Abstract
Relevance. This work is the first in a series of publications on the selection of a suitable analytical surface for implementation as a self-supporting structure for a thin shell footbridge. The study on the influence of concrete strength, live load position and support types on the stress-strain state of a hyperbolic paraboloid (hypar) shell is presented. Objective - to define the initial design parameters such as the appropriate concrete strength and the support type that generates the best structural behaviour to perform the subsequent structural design of a thin shell footbridge. Methods. The static finite element analysis was performed for 4 compressive strengths of concrete (28, 40, 80, 120 MPa) which correspond normal, high and ultra-high resistance concrete, 5 different live load arrangements and 3 different support conditions. Results. The shell model with pinned (two-hinged) supports shows the same vertical displacements as the model with fixed supports (hingeless). For the studied shell thickness, in terms of stress behaviour, the model with pinned ends is more efficient. The combination of two-hinged supports with 80 MPa concrete strength shows a better structural performance.
Highlights
Thin shells, as well as long-span structures, spatial grids, tensegrity systems, tall buildings, among other systems, are related to “special structures” [1]
The static finite element analysis was performed for 4 compressive strengths of concrete (28, 40, 80, 120 MPa) which correspond normal, high and ultra-high resistance concrete, 5 different live load arrangements and 3 different support conditions
In 1951 Candela built a 11 m span and 15 mm thickness hyperbolic paraboloid shell in Mexico [3,4,5], what was an innovative project at these time
Summary
As well as long-span structures, spatial grids, tensegrity systems, tall buildings, among other systems, are related to “special structures” [1]. Shells are form-resisting structures, as they mainly resist loads because of their form rather than the amount of their material (cross-section). Because of their special qualities, shells are used wherever high efficiency is required, such as to cover long spans with high resistance and minimum material [2]. In 1951 Candela built a 11 m span and 15 mm thickness hyperbolic paraboloid shell in Mexico [3,4,5], what was an innovative project at these time. The widespread building of thin reinforced concrete shells ended abruptly at the end of the 1960s [7] and for many time the use of large span shell structures has lost its popularity compared to the peak of their construction in the 1950–1960s [8]
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