جستجوی مقالات مرتبط با کلیدواژه « پاسخ دینامیکی » در نشریات گروه « عمران »

This paper is devoted to investigating the effect of applied torsional moment on the out-of-plane behavior of horizontally curved beams (HCBs) subjected to the excitation induced by a moving mass. As the mass travels along the top surface of HCBs, a torsional moment will be introduced into the system due to the eccentricity of the in-plane centrifugal action with respect to the shear center of the HCB section. The differential equations governing the HCB-moving mass system are first established considering the effect of mass inertia, Coriolis and centrifugal forces, and then numerically solved within the transition matrix approach. Thereafter, a parametric study is conducted to evaluate the influence of radius of curvature and central subtended angle of HCB, as well as the mass and velocity of the moving object. In general, with an increase in the values of radius of curvature and subtended angle of HCBs, a decreasing effect in the response of the system is observed. Moreover, a general magnifying effect is essentially experienced due to an increase in the mass and velocity of the moving object. As the results suggest, the magnifying effect of the induced torsional moment due to the in-plane centrifugal force is at most six percent for the results studied herein. For long-span HCBs, the torsional effect can be deemed as insignificant on the out-of-plane response of HCB-moving mass systems. In conclusion, it is indicated that considering the contribution of the torsional moment can offer a more realistic response estimation regarding the dynamics of HCBs acted upon by a moving inertial load.

By studying the literature on liquid storage tanks and their seismic behavior, it is observed that sloshing waves have caused severe damages to the walls and upper parts of these structures. As a remedy, some researchers have provided passive control systems to mitigate the seismic responses; one of these passive systems is annular baffles which are mounted on different heights of the tank wall. In the present study, seismic behavior of the slender and broad fixed-based tanks with baffles of different geometries have been examined; for this purpose, the deformation of the tank shell and baffles in the time and frequency domains are considered. The coupled acoustic-structure formulation based on fluid pressure and structure displacement has been used in the framework of linear finite element method in ABAQUS commercial software. At the interaction surface, fluid pressure and the normal acceleration of the structure interact with each other using the surface-based interaction capability of the ABAQUS software. The liquid is assumed to be compressible, inviscid and irrotational, and seismic loading is applied to the liquid-filled storage tanks' supports. The models are verified by comparison with the results that are reported in the literature in frequency and time domains. A parametric study is performed on Ri/R radius ratio and h/H distance ratio of baffles in the slender and board tank. Results indicated that in the frequency domain, the geometry with ratios (Ri/R=0.3, h/H=0.1 ) of the baffles which has the biggest radial coverage and the smallest distance ratios from the liquid surface, has the highest reduction effect on the frequency of the first convective mode of the slender and broad tanks, equal to 43% and 68%, respectively. Therefore, top-mounted baffles with considerable radial coverage, have higher effects on reducing the frequency of the first convective mode of the tanks. Baffles have fewer effects on the frequency of the first impulsive mode than on the first convective mode. Besides, analyses in the time domain revealed that top-mounted baffles with medium and small radial coverage in the broad tanks caused the increase of the sloshing wave amplitudes by about 68%, at worst cases. Baffles with less effects on the first convective modes were more effective on decreasing the sloshing wave amplitudes. Therefore, satisfactory performance of the baffled liquid tanks may not be obtained by solely relying on the frequency of the first convective mode of the tanks, due to unwanted increase of sloshing amplitudes in the special cases of liquid tank geometry and baffles. According to the results, in the board tanks, top-mounted baffles may amplify the seismic response of the system and thus, considerable attention is required on the use of passive devices in such tanks. Unlike the broad tanks, baffles have satisfactory influences on the seismic behavior of the slender tank. It’s recommended that when the baffles are used as a passive controlling system in a broad tank, all of the tank responses such as base shear, hydrodynamic pressure, and etc. to be considered; since, these responses may increase significantly if top-mounted baffles are used.  Analysis in time domain also indicates that the differentiation between the slender and broad tanks in studying the baffles' effects is crucial. In general, using middle-mounted baffles is recommended as an efficient passive system to mitigate the sloshing waves in broad tanks.

The degree of control of the response and performance of structures under external loads is one of the most important issues in structural and earthquake engineering. Today, the use of modern systems to control structural vibrations has expanded significantly. Viscous dampers are one of the most common tools for controlling structural vibrations against external loads. One of these foreign burdens could be an explosion caused by terrorist attacks. In this research, it has been tried to investigate the behavior of structures with viscous dampers based on energy balance under explosion load. For this aim, two 10-story structures with Moment Resistance Frame (MRF) system and steel Moment Resistance Frame with viscous damper under different explosion scenarios have been analyzed and the dissipated and absorbed energies in the energy balance due to external work have been evaluated. First, to better understand the behavior of these structures, the performance of the structures is evaluated based on the plastic hinges and the relative displacement of the studied stories and finally the effect of viscous damper in reducing the damage of structures using energy balance concepts. The results show that in general, viscous dampers can reduce the damage to an acceptable level and control the behavior of the structure.

Soil-structure interaction is one of the important and influential factors on the seismic behavior of structures, especially reinforced concrete structures. In this study, the effect of soil-structure interaction on a 9-story reinforced concrete structure with a flexural frame system designed based on low-risk seismic requirements and for nonlinear analysis with OpenSees finite element software in two different modes with rigid base without considering the interaction And with a flexible base, the effect of soil-structure interaction has been modeled and evaluated. The results show that due to the interaction, the base shear, the shear within the floors and the amount of relative displacement are reduced, while the actual periodicity of the building and the absolute displacement of the floors is increased.

Pile foundations are widely used to ensure the stability of structures subjected to seismic excitation. Numerous structures and foundations in soil-pile-structure systems have been destroyed during occurrence of earthquakes. Because of complexities involved in soil-pile interaction problems and the lack of precise methods, it is necessary to use numerical methods for analyzing soil-pile interaction problems. There are several factors affecting the dynamic response of a pile in soil-pile system. These factors can be divided into three main categories: geometrical factors, material properties, and load characteristics. Studying the effects and importance of these factors in the response of the pile will help geotechnical engineers to optimize their design. In this research, three-dimensional modeling has been developed using FLAC3D computer program, and the effects of various soil and pile properties on the dynamic behavior of a single pile in clayey soils are evaluated. One of the most important subjects in the numerical modeling of soil-pile system dynamic response is the constitutive model considered for the soil. This strongly affects the accuracy of results. In this study a softening model has been used for the behavior of the soil under dynamic loads.Sinusoidal harmonic loading has been applied to the model base as the acceleration time history, and the variations of bending moments, shear forces, and displacements along the pile are obtained for all analyses carried out in this study.The results show that kinematic interaction coefficient depends on the loading characteristics and in the high frequencies head pile response is lower than free field.

Machine foundations induce a wide range of dynamic shear strains in foundation bed. Dynamic properties of soils including the damping ratio and the dynamic stiffness intensely depend on the level of generated dynamic shear strain. Therefore, considering the appropriate dynamic properties of a foundation bed corresponding to the generated dynamic shear strain is crucial to having a better evaluation of the dynamic response of a machine foundation. This paper presents the design and construction of an apparatus namely “Foundation Model Response Test (FMRT)”. This apparatus provides the tests to investigate the dynamic properties of machine foundation and underlying bed in a wide range of dynamic shear strains employing a various range of dynamic excitation forces and static weight (dead weight). The FMRT apparatus could be used in the field to evaluate the dynamic response of the undisturbed bed and on the prepared bed in the laboratory test pit. Two types of steady-state and free vibration tests could be conducted by employing the FMRT apparatus. Steady-state vibration tests induce larger shear strain in bed, whereas free vibration tests induce smaller shear strain. Correlation of the results of these two types of tests, dynamic responses, and dynamic properties of foundation bed in a wide range of dynamic shear strain would be achieved. The accuracy and validity of all FMRT tests are possible to monitor precisely and any unwanted noises and modes of vibration are possible to be controlled by evaluating the Fast Fourier Transform (FFT) of all sensors data when conducting tests. Several steady-state and free vibration tests were conducted to illustrate the performance of the designed apparatus. Moreover, the method of calculation, controlling unwanted vibration, and correlation of free and steady-state example tests were submitted. FMRT tests are inexpensive, repeatable, non-destructive and reliable tests that ensure the dynamic response of machine foundation possible accurately.

Because of having amazing mechanical physical properties including noise pollution reduction, quiet, reliability, most cost-effective, sustainable and lasting life, asphalt pavement system has been utilized for parking lots, roadways, airstrips by the most state and federal governments highly prefer asphalt pavement by many civil engineers. Generally, asphalt pavement is made up of sand, stone (aggregate), liquid (petroleum) asphalt and additives. In the present study, the thermo-dynamic behavior of porous viscoelastic asphalt pavement system under a moving harmonic load based on the classical plate theory is analyzed. The asphalt pavement system is modeled as a rectangular sandwich plate structure. Three states of porosity distribution pattern, i.e., uniform porosity, non-uniform symmetric porosity, non-uniform asymmetric porosity distributions are considered for porous asphalt layer which are supposed to vary along the in-plane and thickness directions. The equations of motion are extracted in accordance with Hamilton’s variational principle and then solved using the expanded Fourier series. The accuracy and correctness of the extracted formulation are firmly demonstrated by comparing the data accessible in the literature and finite element simulation COMSOL Multiphysics®. In this study, the dynamic response of the asphalt pavement system was evaluated analytically and numerically by considering the porous asphalt layer under the harmonic load at various velocities in a thermal environment. The classical theory of plates was used for the analytical modeling of the system. The dynamic equations were derived in view of the relations for porosity and thermal strain in the stress-strain matrices in combination with Hamilton’s principle. With the aid of Fourier series expansions, and given the considered boundary conditions, the partial dynamic equations were transformed into differential dynamic equations. Furthermore, the dynamic response of the system was obtained using Laplace transform, which was then evaluated in terms of effective parameters. A finite element simulation software was also used to validate the results against the published articles. In this study, three case of uniform porosity, non-uniform symmetric porosity, non-uniform asymmetric porosity distributions are considered for modeling porous asphalt layer. Parameter studies reveal the impacts of the velocity and the excitation frequency of the harmonic moving load, porosity distributions, and temperature changes on the dynamic response of the pavement system. According to the conducted studies thus far, the dynamic behavior of asphalt pavement system is inevitably affected by such outcomes. Furthermore, the results demonstrated that non-uniform symmetric porosity case is more suitable than the other two types of porosity, The temperature changes lead to a softer asphalt pavement system, With increasing porosity, the dynamic response of the system rises in all the cases of porosity distributions and The amplitude of nondimensional dynamic deflection is directly proportional to the frequency of excitation up to the resonance.

Dam behavior investigation has been considered for a long time, with many studies conducted to identify and predict factors influencing such structures. In common dynamic analyses of dams, an input acceleration is typically used. At the same time, it was proved that such structures with a large contact with the ground usually experience different accelerations in their various supporting points. Applying different accelerations on different supports of a structure can increase their stresses and displacements. The stresses can be among factors affecting dam stability. Thus, it is very important to accurately study its effect on the dynamic behavior of arc concrete dams. Furthermore, in most arc dam analyses, their bodies have been treated as integrated, while such dams are constructed by putting together concrete blocks with vertical joints in practice. In the current study, after building an ABAQUS three-dimensional model of Karoon-4 Dam as the tallest arc concrete dam in Iran, it was attempted to apply the vertical joints to compare the dynamic behavior of arc concrete dams under uniform and non-uniform analyses and the case in which the dam body is modeled in an integrated form. The results revealed that the non-uniform analysis increased  stresses and displacement of  dam.....

To investigate the seismic responses of dams due to ground non uniform displacements, the records of earthquake displacements are required. Such data is seldom recorded during a specific earthquake and in the most cases the recorded data in not sufficient for non-uniform analysis of a dam. In this study non uniform accelerations are generated using Kanai-Tajimi spectrum with considering wave passage, incoherent effects and coherence spectrum model. A 3-d finite element model of dam-foundation of Karun 4 arch dam as the highest dam in Iran is modeled. The model is analyzed under uniform and non-uniform generated accelerations and its responses are investigated. The results show that, non-uniform excitation leads to differences in seismic response than uniform excitation on dam. It is indicated that considering non-uniform excitation in seismic analysis increases the stresses and displacements on the dam body. To investigate the seismic responses of dams due to ground non uniform displacements, the records of earthquake displacements are required. Such data is seldom recorded during a specific earthquake and in the most cases the recorded data in not sufficient for non-uniform analysis of a dam. In this study non uniform accelerations are generated using Kanai-Tajimi spectrum with considering wave passage, incoherent effects and coherence spectrum model. A 3-d finite element model of dam-foundation of Karun 4 arch dam as the highest dam in Iran is modeled. The model is analyzed under uniform and non-uniform generated accelerations and its responses are investigated. The results show that, non-uniform excitation leads to differences in seismic response than uniform excitation on dam. It is indicated that considering non-uniform excitation in seismic analysis increases the stresses and displacements on the dam body.

Shallow foundations are among the most common typesof foundations used to support mid-rise buildings in ar-eas with high seismic hazard. Recent studies have indi-cated that dynamic interaction of soil-foundation andbuilding can a ect the seismic response of structuresduring an earthquake. Therefore, the foundation fea-tures can also change the dynamic characteristics, suchas natural frequency and damping of the soil-foundation-structure system. In this research, a 14 story momentresistant frame building built on shallow foundationswith various dimensions has been considered and thethree dimensional prototype of all three components ofsoil-foundation-structure system has been modeled byABAQUS nite element software. Also modal analysiswas performed to calculate the natural frequencies ofeach model. In the present study, in nite boundarieswere applied in order to simulate free eld conditionand appropriate contact elements were used to modelthe slip and separation phenomena between foundationand soil elements. To do so, nite element direct modelswere developed. Cone model, as one of the approximatemethods that considers SFSI with practical engineeringprecision was veri ed and then applied in the series ofsimulations. An assessment procedure was applied tocheck the accuracy of Cone model as an approximatemethod in comparison with direct method. Structuralresponses including lateral deformation, drift, rotationand shear force distribution were studied for all cases in-cluding xed-base, cone model and SFSI direct models.Modal analysis implies that SFSI can reduce the natu-ral frequencies of the building. The results show thatshallow foundation size, due to the interaction betweensoil, foundation and structure, in uences the dynamiccharacteristics and seismic response of building. As aresult, engineers should carefully consider these param-eters to ensure the safety and economic seismic design.Cone Model with an appropriate engineering precision,functionality and high analysis speed is capable of assess-ing dynamic sti ness of soil due to the soil-foundation-structure interaction phenomena.

Vibration of structures under moving loads has been extensively dealt with by numerous researchers. In particular, this problem is of importance to bridge engineers. In this regard, there are a great number of studies on vibration analysis of single - span thin beams under moving loads. It is noteworthy to highlight that there is lack of research on the dynamic behavior of multi-span beams under moving inertial loads. Moreover, most of these studies neglect the inertia of the moving vehicle and consider the moving force approach. However, several investigations using moving mass approach highlighted the considerable contribution of load/structure inertial interaction for heavy masses moving at high speeds. In moving mass simulation framework, a solid mass is considered to slide on the base structure while remains directly in contact with the base structure. Therefore, the transverse acceleration of the moving object corresponds to that of the beam beneath the traveling load and the effects of vehicles flexibility are neglected. Moving oscillator model is composed of a mass supported by a spring-damper system in order to allow for the vehicle suspension system. Hence, moving oscillator can capture a wider range of possible structural behaviors with regard to the variation of vehicle stiffness. In this research, dynamic behavior of a multi-span continuous beam subjected to the excitation of an accelerated moving oscillator is studied to simulate vibration of a multi-span bridge acted upon by the accelerated movement of a vehicle. Euler-Bernoulli beam theory is employed as the governing equation for each span of the beam. The proposed solution is applicable to general beam fixity conditions. Moving oscillator model, as a reduced order model of a moving system, is of higher accuracy rather than old-fashioned methods of moving force and moving mass due to importing suspension system effects on the corresponding computational model. The solutions are verified and very close agreement is observed with published results via other methods in the asymptotic states of moving oscillator, where soft and rigid springs correspond to moving force and moving mass, respectively.

In structural dynamics, loads having varying positions has been broadly studied. Such loads are so called moving loads which appears in various applications in industry. High speed machining systems, overhead cranes, cable ways, pavements, computer disc memories and robot arms are a few examples of moving load dynamic problems. Vibration of bridge structures subject to moving vehicles is often referred to as an application of moving load problems. A great number of researchers proposed numerical and analytical methods to deal with the vibration of solids and structures under travelling loads. A famous classic approach in the simulation of moving loads is the moving force. In moving force model, a constant traveling force is assumed to act upon the base structure. However, this assumption yields to reasonable structural analysis if the mass of the moving object is negligible. Nowadays, with ongoing advances of transportation technology, the mass, speed and acceleration of moving vehicles are notably increased. In this regard, during the last few decades, many researchers showed that the moving force is no longer valid for large moving masses. Therefore, the moving mass simulation has been proved to be closer to the physical model of vehicle bridge interaction. As a common practice, bridges carrying moving vehicles has been assumed as vibrating beams excited by point moving masses. It has been very customary to consider the midspan or center point of the base beam as the reference point in order to assess the maximum dynamic response of the structure under moving mass; therefore, most of the existing computed design envelopes are related to the values occurring at the midpoint of the structure. However, the location of the maximum values occurrence is not necessarily at midspan. To shed light on this issue, in this research an analytical-numerical method is established to capture dynamic response of an Euler-Bernoulli beam traversed by a moving mass. Most of the available literature on moving load problem is concerned with the travelling loads having constant speeds. To remove this restrictive presumption, in this paper, the considered moving mass is assumed to move at non-zero constant acceleration. The beam is considered to be undamped and initially at rest. The moving mass is assumed to maintain full contact condition with the base beam while sliding on it. By exploiting a series of continuous shape functions having time varying amplitude factors, a norm space is provided by which the beam spatial domain is discretized. The problem is then transformed into time domain for which a time integration method is utilized. Absolute maximum dynamic response of the supporting beam under the passage of accelerated moving mass is extensively sought over the beam length. In this manner, whole beam length is being monitored for the maximum values at each time step of time integration procedure. The beam absolute maximum dynamic response is comprehensively computed considering different mass ratios and extensive range of linearly time varying velocities. Parametric studies are carried out on the absolute maximum values of dynamic flexural moments and deflections and compared to those captured at midspan. Finally, it highlighted that the midspan of the beam cannot be a valid reference to obtain the true maximum deflections and flexural moments of the base beam.

One of the major issues facing structural engineers is assessing the effects of dynamic loads on structural systems, including beams. The importance of this matter arises in moving vehicles such as cars and trains on bridge structures that are usually simulated by beam structures. Hence, in several studies, in order to explore the dynamic response of the beam structures under the excitation of dynamic loads, various analytical and numerical methods have been utilized. In this study, to examine the easier and faster procedures aimed at finding the dynamic response of Euler-Bernoulli, Timoshenko and Higher-Order beams, a simple semi-analytical method based on the characteristic orthogonal polynomials and trigonometric functions compatible with boundary conditions is presented. To this end, discrete equations of motion are derived for the three mentioned theories due to a moving mass according to the Hamilton’s principle. Then, the governing equations are transformed into ordinary differential equations in the time domain, and by applying an approximate method, displacement field of the beam is achieved. In order to consider the efficiency, convergence rate and accuracy of this method, two numerical examples are provided to compare the results of this paper with those presented by other researchers. In this regard, in the former one, free vibration frequencies of the beam with various theories for different boundary conditions were obtained, and it is shown that, the results for all three theories, give a good convergence rate and a high accuracy. Furthermore, in the latter example, the dynamic response of the beams subjected to a moving mass for different values of the base beam slenderness was achieved and compared with other studies. Analysis of the maximum dynamic response of the beam and the time history diagrams illustrated the obtained results are in a close agreement with those issued from the numerical method; despite using the lower number of the shape functions.

I‌n r‌e‌c‌e‌n‌t y‌e‌a‌r‌s, i‌n‌t‌e‌r‌e‌s‌t i‌n t‌h‌e d‌y‌n‌a‌m‌i‌c‌s o‌f r‌a‌i‌l‌w‌a‌y b‌r‌i‌d‌g‌e‌s, a‌s n‌e‌c‌e‌s‌s‌a‌r‌y p‌r‌e‌l‌i‌m‌i‌n‌a‌r‌i‌e‌s f‌o‌r c‌o‌n‌s‌t‌r‌u‌c‌t‌i‌o‌n o‌f h‌i‌g‌h-s‌p‌e‌e‌d r‌a‌i‌l‌w‌a‌y‌s, h‌a‌s i‌n‌c‌r‌e‌a‌s‌e‌d r‌a‌p‌i‌d‌l‌y. I‌n‌c‌r‌e‌a‌s‌i‌n‌g t‌r‌a‌i‌n s‌p‌e‌e‌d‌s m‌e‌a‌n‌s t‌h‌a‌t b‌r‌i‌d‌g‌e‌s a‌r‌e s‌u‌b‌j‌e‌c‌t‌e‌d t‌o m‌u‌c‌h h‌i‌g‌h‌e‌r d‌y‌n‌a‌m‌i‌c e‌f‌f‌e‌c‌t‌s. T‌h‌e‌r‌e‌f‌o‌r‌e, t‌h‌e b‌e‌a‌r‌i‌n‌g c‌a‌p‌a‌c‌i‌t‌y o‌f s‌t‌r‌u‌c‌t‌u‌r‌e‌s m‌u‌s‌t b‌e i‌n‌c‌r‌e‌a‌s‌e‌d i‌n p‌r‌o‌p‌o‌r‌t‌i‌o‌n t‌o d‌e‌m‌a‌n‌d l‌o‌a‌d, a‌n‌d d‌y‌n‌a‌m‌i‌c e‌f‌f‌e‌c‌t‌s m‌u‌s‌t b‌e c‌o‌n‌s‌i‌d‌e‌r‌e‌d i‌n t‌h‌e s‌t‌r‌u‌c‌t‌u‌r‌a‌l d‌e‌s‌i‌g‌n. I‌n p‌r‌e‌v‌i‌o‌u‌s d‌e‌s‌i‌g‌n m‌e‌t‌h‌o‌d‌s, d‌y‌n‌a‌m‌i‌c e‌f‌f‌e‌c‌t‌s w‌e‌r‌e o‌f‌t‌e‌n c‌o‌n‌s‌i‌d‌e‌r‌e‌d b‌y i‌n‌t‌r‌o‌d‌u‌c‌i‌n‌g d‌y‌n‌a‌m‌i‌c a‌m‌p‌l‌i‌f‌i‌c‌a‌t‌i‌o‌n f‌a‌c‌t‌o‌r‌s, b‌u‌t, i‌t c‌a‌n b‌e s‌e‌e‌n t‌h‌a‌t, i‌n m‌o‌s‌t c‌a‌s‌e‌s, w‌h‌e‌r‌e t‌r‌a‌i‌n s‌p‌e‌e‌d i‌s m‌o‌r‌e t‌h‌a‌n 200 k‌m/h, d‌y‌n‌a‌m‌i‌c a‌n‌a‌l‌y‌s‌i‌s o‌f t‌h‌e b‌r‌i‌d‌g‌e i‌s r‌e‌q‌u‌i‌r‌e‌d b‌y i‌n‌c‌r‌e‌a‌s‌i‌n‌g t‌r‌a‌i‌n s‌p‌e‌e‌d. C‌o‌r‌r‌e‌c‌t u‌n‌d‌e‌r‌s‌t‌a‌n‌d‌i‌n‌g o‌f t‌h‌e d‌y‌n‌a‌m‌i‌c‌s o‌f r‌a‌i‌l‌w‌a‌y b‌r‌i‌d‌g‌e‌s r‌e‌s‌u‌l‌t‌s i‌n a r‌e‌a‌l‌i‌s‌t‌i‌c a‌s‌s‌e‌s‌s‌m‌e‌n‌t o‌f t‌h‌e‌i‌r s‌t‌r‌u‌c‌t‌u‌r‌a‌l r‌e‌s‌p‌o‌n‌s‌e‌s u‌n‌d‌e‌r t‌r‌a‌i‌n l‌o‌a‌d‌s. N‌e‌w b‌r‌i‌d‌g‌e d‌e‌s‌i‌g‌n‌s w‌i‌l‌l b‌e e‌c‌o‌n‌o‌m‌i‌c‌a‌l a‌n‌d a‌l‌s‌o u‌t‌i‌l‌i‌z‌a‌t‌i‌o‌n o‌f e‌x‌i‌s‌t‌i‌n‌g b‌r‌i‌d‌g‌e‌s w‌i‌l‌l b‌e p‌r‌o‌p‌o‌r‌t‌i‌o‌n‌a‌l t‌o t‌h‌e‌i‌r c‌a‌p‌a‌c‌i‌t‌y. I‌n t‌h‌i‌s s‌t‌u‌d‌y, w‌e h‌a‌v‌e e‌n‌d‌e‌a‌v‌o‌r‌e‌d t‌o s‌p‌e‌c‌i‌f‌y t‌h‌e d‌y‌n‌a‌m‌i‌c r‌e‌s‌p‌o‌n‌s‌e o‌f a d‌o‌u‌b‌l‌e-t‌r‌a‌c‌k r‌a‌i‌l‌w‌a‌y b‌r‌i‌d‌g‌e t‌o m‌o‌v‌i‌n‌g t‌r‌a‌i‌n‌s, a‌n‌d t‌h‌e i‌n‌f‌l‌u‌e‌n‌c‌e o‌f b‌r‌i‌d‌g‌e s‌k‌e‌w‌n‌e‌s‌s. D‌y‌n‌a‌m‌i‌c a‌n‌a‌l‌y‌s‌i‌s i‌s b‌a‌s‌e‌d o‌n a t‌h‌r‌e‌e-d‌i‌m‌e‌n‌s‌i‌o‌n‌a‌l m‌o‌d‌e‌l o‌f b‌r‌i‌d‌g‌e-t‌r‌a‌i‌n i‌n‌t‌e‌r‌a‌c‌t‌i‌o‌n. T‌h‌e Y‌a‌z‌d‌a‌n v‌i‌a‌d‌u‌c‌t i‌s a‌n u‌n‌d‌e‌r c‌o‌n‌s‌t‌r‌u‌c‌t‌i‌o‌n b‌r‌i‌d‌g‌e l‌o‌c‌a‌t‌e‌d o‌n t‌h‌e Q‌o‌m-S‌a‌g‌h‌e d‌o‌u‌b‌l‌e-t‌r‌a‌c‌k r‌a‌i‌l‌w‌a‌y. I‌t i‌s a‌l‌s‌o a s‌i‌m‌p‌l‌e s‌p‌a‌n b‌r‌i‌d‌g‌e w‌i‌t‌h 22m s‌p‌a‌n l‌e‌n‌g‌t‌h t‌h‌a‌t h‌a‌s b‌e‌e‌n i‌n‌v‌e‌s‌t‌i‌g‌a‌t‌e‌d u‌n‌d‌e‌r d‌i‌f‌f‌e‌r‌e‌n‌t s‌k‌e‌w‌n‌e‌s‌s o‌f 0, 15, 30, 45 a‌n‌d 60 d‌e‌g‌r‌e‌e‌s. T‌o v‌a‌l‌i‌d‌a‌t‌e t‌h‌e a‌c‌c‌u‌r‌a‌c‌y o‌f t‌h‌e m‌o‌d‌e‌l a‌n‌d t‌h‌e r‌e‌s‌u‌l‌t‌s o‌f t‌h‌i‌s s‌t‌u‌d‌y, a 30m s‌p‌a‌n b‌r‌i‌d‌g‌e f‌r‌o‌m e‌x‌i‌s‌t‌i‌n‌g m‌o‌d‌e‌l‌s i‌n r‌e‌p‌u‌t‌a‌b‌l‌e i‌n‌t‌e‌r‌n‌a‌t‌i‌o‌n‌a‌l p‌a‌p‌e‌r‌s w‌a‌s u‌s‌e‌d. T‌h‌e r‌e‌s‌u‌l‌t‌s o‌f a‌n‌a‌l‌y‌s‌i‌s d‌e‌m‌o‌n‌s‌t‌r‌a‌t‌e‌d t‌h‌a‌t t‌h‌e v‌e‌r‌t‌i‌c‌a‌l d‌i‌s‌p‌l‌a‌c‌e‌m‌e‌n‌t a‌n‌d a‌c‌c‌e‌l‌e‌r‌a‌t‌i‌o‌n o‌f t‌h‌e b‌r‌i‌d‌g‌e i‌n‌c‌r‌e‌a‌s‌e u‌n‌d‌e‌r h‌i‌g‌h s‌p‌e‌e‌d l‌o‌a‌d‌s. A‌t t‌r‌a‌i‌n s‌p‌e‌e‌d‌s c‌l‌o‌s‌e t‌o c‌r‌i‌t‌i‌c‌a‌l s‌p‌e‌e‌d, d‌u‌e t‌o m‌o‌v‌i‌n‌g a‌x‌l‌e g‌r‌o‌u‌p‌s, t‌h‌e b‌r‌i‌d‌g‌e r‌e‌s‌p‌o‌n‌s‌e‌s g‌r‌e‌w c‌o‌n‌s‌i‌d‌e‌r‌a‌b‌l‌y a‌s r‌e‌s‌o‌n‌a‌n‌c‌e o‌c‌c‌u‌r‌r‌e‌d. S‌k‌e‌w‌n‌e‌s‌s w‌a‌s f‌o‌u‌n‌d t‌o i‌n‌c‌r‌e‌a‌s‌e t‌h‌e f‌u‌n‌d‌a‌m‌e‌n‌t‌a‌l f‌r‌e‌q‌u‌e‌n‌c‌y o‌f t‌h‌e b‌r‌i‌d‌g‌e, a‌n‌d w‌i‌t‌h a‌n i‌n‌c‌r‌e‌a‌s‌e i‌n b‌r‌i‌d‌g‌e s‌k‌e‌w‌n‌e‌s‌s, t‌h‌e d‌y‌n‌a‌m‌i‌c r‌e‌s‌p‌o‌n‌s‌e‌s o‌f t‌h‌e b‌r‌i‌d‌g‌e d‌e‌c‌r‌e‌a‌s‌e‌d.

In this research, horizontal dynamic response of foundation on homogeneous half-space was investigated using physical modeling. In order to carry out a comprehensive study on the effect of embedment depth ratio on horizontal impedance functions, 173 different tests in three series were conducted. In these tests, the embedment ratio of footing was increased from zero to 0.5 and finally reached to one by implementing the mentioned sand raining method. In each series of tests, the steady-state response of footing to horizontal vibrations was investigated. Using recorded data and related motion equations, foundation responses were analyzed. The obtained results were presented by graphs of horizontal impedance functions of square foundation on homogenous half-space against dimensionless frequency. Comparing horizontal impedance functions shows that an increase in embedment depth ratio resulting from amplifying impedance function coefficients up to dimensionless frequency of 3.5 Hz.