• Steel and Composite Structures
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• v.10 no.3
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• pp.223-243
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• 2010

This paper reports recent developments concerning the application of Generalised Beam Theory (GBT) to the structural analysis of steel-concrete composite bridges. The potential of GBT-based semi-analytical or finite element-based analyses in this field is illustrated/demonstrated by showing that both accurate and computationally efficient solutions may be achieved for a wide range of structural problems, namely those associated with the bridge (i) linear (first-order) static, (ii) vibration and (iii) lateral-torsional-distortional buckling behaviours. Several illustrative examples are presented, which concern bridges with two distinct cross-sections: (i) twin box girder and (ii) twin I-girder. Allowance is also made for the presence of discrete box diaphragms and both shear lag and shear connection flexibility effects.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.1
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• pp.25-35
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• 2000

The superstructure of general bridge like slab bridge and slab on girder bridge is composed of elastically supported isotropic plate. The objective of this study is to develop the new analysis method for elastically supported plate with general edge beam or girder(boundaries) under arbitrary out of plane loading. The displacement solutions for the macro-element of plate and beam are obtained by solving for the unknown interactive forces and moments at the beam or nodal line locations after satisfying equilibrium equation along the nodal line. The displacement functions for macro-elements ate proposed in single Fourier series using harmonic analysis, and the equilibrium equations of nodal line are composed by using slope-deflection method. The proposed analysis method is programmed by MS-Fortran and can be applied to all types of isotropic decks with bridge-type boundaries. Numerical examples involving elastically supported plates with various aspect ratio, loading cases, and bridge-type boundary conditions are presented to demonstrate the accuracy of this program. The major advantage of this new analysis method is the development of a simple solution algorithm, leads to obtain rapidly responses of bridge deck system. This proposed method can be used in parametric study of behavior of bridge decks.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.2
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• pp.123-130
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• 2013

The responses of a bridge due to a moving vehicle are obtained analytically by modeling a vehicle as a constant point force. From the results it is found that the responses after a vehicle leaves the bridge become very small for some speeds of a vehicle. When a vehicle is modeled as a two dof system for a more accurate analysis, the same phenomenon is observed while the roughness of the surface of the bridge is small. Determining the fundamental frequency of a bridge so that one of the above speeds coincides with a frequent speed of vehicles, the responses of a bridge can be minimized.

• Interaction and multiscale mechanics
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• v.5 no.3
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• pp.169-185
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• 2012

The concrete bridge is likely to produce fatigue cracks during long period of service due to the moving vehicular loads and the degeneration of materials. This paper deals with the time-frequency analysis of a coupled bridge-vehicle system. The bridge is modeled as an Euler beam with breathing cracks. The vehicle is represented by a two-axle vehicle model. The equation of motion of the coupled bridge-vehicle system is established using the finite element method, and the Newmark direct integration method is adopted to calculate the dynamic responses of the system. The effect of breathing cracks on the dynamic responses of the bridge is investigated. The time-frequency characteristics of the responses are analyzed using both the Hilbert-Huang transform and wavelet transform. The results of time-frequency analysis indicate that complicated non-linear and non-stationary features will appear due to the breathing effect of the cracks.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.141-146
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• 2001

A post-tensioned steel plate girder bridge with cross-beams is analyzed by specially orthotropic laminate theory. The cross-sections of both girders and cross-beams are WF types. The result is compared with that of the beam theory. This bridge with simple support is under uniformly distributed vertical load, and axial loads and moment due to post-tension. In this paper, finite difference method for numerical analysis of simple supported bridge is developed. Relatively exact solution is obtained even with small number of meshes. Theory and analysis method of specially orthotropic laminate plates used in this paper can be used in design of new bridges, and maintenance and repair of old bridges.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1062-1067
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• 2007

This study presents an experimental technique to monitor the dynamic behavior of the railway bridge system simultaneously using multiplexed fiber Bragg grating (FBG) sensors. The measuring quantities include stains, curvatures, vertical deflections, and vertical accelerations. The strains are directly measured from multiplexed FBG sensors at various locations of the test bridge followed by curvature calculations based on the plane section assumption. Vertical deflections are then estimated using the Bernoulli beam theory and regression analysis. Finally, vertical accelerations are obtained from the numerical differentiation in time domain. In order to verify the proposed method, several conventional electric strain gauges, displacement transducers, and accelerometers are installed at the mid-span of the bridge for comparisons. A test train is passed over the bridge to monitor the dynamic response of the bridge. The monitoring results show that the multiplexed FBG sensing system is able to capture the essential behavior of the test bridge while resolving wiring problem in practice.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.99-106
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• 2002

This paper presents an analytical investigation on the behavior of simple span integral abutment bridge. An integral abutment bridge is a simple span or multiple span continuous deck type bridge having the deck integral with the abutment wall. Although the temperature variation and earth pressure are the major attributor to the total stress in integral abutment bridge, the superstructure has been designed by modeling it as a simple or continuous beam In order to investigate the effect of temperature change and earth pressure on the superstructure of integral bridge, the simple span integral bridge is modeled as a plane frame element. Performing frame analysis, the variations of bending moment and axial force of superstructure due to the various loading combination are investigated with respect to the flexural rigidity of piles, and the bending moment and axial force obtained by frame analysis are compared with the maximum bending moment obtained by conventional design method and initial prestressing force respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.2
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• pp.177-184
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• 1998

The equation of motion on the vehicle-bridge system is established as the simultaneous equations which are combined the equation of vehicle and bridge by the interaction elements. A vehicle element is modeled as lumped masses supported by springs and dashpots, and a bridge element with pavement roughness is modeled as beam elements. An interaction element is defined to consist of a bridge element and the suspension units of the vehicle resting on the element. By the dynamic condensation method, the degrees of the freedom are eliminated, and compared with all the degrees of freedom on the bridge, the efforts of calculation is decreased. Thus, although a very small computational error is occured, the present technique appears to be computationally more efficient. It is particularly suitable for the simulation of bridges with a series of vehicles moving on the deck.

• Steel and Composite Structures
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• v.49 no.1
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• pp.81-89
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• 2023

A simplified calculation method of natural vibration characteristics of high-speed railway multi-span bridge-longitudinal ballastless track system is proposed. The rail, track slab, base slab, main beam, bearing, pier, cap and pile foundation are taken into account, and the multi-span longitudinal ballastless track-beam-bearing-pier-cap-pile foundation integrated model (MBTIM) is established. The energy equation of each component of the MBTIM based on Timoshenko beam theory is constructed. Using the improved Fourier series, and the Rayleigh-Ritz method and Hamilton principle are combined to obtain the extremum of the total energy function. The simplified calculation formula of the natural vibration frequency of the MBTIM under the influence of vertical and longitudinal vibration is derived and verified by numerical methods. The influence law of the natural vibration frequency of the MBTIM is analyzed considering and not considering the participation of each component of the MBTIM, the damage of the track interlayer component and the stiffness change of each layer component. The results show that the error between the calculation results of the formula and the numerical method in this paper is less than 3%, which verifies the correctness of the method in this paper. The high-order frequency of the MBTIM is significantly affected considering the track, bridge pier, pile soil and pile cap, while considering the influence of pile cap on the low-order and high-order frequency of the MBTIM is large. The influence of component damage such as void beneath slab, mortar debonding and fastener failure on each order frequency of the MBTIM is basically the same, and the influence of component damage less than 10m on the first fourteen order frequency of the MBTIM is small. The bending stiffness of track slab and rail has no obvious influence on the natural frequency of the MBTIM, and the bending stiffness of main beam has influence on the natural frequency of the MBTIM. The bending stiffness of pier and base slab only has obvious influence on the high-order frequency of the MBTIM. The natural vibration characteristics of the MBTIM play an important guiding role in the safety analysis of high-speed train running, the damage detection of track-bridge structure and the seismic design of railway bridge.

• Structural Engineering and Mechanics
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• v.78 no.2
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• pp.163-174
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• 2021

Track-bridge interaction has become an essential part in the design of bridges and rails in terms of modern railways. As a unique ballastless slab track, the longitudinal continuous slab track (LCST) or referred to as the China railway track system Type-II (CRTS II) slab track, demonstrates a complex force mechanism. Therefore, a comprehensive track-bridge interaction study between multi-span simply supported beam bridges and the LCST is presented in this work. In specific, we have developed an integrated finite element model to investigate the overall interaction effects of the LCST-bridge system subjected to the actions of temperature changes, traffic loads, and braking forces. In that place, the deformation patterns of the track and bridge, and the distributions of longitudinal forces and the interfacial shear stress are studied. Our results show that the additional rail stress has been reduced under various loads and the rail's deformation has become much smoother after the transition of the two continuous structural layers of the LCST. However, the influence of the temperature difference of bridges is significant and cannot be ignored as this action can bend the bridge like the traffic load. The uniform temperature change causes the tensile stress of the concrete track structure and further induce cracks in them. Additionally, the influences of the friction coefficient of the sliding layer and the interfacial bond characteristics on the LCST's performance are discussed. The systematic study presented in this work may have some potential impacts on the understanding of the overall mechanical behavior of the LCST-bridge system.