Keywords: railway bridge, CFRP tendons, external prestressing reinforcement, static test, fatigue test, field test.

This paper presents a comprehensive study on the mechanical performance of heavy haul railway bridge reinforced by external pre-stressing CFRP tendons. According to the characteristics of CFRP tendons [1] and the research status of concrete beams retrofitted by external pre-stressing CFRP tendons, a reinforcement scheme is first proposed in this paper, which involves wedge-type anchorage of pre-stressing CFRP tendons anchored at the beam bottom using a self-developed connecting device. It is very appealing since it can meet the requirements of rapid, continuous transportation. To verify its effect on improving the mechanical performance of the bridge, some tests including static, fatigue and field tests along with numerical simulation were carried.

The static test of a retrofitted concrete beam was conducted first. It was found that after retrofitting using external pre-stressing CFRP tendons the bearing capacity of the beam is improved greatly. The cracking load is improved more obviously than the yield and ultimate loads, which is of great significance to railway prestressed concrete bridges. Subsequently, the fatigue test was conducted, which shows that the anchorage device developed in this paper can work reliably. The flexural stiffness of the retrofitted beam degenerates, with the increasing number of cycles,. more slowly than the beam without retrofitting. After retrofitting, the fatigue life of the beam is improved greatly, which reaches 3 million cycles as required.

The numerical simulation was performed to investigate the stress distribution near the hole in the anchorage zone of a simple supported beam bridge retrofitted with externally prestressed CFRP tendons using the finite element software ABAQUS. The displacement of the bridge beam subject to standard railway live loading of China [2,3] was also obtained. The analysis results are in accordance with the current design code for railway bridges [4], which shows the effectiveness of the reinforcement scheme. Based on the analysis results, the field test was subsequently carried out on a 16m pre-stressed simply supported concrete bridge of Daqin railway, which shows that the external pre-stressing was effectively applied to the bridge beam, and after retrofitted the dynamic displacement and the dynamic strain decreased in varying degrees when subject to the existing vehicle load.

1

L.P. Ye, P. Feng, "Applications and development of fiber reinforced polymer in engineering structures", China Civil Engineering Journal, 39(3), 24-34, 2006.

2

Professional Standard of the People's Republic of China, "Fundamental code for design on railway bridge and culvert", China Architecture & Building Press, Beijing, 2005.

3

Professional Design Institute of Railway Ministry, "Railway engineering design manual-Concrete bridge", China Railway Publishing House, Beijing, 1998.

4

Professional Standard of the People's Republic of China, "Code for design on reinforced and prestressed concrete structure of railway bridge and culvert", China Architecture & Building Press, Beijing, 2005.

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