• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05a
• /
• pp.415-418
• /
• 2005

Prestressed composite girder bridges with PS tendon at positive flexural moment region offer elastic behavior to higher loads, increased ultimate capacity and reduced structural steel weight. Two beams were tested to examine ultimate behaviors of prestressed composite girder bridges subjected to positive flexural moment. The experimental observations of the Prestressed composite girder bridges subjected to positive flexural moment are investigated and compared to the numerical results obtained by sectional analysis method, and 1-D. and 3-D. finite element analysis methods.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.389-392
• /
• 2006

A In this paper, a new prestressed concrete girder system is presented which is designed using a detensionable and retensionable system. Experiments were carried out in order to comprehend the behavior of detensionable and retensionable prestressed concrete girder system. Tension control tests were performed for the detensionable and retensionable system followed by the static loading tests to check the applicability of the girder system. The test results were found in good agreement with the analytical results which clearly indicates the reliability of the concept of detensionable and retensionable prestress concrete girder with projected flange.

• Computers and Concrete
• /
• v.29 no.3
• /
• pp.161-168
• /
• 2022

Bridges using double-tee (DT) girders from 12 m to 15 m are one of the good choices to improve accessibility in rural areas of the Mekong River Delta. In this study, nonlinear finite element method (FEM) analysis was conducted with different constitutive laws of materials. The FEM analysis results were compared to experimental results to confirm the applicability of the constitutive laws of materials for DT girders. A parametric study through FEM analysis was then conducted to investigate the effect of span lengths, top flange depths, and a number of prestressing tendons on the capacity of DT girders in order that propose DT girders for rural bridges. Parametric results showed that the top flange depth of a DT girder for rural bridges could be 120 mm. The DT girder with a span length of 12 m or 13 m could be used 16 tendons, while the DT girder with a span length of 14 m or 15 m could be set up with 20 tendons. The prestressed concrete DT girders based on FEM results can be suggested for the construction of rural bridges.

• Advances in Computational Design
• /
• v.2 no.2
• /
• pp.147-168
• /
• 2017

Over the past couple decades, externally bonded fiber reinforced polymer (FRP) composites have emerged as a repair and strengthening material for many concrete infrastructure applications. This paper presents an analytical investigation of the use of carbon FRP (CFRP) for a specific problem that occurs in concrete bridge girders wherein the girder ends are damaged by excessive exposure to deicing salts and numerous freezing/thawing cycles. A 3D finite element (FE) model of a full scale prestressed concrete (PC) I-girder is used to investigate the effect of damage to the cover concrete and stirrups in the end region of the girder. Parametric studies are performed using externally bonded CFRP shear laminates to determine the most effective repair schemes for the damaged end region under a short shear span-to-depth ratio. Experimental results on shear pull off tests of CFRP laminates that have undergone accelerated aging are used to calibrate a bond stress-slip model for the interface between the FRP and concrete substrate and approximate the reduced bond stress-slip properties associated with exposure to the environment that causes this type of end region damage. The results of these analyses indicate that this particular application of this material can be effective in recovering the original strength of PC bridge girders with damaged end regions, even after environmental aging.

• Interaction and multiscale mechanics
• /
• v.4 no.4
• /
• pp.273-289
• /
• 2011

The vibration response of the bridges under the moving vehicular load is of importance for engineers to estimate the serviceability of existing bridges and to design new bridges. This paper deals with the three dimensional vibration analysis of prestressed concrete bridges under moving vehicles. The prestressed bridges are modeled by four-node isoparametric flat shell elements with the transverse shearing deformation taken into account. The usual five degrees-of-freedom (DOFs) per node of the element are appended with a drilling DOF to accommodate the transformation of the local stiffness and mass matrices to the global coordinates. The vehicle is modeled as a single or two-DOF system. A single-span prestressed Tee beam and two-span prestressed box-girder bridge are studied as the two numerical examples. The effects of prestress forces on the natural frequencies and dynamic responses of the bridges are investigated.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1995.04a
• /
• pp.385-390
• /
• 1995

In segmentally erected bridges, the structural systems are changed as the construction stages progress and redistribution of member forces occurs due to time dependent effects of concrete and relaxation of perstressing steel. Therefore, structural analysis is required at each construction stage. In this study, nonlinear analysis program of the segmentally erected prestressed concrete box girder bridges is developed to raise the efficiency in making input file for the main program and analysis of the results produced by the main program.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.319-322
• /
• 2005

When a concrete structure is subjected to load, its response is both immediate and time dependent. Under sustained load, the deformation of a structure gradually increases with time and eventually may be many time greater than its instantanneous value. The gradual development of strain with time is caused by creep and shrinkage. On this study, to estimate of stress variations on time effects in partially prestressed concrete composite girder bridges, computer program applied Age-adjusted Effective Modulus Method(AEMM) in used.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.10b
• /
• pp.701-705
• /
• 1998

The objective of this study is to develop the practical program which can check the constructible possibility of prestressed concrete box girder bridges for design. Checking constructible possibility is defined as checking the interference of each elements in a PSC box girder bridge and computing the distances of each elements. To check the constructible possibility of a PSC box girder bride, bridge must be modelled using solid in three dimension. By using a 3 dimensional solid modeling system, engineers can get the photo realistic 3D viewing images of the bridge and produce FEM analytic model of it. Users can manipulate their drawings easier and take off quantity of the whole structure and its elements as well as check the constructible possibility of their PSC box girder bridges.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1995.10a
• /
• pp.35-42
• /
• 1995

One of the main objectives of this study is to propose a realistic limit state model for reliability-based safety assessment of precast segmental prestressed concrete box girder bridges, considering 1) combined effects of bending, shear and torsional forces, and 2) the difference between transverse reinforcments of box girder. A improved limit state model is derived from a modified interaction equation compared with the Bruno's equation. A Drectional sampling algorithm is used for reliability analysis of the proposed model.

• Journal of the Korean Society of Industry Convergence
• /
• v.4 no.2
• /
• pp.157-166
• /
• 2001

The purpose of this study is to examine the accuracy of the code provisions on lateral load distribution factors of prestressed concrete girder bridges. Most designers in Korea use the lever method or lateral load distribution formula in the existing design codes. However, the methods do not account for the effect of bridge skew or direction of diaphragm. Therefore, this study analysed the prestressed concrete girder bridge with grillage model for various girder spacings, directions of diaphragms, span lengths, and skews, and compared the results with those of existing design code. It has been found that lateral load distribution factors were proportional to the girder spacing while they were not significantly affected by the change of span length, direction of diaphragm, and skew. For bending moments, lateral load distribution factors from the grillage analysis were 60%~68% of those from Korean bridge design code. Therefore, the code provisions result in very conservative design. For support reactions, however, lateral load distribution factors from the grillage analysis were slightly greater than those from Korean bridge design code. Therefore, the capacity of bearings of the bridge with a large skew should be determined by grillage analysis.