Shear Strength of HVFA-SCC Beams without Stirrups

Various concretes have been developed to meet the principles of sustainability. High volume fly ash-self compacting concrete (HVFA-SCC) is one example. The utilization of HVFA-SCC for structural applications, however, raises a concern among designers: that HVFA-SCC may not be as strong as conventional concrete when carrying shear forces. This concern is related to slow strength development and relatively smoother crack surface formation in HVFA-SCC, which, consequently, reduces the aggregate interlock mechanism contribution to the shear strength. In this respect, the design code for estimating the shear strength of HVFA-SCC may not be valid for the reason that the code was developed on the basis of the conventional concrete database. Previous research on the shear strength of HVFA-SCC was limited and no database can be extracted to justify the validity of the shear design code. This research was conducted to clarify the suitability of shear design code for HVFA-SCC. The research began with a limited laboratory investigation, followed by a numerical investigation to expand the range of results. Two types of HVFA-SCC beams with dimensions of 100 mm × 150 mm × 1700 mm were prepared, utilizing 50% and 60% fly ash. The shear behavior obtained from the laboratory investigations was then numerically modeled with the help of 3D ATENA Engineering software. The numerical model was used to explore the influence of reinforcement ratio, shear span to beam effective depth ratio, and beam size on the shear strength of the HVFA-SCC beam. The results were compared with the shear strength database of conventional and unconventional concrete beams to judge if the provisions in the design code can be applied to the shear design of an HVFA-SCC beam. The results confirm that the ACI shear design code is applicable for HVFA-SCC.

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