The Stiffness Change in Pre-Stressed Concrete T-Beams during Their Life-Cycle Based on a Full-Scale Destructive Test.

In order to study the stiffness degradation of pre-stressed concrete T-beams throughout their entire service life, full-scale destructive tests were conducted on newly constructed T-beams. The test process characterized the relationship between load and deflection at different load levels. Meanwhile, the equivalent stiffness and short-term stiffness of the T-beams at different load levels were calculated based on formulas from the code, and a segmental stiffness back-calculation method for pre-stressed concrete T-beam bridges was proposed based on system identification theory. The results show that, during the destructive test process, the T-beams experienced complete, partial linear, and non-linear stages. By using the equivalent stiffness and short-term stiffness to predict the stiffness changes during the overall failure process of the T-beams, it was found that, when cracks appeared, the stiffness of the T-beams decreased by 31% compared to the initial value, and the stiffness continued to decrease as the cracks extended further. The segmental stiffness system identification back-calculation method more accurately described the destructive test process of each section of the T-beams. This method can help to evaluate the extent of damage in each section of the beams during the overall destructive test process and further assess the overall structural integrity of the beams. [ABSTRACT FROM AUTHOR]