November 2005 Civil Engineering

15

CI V I L ENGI N E E R I NG N EWS

STRUCTURAL ENGINEERING

Nashville Concert Hall Features Unique Acoustic Elements

M

odeled on some of the world’s
greatest concert halls, the

Schermerhorn Symphony Center—the
future home of the Nashville Sym-
phony—will be neoclassical in appear-
ance but will incorporate distinctly
modern approaches to controlling
sound and vibration within the perfor-
mance area.

Designed by David M. Schwartz/

Architectural Services, Inc., of Wash-
ington, D.C., the center is “respectful
of Nashville’s tradition of neoclassical
architecture and grand civic buildings,
while simultaneously reinterpreting it
for contemporary times,” according to
a statement from the Nashville Sym-
phony. Named in honor of Kenneth
Schermerhorn, the symphony’s late
director, the $120-million center fea-
tures a limestone exterior and columns,
stylized detailing, and streamlined
proportions.

Occupying a full city block in

downtown Nashville, the 197,000 sq
ft (18,300 m²) center consists of a main
building measuring 298 by 204 ft (91
by 62 m) and 98 ft (30 m) tall—includ-
ing the basement—and two wings mea-
suring 24 by 68 ft (7.3 by 21 m). Besides
the 30,000 sq ft (2,800 m²) concert hall,
which will accommodate 1,872 seats
on three levels, the center will include
a backstage area, office space, a class-
room, a ticket office, a banquet room,
and public gardens.

The Nashville Symphony currently

performs at the Tennessee Performing
Arts Center’s Andrew Jackson Hall, a
facility better suited to theatrical per-
formances than to orchestral music, says
Christy Crytzer, the orchestra’s direc-
tor of media relations. In constructing
the new center, the symphony is striv-
ing to create an acoustically superior
performance hall that “we can call our
own space,” Crytzer says.

The design of the concert hall

includes “two key elements” to isolate

stray sounds and vibrations and pre-
vent them from being heard during
performances, says Paul Scarbrough,
a principal of Akustiks llc, an acous-
tics consulting firm based in Norwalk,
Connecticut. The first element is an
acoustic isolation joint that takes the
form of a 2 in. (50 mm) space between
the concert hall and the remainder of
the center. The approach can be lik-
ened to constructing “two buildings
right next to each other with a two-
inch gap” between them, Scarbrough
says. The gap extends from the founda-
tion to the roof, where a neoprene pad
in the roof joint provides the only con-
tact between the two structures. “You
could run an object from the bottom of
the foundation up through the building
to the roof within the joint,” says Kurt
Swensson, P.E., m.asce, a principal of
ksi/Structural Engineers, an Atlanta-
based firm hired to perform the struc-
tural engineering for the project.

Because of the acoustic isolation

joint, the concert hall essentially

reposes within a U-shaped struc-
ture that houses the elevators, major
mechanical equipment, an electri-
cal substation, and other equipment
expected to generate noise or vibra-
tions. This approach led to some
unusual structural accommodations,
Scarbrough says. For example, in some
places “two thick concrete columns”
stand a mere 2 in. (50 mm) apart, he
says, each supporting the structure on
one side of the acoustic isolation joint.
This approach also “created major
framing issues and resulted in compli-
cated cantilever positions,” Swensson
says.

The second main element of the

strategy to isolate sound and vibrations
involves the use of what Scarbrough
calls a double concrete envelope. To
minimize sound, two layers of concrete
blocks are placed between the walls
of the concert hall and the building’s
exterior. Along the roof, two layers of
precast-concrete panels are used for the
same purpose.

Despite its neoclassical appearance, the Schermerhorn Symphony Center, in Nashville, Tennessee,
will shield patrons from the sounds and vibrations of the surrounding city using distinctly modern
methods.

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16

Civil Engineering November 2005

Inspired by some of the great con-

cert halls of Europe, the Nashville
Symphony chose to include windows in
the concert hall to admit natural light.
The 30 soundproof windows to be
installed at the top of the concert hall
were designed with thunderstorms in
mind, Scarbrough says. “We designed
it so that the windows would keep out
the loudest potential storm that passed
within a quarter of a mile of the con-
cert hall,” he notes. Should a thunder-
storm pass directly over the concert
hall, Scarbrough says, patrons probably
would hear no more than a “dull thud”
or a “very low level thump.”

To achieve this level of soundproof-

ing, the windows will be supported by
two concrete walls separated by a 24 in.
(610 mm) gap. A 12 in. (305 mm) thick
interior wall made of concrete blocks
filled with grout will hold windows of
solid glass 2 in. (50 mm) thick. A simi-
larly constructed 8 in. (203 mm) thick
wall will support windows of solid glass
3 in. (76 mm) thick .

The concert hall will also feature

a unique system of “movable” seats
designed so that the hall can be rapidly
reconfigured. It will have the ability to
become a 5,400 sq ft (500 m²) ballroom
with hardwood floors devoid of seats.
In this way, the hall can meet a vari-
ety of needs, and the changes require
no more than a couple of hours. To
facilitate the transformation, the mov-
able chairs will be supported on self-
propelled “chair wagons” that move
vertically by mechanical lift, Swensson
says. When not in use, the chairs will
be stored beneath the concert hall.

Because the site of the building was

underlain by fill and other relatively
weak material, the decision was made
to excavate the material and create a
basement for the mechanical equip-
ment, Swensson says. The foundation
employs drilled piers and shallow spread
footings bearing on rock. The design of
the basement also helps to address seis-
mic concerns, Swensson says.

Excavation began at the site in

December 2003. Substantial construc-
tion is on track to be completed next
June, and the Schermerhorn Symphony
Center is to open in September.

—Jay Landers

B U S I N E S S B R I E F

Parsons Corporation, an engineering and construction firm based in Pasadena,
California, with 9,000 employees, has acquired the Alaris Group,

LLC,

a construc-

tion management and environmental consulting firm with 100 employees headquar-
tered in San Francisco.