VSH Turòa nad Bodvou - Nemetschek Scia
VSH Turòa nad Bodvou - Nemetschek Scia
VSH Turòa nad Bodvou - Nemetschek Scia
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Project Details<br />
Location: Elm Road, Wembley, Middlesex HA9<br />
Size: Approx plan area is 130m long by 30m wide<br />
Height: 1 to 2-storey underground car parks with 4 to 5-storey<br />
timber framed buildings, 4-storey reinforced concrete framed<br />
buildings and a 10-storey reinforced concrete tower block.<br />
Cost: Approx £17 million<br />
History<br />
The Client tendered for the Elm Road Project from the London<br />
Borough of Brent as part of a regeneration package. The site was<br />
previously used as a poor quality ground level car park on semiderelict<br />
land. The agreement between the Client and London<br />
Borough of Brent was to develop the site for affordable housing<br />
with the provision of underground car parking. Furthermore,<br />
the site was surrounded by three roads, two of which were poor<br />
quality surfaced service roads.<br />
The Client, as part of the agreement, upgraded the two poor<br />
quality service roads to highway works standards which will later<br />
be adopted by the Local Authority following final completion of<br />
the project.<br />
Project Overview<br />
The underground car park covers the entire site area (i.e. between<br />
gridlines 01 to 18 and A to F). As a consequence of the site being<br />
on a fairly steep slope, the underground car park comprises two<br />
independent car parks each on separate floor levels (i.e. lower and<br />
upper underground car parks).<br />
These independent underground car parks overlap in the central<br />
portion of the site hence creating a two-storey underground car<br />
park. Both lower and upper car parks have entrances at ground<br />
level. The concrete framed superstructure occupies just under a<br />
third of the site plan area (i.e. between gridlines 13 to 18). The<br />
timber framed superstructure and ground floor landscaped<br />
gardens extend over the remaining area of the site (i.e. between<br />
gridlines 01 to 13).<br />
Timber Frame Buildings Support Area<br />
The timber frame building support area comprises 1 to 2-storey<br />
underground car park supporting 4-storey timber frame buildings<br />
referred to as Blocks A to E and a 5-storey timber frame building<br />
referred to as Block Z. The remaining area of the site consists of a<br />
ground level landscaped area. The timber frame buildings will be<br />
used for residential purposes only.<br />
The timber frame buildings are supported on a 550mm thick reinforced<br />
concrete transfer slab. The one to two storey underground<br />
car park is below the transfer slab hence supporting the timber<br />
frame buildings. The single storey underground car park comprises<br />
a piled foundation raft with concrete columns supporting the<br />
transfer slab. The two storey underground car park comprises a<br />
piled foundation raft with concrete columns supporting an intermediate<br />
car park flat slab and further columns supporting the transfer<br />
slab. Thomasons undertook the detailed design of the concrete<br />
frame structure; this concrete frame structure was modelled using<br />
ESA-Prima Win finite element analysis.<br />
Concrete Framed Buildings Area<br />
The concrete frame buildings area comprises 1 to 2-storey underground<br />
car park supporting 4-storey concrete frame building and<br />
a 10-storey concrete tower block. The concrete frame buildings will<br />
be used for residential purposes only.<br />
The concrete frame building and tower block are supported on<br />
a 900mm thick reinforced concrete transfer slab. The one to two<br />
storey underground car park is below the transfer slab hence<br />
supporting the concrete frame building and tower block. The<br />
concrete framed tower block and underground car park form a<br />
single independent structure; this structure is entirely a reinforced<br />
concrete structure supported on a piled foundation.<br />
The floors for both the concrete framed buildings and tower block<br />
are of flat slab construction. The single storey underground car park<br />
comprises pile caps with concrete columns supporting the transfer<br />
slab. The two storey underground car park also comprises pile<br />
caps with concrete columns supporting an intermediate car park<br />
flat slab and further columns supporting the transfer slab. The car<br />
park basement slab was designed as a suspended slab spanning<br />
between the pile caps. Thomasons undertook the detailed design<br />
of the entire concrete frame structure; this concrete frame structure<br />
was modelled using ESA-Prima Win finite element analysis.<br />
Design Challenges<br />
1) Void formers were not adopted below the suspended foundation<br />
slabs in order to reduce the excavation depth. The reduced<br />
excavation depth was a requirement for a number of reasons<br />
which included (a) reducing excavation process, (b) reducing<br />
the spoil quantity that would need to be removed from the site<br />
and (c) reducing the height of cantilever retaining contiguous<br />
piled wall along the entire perimeter of the site in order to limit<br />
the ground deflection due to the close proximity of nearby<br />
existing buildings. As a consequence of omitting the void<br />
formers, the foundation slabs were designed for ground heave<br />
pressures. As the site is on a fairly steep slope, the ground heave<br />
pressure varies uniformly across the site. Using ESA-Prima Win,<br />
we were able to accurately simulate this varied loading directly<br />
onto the FE model foundation slab hence provide a more efficient<br />
foundation slab design and a more accurate pile design<br />
for the piles in tension. Furthermore, the reduced excavation<br />
depth enabled the adoption of a cantilever contiguous piled<br />
retaining wall along the entire perimeter of the site therefore<br />
reducing construction costs by keeping the site clear from any<br />
temporary prop obstructions.<br />
Multi-storey residential complex in Wembley UK<br />
2) The timber frame loadings were produced by the timber frame<br />
building consultant. There were many timber frame loadings<br />
on the transfer slab comprising of point loads and line loads.<br />
Nevertheless, although a time consuming and tedious process,<br />
the application of these loads using ESA-Prima Win was easy<br />
to apply. However, after completion of the detailed design of<br />
the concrete frame supporting the timber framed buildings, the<br />
timber frame loadings were changed therefore the whole exercise<br />
had to be redone. Fortunately it was easy and quick to reapply<br />
these new loads to the ESA-Prima Win FE model.<br />
3) Architectural changes included re-profiling a corner of the<br />
transfer slab within the landscaped area. The transfer slab was<br />
modelled as a single 2D element with all the timber frame loadings<br />
applied to this single 2D element. Nevertheless, using ESA-<br />
Prima Win we were able to modify the corner profile of the<br />
transfer slab without loosing any of the numerous timber frame<br />
loads.<br />
4) The introduction of large openings within the slabs during late<br />
stages of the design process required modifying the FE model.<br />
This was easily undertaken with ESA-Prima Win and the areas<br />
affected were re-assessed and re-designed accordingly.<br />
5) One of the tower cranes was founded on the piled foundation<br />
raft below the timber framed buildings in order to utilise the<br />
piled foundations. The crane base foundation was analysed<br />
using ESA-Prima Win which resulted in an economical crane<br />
base slab design and a reduction in the number of additional<br />
piles that would have otherwise been needed for an independent<br />
crane base.<br />
6) ESA Prima was also used to model the complex core pilecap<br />
below the concrete framed tower block. This resulted in an<br />
economical pilecap design and pile design.<br />
7) After reviewing the results from the ESA-Prima Win finite<br />
element model we were able to reduce the reinforced concrete<br />
transfer slab thickness hence provide considerable cost savings<br />
to the Client.<br />
8) By modelling the tower block using ESA-Prima Win finite element<br />
package we were able to accurately assess the deflections of<br />
the cantilever concrete balconies. As a result we were able to<br />
maintain the long cantilever balconies detailed by the architect<br />
whilst meeting the maximum deflection requirements. Where<br />
deflections were excessive, in particularly at the glazed corners<br />
of the tower block, structural steelwork posts were provided to<br />
limit cantilever balcony deflections to acceptable magnitudes.<br />
9) The degree of accuracy using the ESA-Prima Win finite element<br />
package enabled us to reduce the project cost by some £2<br />
million, which was instrumental in making the project viable.<br />
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