Commercial Architecture February 2018 - 35

PROJECT
structural-steel tubes cantilevered from the steel framework

the building envelope to support the

within the heated building envelope, requiring an inventive

load of the board, which is bolstered

engineering solution on the part of HKS Inc., Dallas

by horizontal and vertical girts to

(hksinc.com), the project's architectural firm, and engineer-

provide additional support. The in-

ing firm Thornton Tomasetti, New York (thorntontomaset-

stallation entailed 34 building-enve-

ti.com). They needed to prevent the structure from forming

lope penetrations, each by a 6 x 4-in.

condensation and rust on the warm interior side of the insu-

steel tube. The tubes serve as outrig-

lated building envelope. Structural thermal breaks provided

gers that cantilever from the build-

the answer.

ing structure in a grid pattern spaced

The video board sits 150 ft. above grade on the exterior

approximately 9-ft. vertically and 8-

of the western prow and displays game schedules, ads, up-

to 17-ft. horizontally. Each tube is

coming concerts, and other events in extremely high resolu-

divided into two opposing flanged

tion. The behemoth board weighs 45,000 lb. and measures

sections fastened on opposite sides

80 ft. across its top but only 48 ft. across the bottom, with

of the STBs.

the left side at 53 ft. high and the right at 45 1/2 ft., fitting
neatly within the stadium's extremities.

lighting & electrical

The resulting assembly reduces
heat loss through the penetration by

Thornton Tomasetti engineers were charged with devis-

as much as 50%, reducing heat ener-

ing a plan for the board's installation and overseeing the

gy costs, carbon emissions, and

process. "The geometry was extremely complex," said Greg

heating-system

Litterick, senior associate at the firm. "We had to determine

ments accordingly. Most important-

how to precisely adjust the structural supports and attach

ly for the video-board application,

the video board so that it would integrate seamlessly with

the STBs prevent the interior side of

the wall."

the supports from becoming cold,

capacity

require-

Adding to the challenge was the thermal conductivity of

reaching dew point, and forming

the structural steel that supports the board. The board con-

condensation that would rust, com-

nects to an exterior metal panel, behind which sits an array

promising the structure and incur-

of metal studs with an insulated waterproofing barrier-all

ring ongoing maintenance costs.

surrounded by a steel superstructure. The high thermal con-

According to Lance Evans, prin-

ductivity of steel increases thermal bridging between the

cipal and senior vice president for

sub-zero temperatures of Minnesota winters and the heated

HKS, "Our design had to address

interior of the supporting steelwork. "It was imperative to

severe Minnesota weather condi-

prevent cold exterior steel from touching warm interior steel

tions. Outside temperatures can dip

and causing a thermal bridge," said Eric Grusenmeyer, proj-

to 20 degrees or more below zero,

ect engineer.

while the stadium has to maintain a

Creating a thermal break between the exterior and interi-

comfortable temperature for the

or sides of each steel cantilever is an Isokorb structural ther-

people inside. Preventing thermal

mal break (STB) installed precisely where each support pen-

bridging was essential to ensuring

etrates the insulated building envelope. Schöck North

the integrity and performance of the

America, Princeton, NJ (schock-na.com), supplied the Type

stadium structure. STBs provided an

S22 STBs. Each module is constructed with stainless-steel

effective barrier to accomplish that."

bolts and a rectangular HSS within a 3 1/8-in.-thick block of

"The bolted steel plates can han-

Thermal bridging was mitigated by supporting the 3,000-sq.-ft. steel video signboard using
cantilevered steel tubes, insulated from the building's interior steel support structure using
structural thermal breaks.

HCFC-free polystyrene foam insulation. The insulation re-

dle the significant structural stresses involved in securing

duces the transmission of heat and cold, thus minimizing

the video board to the building," engineer Eric Grusenmey-

thermal bridging between the cold exterior and warm interi-

er explained. "They are specifically designed for this kind of

or sides of the bolted assembly.

application." CA

The same approximate width as the insulated building
wall, an STB is a fabricated assembly that creates a structural
insulated break between the exterior portion of a structural
penetration and the interior structure that supports it to
minimize thermal conductivity between the two masses

Want more information? To download the information listed below,
visit commercialarchitecturemagazine.com/1802schock.

while optimizing load-bearing capacity. The STBs are
equipped with flanges and bolts for fastening to flanged rect-

Circle 4 on the Reader Service Card.

Download a brochure on Isokorb.

angular steel tubes on the interior side and on the exterior

Access information on steel structural thermal breaks.

Learn more about thermal bridging.

side to opposing flanged steel tubes supporting the massive
video board.

Learn of the benefits of structural thermal breaks.

The video board's rectangular support tubes cantilever at
commercialarchitecturemagazine.com

FEBRUARY 2018

COMMERCI A L A RCHI T EC T URE

http://www.hksinc.com http://www.thorntontomasetti.com http://www.schock-na.com http://www.commercialarchitecturemagazine.com/1802schock http://www.commercialarchitecturemagazine.com

Table of Contents for the Digital Edition of Commercial Architecture February 2018