Abstract
Abstract Knowledge of prestressing force’s value is in the case of prestressed concrete structure the most important basis for defining load-carrying capacity and remaining service life. Numbers of prestressed concrete structures are about to reach their limit of service life and they are exhibiting signs of deterioration due to the conceptional errors, inadequate maintenance and environmental distress. All of these factors negatively influence the actual state of prestressing. Thus, it is essential to determine the value of prestressing force considering the degradation of materials, such as corrosion of prestressing strands or wires. While assessing structure in service, it is difficult to apply magnetoelastic sensors or use other direct methods for determining the state of prestressing. Hence, the indirect methods enable to analytically calculate the prestressing force based on the results of measurement, e.g. strain, stress, deflection, or width of the crack. The present paper focuses on numerical analysis of prestressing in a twosome of precast prestressed concrete beams. For the numerical analysis, two indirect methods are applied, specifically Saw-cut method and Crack initiation method. Finally, the results are discussed and recommendations for the experimental campaign are summarized.
Highlights
The essence of prestressed concrete is the application of prestressing force which induce an axial compression that counteracts all, or part of, the tensile stresses
The techniques with only local effect on the structure can be considered as non-destructive, as damages caused by their application can be properly and fixed without any influence on the structure's integrity. This group of methods include, e.g. methods based on stress relief in concrete member (Saw-cut method, Stress-relief coring technique/Drilling method), Strand-cutting method, Exposed strand method, and Structural response method (Crack initiation method, Crack reopening method)
A 2D numerical analysis with the assumption of nonlinear behaviour was performed in ATENA 2D Software applied on precast prestressed concrete beams with parameters mentioned above
Summary
The essence of prestressed concrete is the application of prestressing force which induce an axial compression that counteracts all, or part of, the tensile stresses. The pre-tensioned concrete member is cast around the strands which are tensioned between stands In this case, the prestressing force is transformed into the structure through the bond between the steel reinforcement and concrete. Available standards offer the approaches for determining the value of prestressing losses considering construction stages, methods of prestressing, and expected service life of the structure. The techniques with only local effect on the structure can be considered as non-destructive, as damages caused by their application can be properly and fixed without any influence on the structure's integrity This group of methods include, e.g. methods based on stress relief in concrete member The prestressing force is evaluated from known stress (tensile strength of concrete) and applied external load which initiated a critical moment. Assuming a statically indeterminate structure, the contribution of the secondary moment must be taken into consideration
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