钢结构具有低碳环保、轻质高强和抗震性能卓越等多重优势，目前已经广泛应用在高层建筑、大跨度建筑和一些民用建筑；但是其固有的易发生屈曲、腐蚀以及成本较高等问题阻碍了钢结构的进一步应用。目前关于钢结构防屈曲和防腐蚀的措施会大大提高结构的成本并对结构承载能力带来一定的负面影响。超高性能混凝土（UHPC）是一种基于最大堆积密度理论的新型纤维增强水泥基复合材料，具有较高的强度和较强的变形能力，并且在抗水渗透性、抗氯离子渗透性以及抗冻融性等耐久性方面有着优异的性能。如今UHPC已经广泛应用于各种结构的力学加固以及耐久加固之中。近期的研究工作表明，将钢结构与UHPC结合使用，可以有效地实现两者的优势互补，在发挥钢结构轻质高强优异特征的同时，极大地减缓了疲劳、腐蚀和失稳对钢结构的危害。该文研究了一种已经广泛投入使用的工字钢外包薄层UHPC新型组合梁，并通过Abaqus有限元软件进行仿真分析建立样本数据库。同时利用雷达图法提出组合梁抗剪性能和抗剪性价比综合评价指标，采用响应面-蒙特卡罗法，共设计4种响应面对组合梁腹板尺寸参数进行分析。分析结果表明，组合梁的抗剪性能与其性价比之间存在显著的正相关性。此外，随着工字钢腹板厚度的增加，抗剪性能和性价比先增加后降低，并在某一特定厚度处达到峰值。该研究对于优化工字钢外包UHPC组合梁的设计具有重要的工程意义。

The steel structure has multiple advantages, including low carbon footprint, environmental friendliness, lightweight yet high strength, and excellent seismic performance. It has been widely used in high-rise buildings, large-span buildings and some civil buildings. However, its inherent problems such as buckling, corrosion and high cost hinder the further application of steel structures. The current anti-buckling and anti-corrosion measures for steel structures will greatly increase the cost of the structure and have a negative impact on the bearing capacity of the structure. Ultra-high performance concrete (UHPC) is a new type of fiber-reinforced cement-based composite material based on the maximum bulk density theory. It features high strength and excellent deformation capacity, along with outstanding durability properties, including superior resistance to water penetration, chloride ion infiltration, and freeze-thaw cycles. Nowadays, UHPC has been widely used in mechanical reinforcement and durability reinforcement of various structures. Recent research work shows that the combination of steel structure and UHPC can effectively realize the complementary advantages of the two. While giving full play to the excellent characteristics of light weight and high strength of steel structure, it greatly reduces the harm of fatigue, corrosion and instability to steel structure. This study focused on a newly developed thin-layer UHPC encased I-beam, which has been widely applied in practice. A sample database was established through finite element simulation analysis using Abaqus. At the same time, the comprehensive evaluation index of shear performance and shear cost performance of composite beams was proposed based on the radar chart method. The response surface-Monte Carlo method was employed to analyze the influence of four different response surfaces on the web size parameters of the composite beam. The analysis results show that there is a significant positive correlation between the shear performance of the composite beam and its cost performance. Moreover, as the thickness of the I-beam web increases, both shear performance and cost-effectiveness initially rise and then decline, reaching a peak at a specific thickness. This study provides valuable engineering insights for optimizing the design of I-beam encased UHPC composite beams.