## 3 Results and Discussion
### Mechanical Properties Analysis
#### 3.5.1 Load-Bearing Capacity Analysis  
(1) Comparison of test pieces Z1 and Z2-1 (50 mm eccentricity)  
The ultimate bearing capacity of reinforced specimen Z2-1 was increased by 172.30% compared with comparison specimen Z1. This was due to the excellent tensile properties of UHPC and the lassoing effect of the UHPC reinforcement on the core concrete. The UHPC reinforcement layer provided more effective restraint to the core concrete, which significantly increased the ultimate load capacity of the specimen.  
(2) Reinforced specimens Z2-1, Z2-2, and Z2-3 (reinforcement thickness of 30 mm)  
When the reinforcement thickness was 30 mm and the steel fiber dosage was 2%, the eccentricity values of Z2-1, Z2-2, and Z2-3 were 50 mm, 100 mm, and 150 mm, respectively. The ultimate bearing capacity of reinforced specimen Z2-1 was increased by 42.7% and 141.80% compared with Z2-2 and Z2-3. The effect of eccentricity on eccentrically compressed columns after UHPC reinforcement was similar to that on the normal eccentrically compressed columns, whereby the ultimate bearing capacity decreased with increasing eccentricity.  
(3) Reinforced specimens Z2-3 and Z3 (reinforcement thickness 30 mm)  
The ultimate load-carrying capacity of specimen Z2-3 with 2% steel fiber doping increased by 8.96% compared with specimen Z3 with 1% steel fiber doping when the reinforcement thickness was 30 mm and the eccentricity was 150 mm. This was mainly because the UHPC steel fiber volume admixture was in the appropriate range, and steel fiber can inhibit cracks more effectively and possess better tensile capacity, which improves the ultimate bearing capacity of the specimen. The strength and ductility of UHPC after cracking were mainly provided by fiber-reinforced toughening. For example, [PERSON] studied the tensile fracture properties of UHPC considering the effect of the steel fiber content. In this case, the steel fiber volume ratio was changed from 0% to 5%.The flexural tensile strength of UHPC increased linearly with the increase in the steel fiber volume ratio [28].  
(4) Reinforced specimens Z2-3 and Z4 (2% steel fiber)  
The ultimate load capacity of specimen Z4 reinforced with a 50 mm thickness was increased by 45.11% compared with specimen Z2-3 reinforced with a 30 mm thickness when the thickness of the reinforcement was 30 mm and the eccentricity was 150 mm. This shows that the thickness of the UHPC reinforcement increases the specimen's ultimate load capacity. Enhancing the thickness of the reinforcement can significantly enhance the force  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Specimen Number** & **Cracking Load N\({}_{\text{or}}\) (kN)** & **Peak Load N\({}_{\text{or}}\) (kN)** & **Mid-Span Deflection Value at Peak Load A\({}_{\text{or}}\) (mm)** & **Mid-Span Deflection Value at 85\% Remaining after Peak Load A\({}_{\text{or}}\) (mm)** & **Ductility Factor** \\ \hline Z1 & 1037.70 & 2401.40 & 7.394 & 8.232 & 1.113 \\ Z2-1 & 2078.40 & 6539.20 & 9.222 & 16.040 & 1.739 \\ Z2-2 & 1532.60 & 4596.30 & 8.931 & 14.512 & 1.625 \\ Z2-3 & 1314.30 & 2703.90 & 7.184 & 10.201 & 1.420 \\ Z3 & 102 distribution in the reinforcement member column, thereby reducing the original column's eccentricity by enlarging the member's cross-section. This transformation converts the member from a partially loaded section to a fully loaded section. The eccentricity of the original column causes a portion of the cross-section to experience compression, resulting in full cross-section compression. The member undergoes a transformation from a partially compressed segment to a fully compressed section, resulting in enhanced utilization of the concrete material. This leads to a substantial increase in stiffness, and the rigidity and maximum load-bearing capability of the component are significantly enhanced.