Effect of compression pre-force and web openings on torsional strength of UHPC hollow beams using numerical and mathematical modeling

In this paper, a new formula is proposed to accurately predict the torsional strength of ultra-high-performance concrete (UHPC) solid and hollow beams with and without openings. A comprehensive parametric numerical study is carried out to investigate the effect of both compression pre-force and web openings parameters on the torsional strength of UHPC solid and hollow beams. This study is based on numerical results of 44 applied finite element (FE) models with Abaqus software. Furthermore, five recent available formulas, capable of predicting the torsional strength of UHPC beams, were introduced and compared and to clarify their deficiency, three of them were calibrated to the 44 FE models. The proposed new formula was not only compensated for the deficiency of former formulas, but it also included parameters not previously considered. To examine its validity, the results of the derived formula were reviewed with those of 44 FE models and other 46 previously tested UHPC beams. In both cases, the proposed new formula demonstrated high accuracy in predicting the torsional strength of UHPC beams.