Modeling of bond stress-slip relationships of mono-prestressing strands with H-anchorage dead end

Abstract

One of the innovative structural techniques is post-tensioning members with H-anchorage dead end (onion dead end). The H-anchorage dead end is an economic anchorage technique as it enables the use of one anchor device at the live end only where the strand is tensioned and introduces a mechanical resistance against strand movement based on the implemented local bends of the strand wires. This paper presents an experimental and analytical assessment for bond behavior of prestressing strand 0.6 in (15.24 mm) diameter embedded in concrete leading to development of bond stress-slip relationship for post-tensioned mono-prestressing strand. Experimental work was conducted using nine cylindrical specimens with 150 mm diameter at Concrete Research Center -Ain Shams University, Cairo. Different specimen lengths were tested including 350, 550, 750 mm to differentiate the major affecting parameters for the bond stress-slip relationship. Based on the experimental results, an empirical bond model was developed to simulate bond stress-slip relationship between concrete and mono-prestressing strand with H-anchorage dead end. The developed bond model comprises four portions: an ascending curvilinear portion, a constant plateau, a linear ascending portion representing the H-anchorage resistance, and a linear descending portion at post-peak failure stage. Based on the experimental results, the minimum embedment length of the strand in concrete was determined, which shall guarantee that the strand reaches ultimate capacity without bond failure.

Keywords

• Bond model
• Stress-slip relationship
• H-anchorage dead end
• Mechanical interlocking resistance