Novel trends in application of laser-welded steel sandwich panels in load carrying structures demand the conceptual development of optimum design guidelines. These sandwich panels, made by a process of laser welding faceplates to core-stiffeners, express advanced cost/weight ratio properties compared with the panel load carrying capacity versus the own weight. A particular problem in application of lightweight sandwich panels is ability of fast structural assembly by welded or mechanical joining techniques. For effective implementation of these sandwich structures for optimum design, new type of design methods should be introduced. For this reason, the optimization technique of building metamodels has been developed employing the response surface methodology (RSM) and design of experiments (DoE). Additionally for designer convince, metamodels used for design optimization can be implemented for parametrical studies and sensitivity analysis. The resulting design procedure provides an effective optimal design tool that permits optimizing of different core type sandwich panels with respect to jointing capabilities. In particular case different core-stiffened type sandwich panels under bending loading are considered. The choice of design variables depends on the core type of steel sandwich panel and industrial demands. Therefore design variables should suit all scope core type panel designs. For the optimum design the following parameters are taken: the panel length and width, the sandwich stiffener height and spacing factor, the top and bottom as well as core plate thicknesses. Validation with physical experiments within the design space is performed and good agreement achieved. As a logical addition to the optimization of the sandwich panels is to investigate behavior of the mechanical joint for sandwich steel panels subjected to combined loading. Variety of the different geometries and panel edge shapes are analyzed employing optimization technique based on the design of experiments and response surface method, to evaluate joint type and stiffener shape influence on the mechanics of the joint deformation and stress distribution through the joint parts. An influence of the joint type and material on the stress rate and locations of the stress concentrations are investigated. FEM results are optimized on subject of the lower stress concentrations.