Investor Presentaiton
4
Mega-
Column
Embedded Core
Perimeter Truss
Belt-Truss
444
Mega-
Diagonal
Outrigger
Truss
OUTRIGGER TRUSSES
Figure 5
Figure 5. Outrigger trusses tie columns, diagonals and belt trusses to
the concrete shear walls of the service core.
Driven by the beauty of the architecture and by the
limitations of the existing foundation piling, the new
structural system reduced the cost of the structure and
provided for speedier construction.
KPF was able to capitalize on the presence of the
outrigger trusses by incorporating them into the
architectural design of the skylobby floors.
Seeking to improve the quality of the office spaces,
on each of the four orthogonal faces, the new structural
system decreased the perimeter framing from the
seventeen wide columns of the moment-resisting frame to
a maximum of just three narrow columns.
Depending on the breadth, for the two sloping faces,
there are either none or one narrow column along its
width. Hence, building occupants will be provided an
extraordinary sense of openness and unparalleled views
of the surrounding city of Shanghai.
The mega-structure is displayed subtly behind the
facade of the building. Architecturally founded on a
heavy stone base, the mega-structure gives the impression
of both strength and of permanence. Indeed, it is one of
the goals of both KPF and Mori Building Company to
communicate these two attributes while retaining the
wonderful elegance of the architectural form.
The Diagonals of the Mega-Structure
Turning more to the engineering detail, as shown in
Figure 6 the diagonals of the mega-structure are formed
of welded boxes of structural steel. These steel boxes are
in-filled with concrete, thus providing increased stiffness,
non-linear structural behavior, and structural damping. As
well, in the upper reaches of the building, enhanced with
stud shear connectors, the concrete is used to stabilize
against buckling the thin steel plates of the diagonals.
Figure 6. The diagonals of the mega-structure, formed from welded
boxes of structural steel.
The Columns of the Mega-Structure
The columns of the mega-structure are of mixed
structural steel and reinforced concrete. At the connection
of the mega-diagonals to the columns (see Figure 7.), the
steel columns must be of a size capable of fully
transferring the vertical component of the load in the
diagonals to the composite columns. Above and below
this connection, the size of the steel column is reduced.
Away from the area where the steel columns transfer
loads to the surrounding concrete, the steel columns need
only be strong enough to carry the construction load of
the steelwork above and to meet specific requirements of
the Building Codes.
As shown in Figure 8, in the lower reaches of the
building the composite columns are of impressive size.
Reinforcing steel must necessarily be 50mm (2inches) in
diameter, the largest size available, and bundled into sets
of four bars to a bundle.
Robustness and Redundancy
FINITE ELEMENT ANALYSES
MEGA-COLUMN TO MEGA-DIAGONAL CONNECTION
CJP
W.P
REF EL
>
GJP
EARTHQUAKE LOAD COMBINATION
Figure 7. Finite element analysis of a mega-column to mega-diagonal
connection.
CTBUH 8th World Congress 2008View entire presentation