## 5 Conclusions  
This study investigates the ultimate bearing capacity of UHPC walls under combined unilateral thermal loading and eccentric compression. First, the fire resistance limits of UHPC eccentrically compressed columns under high-temperature conditions were analyzed by comparing finite element simulations with experimental results, thereby validating the rationality of the modeling approach and material constitutive parameters. Subsequently, a finite element model of UHPC walls under unilateral accidental thermal loading was established. Parametric analyses were conducted to evaluate the influence of eccentricity, reinforcement ratio, steel fiber volume fraction, and concrete strength grade on the bearing capacity. Finally, a calculation method for the normal section bearing capacity of rectangular UHPC large eccentric compression specimens under high-temperature conditions (compression zone) was proposed. The main conclusions are as follows:  
1. In validation via fire resistance tests (four-sided fire exposure): Temperature field analysis revealed that finite element simulations cannot capture the heat-carrying effect of escaping water vapor, causing simulated temperatures to increasingly exceed experimental values at higher temperatures. Thermo-mechanical coupling analysis showed three characteristic stages (expansion, contraction, and failure), with excellent agreement between simulated and experimental displacement-time curves. 2. For parametric analysis under unilateral thermal loading: Load eccentricity was identified as the dominant factor affecting ultimate load, with larger eccentricities reducing capacity but slowing its temperature-dependent attenuation. Increased reinforcement ratios and steel fiber content significantly improved high-temperature performance, while higher concrete strength grades accelerated degradation. 3. The proposed calculation method, based on moment equilibrium equations using the equivalent cross-section approach, provided reasonable bearing capacity estimates for unilateral thermal loading scenarios, with errors within acceptable limits despite slight overestimation. The method's applicability was extended to multi-sided fire exposure cases. The key findings demonstrate that while UHPC walls exhibit complex thermomechanical behavior, their performance can be effectively predicted and optimized through careful parametric analysis. The validated calculation method offers practical tools for nuclear power plant structural design, particularly highlighting the importance of balancing material properties rather than relying solely on concrete strength improvements. Future research will systematically analyze the multi-parameter coupling effects through orthogonal experiments or response surface methodology to provide a more comprehensive understanding of the interactive influences among parameters. * [22] [PERSON]; [PERSON]; [PERSON] Design methods for ultra-high performance concrete structures. _J. Archit. Civ. Eng._**2017**, _34_, 59-67. * [23] [PERSON] Study on Explosive Spalling Rules and Mechanical Properties of Reactive Powder Concrete at Elevated Temperatures. Ph.D. Dissertation, Harbin Institute of Technology, Harbin, China, 2013. * [24] [PERSON] Study on the Elastoplastic Damage Constitutive Relationship of Ultra-High Performance Concrete. Ph.D. Dissertation, Wuhan University, Wuhan, China, 2022. * [25] [PERSON]; [PERSON]; [PERSON] Quantifying fire insulation effects on the fire response of hybrid-fiber reinforced reactive powder concrete beams. _J. Fire Technol._**2020**, _56_, 1487-1525. [CrossRef]
* [26] [PERSON]; [PERSON] Experimental Study on the Ultimate Bearing Capacity of Reactive Powder Concrete Arches. _J. Eng. Mech._**2013**, _30_, 42-48. * [27] [PERSON] Study on Thermophysical Parameters and Temperature Field of Reactive Powder Concrete at High Temperatures. Master's Thesis, Shijiazhuang Tiedao University, Shijiazhuang, China, 2018. * [28] European Committee for Standardization.