Commercial Architecture June 2019 - 18

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FEATURE

| building technology

many sequences of the restoration over-

FOUNDATION

lapped. Existing conditions could have

IMPROVEMENTS

been installed three years ago or three

Geotechnical conditions were a chal-

days ago. Laser scanning ensured a com-

lenge because the project involved so

plete understanding of where progress

much underground construction. There

happened. Essentially, the team used

are a number of areas where earth reten-

laser scanning as a different way to man-

tion and/or shoring systems were used to

age a punch list. Each new scan updated

keep the existing foundations in place or

the 3D model so that opportunities

to allow basement construction to take

could be immediately recognized and

place within the project boundaries. The

acted upon, allowing the team to be

various parts of the project involved a

nimble and responsive.

wide range of foundation construction
types/techniques, and combined deep

Laser scanning also helped the structural engineer inspect all trusses, eliminating the need to field measure each of
the thousands of riveted connections, as

3d laser scanning in the left- and right-field expansion areas detailed existing conditions, enabling the team to
plan for steel and prefabricate a new concrete stadium floor.

foundations and spread footings. Some
of the techniques used were soldier beam
and lagging, steel-sheet piling, secant
piles, caissons, micropiles, jet grouting,

well as the exact size and angles of plat-

and top-down construction.

ing. This saved an immense amount of
time, put information in the team's hands

Like most of Chicago, Wrigley Field is

sooner, and allowed more people to weigh

built on a sandy lake bed that had to be

in on the best strategies. Because the truss

raised with repeated infilling. Bedrock

work happened over multiple years, it also

begins almost 75 ft. below the surface, mak-

provided a consistent flow of progress

ing soil stabilization of utmost importance.

documentation.

Based on new loading requirements and

By implementing BIM, the project

building codes, many of the foundations

achieved higher levels of certainty through-

supporting the ballpark needed augmenta-

out the design and construction phases.

tion or replacement.
Geotechnical experts Hayward Baker,

This led to better coordination, prefabrication, and more-efficient layouts. Whether
integrating new design elements, analyzing

3D laser scanning produces a point cloud, which is a large set of data points in space that translate real
world conditions into 3D. Solid red areas show new construction.

Hanover, MD, and engineering firms
Thornton Tomasetti, New York City, and

shoring strategies, maximizing seating, or

GEI Consultants, Chicago, augmented the

planning the project's future construction

foundations, which increased the ballpark's

phases, the visual nature of the model

foundational load capacity. The team

enabled the team to see opportunities dif-

installed four 500-kip-capacity micropiles

ferently. The earlier this happened in the

100 ft. under each major column before

process, the greater the value.

welding on a new zero-tolerance column

The main concourse that now circles

base. In all, 24 major columns were lifted,

the entire ballpark is a key part of the reno-

structurally reinforced, and underlying

vation, supporting the expanded seating in

foundations replaced. A total of 213 micro

the bleachers, providing more accessibility,

piles have been installed throughout the

and improving access to increased conces-

ballpark.

sion locations and restrooms. Laser scan-

As a unit of force, a kip equals 1,000 lb.

ning also helped modernize communica-

Each micropile installed at Wrigley Field

tions and technology within the ballpark.

can withstand 500,000 lb. of force or 500

The ceiling and below-grade areas house
the mechanical, piping, and steel structural supports

ing the most efficient way to phase the work and
remain flexible.

kips. In context, that's enough to support
the weight of the Statue of Liberty.

of the bleachers and main grandstands. Hundreds of

Not surprisingly, this much laser scanning pro-

Like the ballpark, soil stabilization also played a

miles of cable now circle the park within these small

duced an enormous amount of data. The laser scan-

key role in the clubhouse and plaza building. Steel-

areas, ensuring broadcast communication and techni-

ning alone exceeded 2 TB. Because it would take days

sheet piles and concrete secant piles were driven into

cal capabilities. The completed conduit and piping

to download that much data, the team housed it on

the silty clay layer where it meets the hardpan to sepa-

runs look like artwork while functioning as the back-

site, enabling instant access for the teams. In addition

rate the excavated area from the ballpark. The team

bone of the updated infrastructure. By creating a mod-

to storage, access to information was further en-

then used a process called top-down construction to

el of this area, engineering and construction teams

hanced with wi-fi-boosting access points to eliminate

stabilize the sandy soil and expedite the schedule.

could make well-informed decisions, and the 3D coor-

any need to travel back to an office. Across the job-

Top-down construction is typically used in an urban

dination enabled the newest technology to be accom-

site, team members could instantly find and compare

setting with limited space and unique structural

modated in these constrained spaces, while illuminat-

information.

requirements, which is exactly the condition around

JUNE 2019

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Commercial Architecture June 2019

Table of Contents for the Digital Edition of Commercial Architecture June 2019