• Structural Engineering and Mechanics
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• v.71 no.4
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• pp.433-444
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• 2019

Shear studs are often used to connect steel girders and concrete deck to form a composite bridge system. The application of precast concrete deck to steel-concrete composite bridges can improve the strength of decks and reduce the shrinkage and creep effect on the long-term behavior of structures. How to ensure the connection between steel girders and concrete deck directly influences the composite behavior between steel girder and precast concrete deck as well as the behavior of the structure system. Compared with traditional multi-I girder systems, a twin-I girder composite bridge system is more simplified but may lead to additional requirements on the shear studs connecting steel girders and decks due to the larger girder spacing. Up to date, only very limited quantity of researches has been conducted regarding the behavior of shear studs on twin-I girder bridge systems. One convenient way for steel composite bridge system is to cast concrete deck in place with shear studs uniformly-distributed along the span direction. For steel composite bridge system using precast concrete deck, voids are included in the precast concrete deck segments, and they are casted with cast-in-place concrete after the concrete segments are erected. In this paper, several sets of push-out tests are conducted, which are used to investigate the heavier of shear studs within the voids in the precast concrete deck. The test data are analyzed and compared with those from finite element models. A simplified shear stud model is proposed using a beam element instead of solid elements. It is used in the finite element model analyses of the twin-I girder composite bridge system to relieve the computational efforts of the shear studs. Additionally, a parametric study is developed to find the effects of void size, void spacing, and shear stud diameter and spacing. Finally, the recommendations are given for the design of precast deck using void for twin I-girder bridge systems.

• Steel and Composite Structures
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• v.23 no.5
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• pp.557-570
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• 2017

In this study, the seismic performance levels of four bridges are determined using finite element modeling based on ambient vibration testing. The study includes finite element modeling, analytical modal analyses, ambient vibration testing and earthquake analyses of the bridges. For the purpose, four prestressed precast I beam bridges that were constructed for the Ankara-Sivas high speed railway line are selected for analytical and experimental studies. In the study, firstly a literature review related to the dynamic behavior of bridges especially precast beam bridges is given and then the formulation part related to ambient vibration testing and structural performance according to Turkish Seismic Code (2007) is presented. Next, 3D finite element models of the bridge are described and modeled using LARSA 4D software, and analytical dynamic characteristics are obtained. Then ambient vibration testing conducted on the bridges under natural excitations and experimental natural frequencies are estimated. Lastly, time history analyses of the bridges under the 1999 Kocaeli, 1992 Erzincan, and 1999 Duzce Earthquakes are performed and seismic performance levels according to TSC2007 are determined. The results show that the damage on the bridges is all under the minimum damage limit which is in the minimum damage region under all three earthquakes.

• Journal of the Korea Concrete Institute
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• v.12 no.6
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• pp.43-50
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• 2000

In this paper, a new splicing method was applied to design the girder section of bridges with the span length of 25m, 30m, 35m, 40m and 45m. A U-type precast prestressed section was also determined for each bridge. Additionally, the sectional area, beam depth and Guyon's efficiency factor of the spliced U-type sections in each span were analyzed in comparison with the present I-type PSC bridges. As a result, in spite of an increase of 31%∼50% in the sectional areas compared with the I-type precast girders, the spliced U-type the beam depth of the spliced U-type girder was designed as 2,050 mm compared with the I-type precast girder of 2,600mm in a 40m span bridge. The sectional efficiency factors of the spliced U-type sections were analyzed as 0.76∼0.99. It shows that the spliced U-type sections ar of a superior structural efficiency in contrast to the average sectional efficiency factor of 0.66 value in the I-type girders.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.193-200
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• 1998

The precast prestressed concrete girders of I-type section are frequently employed to design the short-to-medium span bridge. However, its beam depth is greatly increased as its span length is increased over than about 30m. Therefore, the economic and aesthetic effectiveness are rapidly decreased in case of the span length over 30m. The purpose of this paper is to verify the structural safety on the new spliced two span bridge and analyze the variation of member forces and stress distribution according to the construction stages and time. The new spliced technique is performed by partial post tensioning and release in the U-type girders. The structural characteristics of this technique is the introduction of secondary moment to reduce the bending moment by self weight of precast U-type girders constructed in simply supported beam type. So, it is expected that the structural efficiency of this spliced bridge may be improved more than other techniques.

• Steel and Composite Structures
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• v.21 no.5
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• pp.981-997
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• 2016

To avoid the cracks of cast-in-place concrete in shear pockets and seams in the traditional composite beam with precast decks, this paper proposed a new type of prefabricated steel truss-concrete composite beam (ab. PSTC beam) with pre-embedded shear studs (ab. PSS connector). To study the initial cracking load of concrete deck, the development and distribution laws of the cracks, 3 PSTC beams were tested under hogging moment. And the crack behavior of the deck was compared with traditional precast composite beam, which was assembled by shear pockets and cast-in-place joints. Results show that: (i) the initial crack appears on the deck, thus avoid the appearance of the cracks in the traditional shear pockets; (ii) the crack of the seam appears later than that of the deck, which verifies the reliability of epoxy cement mortar seam, thus solves the complex structure and easily crack behavior of the traditional cast-in-place joints; (iii) the development and the distribution laws of the cracks in PSTC beam are different from the conventional composite beam. Therefore, in the deduction of crack calculation theory, all the above factors should be considered.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.1
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• pp.1-9
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• 2022

Semi-integral abutment bridges are a type of integral abutment bridges. These bridges eliminate expansion joints on the structure and can be used in situations not suitable for full-integral abutment bridge. Moreover, Semi-integral bridges have excellent maintenance and can be economically constructed. This study is about precast wall-type blocks at each end which provide lateral support for PSC girder, as well as acting as retaining walls to resist longitudinal movement of semi-integral abutment bridge. The end-diaphragm connection between ended blocks of PSC girders can be achieved by in-suit nonshrinkage concrete. The results show that 3-point experiment of end-diaphragm beam have an acceptable performance which is so better than results of structural design. Moreover, the effects of backfill soil on semi-integral abutment bridge constructed are analyzed the behavior according to the temperature changes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1A
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• pp.15-24
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• 2008

This paper presents the analytical method for the long-term behavior of simply supported composite beams with precast decks prestressed in the longitudinal direction. The objectives of time-dependent analysis are to estimate losses of prestress on the concrete slab and long-term deflection due to creep and shrinkage of concrete, relaxation of prestressing steel. Also, the time-dependent analysis was carried out using the presented analytical method to evaluate the effects of several parameters on the long-term behavior of composite bridge with precast deck, including geometrical shapes of composite beams, compressive strength of concrete and magnitude of initial prestress. The results of the analysis indicated that, in the effects of geometrical shapes of composite beams, the main parameters affecting the losses of prestress and the long-term deflection were the cross sectional area and the moment of inertia of steel beam, respectively. Finally, the determination method for the required initial prestress was proposed by evaluation of the loss characteristics due to shrinkage and creep of concrete.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.400-407
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• 2005

The reinforcing effect of modified structure of PSC beams is analyzed in this study. The PSC beams are closed by precast half panels embeding PS tendons at the bottom flange of I-bear The stiffness of box structure is larger and the PS force at half panels makes a time-dependent upward camber of superstructures. The superstructure becomes a second composite structure among 3 elements-PSC ben RC slab, PSC Panel. The time-dependent creep and shrinkage effect at PSC Panels and structural behavior is verified considering construction sequences. The optimal range of to-box reinforcing method is surveyed through reliability analysis.

• Earthquakes and Structures
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• v.9 no.1
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• pp.195-219
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• 2015

A partial (hybrid) seismic isolation scheme for precast girder bridges in the form of a "buffer-gap-elastomeric bearings" system has been endorsed in the literature as an efficient seismic design system. However, no guides exist to detail an optimal gap size for different configurations. A numerical study is established herein for different scenarios according to Euro code seismic requirements in order to develop guidelines for the selection of optimal buffer-gap arrangements for various design cases. Various schemes are hence designed for ductile and limited ductility behavior of the bridge piers for different seismic demand levels. Seven real ground records are selected to perform incremental dynamic analysis of the bridges up to failure. Bridges with typical short and high piers are studied; and different values of initial gaps at piers are also investigated varying from a zero gap (i.e., fully locked) condition up to an initial gap at piers that is three quarters the gap left at abutments. Among the main conclusions is that the as-built initial gaps at piers (and especially large gap sizes that are ${\geq}1/2$ as-built gaps at abutments) do not practically reduce the seismic design demand and do not affect the reserve capacity of the bridge against failure for bridges featuring long piers, especially when these bridges are designed a priori for ductile behavior. To the contrary, the "buffer-gap-elastomeric bearings" system is more effective for the bridge schemes with short piers having a large difference between the stiffness of the bearings and that of their supporting (much stiffer) squat piers, particularly for designs with limited ductility. Such effectiveness is even amplified for the case of larger initial as-built gap sizes at piers.