Flexural Behavior of Slender UHPC Prestressed Beams Without Passive Reinforcement

Area of Science:

• Civil Engineering
• Materials Science

Background:

• Ultra-high-performance fiber-reinforced concrete (UHPC) offers enhanced mechanical properties.
• Scalable precast production requires optimized structural member designs.

Purpose of the Study:

• To investigate the flexural behavior of prestressed UHPC beams with novel cross-sections.
• To evaluate the impact of fiber content and prestressing on structural performance.
• To assess the suitability of I- and H-shaped sections for precast applications.

Main Methods:

• Experimental program involving eighteen prestressed UHPC beams.
• Testing of three cross-sectional typologies (rectangular, I-shaped, H-shaped).
• Varying UHPC mixes (fiber contents) and prestressing layouts.
• Four-point bending tests and measurement of time-dependent prestress losses.

Main Results:

• I- and H-shaped sections achieved higher residual flexural tensile stresses (>35 MPa) than rectangular sections.
• Prestressing effectively controlled deflections, while UHPC's post-cracking strength enabled stable multiple cracking.
• Significant self-weight reductions were achieved without compromising structural reliability.

Conclusions:

• Prestressed UHPC members with I- and H-shaped sections are feasible for scalable precast production.
• These members offer a lightweight and durable alternative to traditional concrete structures.
• The study demonstrates the potential for advanced concrete materials in innovative structural designs.