Strand bond performance in prestressed concrete accounting for bond slip

Abstract

(José R. Martí-Vargas) 10 11 Abstract: 12This paper presents the results of an experimental research program addressing the bond 13 behavior of prestressing strands in pretensioned prestressed concrete members after anchorage 14 failure has occurred. A test methodology based on measuring the prestressing strand force and 15 strand end slip at the specimens' free end was employed. Transmission-and anchorage-length 16 tests were performed on several series of prestressed specimens with different embedment 17 lengths using twelve concrete mixes. Average bond stresses along the transmission length and 18 the anchorage length were obtained for specimens with release strengths ranging from 24 19MPa to 55 MPa. For the anchorage analysis, a parameter was developed that includes strand 20 slip to be used in determining anchorage length. Based on the test results, an analysis to 21 experimentally substantiate the Stress Waves Theory of Janney has been proposed. 22Additionally, the potential bond performance of prestressing strands after anchorage failure at 23 the end regions has been suggested. 24

Anchorage and residual bond characteristics of 7-wire strand

“…The bond stress is calculated using Eq. 16, following the method used by both Mattock (as cited by Tabatabai and Dickson [39]) and Marti-Vargas et al [40] to calculate the actual circumference from nominal strand diameter:…”

Strengthening system using post-tension tendon with an internal anchorage of concrete members

“…The study presented variations in shear stresses along the thickness of the mortar layer and interfacial shear stress along the embedment length. Martí-Vargas et al [11][12][13] investigated the transmission and anchor length of pre-tensioned prestressed concrete members. Test specimens were made with seven-wire prestressing steel strands of 13 mm diameter.…”

A two-stage modelling approach for the analysis of the stress distribution in anchorage zones of pre-tensioned, concrete elements

“…The appropriate strain distribution in the anchorage zone is also checked by referring to existing experimental data. The bond behaviour of 7-wire strands differs quite significantly from that of plain wires, as can be concluded from experimentally identified bond-slip relations [31] (figure 1). The bond strength at the steel-concrete interface is attributed to three aspects; chemical adhesion, mechanical resistance, and frictional forces between steel and concrete [32].…”