Abstract

The present study illustrates observations, record accurate description and discussion about the behavior of twelve tested, simply supported, precast, prestressed, segmental, concrete beams with different segment numbers exposed to high fire temperatures of 300°C, 500°C, and 700°C. The test program included thermal tests by using a furnace manufactured for this purpose to expose to high burning temperature (fire flame) nine beams which were loaded with sustaining dead load throughout the burning process. The beams were divided into three groups depending on the precast segments number. All had an identical total length of 3150mm but each had different segment number (9, 7, and 5 segments), in other words, different segment lengths. To simulate genuine fire disasters, the nine beams were exposed to high-temperature flames for one hour along with the control specimens. The selected temperatures were 300°C (572°F), 500°C (932°F), and 700°C (1292°F) as recommended by the standard fire curve (ASTM–E119). The specimens were cooled gradually at ambient laboratory conditions. The performance of the prestressed segmental concrete beams through the burning process was described with regard to the beams camber, spalling, and occurred deterioration.

Highlights

  • Segmental box girder bridges represent one major recent development in bridge engineering

  • The segmental prestressed concrete (SPC) beams camber was measured with a mechanical dial gauge of 0.002mm/div set in the midspan of the beam while the prestressing process was performed

  • It reveals a decrease percentage in the average camber by 79% for SPC beams of 7 segments (Group II) and 62% for SPC beams of 5 segments (Group III) compared with the SPC beams of 9 segments (Group I)

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Summary

INTRODUCTION

Segmental box girder bridges represent one major recent development in bridge engineering. This research seeks to give an explanation and a simplified estimation of fire-induced damages produced in precast segmental prestressed concrete (SPC) beams via monitoring experimentally the behavior of internally prestressed precast concrete segmental beams with selective parameters such as segment length, number of joints between segments, and the exposure to different burning temperatures. Authors in [2, 3] presented the results of nonlinear finite element analysis on segmental concrete beams with external tendons. Authors in [4] investigated the structural behavior of dry joined externally prestressed segmental (EPS) beams under combined stresses, i.e. bending, shear and torsion stresses. Authors in [5] studied the mechanical properties of high-performance concrete (HPC) and the normal-strength concrete (NSC) after exposure to high temperature. Hekmet & Izzet: Performance of Segmental Post-Τensioned Concrete Beams Exposed to High Fire. The mechanical characteristics of prestressing steel at high temperatures, the information found was somewhat scattered and still inadequate

SPC BEAMS SET UP
EXPOSURE TO FIRE TEST
Camber at Prestressing Stage
Deflection Due to Superimposed Load
Thermal Test Results
CONCLUSIONS

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