Performance control for efficient design of double-layer grids under uniform loading

Performance control (PC) is a recently developed, observation based, design process that aims at rational and efficient selection of structural elements rather than investigating their usefulness through iterative processes. The basic notion behind PC is that structural response is mainly a function of design and detailing, rather than numerical computations. The design concept uses pre-selected target displacements and failure mechanisms as key control objectives. While elastic analysis is still the predominant design methodology for double-layer grids (DLG) and similar structures under service conditions, performance-based procedures could further enhance their functional uses up to plastic limit states. The current contribution presents a general technique for the estimation of maximum plastic displacements of twistless, orthotropic, DLG of regular formation, simply supported along the sides of a parallelogram, and subjected to monotonically increasing uniform distribution of normal nodal forces. In the interim, a new application for the uniqueness theorem has also been discussed. The proposed methodology is ideally suited for preliminary design as well as capacity analysis purposes. It lends itself well to both manual and spreadsheet computations. The applications of the proposed solutions have been illustrated through a number of generic examples. The paper does not address seismic conditions.