Panel structure

A panel structure, comprising:

• a panel made of metal;
• a hollow frame made of metal disposed on a peripheral edge portion of the panel to restrain a periphery of the panel;
• and
• a reinforcement joined to only one side of the panel and made of a plurality of FRP layers including continuous fibers, wherein:
• each of the plurality of FRP layers has a single fiber direction;
• at least one layer out of the plurality of FRP layers has a fiber direction different from that of another layer;
• in the plurality of FRP layers, a proportion of layers having an angular difference in the fiber direction of 30° or more is 15% or more of all of the layers;
• and
• when calculating, by defining a long side direction being a long direction of a long edge of the panel as a 90° direction and a direction orthogonal to the 90° direction as a 0° direction, each of a 90° direction component and a 0° direction component regarding the fiber direction of each FRP layer of the reinforcement joined to the panel, by using a trigonometric function, a following expression (1) is satisfied:
• 0.38×K≤(A×4+B)/(C+D) (1)
• A:
• the 0° direction component of the FRP layers positioned on an outer side of a center of a sheet thickness of the reinforcement,
• B:
• the 0° direction component of the FRP layers positioned on an inner side of the center of the sheet thickness of the reinforcement,
• C:
• the 0° direction component of the plurality of FRP layers as a whole,
• D:
• the 90° direction component of the plurality of FRP layers as a whole,
• K:
• a length of the long edge of the panel/a length of a short edge of the panel.