EDITOR ’ S CHOICE length of the canopy . In the normal permanent condition the moment and shear loads were 900kNm and 360kN respectively . Due to the complexity of the loads and arrangement of the
Isometric viewed from bespoke Schöck Isokorb below ( cantilever beam elements required to highlighted in red ). transfer such high forces Courtesy of Architect :
into a relatively small O ’ Donnell + Tuomey . concrete section of beam , the main supporting Isokorb rods were designed using Finite Element Software .
construction of the beams . This was a challenging section to model and calculate , due to the additional support factor of the raked end which sits on a rigid wall . Conventional Schöck Isokorb structural thermal breaks were also incorporated into the project at level two , for a much less technically demanding smaller canopy .
The cantilever beams are aligned with internal supporting beams which allow the internal sections of the Isokorb rods to penetrate far enough into the structure to distribute the demanding loads . In addition , it was necessary to consider bomb blast loading which introduced uplift forces . So the design had to accommodate loads in both positive and negative directions for both moment and shear .
A typical beam section . Courtesy of Architect : O ’ Donnell + Tuomey .
One of the deformation plots completed to show expected deflection to a given load combination – this is for dead load only
DEFLECTION AND NATURAL FREQUENCY Very tight deflection requirements and natural frequency had to be overcome too . The Isokorb detailing was once again calculated using Finite Element Software , with the contractor and design teams providing values for both long-term deflection and dead load deflection only – which determined the amount of pre-camber required during the
Typical view of Stacon type SLD dowels in position
EXPANSION AND CONTRACTION ISSUES AS WELL
The length of the main canopy and size of the rods required to transfer the main forces , meant that consideration also had to be given to the thermal stresses that would be caused by the expansion and contraction of the external concrete . Expansion joints therefore had to be introduced at every third beam ( approximately 8.4m centres ) which carry the load from one set of precast canopy sections onto the supporting beam , with the other canopy sections resting onto the beam directly . Schöck incorporated its newly introduced heavy-duty Stacon shear force dowel type SLD for the expansion joint requirements . This new dowel is a uniquely compact product and as the anchoring bodies have been reduced in size , it has the advantage of enabling higher loads to be installed in thinner slabs and walls . On-site reinforcement is optimised and Stacon provides a reliable and economical alternative to other expansion joint constructions .
TOTALLY VERIFIABLE PERFORMANCE The dependable and fully compliant range of Schöck Isokorb structural thermal break solutions helps projects meet full compliance with the necessary UK Building Regulations . There are solutions for concrete-to concrete , concrete-to-steel , steel-to-steel , renovation projects – and even a maintenance free alternative to wrapped parapets . All products have the security of independent BBA Certification , which provides NHBC approval . Also , the newly introduced Stacon dowel product has been awarded United Kingdom Technical Assessment ( UKTA ) along with fire protection classification R 120 .
Contact Schöck on 01865 290 890 ; or for full details of the Isokorb and Stacon products visit the solutions page on the website at www . schoeck . com / en-gb / solutions
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