A comprehensive study is made of two types of sandwich plates under normal loads applied to their faces. The plates are composed of two plate facings separated by, and laser-welded to, either corrugated sheets or standard I-beams. The objective of this study is to provide the capability to design these plates for technical applications which require high bending stiffnesses. The plates are analyzed according to classical plate theory. The four stiffnesses of the orthotropic plates are derived from the component properties of the plates. The finite element method is used to analyze the plates. The plate models are constructed using three-dimensional elements and the deflections, strains, and stresses are evaluated for different sections. Experimental loading tests were performed on the two sandwich plates. The deflections and strains recorded during loading compared satisfactorily with the results of both theoretical solutions.