breaking on a sloping beach. The basic elements of numerical model are Reynolds Averaged Navier-Stokes (RANS) equations that describe the mean flow motion of a turbulent flow a k turbulence closure model that describes the turbulent transport and dissipation process an efficient technique (VOF- Volume Of Fluid method) for tracking the free surface motion and a new scheme developed by Lin and Liu (1999) for wave generation. Shoaling, breaking and overturning of solitary wave on a slope of 1/16 have been studied with the main emphasis on turbulence characteristics. Turbulence characteristics i.e., turbulence kinetic energy, k turbulence dissipation rate, turbulence production, pr turbulence eddy viscosity, vt and their spatial distribution during the breaking process have been discussed in great details. Spatial distribution of turbulence characteristics and the order of magnitude have been found to be in agreement with existing experimental and numerical studies. The main characteristic of plunging breaking waves, the shoreward advective transport of turbulence, has also been investigated and numerically proved.

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Time–Area method is one of the most widely applied techniques of watershed routing, and can be potentially used as a distributed model. In this paper, a fundamental flaw in the arrangement of subareas in the original time-area histogram is identified for one-dimensional flow. This is conducted on the basis of comparing time-area hydrograph with that of the kinematic wave theorem. Accordingly, a revised time-area algorithm is developed as a substitute for the original time-area. It is proved that in the revised approach, subareas must be reversely arranged. It is also shown that the revised time-area hydrograph is in perfect agreement with the hydrograph derived by the kinematics wave theory.

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Local site conditions have a strong effect on ground response during earthquakes. Two important soil parameters that control the amplification effects of seismic motions by a soil column are the soil hysteretic damping ratio and shear wave velocity. This paper presents the results of in situ damping ratio measurements performed using continuous surface wave attenuation data at a site in Semnan University campus and analysis used to obtain the near surface soils damping ratio profile. Once the frequency dependent attenuation coefficients are determined, the shear damping ratio profile is calculated using an algorithm based on constrained inversion analysis. A computer code is developed to calculate the shear damping ratio in each soil layer. Comparisons of the in situ shear damping ratio profile determined from continuous surface wave with cross hole independent test measurements are also presented. Values of shear damping ratio, obtained using continuous surface wave measurements, were less than the measured using cross hole tests, possibly because of the higher frequencies used in cross hole tests.

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A finite-difference based continuum numerical model is developed for the pile-soil dynamic response during pile driving. The model is capable of simulating the wave propagation analysis along the pile shaft and through the soil media. The pile-soil media, loading and boundary conditions are such that axisymmetric assumption seems to be an optimized choice to substantially reduce the analysis time and effort. The hydrostatic effect of water is also considered on the effective stresses throughout the soil media and at the pilesoil interface. The developed model is used for signal matching analysis of a well-documented driven pile. The results showed very good agreement with field measurements. It is found that the effect of radiation damping significantly changes the pile-soil stiffness due to the hammer blow. The pile tip response shows substantial increase in soil stiffness below and around the pile tip due to driving efforts.

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The main objective of this article is evaluation of the simplified models which have been developed for analysis and design of liquid storage tanks. The empirical formulas of these models for predicting Maximum Sloshing Wave Height (MSWH) are obtained from Mass Spring Models (MSM). A Finite Element Modeling (FEM) tool is used for investigating the behavior the some selected liquid storage tanks under available earthquake excitations. First, the results of FEM tool are verified by analyzing a liquid storage tank for which theoretical solution and experimental measurements are readily available. Then, numerical investigations are performed on three vertical, cylindrical tanks with different ratios of Height to Radius (H/R=2.6, 1.0 and 0.3). The behaviors of the tanks are initially evaluated using modal under some available earthquake excitations with various vibration frequency characteristics. The FEM results of modal analysis, in terms of natural periods of sloshing and impulsive modes period, are compared with those obtained from the simplified MSM formulas. Using the time history of utilized earthquake excitations, the results of response-history FEM analysis (including base shear force, global overturning moment and maximum wave height) are compared with those calculated using simplified MSM formulations. For most of the cases, the MSWH results computed from the time history FEM analysis demonstrate good agreements with the simplified MSM. However, the simplified MSM doesn’t always provide accurate results for conventionally constructed tanks. In some cases, up to 30%, 35% and 70% average differences between the results of FEM and corresponding MSM are calculated for the base shear force, overturning moment and MSWH, respectively.

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Future design procedures for civil structures, especially those to be protected from extreme and blast related

loads, will need to account for temporal evolution of their frequency content. There are, however, several instances

where acceleration time histories are required as seismic input. For example, to determine the ultimate resistance and

to identify modes of structures’ failure, a nonlinear time history analysis is needed. In other cases, acceleration time

histories are required for linear analyses. Many seismic codes require this type of analysis for buildings which have

irregularities. The process of time-frequency analysis made possible by the wavelet transform provides insight into the

character of transient signals through time-frequency maps of the time variant spectral decomposition that traditional

approaches miss. In this paper an approach is examined and a new method for processing the ground motion which is

modeled as a non-stationary process (both in amplitude and frequency), is proposed. This method uses the best basis

search algorithm with wavelet packets. In this approach, the signal is expressed as a linear combination of timefrequency

atoms which are obtained by dilations of the analyzing functions, and are organized into dictionaries as

wavelet packets. Several numerical examples are given to verify the developed models.

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Seismic piezocone device (SCPTu) together with Resonant Column and Cyclic Triaxial test apparatus are

employed to measure small strain shear modulus (G0) of carbonate sandy and clayey soils of southern coasts of Iran.

A large area of southern regions of Iran is formed from clay, silt and sand. In this study, maximum shear modulus that

is derived from both field (by seismic piezocone) and laboratory (by Resonant Column and Cyclic Triaxial) tests on

soil samples from the southern region, indicated a meaningful effect of sample disturbance. Results show that in

laboratory tests, loose samples tend to become denser and therefore exhibit greater stiffness whereas dense samples

tend to become looser, showing a reduction in stiffness. According to the results of the present study, there are narrow

limits of soils shear moduli for which the laboratory tests and the field measurements yield approximately the same

amounts. This limit of shear moduli is about 30-50(MPa) for clay deposits and 70-100 (MPa) for sandy deposits. Since

the shear moduli of soils in small strains can also be computed from the shear wave velocity, also correlations based

on parameters derived from SCPTu test for shear wave velocity determination of sandy and clayey soils of the studied

area are presented. This study shows that shear wave velocity can be related to both corrected tip resistance and total

normal stress. The measurements of the damping ratio and shear module, because of a great disturbance of stiff

deposits during the sampling process and also due to considerable differences between the laboratory and field

results, by the laboratory approaches are not reliable and advised.

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In this paper, a two-dimensional Reynolds Averaged Navier-Stokes (RANS) model is developed to simulate the shoaling, breaking and overtopping of a solitary wave over a vertical breakwater. Turbulence intensity is described by using a k turbulence closure model and the free surface configuration is tracked by Volume Of Fluid (VOF) technique. To validate the numerical model the simulation results is compared with the Xie (1981) experimental data and a very good agreement between them is observed. The results revealed that wave height and wave energy decrease considerably during the reflection from vertical wall, which illustrates a considerable energy lost during the impaction and wave overtopping process. The turbulence production during the broken wave interaction with vertical breakwater is very significant consequently the vertical breakwater undergoes sever turbulent and dynamic drag force.

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Laboratory data, which relate the liquefaction resistance of Firoozkooh sand and non-plastic silt mixtures to shear wave velocity are

presented and compared to liquefaction criteria derived from seismic field measurements by Andrus and Stokoe [1]. In the work

described herein, cyclic triaxial and resonant column tests were conducted on specimens of clean sand and sand-silt mixtures with silt

content up to 60%, prepared at different densities. Cyclic undrained strength and small strain shear wave velocity were determined

for identical specimens formed by undercompaction method. It was found that silt content affects cyclic resistance and shear wave

velocity. In addition, the laboratory results indicated that using the existing field-based correlations will overestimate the cyclic

resistance of the Firoozkooh sand-silt mixtures when silt content is 60%. For clean sand and the specimens containing up to 30% fines,

results of this study on cyclic resistance are fairly consistent with Andrus and Stokoe correlations. These findings suggest the need for

further evaluation of the effects of non-plastic fines content upon liquefaction criteria derived from seismic field measurements.

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In this article, the two-dimensional depth-averaged Saint Venant equations, including the turbulence terms, are solved in a

supercritical flow with oblique standing waves. The algorithm applies the finite volume Roe-TVD method with unstructured

triangular cells. Three depth-averaged turbulence models, including the mixing length, k-&epsilon and algebraic stress model (ASM),

are used to close the hydrodynamic equations. The supercritical flow in a channel downstream from a side-baffle in plan is then

simulated, and the numerical results are compared with the data obtained from a laboratory model. The application of different

models demonstrates that the consideration of turbulence models improves the results at the shock wave positions. The qualitative

study of the results and error analysis indicates that the ASM offers the most desirable solutions in comparison with the other

models. However, our numerical experiments show that, amongst the source term components, the negligence of turbulence terms

produces the least error in the depth estimation in comparison with the removal of the bed slope or bed friction terms.

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In almost all of the present mathematical models, the upstream subbasins, with overland flow as the dominant type of flow, are

simulated as a rectangular plane. However, the converging plane is the closest shape to an actual upstream subbasin. The

intricate nature of the governing equations of the overland flow on a converging plane is the cause of prolonged absence of an

analytical or semi analytical solution to define the rising limb of the resulted hydrograph. In the present research, a new

geomorphologic semi analytical method was developed that tries to establish a relationship between the parallel and converging

flows to reduce the complexity of the equations. The proposed method uses the principals of the Time Area method modified to

apply the kinematic wave theory and then by applying a correction factor finds the actual discharge. The correction factor, which

is based on the proportion of the effective drained area to the analytically calculated one, introduces the convergence effect of

the flow in reducing the potentially available discharge in a parallel flow. The proposed method was applied to a case study and

the result was compared with that of Woolhiser's numerical method that showed the reliability of the new method.

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Spatial Variation of Earthquake Ground Motion (SVEGM) is clearly indicated in data recorded at dense seismographic arrays

The main purpose of this paper is to study the influence of SVEGM on the seismic response of large embankment dams. To this

end, the Masjed Soleyman embankment dam, constructed in Iran is selected as a numerical example. The spatially varying ground

motion time histories are generated using spectral representation method. According to this methodology, the generated time

histories are compatible with prescribed response spectra and reflect the wave passage and loss of coherence effects. To

investigate the sensitivity of the dam responses to the degree of incoherency, three different coherency models are used to simulate

spatially variable seismic ground motions. Finally, the seismic response of the dam under multi-support excitation is analyzed

and compared to that due to uniform ground motion. Also, the Newmark's method is used to estimate seismic-induced permanent

displacements of the embankment dam. The analysis results reveal that the dam responses can be sensitive to the assumed spatial

variation of ground motion along its base. As a general trend, it is concluded that the use of multi-support excitation, which is

more realistic assumption, results in lower acceleration and displacement responses than those due to uniform excitation.

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Corrosion of reinforcing steel and other embedded metals is the main cause of severe deterioration in reinforced concrete structures which subsequently imposes adverse effects on ultimate and serviceability limit state performance of the whole structure. In this paper, a new corrosion detection method for reinforced concrete beams, based on wavelet analysis is presented. To evaluate the capability and efficiency of the method, a simply supported RC beam was modeled in 3-D taking into account the behaviors of concrete, steel and bond degradation. Deflection profile and mode shapes were extracted numerically and analyzed by wavelet transform. From the findings of the modeling, it can be concluded that this wavelet-based method is capable of detecting corrosion at its earliest stage. It is also concluded that both discrete and continuous wavelet transforms can be used and mother wavelet type has no significant effect on the results.

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The concept of Geosynthetic Cellular Systems (GCS) has recently emerged as a new method in construction of breakwaters and coastal protective structures. The method potentially has significant advantages compared to conventional systems from the standpoint of constructability, cost effectiveness, and environmental considerations. This paper presents the results of physical model testing on the hydraulic responses of GCS structures under wave action. A series of model tests were carried out in a wave flume on GCS models with different shapes and soil types, subjected to various wave characteristics. Horizontal wave forces acting on the models were measured at different elevations. The maximum horizontal force in each test was calculated and compared with conventional formula of predicting wave pressure on breakwaters. The results show that Goda’s equation overestimates the hydrodynamic water pressure on these structures. This can be attributed to the influence of seeping water through the GCS models because of relative permeability of the GCS.

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In this paper, a new approach is presented for estimating the vertical and horizontal distribution of undertow in the surf zone for reflective beaches. The present model is a modification of the original model presented by Okayasu et al., (1990) for natural, non-reflective beaches to include the effect of partially reflected waves. The nonlinearity of waves, wave-current interaction and nonlinear mass drift of the incident wave are also included in the present model. The results of experimental investigation and model development show that existence of reflective conditions on beaches results in a reduction in the magnitude of undertow and modifies its distribution across the beach profile. Comparison of the results by those obtained from the experiments clearly indicates that by taking the nonlinearity and wave-current interaction, the predictions of undertow in the surf zone are much improved. In particular, due to the effect of turbulence induced by wave breaking for nonlinear waves, the predicted results show more consistence with the measurements.

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Dynamic analysis of the seismic performance of power substation equipment is time-consuming, expensive and uses responses that are sensitive to ground motion. This research proposes a method to derive input waves for dynamic analysis in place of original records from seismic events in Iran. In this study, a power transformer, current transformer, circuit breaker and disconnect switch are analyzed using fifty records from the far-field and near-field earthquake ground motions. Statistical analysis is done on the maximum acceleration and displacement responses to obtain their pushover curves. Sinusoidal waves were created using the fundamental frequencies of the equipments and PGA of 0.1g through 0.5 g as the amplitude. The results are compared with the original records and show that the proposed input waves provide a reasonable fit for an extensive range of near-field and far-field ground motion results.

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This paper presents time domain fundamental solutions for the extended Biot's dynamic formulations of two-dimensional (2D) unsaturated poroelasticity. Unsaturated porous media is considered as a porous media in which the voids are saturated with two immiscible fluids, i.e. liquid and gas. At first, the corresponding explicit Laplace transform domain fundamental solution is obtained in terms of skeleton displacements, as well as liquid and gas pressures. Subsequently, the closed-form time domain fundamental solutions are derived by analytical inversion of the Laplace transform domain solutions. Finally, a set of numerical results are presented which verifies the accuracy of the analytically inversed transient fundamental solution and demonstrates some salient features of the elastic waves in unsaturated media..

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In this paper, normalized displacement amplitude of the ground surface was presented in the presence of the semi-sine shaped valley above the truncated circular cavity embedded in a homogenous isotopic linear elastic half-plane, subjected to obliquely propagating incident SH waves as Ricker wavelet type. The proposed direct time-domain half-plane boundary element formulation was used and extended to analyze the combined multi-boundary topographic problems. While using it, only boundary of the valley and the surrounding cavity should be discretized. The effect of four geometric parameters including shape ratio of the valley, depth ratio, horizontal location ratio and truncation thickness of the cavity and incident wave angle was investigated on the responses at a single dimensionless frequency. The studies showed that surface behavior was completely different due to complex topographic features, compared with the presence of either valley or cavity alone. In addition, the cavity existence below the surface could play a seismic isolation role in the case of vertical incident waves and vice versa for oblique waves.

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In this paper, an advanced formulation of the spectral finite element method (SFEM) is presented and applied in order to carry out site response analysis of 2D topographic structures subjected to vertically propagating incident in-plane waves in time-domain. The accuracy, efficiency and applicability of the formulation are demonstrated by solving some wave scattering examples. A numerical parametric study has been carried out to study the seismic response of rectangular alluvial valleys subjected to vertically propagating incident SV waves. It is shown that the amplification pattern of the valley and its frequency characteristics depend strongly on its shape ratio. The natural frequency of the rectangular alluvial valley decreases as the shape ratio of the valley decreases. The maximum amplification ratio along the ground surface occurs at the center of the valley. A simple formula has been proposed for making initial estimation of the natural period of the valley in site effect microzonation studies.