Global Pressure Coefficients for Building Roofs Revisited

In the assessment of structural reliability for design against wind actions, Eurocode 1 provides two sets of pressure coefficients, one for fixings and cladding elements, the other for main structural elements. In addition, the Italian CNR Guidelines introduced a third set of coefficients for a quicker and simpler evaluation of the overall effects of wind on main supporting structures and on foundations. These are denoted as global pressure coefficients. However, despite some common features, the three sets turn out to be inconsistent from a statistical point of view. In this paper, a revision of the global pressure coefficients is made, in view of a possible reconsideration of the values given by Eurocode 1. To make it consistent from a statistical point of view, Cook and Mayne’s statistical definition of the pressure coefficient is adopted. Then, based on wind tunnel measurements available from aerodynamic databases, global pressure coefficients for flat and gable roofs are derived. In particular, the aerodynamic database of the Tokyo Polytechnic University is used, providing measurements on model-scale buildings with roof pitches up to 45 degrees.