The energy method is the basis for the derivation of the member stiffness matrix. This method can be applied to analyze structures with any geometric shape. The major assumption made in this method is that the members does not have any geometric non-linearity or P-Δ effect. Based on this assumption, the following assumption is valid: d 2 y d x 2 = M E I https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429398544/5072168d-64f7-41d9-a769-a535b7f4190c/content/TNF-CH999_eqn_0001.tif"/>