For the energetic utilization of sun-lit roof areas, photovoltaic and solar thermal plants are installed on the existing roof surface by means of different fastening systems. For the installation on trapezoidal profiles, hanger bolts, solar fasteners and solar calottes are primarily applied. Especially for the application of hanger bolts and solar fasteners, only insufficient design approaches are available up to now. The load bearing be-havior due to effects from roof shear, wind and snow loading into the substructure is the main problem.The methods and equations presented within this article facilitate to determine the shear bearing capacity considering the influences of eccentrically induced compressive forces. For this purpose, the torsion spring stiffness C_a of the fastener in the substructure, the trapezoidal profile stiffness K_b and the yield moment M_y ,_(RK) of the fastener must be provided for the user. An conservative assess-ment can also be realized by using the shear bearing capacity of the trapezoidal profile F_b and the yield moment M_y ,_(RK) neglecting the torsion spring stiffness.
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