Building Tech. 3 - Altering Structural System to Achieve Similar Result, Case: Federal Reserve Bank

Outline Building Overview Design Guidelines Structural System How the System Works Structural Intervention

Federal Reserve Bank

Structural Intervention

Ideas Load Analysis & Breakdown Comparison

HG 1 - B

Conclusion &

Deandra Adellia S. -

1706973451

Gabriella S

-

1706037781

M.F. Pristantyo

-

1506671796

Evaluation

Building Overview Marquette Plaza

Federal Reserve Bank Architect:

Gunnar Birkerts Year of Projects:

1973

Designed by Gunnar Birkerts, it was home to the Federal Reserve Bank of Minneapolis from 1973 to 1997 (hence, many people refer to it as "the old Federal Reserve building"). Designed much like a suspension bridge, most of the original floors are supported by two sets of catenary cables. Underground chambers were used for vault space, and an external elevator shaft was attached on the east face of the building to connect a ground-floor lobby with the rest of the building. There was originally a gap between the lobby and the rest of the above ground structure to emphasize the construction method.

Design Guidelines The building is required to span over the public square underneath it so that it has a continuous landscape which can provide broad views and place for people to stay.

Another concept of the building is for it to receive maximum sunlight by the use of curtain wall.

Continuous Landscape

Maximum Sunlight

Structural System

Catenary suspended structure which popularized by Bridges that use two tower to support load that held by tensioned element that shape natural curvature.

Compression Truss torque

“Catenary�

Tensioned Element

torque load

Tower

compression tension

tension

load load Catenary Bridges

Federal Reserve Bank

The differences lies in the existence of compression truss in the top of the building to resist the torque of both tower.

How the

system works

Front Elevation The third tower in the middle are build to protect the building from lateral load (mainly wind load)

Top View

Structural Intervention Ideas

Parameters: The primary & overall form should be the same as the previous Federal Reserve Bank.

The gap in between lobby and the rest above the ground should be present.

Try to use a different structural ideas and mechanism

Inverted Catenary

Diagrid Belt

Exo-Suspended Cantilever

Key Ideas

Key Ideas

Key Ideas

Changing tension receiving component into compression receiving component

Dividing the load into 2 separated load. And then the load are transferring load to core uniformly by using perimeter diagrid column

Evaluation The system is too similar with previous existing structural system. So we won’t learn anything new from experimenting this idea

Evaluation The load in the center ( in between the twin towers) would be too much.

Dividing the load into 3 separated load and each carried by a tower as a cantilever. The torque is cancelled by adding cable that anchored to the ground.

Evaluation The cable system takes too much space

1

D e s i g n P r o c e s s

2

The floor are separated into three different groups to reduce the cantilever span

3

The core are extended 12m beneath the ground, and then basement as balance counter are added in the direction opposite to the cantilever floor

5

The core are added that support each of the cantilever floor

4

The Core are pre-stressed with tensioned cable to withstand the enormous torque and connected to the balance counter

The pile foundation were added that combine vertical and diagonal element to help withstand the torque

6

To stiffen the cantilever, instead of making the slab thicker, we choose to add internal column that transfer vertical load to belt trusses that connect with the core

7

8

Because of the separation gap between three cantilever, exoskeletal bracing are needed to withstand lateral load. The lateral load are mainly distributed to the middle core

Additional diagonal column are added beneath the trusses to increase the stiffness of the cantilever

Structural Elements

Top view

Left view

Front view

Rear view

axonometry

Right view

Core Cantilever slab Core Truss Exoskeleton Bracing Foundation

Load Analysis & Breakdown Load from each floor are carried vertically by column From column, the load are transferred to cantilever truss into the core The core carried the load into the ground

The foundation is expanded on the opposite side of the cantilever to help resist torque

The exoskeleton bracing transfers the lateral load from the floor slabs and truss to the core

Load Analysis & Breakdown

Cantilever slab

Cantilever slab Truss

Column Truss

Core

Core

Vertical Load

Foundation

Lateral Load

Foundation

Comparison Precedent

The precedent uses suspended catenary structure. ● ● ●

● ●

continuous floor slab from one end to another suspended catenary element to transfer load upwards truss on top of the building to transfer the suspension load and as the compression element 2 core located on each sides and 1 core in the middle foundation below each core

Reconstructed

The experiment uses cantilever structure. ● ● ● ● ●

3 separated floor slabs columns on each floor to transfer vertical loads truss on each 5 floors as the cantilever element 2 core located on each sides and 1 core in the middle foundation below each core expanded to withstand the torque

Conclusion & Evaluation The reconstruction experiment shows that we can construct a building with specific form and concept with various types of structure.

Both of the suspended and the cantilever structure can efficiently receive the lateral and vertical load with its structural elements.

Based on the experiment and the comparison between the two structures, we can say that the existing structure that is implemented on the precedent (suspended catenary) is more efficient on transferring the loads with less structural elements, also providing more space to occupy?

Maquette Documentation