FLEXURAL BEHAVIOR OF CONTINUOUS CONCRETE BEAMS PRESTRESSED WITH BONDED AND UNBONDED TENDONS
الباحث الأول:
ABDULEMAM K. ABU-SAIBIA
الباحثين الآخرين:
Prof. Dr. Hani H. Nassif
المجلة:
Rutgers, The State University of New Jersey
تاريخ النشر:
None
مختصر البحث:
ABSTRACT:
Post-tensioning techniques have become very popular and a primary method in long spans continuous bridges and other structures due to their excellent performance in controlling cracking and excessive deflection. Moreover, the use of conti…
ABSTRACT:
Post-tensioning techniques have become very popular and a primary method in long spans continuous bridges and other structures due to their excellent performance in controlling cracking and excessive deflection. Moreover, the use of continuous prestressed concrete beams leads to shallower cross-sections, requires less maintenance cost, and enhances the durability of concrete in the negative moment region. Since using post-tensioned unbonded tendon requires particular analysis methods to predict the stress in the unbonded tendon because of the bond lack between the tendon and the adjacent concrete, thus this research presents an analytical approach to estimate the stress in the tendon and provide full-range of load versus deformation at different location of the span length at various load levels. The model used a trussed-beam system in additional to moment and force equilibrium equations to find the unknowns which include the stress in the unbonded tendon, deflection, and neutral axis depth. The analytical part included analyzing and estimating the stress in the unbonded tendon for beams subjected to a third-point and single-point load.
The proposed approach was validated with results from the performed beam tests in addition to test data in the literature. The experimental part included 20-ft long continuous High Strength Concrete (HSC) beams post-tensioned internally with bonded and unbonded tendons. The experimental approach included casting, instrumenting, and load testing of 8 continuous span beams at various levels of prestressing and combination of tendons. Various design parameters such as the area of non-prestressed steel in tension at the maximum positive and negative moment locations and effective prestress in the bonded, and unbonded tendons are considered.
Both models show a good correlation between predicted and experimental results. Furthermore, the effect of different design parameters on the flexural response was investigated. This study demonstrates that some design parameters have a significant influence on the results while the impact of other variables can be ignored.
