Post-cracking shear behaviour of concrete beams strengthened with externally prestressed tendons
| Autor: | Yi Bao, Jianan Qi, Jingquan Wang, Zhongguo John Ma |
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| Rok vydání: | 2020 |
| Předmět: |
Materials science
0211 other engineering and technologies Stiffness 020101 civil engineering 02 engineering and technology Building and Construction Spall 0201 civil engineering law.invention Cracking Prestressed concrete Shear (geology) law Deflection (engineering) 021105 building & construction Architecture medicine Shear strength medicine.symptom Composite material Safety Risk Reliability and Quality Beam (structure) Civil and Structural Engineering |
| Zdroj: | Structures. 23:214-224 |
| ISSN: | 2352-0124 |
| DOI: | 10.1016/j.istruc.2019.09.009 |
| Popis: | External prestressing technology has been successfully adopted for enhancing the load-carrying capacity of beams in bridge engineering. Previous studies on the shear behaviour of externally prestressed concrete (EPC) beams mainly focused on the ultimate shear strength. The post-cracking shear behaviour of EPC beams remains unclear. This study aims to investigate the post-cracking shear behaviour of EPC beams. To this end, nine EPC beams with different design parameters were tested to failure. The investigated parameters included the prestressing condition, shear span to depth ratio, shear reinforcement ratio, and bend angle of external tendons. In contrast to reinforced concrete beams, the EPC beams demonstrated shear tension sliding with concrete spalling failure. The applied prestressing increased the concrete shear contribution by 68%. The percentage of the concrete shear contribution out of the total shear strength of the test beams ranged from 45% to 79%. The post-cracking shear strength reserve ability index, defined as the ratio of the shear strength and shear cracking strength, ranged from 1.72 to 2.96 in the EPC beams. A new ductility index, defined as the ratio of the ultimate deflection and the deflection corresponding to first shear cracking, was used to evaluate the post-cracking deformability of EPC beams. The ductility index of the EPC beams ranged from 3.0 to 7.6, indicating considerable post-cracking deformability. The beam’s stiffness at first shear cracking was 39–81% of the beam’s initial stiffness; the beam’s stiffness at the ultimate state was 18–41% of the beam’s initial stiffness. Finally, the current shear provisions were evaluated by the test results. |
| Databáze: | OpenAIRE |
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