Flexural Behavior of an Ultrahigh-Performance Concrete I-Girder

TLDR

The study proposes a flexural design philosophy for ultrahigh‑performance concrete I‑girder. The authors tested a full‑scale 80‑ft UHPC prestressed I‑girder, measuring cracking, flexural stiffness, and moment capacity to analyze its intermediate and final behavior. Tests showed that UHPC’s uniaxial stress‑strain response and crack‑spacing–tensile‑strain relationship match predictions, confirming the girder’s flexural stiffness and moment capacity.

Abstract

The flexural behavior of an ultrahigh-performance concrete (UHPC) was investigated through the testing and related analysis of a full-scale prestressed I-girder. A 28ksi(193MPa) compressive strength steel fiber reinforced concrete was used to fabricate an 80ft(24.4m) long AASHTO Type II girder containing 26 prestressing strands and no mild steel reinforcement. Intermediate and final behaviors, including cracking, flexural stiffness, and moment capacity, were investigated. Test results are compared to predictions based on standard analytical procedures. A relationship between tensile strain and crack spacing is developed. The uniaxial stress-strain response of UHPC when subjected to flexural stresses in an I-girder is determined and is verified to be representative of both the stress and flexural stiffness behaviors of the girder. A flexural design philosophy for this type of girder is proposed.