Panelized construction of residential buildings is gaining popularity due to the architectural and energy efficiency benefits that can be achieved. An important challenge to the design of panel structures for buildings is the balance between long-term structural performance and the thermal insulating requirement. In this study, foam core and web core panels are designed for residential roofs. Both panels are comprised of two face sheets and an insulating foam core. In the web core panel, thin metal webs that connect the face sheets are added to improve panel shear stiffness and enable longer spans. A design procedure is developed that considers R-value, panel deflection, core shear failure, bearing failure, and buckling of the face sheets and webs. The buckling model includes the ability of the foam core stiffness to restrain the buckling deformation. Panel designs are presented that provide R-5.3 m 2 K/W for roof loads of 1500, 2000, and 3000 N/m 2 , corresponding to climate zones in the US. It is demonstrated that the web core panel can be designed for these structural and thermal requirements with unsupported span lengths as long as 7 m, while span lengths for foam core panels are limited to 4 m. Web shear buckling and R-value are the two performance criteria that limit panel span length and depth.

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In-plane bending loads occur in many thin-walled structures, including web core sandwich panels (foam-¯lled panels with interior webs) under transverse loading. The design of such structures is limited in part by local buckling of the thin webs and the subsequent impact on sti®ness and strength. However, the core material can have a signi¯cant impact on web buckling strength and thus must be considered in design. This paper presents solutions for the buckling strength of simply supported plates under in-plane bending loads. The location of the neutral bending axis is allowed to vary and is characterized by a load parameter. A Pasternak model is used to account for the resistance of the foundation to compression and shear. Using the principle of minimum potential energy, buckling solutions are developed for in¯nitely long plates and representative foundation materials. The solutions match known results for two special cases: Uniform loading with variable foundation, and bending loads with no foundation. An order of magnitude increase in buckling strength is possible, depending on loading and foundation sti®ness. The results suggest an important avenue for future development of lightweight structures, including sandwich panels and structures such as plate girders that are not typically associated with the use of foam¯lling.