Lehrstuhl und Inst. für Massivbau [u.a.]
Zum Verbundverhalten von Spannstahl mit sofortigem Verbund unter Betriebsbeanspruchung
Abstract
dc:descriptionSlender and long-spanning structural members are a characteristic of current architecture. Prestressing of concrete reduces the required depth and extends the possible span of girders and slabs. Therefore the influence of sustained and cyclic loading becomes more and more important. While many investigations on the influence on the concrete and steel behavior are known, only very little research on the influence on the interaction especially the bond of prestressing strands was done yet. In the first part of this work the bond behavior of prestressing strands in the anchorage zone is described. Based on a database covering approximately 400 test results a non-linear approach is presented to describe the bond capacity of strands considering the concrete strength. The influence of cyclic loading on the bond anchorage of strands was tested by more than 60 pull-out tests and 8 tests on prestressed girders. These tests as well as numerical simulations indicated that only high cyclic loading influences the bond anchorage of strands. In this case the bond capacity of strands should be reduced by one third in the area of the flexural bond length. The transfer length remains unchanged as long as no cracking arises in this area under cyclic loading. The second part covers the influencing parameters of the bond behavior on the load bearing of prestressed girders considering the stress redistribution between strands and reinforcing bars. Eight uniaxial tensile tests revealed that the stress redistribution depends on the type of the concrete as well as on the diameter of the steel. Using common diameters of reinforcing bars and prestressing strands stress redistribution from the strand towards the bars as well as vice versa are possible in NSC. In HSC the stress redistribution is always from the strand towards the bar. Therefore the approaches of current standards (e.g., DIN 1045-1) overestimate the participation of the strands on the load bearing. Based on the experimental and theoretical investigations the current bond factor xi for prestressing strands was adjusted. This work allows an overall description of the bond behavior of prestressing strands considering cyclic loading. With the proposed approaches the anchorage zone can be designed safely even if cyclic loading takes place. Furthermore, the load bearing as well as the actual crack opening of prestressed girders can be predicted correctly.
Degree
thesis:*- Grantor dc:publisher
- Lehrstuhl und Inst. für Massivbau [u.a.]
- Year dc:date
- 2008
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Bülte, Sebastian
- Contributors dc:contributor
-
- Hegger, Josef
Subjects
dc:subject × 8Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- ger