| 摘要 |
A free span arch structure is illustrated including transversely spaced elongated flexible structural sections flexed from a substantially straight configuration when unflexed into a substantially parabolic configuration without exceeding the yield point of the structural sections so as to impart a permanent set thereto. Means are provided for supporting and for restraining the structural section adjacent the ends thereof against outward and downward movement retaining the sections flexed in the parabolic configuration. The method contemplates lifting structural sections, which are illustrated in the form of aluminum pipes, by exerting a lifting force as by a crane intermediate the ends thereof in a medial portion, and then raising an intermediate portion of the pipe by the application of the lifting force while supporting the opposed ends of the pipe as on the ground or otherwise as in the case of a roof, on the walls. When the pipe is lifted, the ends restrained and the lifting force removed with the pipe in a natural state of repose after the application of the load imposed by its own weight, the flexed pipe will assume a substantially parabolic configuration.
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