2018 IDEAS2 Awards Brochure - 32

Apple stores are well known for bringing elegant, transparent
design to dense urban landscapes.
One of the newest locations, at the northeast corner of Union
Square in downtown San Francisco, involved major alterations
to an existing structure, with the addition of a new structure
over a functioning below-ground ballroom and loading dock of
a Hyatt hotel.
The project comprises three separate volumes totaling nearly
24,000 sq. ft: the Store, the Bar Building and the Plaza. The Store
connects Union Square on the south side to the quiet, contemplative Plaza on the north. The Bar Building flanks the Store to the
west and forms the backdrop to the Plaza with a green wall and
water features including the historic Asawa Fountain.
The store's design brings enhanced levels of transparency, openness and civic generosity. The sliding glass doors allow the Store to
connect the existing square to the Plaza, creating a sense of urban
permeability. As a foil to the lively activities of Union Square, the
new art-filled plaza serves as a tranquil garden of contemplation,
creating a serene gathering place for the community. The sliding
glass doors are also a part of a natural ventilation system that allows
the store to draw in fresh air before it is expelled through the roof.
The roof structure is designed and integrated to support 130 photovoltaic panels that supply the building with renewable energy.
The Store is a rectilinear volume measuring 105 ft by 83 ft in
plan and approximately 46 ft tall, with an occupied area of nearly
11,000 sq. ft. The unique features of the Store-including the tall
sliding doors, a bridge-scale transfer truss, a grand cantilevered
floor, a voluminous interior space and ductile seismic bracing-
were all made possible because of structural steel, with the majority of the framing system being constructed of wide-flange shapes,
hollow structural sections (HSS) and built-up sections. The sliding
steel-and-glass doors of the south façade are some of the largest
ever built, each measuring 42 ft tall by 20.5 ft wide. The north façade features similar doors, approximately 26 ft tall. The generous
interior volume is divided horizontally by a dramatic cantilevered
floor that extends 37 ft beyond the support to create a 16-ft-high
piano nobile that tapers to less than one foot at the tip.

Special concentrically braced frames (SCBFs) comprise the seismic lateral force-resisting system in both directions. The braced
spine is built on a substantial steel transfer truss that spans over a
functioning below-ground ballroom. The second-floor cantilever is
constructed of tapered built-up steel beams and incorporates tuned
mass dampers to reduce the vibration response. Lightweight tapered
steel trusses support the roof and enclose the generous interior volume. Structural steel brought strength and lightness to the superstructure, which was designed to avoid loading the existing structural elements, as well as maximum reliability and redundancy in
this high-seismic zone. Steel also allowed the structure to be tightly
integrated with the architectural finishes and services within the
constraints of the tapering floor and roof zones of the Store.
The Bar Building is a four-story rectangular structure to the
west of the Store and measures 176 ft by 21 ft. It is the remnant
structure of the 1970s Hyatt House (aka the Levi's building) a triangular building that was demolished to make way for the new
Store. The complexity of the rectangular Bar Building is masked
by its simple form. Numerous steel and concrete transfer structures
were constructed below ground while maintaining the continued
function of the basement ballroom and hotel loading dock. The
use of steel roof bracing to strengthen the existing roof diaphragm
to resist seismic loads helped preserve the existing structure, where
other structural options would have been excessively heavy and required more extensive demolition.
Apple Union Square was a major structural engineering
achievement, combining simultaneous requirements for numerous
challenging structural features, tight integration with architecture
and services, complex existing conditions and high-seismic detailing-not to mention supersized sliding glass doors. Seismic design
principles permeated every aspect of design, and the engineers
carefully located new structural elements in ways that protected
and integrated the existing structure while maintaining the architecture as the centerpiece of the project. The project provides an
extraordinary new mixture of high design, commerce and community in the center of San Francisco, revitalizing and reconnecting
visitors and residents to a previously little-used public space.

One would never guess that beneath the clean, thin lines of this project,
there is a sizeable structure that makes the building possible.
-Lynda Leigh

2018 IDEAS2 Awards Brochure

Table of Contents for the Digital Edition of 2018 IDEAS2 Awards Brochure