Experimental studies on shear behavior of steel-UHPC composite beam with hot rolled shape steel

The present study reported the findings of an experimental investigation of steel-ultrahigh performance concrete (UHPC) composite beams with hot rolled shape steel (HRSS). In order to investigate the shear behavior of HRSS-UHPC composite beams and determine the specific effects of shear span-to-depth ratios on the failure mode, ultimate shear strength and ductility, four shear tests were conducted. The test results showed that pronounced shear failure modes were observed in all specimens. The shear span-to-depth ratio significantly affected the shear behavior of HRSS-UHPC composite beams. As the shear span-to-depth ratio increased from 1.33 to 2.33, the shear resistance decreased by 30.5%. The ductility coefficient increased by 24.2% with the span-to-depth ratio increasing from 1.73 to 2.33. In addition, the measured ultimate shear capacity was compared to the current major shear design approaches, which indicated that the prediction for shear resistance by the standard AFNOR was closer to the experimental results. Finally, an analytical model for predicting the shear resistance of HRSS-UHPC composite beams was developed based on the experimental observations, current AFNOR design approach and previous theoretical method, which was in good agreement with the experimental results where the shear span-to-depth ratio ranged from 1.33 to 2.33.