To study the bending resistance characteristics of steel reinforced ultra-high performance concrete(SRUHPC)beams with rectangular section,four SRUHPC beam specimens with rectangular section were fabricated,with the reinforcing ratios ranging from 0.8％to 1.1％and the steel ratios ranging from 8.7％to 15.6％.The embedded steels are I-shaped,inverted T-shaped,and H-shaped.Flexural ultimate capacity tests were conducted to analyze the damage mechanism and failure modes of SRUHPC beam specimens with rectangular section.Based on test results and theoretical derivations,a calculation method for the flexural capacity of SRUHPC beam with rectangular section was proposed.The flexural capacities of 21 SRUHPC beam specimens with rectangular section and 111 finite element calculation models were calculated,and the calculation results were compared with the test and finite element calculation values.Analysis results indicate that the failure modes of SRUHPC beam specimens with rectangular section are all reinforced failures due to bending.The steels and longitudinal tensile reinforcements yield successively,followed by the crushing of the UHPC in the compression zone.The steels and UHPC work well together until the specimens failure.The specimens with embedded inverted T-shaped and H-shaped steels exhibit higher capacities and stiffnesses compared to those with embedded 1-shaped steel,and they demonstrate better crack resistances.Compared with other specimens,under the same load,the strains and strain development rates of longitudinal reinforcements,UHPC,and steels in specimens with embedded H-shaped steels are relatively smaller.Therefore,setting upper and lower flanges in the steel within SRUHPC beam with rectangular section contributes to enhancing the flexural performance of the composite beam.The calculated results obtained by the proposed method show mean ratios of 0.972 and 1.035 compared with the test and finite element calculation values,with variances of 0.009 and 0.002,respectively.The research results can provide theoretical supports for the promotion and application of SRUHPC beams with rectangular section in practical engineering and the formulations of codes and regulations.3 tabs,21 figs,30 refs.
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