Influence of Support Equivalent Stiffness on Stability Capacity of Concrete-Pier-Supported Elliptical Cylindrical Double-Layer Reticulated Shell

Concrete pier-supported double-layer reticulated shells are widely used in long-span industrial buildings, yet the influence of support equivalent stiffness on structural stability remains insufficiently understood. This study investigates the stability behavior of an elliptical cylindrical double-layer reticulated shell supported by concrete piers with steel bearings. A simplified calculation method for equivalent support stiffness is derived based on a series cantilever system model and validated numerically. Seven steel bearing web thicknesses (10–40 mm) commonly used in engineering practice are selected, yielding equivalent stiffness coefficients ranging from 0.017 to 0.065. Eigenvalue buckling analysis is performed, and three quantitative indicators—critical load factor, sensitivity, and saturation degree—are introduced to systematically evaluate the effect of equivalent stiffness on stability capacity. Results show that the equivalent stiffness coefficient is typically less than 0.1, and using rigid links (infinite stiffness) overestimates the stability capacity by approximately 7% compared with the lowest stiffness case. The sensitivity of stability capacity to stiffness decreases monotonically as equivalent stiffness increases, with a threshold identified at ξ = 0.05. When the saturation degree of the critical load factor exceeds 72%, further increasing equivalent stiffness yields diminishing returns. Buckling modes transition from local end uplift to overall lateral tilting as equivalent stiffness increases. These findings provide a theoretical basis for selecting rational support stiffness values in the design of concrete-pier-supported reticulated shell structures.