Ruy M.O. Pauletti

Some issues on the design and analysis of pneumatic structures

Pneumatic structures are the tensile structures par excellence, since only with them it is possible to have all elements working in tension. This paper describes the evolution of pneumatic structures, as well as several issues related to its design, such as different pattering methods, the distinctions between high and low energy systems, and whether large strain material models, pressure variations or cable sliding are required to proper design. Selected civil engineering applications, designed by means of simple numerical models, are also presented.

Static Analysis of Taut Structures

The article presents a general framework for the nonlinear equilibrium analysis of taut structures, such as cables and membranes. Distinction is done between geometric and constitutive stiffness, and all the relevant matrices for truss and membrane finite element static analyses are derived, including the effects of sliding cables and following forces (such as wind pressures). The peculiarities of the design of taut structures are briefly discussed, considering the design of an existent membrane structure as a benchmark.

Analysis of Nonlinear Oscillations by Gabor Spectrograms

We examine the potential of the Gabor spectrogram as a tool for the study of the temporal behavior of nonlinear oscillators. Numerical simulations of a snap-through system and homogeneous Duffing equation are analyzed by this method. Gabor spectrograms show dynamic properties of nonlinear oscillators in situations where the conventional Fourier analysis is not appropriate.