Shear-Critical Deep Beams with Embedded Functionally Graded Concrete Struts

In this research, novel functionally graded concrete deep beams without transverse reinforcement for transfer girder applications were constructed with varying shaped embedded high-strength struts surrounded by low-cement content concrete. The cement content in the low-cement content concrete also varied, with a maximum total beam cement reduction of 47% compared to the control. The placement method also varied, further revealing issues with fresh-on-hardened concrete casting. The beams were tested in three-point bending and monitored using distributed fiber-optic sensors (DFOS) and digital image correlation. The results of the tests revealed that diagonal-shaped embedded struts designed for three-point bending had the highest load capacity increase of up to 26%. However, using shapes not compatible with three-point bending resulted in load capacity decreases. DFOS also enhanced the understanding of strut-and-tie mechanisms, allowing for the visualization of the strain distribution in struts and quantifying formations of the strut and tie.

Automated summary

Novel functionally graded concrete deep beams without transverse reinforcement were constructed for transfer girder applications. The beams were tested and monitored, revealing the highest load capacity increase in diagonal-shaped embedded struts. Distributed fiber-optic sensors (DFOS) enhanced the understanding of the strut-and-tie mechanisms.