Determination of Prestress Losses in Existing Pre-Tensioned Structures Using Bayesian Approach

Abstract

Deterioration of materials and structures is an unavoidable fact, and prestressed concrete structures are not an exception. The evaluation of load-carrying capacity and remaining service life includes collecting various information. However, one type of information is essential and the most important, the state of prestressing, which inevitably decreases over time. Currently, many possible methods for the evaluation of prestressing are available. These techniques are part of the structural assessment and provide residual prestressing force value which is later used in the evaluation process. Therefore, it is suitable to provide the value of prestressing force based on certain probabilistic backgrounds. This study addresses the determination of residual prestressing force in pre-tensioned railway sleepers one year after their production, using the so-called Bayesian approach. This technique is focused on the validation of results obtained from the application of the non-destructive indirect saw-cut method. The Bayesian approach considers analytic calculation as the primary method of prestressing determination. In this paper, Monte Carlo simulation was used to determine the total variability that defines all Bayesian systems of probability functions. Specifically, a total of 1000 simulations was applied, and the current random vector of prestressing force derived from the analytical calculation has been assumed as a normally distributed function. Finally, obtained results for different depths of saw-cuts are compared. The results of the experimental and statistical determination of residual prestressing force provide its value with a 95% confidence level. This study suggests that the implementation of the probability approach can be an effective tool for determining prestress losses.

Response of prestressed reinforced concrete beam under impact loading through the experiment

“…Overestimating prestress losses may result in conservative and possibly uneconomic designs. On the other hand, underestimating prestress losses can result in tensile stresses in the concrete and possibly cracking, which can affect durability by exposing reinforcement to the environment, and in some cases, combined with other mechanisms [21] [22]. During the design phase of prestressed concrete members, anticipation of losses was done to ensure that the structures will perform as intended throughout their service life.…”

Long-Term Deflection Analysis of Large-Span Continuous Prestressed Concrete Rigid-Frame Bridges Based on a Refined Modeling Approach

“…In order to grasp the spatial prestress state, the horizontal, vertical, and longitudinal prestress tendons at different positions of Bridge A were field tested, and three field test methods were used, the transverse tension method, stress release method and the X-ray diffraction method, as can be seen in Figure 9. The first two methods have been widely employed in the field of bridge detection due to their well-established theoretical foundation and convenient operational procedures [30][31][32][33]. The X-ray diffraction method was first proposed in 1987 [34] and is widely recognized as one of the most powerful nondestructive tools for measuring residual stresses in polycrystalline materials, and it has been extensively employed both in service and laboratory research, where it yields satisfactory predicted results [35,36].…”

Long-Term Prestress Loss Calculation Considering the Interaction of Concrete Shrinkage, Concrete Creep, and Stress Relaxation

“…Short-term prestress loss mainly includes the prestress loss caused by the friction between the prestressed bar and the pipe wall, anchor deformation, retraction of the steel bar, etc., which is easy to measure and calculate because it is independent of time [ 1 , 2 , 3 , 4 ]. The long-term prestress loss caused by prestressed rib relaxation, concrete shrinkage, and concrete creep is time-sensitive and difficult to calculate [ 5 , 6 , 7 , 8 , 9 , 10 ]. Long-term prestress loss accounts for more than 30% of the total prestress loss, and it has a great influence on the long-term performance of concrete bridge structures [ 11 , 12 , 13 , 14 ].…”