Strength Testing of Double-Curved GRC Panels: Differences from Flat Panels, Curved Surface Effects, and Dedicated Testing Methods

Strength testing of double-curved GRC panels must account for the stress distribution characteristics introduced by the curved surface; flat-panel test methods cannot simply be applied. Based on extensive test data, Qinglong Group found that double-curved panels with the same mix proportion have an actual load-bearing capacity 15-30% higher than flat panels, but the coefficient of variation also increases to 8-12%. By establishing a dedicated curved-surface testing system, an accurate basis is provided for the structural design of double-curved GRC panels.

Test methods require targeted improvements. Flat panels commonly use three-point bending tests, while double-curved panels require a hydraulic servo loading system to simulate actual support conditions. Qinglong Group independently developed a curved-surface testing platform that faithfully reproduces wind load effects through coordinated multi-point loading. Test samples should cover typical curvature regions, such as positive Gaussian curvature zones, negative Gaussian curvature zones, and saddle point zones, to comprehensively evaluate performance. Test data show that compressive strength improves markedly in positive-curvature regions, while tensile performance is more critical in negative-curvature regions.

Failure modes differ significantly. Flat panels mostly undergo bending failure, whereas buckling failure is common in double-curved panels. When the ratio of curvature radius to panel thickness R/t < 20, stability issues require particular attention. Qinglong Group uses full-field strain measurement based on digital image correlation (DIC) to precisely capture the buckling modes of curved panels, providing a basis for design.

Design standards need corresponding adjustments. Current codes were formulated on the basis of flat-panel tests and are conservative when applied to double-curved panels. Through extensive testing, Qinglong Group established a database of load-bearing capacity correction factors for double-curved panels, making designs more economical and rational. This refined testing method provides technical support for the safe application of double-curved GRC panels.