The monumental Quatre-Temps shopping mall at La Défense is one of the most frequented centers of its kind in the Paris region. It has been extended by 8,000 sq m and linked, via a walkway, to a cinema complex. This extension has been achieved by expanding upwards above the Place du Dôme with the aid of an 800 ton metal framework. The company Gagne used the Tekla Structures software to model these complex frameworks (3 items modeled simultaneously), thus ensuring highly effective detailing and optimized fabrication of this exceptional structure.
The new section for the shopping mall, housing the restaurant area, is an expanse of glazed facades decked with awnings and includes two light wells covered with glass canopies. The larger is in the shape of a truncated cone, 31 meters in diameter, which appears to be suspended from a tapered mast emerging obliquely 11 meters above the opaque canted section which tops the glass canopy. Weighing 90 tons, this freestanding structure is shaped like a circular crown made of plate web girders supporting tubular Vierendeel girders, themselves supported at the top by the opaque disk fabricated from underpinned H girders. The 34 meters long central mast is stayed top and bottom and skims a pool at its lowest point. The whole has been installed as a single assembly. The second glass roof, which is 19 meters in diameter, is based on the same principle but with no central mast.
Managing and routing building information
Tekla Structures offers several highly desirable functions for this type of projects. The first is management of anchor bolts and multilevel assemblies, taking into account their location and load. Thus any modification to elements requiring connection means that the corresponding anchor bolt is automatically updated and a record of the modification retained. The second function is the possibility to integrate the results of structural calculations obtained via other software packages directly into the 3D model, after validation. The third function is automatic definition of the anchor bolts based on simple principles, such as the loads or stresses calculated by the software or the attributes of the elements to be connected. For example, a table defining the selection of anchor bolts based on admissible loads in the profiles can be used. The detail designer can therefore concentrate on the essential part of the work, avoiding tedious and time consuming operations. The data can then be transferred directly to numerically controlled machines as the 3D software guarantees absolute reliability of the information. This also means that data can be routed upstream to guarantee increased efficiency at the fabrication stage, for example, according to the materials available, the tools used, etc.
A Tekla Structures model covers all the materials and functions of the structure and offers full use of standardized data exchange tools. Once prepared, the 3D model can be handled in different ways: 3D viewing from any angle and specified to the millimeter; production of dimensioned drawings and sections to any scale, including detail and working drawings (these being images of the 3D model they are always up to date in relation to it); integration of the model with available calculation programs; definition of assemblies with the option to model detail drawings; direct control of manufacturing procedures like cutting and drilling; erection plans; full archiving of work completed; maintenance tool. Real time information sharing between all the contributors via an extremely fast internet interface avoids unnecessary duplication of plans and drawings and ensures precision, coordination and synergy between the players whilst limiting the risk of errors and inconsistency. The model may be successively enhanced by the various participants in their respective areas of competence. It also boasts a fourth dimension – that of time – by memorizing the whole revision history and offering the possibility to simulate and thus anticipate modifications or alternative solutions in order to verify the visual, structural or functional outcome. Tekla Structures includes an open API (Application Programming Interface), which means that different software can be tied into a common 3D model. It is the first structural software solution to achieve IFC 2x3 certification.