# Flexural Performance of Reinforced Concrete Members with Steel Bars
## 1 Introduction
[25; 26; 27] reported that high-performance-steel reinforcing bars had a higher tensile strength than conventional steel bars, increasing their useful life when used in the construction of bridges; they predicted that, when integrated with concrete, steel bars could be bent up to 90\({}^{\circ}\) without damage to the ultimate strength. [PERSON] et al. [28] suggested a flexural strength design method for flexural members using high-strength steel bars. According to existing studies, including [PERSON] et al. [29], when conventional Grade 60 steel bars are replaced with high-tension bars, a much larger flexural strength can be obtained while maintaining the ductile fracture characteristics. [PERSON] et al. [29] reported that a specimen reinforced with a high-tension bar had a higher toughness than the specimen reinforced with a conventional steel bar. [PERSON] [30], [PERSON] et al. [31], and [PERSON] [32] reported that ductile flexural failure behaviour could be induced from all specimens reinforced with high-tension bars; in their experiments, the stiffness of beams significantly decreased after cracking, more conspicuously at lower steel ratios. [PERSON] and [PERSON] [33] conducted experiments with reinforced flexural members having the same tensile and compression steel ratios and found that the compressed steel bars reached the yield strain before the compression-side concrete failed. These bars endured a certain load even after the concrete failed, thus preventing the full failure of the members. In particular, strains of 0.005 to 0.006 were observed when the concrete failed; this was considered to be an effect of the compression-side high-tension bar [34; 35]. This phenomenon only rarely occurred with general steel bars, which typically reach the yield strength during the failure of concrete. The results of previous studies show the superiority of ultra-high-performance concrete (UHPC) over that of conventional or normal strength concrete in terms of higher compressive strength [36; 37; 38], higher tensile strength, more sustained post-cracking tensile strength [39; 40], higher durability [41; 42], and lower shrinkage and creep [43; 44; 45]. Over the past decade or two, UHPC has attracted the interest of the industry and research community due to its advanced mechanical and structural properties. UHPC has been adopted and used in several structural applications, particularly in highway and pedestrian bridges. UHPC can reduce the splice length of steel reinforcement [46; 47; 48]; it can be used for the connections between prefabricated bridge deck slabs [49; 50; 51]; it can even fill ducts for precast column-to-footing seismic connections [52]. The literature suggests that the design of flexural members using high-tension bars is possible; however, whether a reduction of steel amount (steel ratio) raises serviceability issues involving the reduction of the modulus of elasticity and an increase of cracks due to the reduced number of steel bars is yet to be established. The objective of flexural member design is ultimately to determine an appropriate range of load, member size, span, and support conditions that can reduce steel consumption while maintaining the same level of structural safety and satisfying serviceability conditions for deflection, cracking, and vibration of beams and slabs. This study performs static load experiments by applying high-tension bars to flexural members and examines the applicability of existing standard equations to the case of high-tension bars.