- 来源:建筑创作 smarty:if $article.tag?>
- 关键字:意大利,水泥集团,结构工程 smarty:/if?>
- 发布时间:2013-08-22 14:42
I.lab：Notes on the Structural Project
The construction of Italcementi i.lab required the reexamination and improvement of the concrete mixtures available on the market. The client，Italcementi， developed a white and gray self-compacting concrete material specifically for this project，aiming both at high strength and high recycled material content- a sustainable element set to attain the highest level of LEED certification.The structural solutions adopted to maintain the linear appearance of the building and its clean geometries required in-depth analyses and painstaking calculations.Among the most interesting ones，I‘d like to mention two that are particularly visible to someone observing the building from the outside.
THE PRE-CAST ROOF SHELLS
The building is characterized by prominent roof cantilevers along the northern and eastern elevations，with a typical 10.6 meter overhang along the highway. The cantilever exceeds 19 meters at the bisector of the angle between the two converging sides of the roof，where a sharp vertex constitutes the “beak” that covers the entrance plaza，from which the building is accessed.
The overhangs are made up of large-scale precast shells-the typical one reaching a surface area of 80 square meters-while the cusp of the “beak” is characterized by a very atypical shape， multidimensional like a diamond. The realization of all these elements， and particularly of the cusp，required extremely subtlework in the design and construction of the formwork，which had to guarantee a perfectly smooth and consistent underside.
One challenge was that after the phase of elastic failure，which was deferred in time，the horizontal planeat the edge of all overhanging elements had to be perfectly leveled and coplanar. This was not easily obtained because the different precast shells with varying cantilevers and weights would undergo different deformations， particularly in the area around the “beak”.The lattice structures used to support the precast elements during the installation were positioned at different heights，based on meticulous calculations of the elastic failure expected for each shell.The upper portion of the precast shells is characterized by stiffeners that act as secondary beams and by formwork that was later to be poured into cantilevered beams，to which the shells were carefully suspended. These beams are anchored to the load-bearing vertical structures inside the building and measured according to the seismic requirements of the area.
CURTAIN WALL WITH CONCRETE LOAD-BEARING MULLIONS
The access Atrium and the Auditorium west wall are bounded by tall curtain walls that accentuate the contrast between solids and voids，horizontal surfaces and vertical elements，characteristic of Richard Meier’s architecture. The intent was to differentiate these curtain walls by abandoning the use of typical aluminum extrusions and employing instead white precast concrete mullions.This is a unique solution，which required the development of uncommon details and had to be tested on full-scale prototypes. One of the main engineering challenges we confronted and resolved was that of keeping these load-bearing structures as slender as possible-mullions should not be mistaken for columns； transoms should not be confused with beams-while still providing sufficient rigidity to avoid deformations beyond the limits acceptable to guarantee the integrity of the glazing.