手法を比較

	二次信頼性解析法 (SORM)	一次信頼性解析法（FORM）
分野	信頼性工学	信頼性工学
系統	Process / pipeline	Process / pipeline
提唱年	1979	1969
提唱者	Bernd Fiessler	Allin Cornell
種類	Reliability analysis method	Reliability analysis method
原典	Fiessler, B., Neumann, H. J., & Rackwitz, R. (1979). Quadratic limit states in structural reliability. Journal of the Engineering Mechanics Division, 105(4), 661-676.	Cornell, C. A. (1969). A probability-based structural code. Journal of the American Concrete Institute, 66(12), 974-985.
別名	SORM, Second-order approximation	FORM, First-order second-moment method
関連	4	4
概要	The Second-Order Reliability Method (SORM) is an extension of FORM that improves failure probability estimates by accounting for the curvature of the limit-state surface at the design point. Introduced by Fiessler, Neumann, and Rackwitz in 1979, SORM provides more accurate approximations for nonlinear failure surfaces while remaining computationally efficient. It has become the standard refinement when FORM accuracy is insufficient.	The First-Order Reliability Method (FORM) is a probabilistic technique for estimating the probability of structural failure given uncertain input parameters. Developed by Allin Cornell in 1969 and refined by Hasofer and Lind in 1974, FORM provides a computationally efficient approximation to the true failure probability by linearizing the limit-state function at the most probable failure point. It has become the cornerstone of modern structural reliability analysis and risk-based design.