Title: Creep Rupture Behavior of FRP Elements for Prestressed Concrete--Phenomenon, Results and Forecast Models

Author(s): H. Budelmann and F. S. Rostasy

Publication: Symposium Paper

Volume: 138

Issue:

Appears on pages(s): 87-100

Keywords: creep properties; fiber reinforced plastics; fracture properties; models; prestressed concrete; rupture; statistical analysis; strength; tensile strength; tensile stress; Structural Research

DOI: 10.14359/3920

Date: 9/1/1993

Abstract:
FRP tensile elements exhibit the so-called creep rupture phenomenon when subjected to a high axial tensile stress. For this reason, the time of endurance until fracture that is dependent on the level of the permanent stress is the relation to be derived experimentally. The creep rupture phenomenon exists principally for all structural materials. However, experiments prove that for prestressing steel it is of no practical relevance: the usual permanent steel stresses that are in the range of 75 percent of characteristic tensile strength can be borne indefinitely without fracture or strength loss. However, this is not the case for FRP, whose stress rupture behavior is also influenced markedly by the micro-environment around the element and is dependent on the type of fiber and matrix employed. Paper presents an outline of the results known so far, the experimental techniques, methods of statistical evaluation, and forecast of the long-term behavior of specific FRP elements. It is shown that the characteristic stress rupture line is the essential basis for the derivation of the admissible permanent prestress of FRP tensile elements.