Method of designing partially composite concrete sandwich panels and such panels
A method for calculating using a digital computer an approximation of properties of a concrete sandwich panel. The method allows for a manufacturer of concrete sandwich panels to design sandwich panels using a range of available components to meet architectural specifications.
1. A method of calculating in a digital computer properties of a concrete sandwich panel having an exterior concrete wythe and a spaced-apart interior concrete wythe and a plurality of connectors which have opposite ends embedded in both of the wythes, wherein the calculated properties of the panel comprise stiffness, strength, and thermal efficiency, comprising the steps of:
(a) providing as input data the thickness of the wythes, the connector spacing in the direction perpendicular to the length of the connectors, the distance between the centroidal axes of the two wythes, the areas of the wythes, the distance from the centroidal axis of the interior wythe to the centroidal axis of the exterior wythe, the stiffness of the connectors, the longitudinal spacing of the connectors, and the mean modulus of elasticity of the wythes;
(b) calculating a first panel factor which approximates the stiffness characteristics and load response of the sandwich panel;
(c) calculating from the first panel factor an equivalent moment of inertia of the panel;
(d) verifying that the properties are within pre-established specifications for the sandwich panel, and wherein the calculated stiffness is no less than 33% of a solid panel of the same overall thickness, the strength of the panel is no less than 50% of the strength of a solid panel of the same thickness, and the thermal efficiency of the panel is no less than 80% of the thermal efficiently of the inter-wythe insulation.