Investigation on Shear Behavior of Precast Monolithic ECC Composite Beams

Area of Science:

• Civil Engineering
• Materials Science

Background:

• Conventional concrete in composite beams can exhibit brittle failure and significant cracking.
• Engineered Cementitious Composites (ECC) offer enhanced ductility and crack control properties.

Purpose of the Study:

• To evaluate the mechanical performance of precast monolithic composite beams utilizing ECC shells as a replacement for conventional concrete.
• To compare the performance of ECC composite beams against traditional reinforced concrete (RC) composite beams.

Main Methods:

• Experimental investigation involving the design and fabrication of six composite beams (five ECC, one RC).
• Quantitative analysis of failure patterns, load-bearing capacity, deformability, and stiffness degradation under testing.
• Parametric study on shear span ratio and stirrup ratio effects.

Main Results:

• ECC composite beams demonstrated finer, more distributed cracks and no significant spalling compared to RC beams.
• ECC beams showed an 8.2% higher peak load and 29.3% greater displacement at peak load than RC beams.
• Increased stirrup ratios significantly improved load-bearing capacity and reduced stiffness degradation, mitigating brittle failure.

Conclusions:

• Precast monolithic ECC composite beams offer enhanced mechanical performance, including higher load capacity and improved ductility.
• ECC's fiber bridging effect delays crack propagation, leading to more gradual stiffness degradation.
• ECC composite beams are a promising alternative for structures requiring high seismic performance.