Author: N. Gorst (British Precast)
1 May 2018
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N. Gorst (British Precast)
This article is the second in a series of three addressing aspects of designing steel-framed buildings with precast concrete floors. The article describes aspects of the design of steel or composite beams which willsupport precast prestressed concrete planks.
In April we marked the 50th edition of the Confidential Reporting on Structural Safety (CROSS) newsletter (page 24). The first newsletter was published in November 2005 with brief comments on a number of short reports under the headings: Near misses, Collapses, Design issues, Building control, Engineers on site, and Fixings. CROSS had started a short while earlier on a six-month trial basis and we had no idea if the project would take off . Since then it has grown and is now the model for versions in other countries. The core topics have remained remarkably similar, showing that lessons must be continuously re-learned so that safety culture can improve. Many thousands read the newsletters around the world and the number continues to grow.
All the articles from the May 2018 issue.
The Armadillo vault, exhibited at the 2016 Venice Architecture Biennale and commended at the 2017 Structural Awards, is a doubly curved, unreinforced, cut-stone, compression-only vault, constructed from 399 limestone blocks. The thickness of the stone varies from 8–12cm at the supports to 5cm at the peak. With a height of 4.4m and spans of over 15m, the structure has a thickness-to-span ratio half that of an eggshell. This paper describes the form-finding process and detailed structural analysis. Steel supports were designed to take the reaction thrusts of the vault and transfer them safely to both the ground and the internal steel tie system. The stone-cutting process for the limestone is also outlined, describing the rough-finished inner surface, which was patterned to follow lines of internal force flow, and the smooth flat outer surface. Finally, the process of erecting the formwork and falsework on site is also set out, including the process of decentring and the use of custom keystones.