Pressure modes for hyperbolic paraboloid roofs

This paper presents a study on Singular Value Decomposition (SVD) of pressure coefficients hyperbolic parabolic roofs. The main goal of this study is to obtain pressure coefficient maps taking into account spatial non-uniform distribution and time-depending fluctuations of the pressure field. To this aim, pressure fields are described through pressure modes estimated by using the SVD technique. Wind tunnel experimental results on eight different geometries of buildings with hyperbolic paraboloid roofs are used to derive these pressure modes. The truncated SVD approach was applied to select a sufficient number of pressure modes necessary to reconstruct the measured signal given an acceptable difference. The truncated pressure modes are fitted through a polynomial surface to obtain a parametric form expressed as a function of the hyperbolic paraboloid roof geometry. The superpositions of pressure (envelopes) for all eight geometry were provided and used to modify mean pressure coefficients, to define design load combinations. Both symmetrical and asymmetrical pressure coefficient modes are used to estimate the wind action and to calculate the vertical displacements of a cable net by FEM analyses. Results clearly indicate that these load combinations allow for capturing large downward and upward displacements not properly predicted using mean experimental pressure coefficients.