# Ultimate Compressive Strains and Reserves of Bearing Capacity of Short RC Columns with Basalt Fiber
## 5 Discussion  
It should be noted that an increase in the actual value of the ultimate compressibility of concrete in specimens with dispersed reinforcement influenced the change in the complete strain diagram, with a record of the descending branch. The strain diagrams of concrete prisms made of heavy concrete on the ascending branch had a sufficiently steep rise in both conventional and FRC specimens. The actual ultimate strains for this group of samples turned out to be slightly higher than the standardized ones. Therefore, at the ultimate stage, they were within 2.70\(\cdot\)10\({}^{-3}\)-3.60\(\cdot\)10\({}^{-3}\). However, in strain at the stage of fracture in the descending section, the curves differed quite significantly. Figure 11 shows the dependence of the racks' bearing capacity on the amount of eccentricity for columns without fiber and with 10% basalt fiber. It can be seen that in the considered range of relative eccentricity, structures with basalt fibers have a higher bearing capacity. Similar results were obtained by [PERSON] et al. [31], in which the properties of the geopolymer concrete crushing reinforced with basalt fiber are investigated. Tests [30] were carried out for compression, splitting, and three-point bending. The results show that the addition of 6 to 12% basalt fiber improves compressive strength, tensile strength, and fracture toughness. Comparison of our results with studies [31] shows that the combination of FRC with the effective use of high-strength steel reinforcement will increase the columns' bearing capacity and reduce material consumption. \begin{table}
\begin{tabular}{c c c c} \hline
**Column Type** & **Longitudinal Reinforcement** & **Longitudinal Reinforcement Spread, kg** & **Steel Saving, \%** \\ \hline Typical, & & & \\ \(b^{\star}h=300\times 300\) mm, & 4028 A400 & 87.01 & 0 \\ \(L_{0}\) = 4500 mm & & & \\ Variant 1 & & & \\ \(b^{\star}h=300\times 300\) mm, & 4022 + 2020 A400 & 75.91 & 12.8 \\ \(L_{0}\) = 4500 mm & & & \\ Variant 2 & & & \\ \(b^{\star}h=300\times 300\) mm, & 6020 A1000 & 66.58 & 23.4 \\ \(L_{0}\) = 4500 mm & & & \\ \hline \end{tabular}
\end{table} 
Table 10: Steel spread in a reinforced concrete column when using fiber reinforcement. [PERSON] et al. studied the use of concrete reinforced with basalt fiber with a volume fraction of 0-2% without steel reinforcement [32]. The authors showed that the inclusion of basalt fibers in 1.5% increases the modulus of rupture while not significantly affecting the compressive strength. Compared to the control concrete sample, the mechanical characteristics of concrete reinforced with basalt fiber by 1.5% increase from 9% to 22%. Comparison with the results obtained by [PERSON] (in [33]) shows that reinforcement with composite materials in the transverse (at \(e_{0}=0\)) and longitudinal (at \(e_{0}=0.32\)\(h\)) directions demonstrated sufficiently high strength. This made it possible to use external reinforcement to increase the bearing capacity of compressed elements, despite exceeding the standard values of the section dimensions \(b/h=0.2\), which is more than 1.5, and the flexibility of the elements strengthened \(\lambda_{h}=20>\lambda_{h}=14\). If, for ordinary samples-prisms, the process of destruction proceeded very quickly, in particular, in the range of load drop up to \(0.8N_{u}^{theor}\), for samples without fibers it sharply decreased, after which complete crushing occurred, then for FRC, this section had a smoother fall, while the strains increased by 1.87 times. The effect of fiber is even more noticeable on the total strain diagrams for lightweight concrete specimens. If in ordinary expanded clay concrete samples, the process of destruction occurred, as in heavy concrete, very intensively (peak longitudinal strain were within \(3.10\cdot 10^{-3}\)-\(3.20\cdot 10^{-3}\)), then for dispersed reinforced samples, a much more plastic nature of strain is characteristic.