Analysis of the bond behaviour between prestressed strands and concrete in fire

Abstract

In this paper a robust model has been developed to predict the average bond stress-slip relationship between the strands and concrete of prestressed concrete structural members. Two bond-slip curves have been proposed to represent the bond-slip characteristics for the three-wire and seven-wire strands. This model considers the variation of concrete properties, strands' geometries and the type of strand surface, smooth or indented. The degradation of materials and bond characteristic at elevated temperatures are also included in the model. The proposed model has been validated against previous experimental results at both ambient and elevated temperatures.

Determination of bond model for 7-wire strands in pretensioned concrete beam

“…The finite element model based on the Model Code 2010 relationship overestimates the values of the strains, whereas the models using the relationships of Orr et al [19] for unstressed strands and Khalaf and Huang [20] underestimate them. In the case of the model based on the Model Code 2010 relationship, the difference has been expected, since this relationship is developed for ribbed reinforcing bars, but not for prestressing tendons.…”

“…Coefficients of determination between the strains according to ARAMIS and the predicted strains are presented in Tables 3 and 4. On the basis of the strain distributions (Figures 5, 7) and the coefficients of correlation (Tables 3, 4), it is established that the finite element models using the bond stress-slip relationships of Model Code 2010 [2] for ribbed bars, Orr et al [19] for unstressed strands, and Khalaf and Huang [20] give results that are significantly different than those obtained with the help of ARAMIS.…”

“…As opposed to the above-mentioned researchers, Khalaf and Huang [20] developed an analytical bond model for both 3-wire and 7-wire strands. It was validated by a comparison of its results and the results of experimental tests.…”

“…The models differ only in a bond stress-slip relationship for prestressing tendons. The relationships for strands deduced by [16,17,19,20] are applied. Additionally, the Model Code 2010 relationship (3)(4)(5)(6) for ribbed bars in the case of a pull-out failure is used to evaluate its appropriateness for 7-wire strands.…”

Numerical investigation on load transfer mechanism of bonded post-tensioned concrete beam-column substructures against progressive collapse

“…For BPT, the bond stress-slip relationship is defined by equation (2) based on Khalaf and Huang (2016).…”