Influence of concrete strength on development length of prestressed concrete members

• The development length was measured for 57 prestressed concrete beams.
• The concrete strength of the beams ranged from 34.5 MPa to 199 MPa.
• An equation to predict development length was developed.
• Development length results were collected from the literature to validate the equation.

Fifty seven prestressed concrete beams were fabricated at the University of Arkansas (UA) to determine the influence of concrete strength on the development length of seven wire prestressing strand. The variables considered in the investigation were the concrete compressive strength (f′c), which ranged from 34.5 MPa to 199 MPa, and the strand diameter, which included 12.7 mm and 15.2 mm. The beams were cast with concrete types which included self-consolidating concrete, high strength concrete, lightweight concrete, and ultra-high performance concrete. Development length was determined through flexural testing. The research project also summarized the findings of several studies from the literature. The measured development lengths were compared to those calculated using the American Concrete Institute (ACI 318-14) prediction equation for development length. The results showed that compressive strength affects the development length and the ACI 318 equation overestimates development length. Also, a development length equation was developed and presented in the paper.