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TOTAL PRECAST SYSTEMSDESIGN GUIDE

2007/2008EDITION


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Glossary123

TABLE OF CONTENTS

Total Precast Systems Specification

Design Considerations

Purpose and Mission StatementThrough mutual education and understanding, we help grow one

anothers success.

As stated in our Partner of Choice Commitment, The Shockey Companies

are dedicated to serving as teachers and learners. It is in that spirit

that The Shockey Precast Group partnered with Hayes, Seay, Mattern &

Mattern, Inc. (HSMM) to create the 2007 Total Precast Systems Design

Guide. This unique reference document is structured to provide a broad

range of information about total precast systems as a viable construction

method, and to be ut ilized as a design guide by architects, owners, and

general contractors. It is provided with the understanding that this docu-

ment and the information contained herein should not be used without

first securing competent advice with respect to its suitability for any

general or specific application.

The 2007/2008 Shockey Total Precast Systems Design Guide includes

chapters on Features & Benefits, Building Envelope, Design Consider-

ations, Components & Connections, LEED, Case Studies, and Shockeys

load-bearing architectural guide specification.

We hope that this guide will give you a thorough understanding of the

capabilities and benefits of total precast systems; and that it serves as a

source of inspiration for your future designs.

Total precast systems represent the new direction of the construction

industry, especially as increased emphasis is placed on aggressive

schedules, leaner budgets, and structures that are aesthetically intrigu-

ing while being practical and functional.

The versatility, cost ef fectiveness, and flexibility of total precast make ita superior building system for a wide range of design applications. For

these reasons, The Shockey Precast Group is proud of its continued ef-

forts to advance the utilization of total precast systems.

The Shockey Companies and Hayes, Seay, Mattern & Mattern, Inc.

make no warranty, guarantee, or representation as to the accuracy or

sufficiency of the information provided herein, and neither assumes any

responsibility or liability regarding the use or misuse of such information.

TABLE OF CONTENTS

Introduction

Total Precast Systems Specification

Features and Benefits Historical Perspective

Typical TPS Applications Featured Applications Architectural Features

Design Considerations

Architectural Structural

MEP

Components & Connections

Typical Components Typical Connections Coordination with Other Trades

LEED Criteria Points Scoring Example

LEED Considerations

Recent Case Studies

Frederick County Public Safety Building Highmark Data Center Stoneleigh at Westfields Office Buildings

TPS Guide Specification

The Building Envelope

Total Precast Systems Design Gu

3

19

55

03 42 00

69

95

111

Eric Taylor Photography.

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Front cover photo:Stoneleigh at WestfieldsOffice Buildings

Left:Frederick County Public SafetyBuilding Erection, Stairs.

Below:The Frederick County Public

Safety Building showcases how the

successful marriage of structural precast

components with architectural precast

features creates the unique building

method known as total precast systems.

Contents page:Stoneleigh at

Westfields, Office Buildings I and II

Eric

TaylorPhotography.

The Shockey Precast Group

219 Stine Lane

Winchester, VA 22604

540-667-7700

www.shockeyprecast.com


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THE SHOCKEY PRECAST GROUP, WINCHESTER, VA WWW.SHOCKEYPRECAST.COM INTRODUCTION

INTRODUCTION

In this chapter, well explore the many benefits total precast systems offer to owners, ar-

chitects, and general contractors. Well also discuss the emergence of total precast from

an overall industry perspective, and its evolution as part of The Shockey Precast Groups

history.

Features and Benefits

Total precast systems seamless-

ly integrate the strength and

integrity of structural precast

with the visual style and aes-

thetics of architectural precast.

The result is a unique build-

ing method that offers both

common sense functionality

and almost unlimited designpossibilities. In both design

and construction, total precast

delivers significant benefits for

owners, architects, engineers,

and general contractors.

SPEED-TO-MARKETThe speed-to-market of

total precast means faster

delivery of the finished build-

ing, which can result in a

significant cost savings forthe owner. Speed-to-market

enables owners to begin

leasing office space sooner,

translating to a faster return

on investment for the owner.

FLEXIBILITY OF SPACE PLANNINGFrom a design perspective, the greatest advan-

tage of a total precast system is the versatility

and flexibility of space planning options. Total

precast delivers interior space unencumbered

by a multitude of columns, allowing for greater

freedom of design options. Using this system

the trend for larger open floor plates is accom-

modated quite easily. Typical total precast

column grid spacing is 50% greater or more

than other framing systems. Room layouts are

not encumbered by the structural elements. In

short, architects and designers will have greater

freedom to obtain the optimum office layout.

A crew of 11-12 workers can easily

erect 12-14 total precast

components per day per crew.

Quick erection times and smaller

crews are just two of the benefits

of total precast that contribute to

overall safer and cleaner jobsite.

Below: Typical example of how TotalPrecast System creates openness.


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THE SHOCKEY PRECAST GROUP, WINCHESTER, VA WWW.SHOCKEYPRECAST.COM4 INTRODUCTION


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Frederick County Public Safety Building - Interior Space Planning Layout


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Frederick County Public Safety Building - Interior Space Planning Layout


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Erection of Stoneleigh at Westfields office building. Eric Taylor Photography.


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CONSTRUCTION COSTSFor general contractors, total precast systems provide a safer, cleaner jobsite, faster access for

follow-on trades, and an overall shorter construction schedule. A shorter construction schedule

can greatly reduce the general contractors costs (General Conditions) of running the job, while

increasing the availability of GC crews for other projects. In this way, total precast systems actu-

ally provide economic benefit to the general contractor by freeing their resources to handle more

work.

Total precast construction allows more flexibility in the General Contractors schedule than otherconstruction methods, especially in the erection of precast. Precast can be erected at an aver-

age rate of 12 pieces per crane per day, and can be erected in weather conditions that would be

problematic for the full erection of steel components. Total precast systems also offer the benefit

of requiring less site space for erection materials. As a result, total precast systems are a more

flexible construction choice for projects with a small site footprint or limited site access.

CONSTRUCTION COSTS COMPARATIVE ANALYSIS FREDERICKCOUNTY PUBLIC SAFTEY BUILDINGThe following analysis presents the costs associated with construction of the Frederick County

Public Safety Building as a total precast structure compared with costs had the equivalent buildingbeen designed as a steel frame structure with architectural precast cladding, a cast-in-place structurewith architectural precast cladding, or a brick masonry bearing structure with architectural precastcladding. As referenced in the schedule below, the use of total precast systems effectively reducedthe overall general conditions by two (2) months.


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The following graph clearly illustrates the cost advantages and savings available to owners

through the use of total precast systems versus more traditional construction methods such as

steel framing, brick masonry, or cast-in-place frame. In the case of the Frederick County Public

Safety Building, the total precast system was $278,000 less than the nearest competing system,

and two months faster than the nearest competing system.


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Historical Perspective

TOTAL PRECAST SYSTEMSThe history of total precast systems is not so much defined by specific projects, but rather by the

evolution of markets in specific areas. Total precast systems have been around and utilized since

the beginning of the precast industry in the mid 1930s. However, precast manufacturers in specific

areas have embraced this construction concept and driven their market to relative levels of success

and application by their sheer desire to prove the value and worth of total precast systems, as well as

to satisfy their passion for constructing in this medium.

The Denver, Colorado precast community, in particular, has readily and openly embraced total

precast systems as a valuable and important construction method. Over a period of several decades,

with extensive marketing, engineering, and architectural design support, as well as mentoring and

research and development efforts, the concept of total precast systems became the construction

method of choice for many office developments in the Denver area. Two excellent examples are the

Denver Tech Center and Meridian Office Park. These projects both date back to the 1970s, and

make extensive use of total precast as an economical and aesthetic value-based system choice.

Over the next several decades, the use of total precast

systems steadily gained acceptance and popularity in

projects across the nation. While it seemingly took

years to build these markets and prove the worth of

total precast, the loss of specific people or companies

significantly curtailed the use of this construction

method in the local markets. Total precast is not

a system that can be built simply to promote the medium. Successful advancement within the

construction industry is dependent upon a passionate and dedicated presence in the local precast

community, both within precast companies as well as individuals.

Today, total precast systems have gained widespread recognition for their versatility and economy.

Total precast systems represent the future of construction as a building method that offers unpar-

alleled value, cost and schedule savings, and flexibility in aesthetic presentation.


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THE SHOCKEY STORYIn 1896, Howard Shockey

opened a wagon-repair and

general contracting business

in Winchester, Virginia. His

reputation for quality con-

struction and do-it-right-the-

first-time attitude quickly put

him in demand for custom

home building. Today, many

of the homes he built at the

turn of the century still stand;monuments to his legacy

of hard work, integrity, and

dedication. Howard passed

that legacy to his sons, and in the 1930s, Jim Shockey joined his father in the business.

He was later followed by his brother Ralph. In 1947, the company became known as

Howard Shockey and Sons.

In 1943, Jim Shockey teamed up with his friend Jim Crider to create the first rural

ready-mixed concrete business west of the Blue Ridge Mountains. Known as Crider &

Shockey, the company that started as the concrete division of Howard Shockey and Sons

grew to include ten plants; and became a leader in furnishing ready-mixed concrete to

the northern Shenandoah Valley region.

With the birth of the precast/prestressed concrete industry in North America, the

Shockey family was quick to recognize the numerous benefits of precast concrete, and

by 1955, had opened a small manufacturing facility for prestressed concrete as a division

of Crider & Shockey. One year later, Shockey Brothers, Inc. became the third Shockey

operating company. Now known as The Shockey Precast Group, the company special-

izes in structural, architectural, and total precast systems; and serves its customers in

the Mid-Atlantic region from two manufacturing facilities in Winchester and Fredericks-

burg, Virginia.

Crider & Shockey company truck.

Shockey Precast Group casting yard.


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The Winchester Medical Center Parking Structure is an excellent example of how the Shockey PrecastGroup seamlessly blends functionality with pleasing aesthetics.

Fairfax Judicial Center ParkingStructure, Fairfax, VA

STRUCTURAL PRECAST SYSTEMS

Parking StructuresParking structures have always been the cornerstone of The Shockey Precast Groups structural

business. To date, weve completed more than 300 parking structures throughout the Mid-

Atlantic region. With an endless variety of finishes and features such as architectural thin-brick,

our precast parking structures satisfy both the owners desire for functionality and the designers

aesthetic vision. Some of The Shockey Precast Groups noteworthy parking structure projects

include the Calvert St. parking structure in Annapolis, Maryland, Shady Grove Metro Station in

Rockville, Maryland, The Winchester Medical Center parking structure in Winchester, VA andFairfax Judicial Center parking structure in Fairfax, VA.

Calvert St. Parking Structure,

Annapolis, MD

Shady Grove Metro Station,Rockville, MD

Largo Metro Station,Rockville, MD


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Shady Grove Metro Station Parking Structure, Rockville, Maryland

Eric

TaylorPhotography.


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TOTAL PRECAST SYSTEMSThrough the years, the development of the precast industry evolved from purely structural applica-

tions such as bridges and parking structures to architectural features such as precast cladding appro-

priate for office buildings. As the almost-limitless design possibilities of architectural precast were

realized in the construction industry, architectural precast systems

became a means for designers to bring their architectural visions

to life. The natural marriage of structural capability with archi-

tectural features and finishes created the unique system known

as total precast. For The Shockey Precast Group, specializationin this building method flowed naturally from its expertise and

experience in structural and architectural precast systems.

SHOCKEY TPS HISTORYIn 1983, The Shockey Precast Group constructed the Tracor

office building in Northern Virginia. The project was significant

because it signaled Shockeys entrance into the total precast sys-

tems industry. With the success of Tracor, industrial warehouse

total precast projects such as Hershey Foods warehouse and Echo-

star Communications followed. For almost 25 years, the Shockey

Precast Group has been the Partner of Choice on numerous totalprecast projects, including most recently the 2006 PCI Design

Award-winning Highmark Data Center in Harrisburg, Pennsylva-

nia, Stoneleigh at Westfields Office Buildings I and II in Chan-

tilly, VA; Frederick County Public Safety Building in Winchester,

VA, and Commonwealth OCX Data Center.

The Tracor office building was SPGs first total precast project.

Tracor office building erection

Tracor office building


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Fredrick County Public Safety Building, Winchester, VA

Echostar Communications uplink facility

Highmark Data Center, Harrisburg, PA

Stoneleigh at Westfields, Chantilly, VA

Eric

TaylorPhotography.

Eric

TaylorPhotography.

Stoneleigh erection

Fredrick County Public Safety Building erection

Highmark Data Center erection

Echostar Communications


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THE BUILDING ENVELOPETHE SHOCKEY PRECAST GROUP, WINCHESTER, VA WWW.SHOCKEYPRECAST.COM

THE BUILDING ENVELOPE

This chapter will provide a glimpse of the wide array of design

possibilities offered through total precast. Featured projects

will explore a sampling of building geometries, while Archi-

tectural Features references the palette of finishes and articula-

tions that can be combined to satisfy even the most demanding

designer.

Typical Total Precast SystemsApplications:

Public Safety Building Mission Critical Data Center Class A Office Building Typical Mixed-Use Retail

Total precast systems offer a myriad of structural design pos-

sibilities. Far more than the stereotypical gray box, the

versatility of total precast lends itself well to a diverse range of

design options. Following is a sampling of the total precast

system possibilities available with Shockey. These designs do

not represent the full extent of our capabilities, but illustrate

the flexibility of total precast in building geometry.

Stoneleigh at Westfields Office Building One erection, 2006

Stoneleigh at Westfields project wall panelRooftop view of completed Stoneleigh at Westfields Office BuildingsOne and Two

Eric

TaylorPhotography,2006

Eric

TaylorPhotography,2

006

Eric

TaylorPhotog

raphy,2006


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20 THE BUILDING ENVELOPE THE SHOCKEY PRECAST GROUP, WINCHESTER, VA WWW.SHOCKEYPRECAST.COM

Featured ApplicationsPUBLIC SAFETY BUILDINGThis 61,500 SF county government building

was constructed to house the Sheriff and Fire

and Rescue Departments. It was designed to

also include space for the Emergency Commu-

nications Center and Emergency Operations

Center. A total of 287 precast components

were used in the erection of this building,

including 105 double tees, 10 columns, 6 stair

modules, 32 cornice pieces, 118 wall panels,10 beams, and 6 flat slabs. The most challeng-

ing engineering design encountered for this

project involved the analysis and design of

two (2) precast header beams for the interior

stair core. In order to accommodate bearing

for stair risers, flat slabs, and double tees, the

cross-sectional geometry of these members

changes several times along the length of the

pieces; requiring rigorous analysis and detailing

of reinforcement.Erection, phase 3.

Erection starts.

Erection complete.

Eric

TaylorPhotography.


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Government Public Safety Building - Typical Office Roof Framing Plan

Roof plan showing double tee layout framing with center line column and beam bearing.

Government Public Safety Building - 3D Building line view

Modeling perspective showing precast panelization along frontage view. Double Tee roof and

floor framing, interior supporting beam line with exterior load bearing wall panels.


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Government Public Safety Building - Elevation on Grid A, South Side


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MISSION CRITICAL DATA CENTER

This 317,000 SF industrial-use data center was constructed for a private corporate owner. Atotal of 1,366 precast components were utilized in the construction, including double tees, in-

verted T-beams, wall panels, stairs, insulated walls, and screen walls. The mission-critical nature

of this building required that it be designed Seismic performance category C basic wind

speed of 162 MPH, with a mechanical room floor live load of 150 PSF, and emergency generator

rooms live load of 225 PSF.

Mission Critical Data Center - Typical Office Floor Framing Plan

Floor plan illustrating double tee floor, beam, column and perimeter wall panel member placement.


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Mission Critical Data Center - East Elevation Along grid A

Building cross section showing double tee, beam and column framing members.

Mission Critical Data Center - West Exterior Along Grid G

Elevation of wall panel layout and placement- (match line indicates building continuation).


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HIGHMARK DATA CENTERThis 82,000 SF, two-level precast building was constructed to house the offices and computers

for Highmark Blue Shield of Camp Hill, PA. The building was designed for a 150-psf live load

plus 70 psf roof loads, and to withstand wind bursts of up to 110 MPH. The exterior of the

building is a combination of multiple-depth sand blasted R-16 insulated precast wall panels and

laid-up brick. 16 screen walls enclose an open courtyard around external mechanical equip-

ment. Precast played an important role in the Leadership in Energy & Environmental Design

(LEED) of the building. Use of slag in the precast concrete mix design provided 20% use of

Mission Critical Data Center - Building Cross Section Along Grid 2 (top) and Building

Cross Section Along Grid 4 (bottom)

Building cross section showing double tee, beam and column framing members.


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recycled materials. The structures design allows for future expansion of the facility. The

structure was erected in only 5 weeks, enabling the General Contractor to compress his overall

schedule to meet the Owners move-in requirements.

Highmark Data Center - First Floor Framing Plan

Floor framing plan illustrating double tee floor, beam, column and perimeter wall panel member

placement. Area in layout shown as highlighted in small 3D reference model at lower right.

Below left: Highmark WestElevation. Below right: Wallalong column line 1.


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Highmark Data Center - Second Floor Framing Plan




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Highmark Data Center - Roof Floor Framing Plan



Below right: Typical roof/floor framing plan. Below left:Typical inverted tee beam-to-column connection.


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Highmark Data Center- North Elevation

Building Elevation of wall panel layout and placement.

Highmark Data Center- East West Elevation. (Top)East Elevation along line F. (Bottom)West Elevation Along Line R.

Building Elevation of wall panel layout and placement.


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CLASS A OFFICE BUILDINGThis project consisted of two 221,000 SF mirror-image office buildings and a single elevated

level, 59,000 SF precast parking garage constructed for an insurance company. Approximately

464 precast components were utilized for each office building, including columns, spandrels, 12

x 26 x 2 flange double tees, stair walls, elevator walls, and stairs. Approximately 195 precast

components were utilized for the parking structure, including columns, spandrels, stair walls,

stairs, shear walls, and 12 x 30 x 4 flange double tees. This represents The Shockey Precast

Groups most recently completed total precast office building project.

Class A Office Building - Typical Office Floor Framing Plan

Floor framing layout showing placement and span integrating three stairwell-elevator areas.

Note center beam bearing line permitting long span column free areas.

Eric

TaylorPhotography.


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Class A Office Building - West Elevation on Grid C

Class A Office Building - East Elevation on Grid A

Stoneleigh at Westfields EastElevation.

Eric

T

aylorPhotography.


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Mixed Use Retail - First Floor Framing Plan

Mixed Use Retail - East Elevation On Grid F


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Mixed Use Retail - West Elevation On Grid F


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Architectural FeaturesFinal design of the faade is an iterative process that begins with the sampling process and ends

with mock-ups.

SAMPLING PROCESS12 x 12 samples are an effective means for realizing the architects concepts into a production

standard. Samples can include one or more colors, finishes, or different materials (such as brick or

stone) cast into the precast. The varieties available are almost endless. These samples establish the

basis for beginning the mock-up process and are the catalyst for other exterior selections such as

glazing, window and door framing, and other exterior design features.

Initial precast selections may be made using the Precast Concrete Institute (PCI) Architectural

Color & Texture Guide, available through your Shockey Precast Group Sales representative. This

Color & Texture Guide presents the vast array of colors, textures, and finishes available with precast

concrete, and establishes a baseline guide for actual samples. Production samples may be obtainedfrom a local PCI-certified producer. Selecting a sample from a producer close to the project site

will demonstrate to the designer the range of available materials, as well as specific production ca-

pabilities and finish qualities. Locally produced precast may be more cost effective due to reduced

material shipping costs both for the raw materials and final delivery to the site.

After the project is awarded

to the general contractor, a

submittal sample should be

obtained from the precast sub-

contractor. Like the produc-

tion sample mentioned above,

obtaining this sample from the

precaster awarded the project

is critical due to variations in individual plant preferences, differences in techniques, and sources

of materials in the various plants, even within the same region. It should be noted that it may be

difficult to obtain an exact match to the original production sample. Slight variations may exist in

color, aggregate, or texture from the original sample. If specified, the architect may request multiple

submittal samples to evaluate the final sample selection. Obtaining an approved sample here is

important as this will become the standard that the full scale panel mock-up will be judged against.

Mock-ups

Sample (4 x 4 or larger) mock-ups will be developed from the approved submittal sample toshow the potential variations that may occur in a larger field of exposure, and taking into account

actual design profiles. The mock-up process must be started early enough in the construction

of the project to allow for the procurement of long lead time items such as thin brick and form

liners, as well as time for precasting to obtain an approved mock-up.

Total precast project mock-ups should specifically be targeted to show the potential variations

that may occur in high-profile or dual-purpose panels where the consolidation methods may vary

due to panel function (cold pour vs. monolithic pour - see page 38). The type of applied finish

to these articulations should be taken into account during this process in order to establish uni-

formity. Slight variations from the submittal sample may be expected but should be evaluated at


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this phase to maintain the overall aesthetic quality. Creating mock-ups of all the precast shapes

and configurations required on a project is usually not feasible, so key or highly visible elements

should be selected by both the architect and precast manufacturer to finalize the finish selection.

Plant visits during the casting process to view first form casts should be an integral part of the

process to ensure that the established criteria is maintained, as well as to view additional shapes

not represented during the early mock-up phase.

In cases where the faade has critical performance criteria such as blast protection, resistance to

high wind-driven rain infiltration, or aesthetics, the architect may specify and owner may autho-rize an additional expenditure for full-scale mock-up of a portion of the building exterior. This

type of mock-up will usually incorporate all of the major building components such as windows,

caulking, and other enclosure elements. In other circumstances where the performance criteria is

more aesthetic, the mock up will serve to verify the overall design intent and remove any uncer-

tainties the architect or owner may have regarding the sample. This additional approval step may

then lead to design modifications which could improve both the project appearance and perfor-

mance. Sufficient time should be built into the project schedule to do the appropriate testing,

incorporate changes, and obtain final approvals before final production begins.

The mock-up is an invaluable tool for verifying overall design intent and for establishing final finishes.


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Cold Pours vs. Monolithic PoursCold pours are required when precast either abuts another piece of precast in the same plane

(parallel) or has a return exceeding approximately one foot (depending on the mix design) in

order to ensure a finish that will match the control sample (cast face down in form). When cold

pours are required it is highly recommended that a quirk be incorporated in the design to ensure

the best aesthetic corner finish.

Mono pours should only be used in situations where the adjacent precast is either perpendicular

to the return, does not abut any other precast or is required for structural reasons. Since thereturn leg is cast vertically the migration of air during vibration, distribution of aggregates due to

gravity and air voids do not allow for the same consolidation and appearance achieved when pre-

cast is cast flat. In most cases this requires a post pour treatment to the vertically cast surfaces to

bring them to an acceptable aesthetic level as long as they do not directly abut a parallel precast

panel that was cast face down.


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Cold Pour Quirk - cold pour line is not visible on any exposed finish areas.

Detailed Section Through 90 degree Corner Cold Pour

Cold PoursThe reason that quirked corners are highly recommended to that of a 90 degree corners is due

to the aesthetic end result based on the fabrication process. When cold pours are required the

break of between pours is made in the corner to hide the transition. For 90 degree corners this

creates a sharp corner during the fabrication process. The coarse aggregate (which helps provide

the required strength) cannot flow into the sharp corner during the casting process. This allows a

slurry mix of fine aggregates and cement paste to get through, creating the following two issues:

1. The extreme corner tends to have a color and appearance slightly different from the mainbody of the panel.

2. Due to the lack of coarse aggregates in the sharp edge, there is a higher probability of

chipping and spalling of the outermost surface when standing the first pour up on edge.


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Step by Step Details on the Cold Pour Process


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Thin Brick VeneerOne finish option to consider in the total precast system is thin brick veneer. This system can

eliminate many of the drawbacks to conventional brick, which is typically field labor intensive,

weather sensitive, and time consuming. Conventional brick is also subject to water infiltration.

These limitations can be overcome when the desired aesthetic application of brick is married

with precast to create a thin brick veneer. Nearly all colors, textures, and finishes available in

hand-laid brick can also befound in thin brick veneers.

When the pleasing visual

appearance of traditional

clay products is combined

with the economy, versatil-

ity, and strength of precast, it

provides numerous benefits

to construction utilizing total

precast.

Incorporation of thin brick

into precast allows for strin-gent quality control methods

to be implemented in a plant

environment. Concrete batch-

ing systems and the curing

environment are more tightly

controlled, and utilizing clay-

faced products in this method

has the advantage of reducing

efflorescence, which is generally

caused by water infiltration.Typical column cover


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In order to successfully marry these two products, the strict modular requirements of

plant-cast precast are incorporated into the dimensionally loose tolerances of traditional

hand-laid brick. Four main thin brick (TBX) suppliers support the dimensional controls

required by PCI found in thin brick Type TBX of ASTM C1088. These manufacturers

provide almost all of the styles, sizes and features available in traditional brick, including,

but not limited to brick corners, edge corners, and three-sided corners, which provide the

look and feel of hand-laid brick.

Thin brick is designed specifically to create an integral bond between the brick veneer

and precast units. This occurs during fabrication of the clay modules by scoring and/

or creating dovetail slots on the rear to increase the bond capacity in both shear and ten-

sion. The bricks are secured into the form through the use of a rubber liner, plastic liner,

or snap liner. Each type of liner has its own unique benefits, and the decision to use a

particular liner or combination of liners is based on specific applications.

Brick veneer panels typically receive an acid rinse after being removed from the form.

The acid rinse removes surface laitance from casting, and etches the precast jointsbetween the brick, exposing the sand to mimic hand-laid brick mortar. Although

thin brick is placed and cast in the concrete, it will retain some of the desirable mild

imperfections found in hand-laid brick, and should be held to the same tolerance and

standards outlined by the Brick Institute of America.


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Brick Bond Types and Joint Treatments for Thin Brick

Almost any bond type and joint treatment that is available with hand-laid brick is available in the

thin brick system including specialty and custom bond types. Clarity in designating the exact

bond type desired is needed since some of the pattern types have slight variations of interpreta-

tion from region to region. Examples of some of the typical bond types available are noted below

and are available with both a tooled joint and raked joint:

Thin Brick Application

Depending on the color or type of thin brick selected, the appropriate liner best suited for that

particular brick is utilized (i.e. elastomeric, plastic or snap grid). Once the full delivery of bricks

are at the precast plant, they then need to be mixed throughout the shipments to insure that the

desired variations in brick are evenly dispersed over the brick fields. Each brick is hand laid into

the form to ensure a snug fit to insure a good seal around its perimeter. Once this is complete

they are now ready for the back-up facing mix which will provide the simulated grout joint color.

Flemish Bond 1/3 Running Bond Running Bond

Stepped 1/3 Running Bond Herringbone Offset Weave

Soldier CourseBasket Weave


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ArticulationsArticulations express the design intent of the architect while adding life to the precast fa-

ade and establishing the unique character of the building. They provide visual interest

for both close up and distant viewing. Flexibility and design freedom are the hallmarks

of precast faade design. A key advantage for the designer is that precast can be formed

to achieve almost any imaginable design and shape. No other building component sys-

tem can rival this flexibility. Applied finishes should always be considered when design-

ing articulations in order to achieve the maximum aesthetic benefits of precast.

Applied finishes are surface treatments that are for the most part achieved after the

precast panel has been cast and stripped from the form. This is done through a variety

of techniques used to break or disrupt the outer paste layer of the precast surface and

expose at various degrees either the fine or coarse aggregates utilized within the mix.

Although specialized tools and equipment are used in this process, it still requires the

specialized skills and eye of the precast finishing artisan to maintain a consistent pleasing

final finish.

Common precast articulations

include the following shapes and

designs:

Lintels

Bull nose Cornice

Reveals

False joints

Medallions

Fins

Projections

Recesses

Quirks


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The use of precastarticulations can

greatly enhance abuildings individualstyle and character.


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Articulations are often incorporated into building designs to create a striking or dramatic faade.


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Mix DesignsMix design represents the proportions of cement, water, pigments, admixtures, fine and coarse

aggregates. These base components comprise the initial sample selection. In a total precast sys-

tem, a variety of mix designs may be utilized based on specific precast performance requirements.

The requirements will vary depending on whether the precast component is structural or purely

architectural in nature.

Depending upon project design requirements, mix design proportions can be adjusted to meet

project requirements averaging, but not limited to 5,000 -- 7,000 psi. This range far exceeds

the 3,000 psi capabilities and performance of traditional cast-in-place concrete. Breakthroughs

such as self consolidating concrete (SCC) have significantly expanded precasts ability to meet

the demands of even the most challenging designs. Advances in chemical technologies have

also made it possible to incorporate specific materials, such as corrosion inhibitors, into the mix

design when structures are placed in extremely harsh environments such as coastal areas.

All of these considerations are taken into account during the formulation of final mix designs.

For architecturally exposed precast surfaces, it is highly recommended that the final finish be

achieved by utilizing only white cement. Gray cement has a higher percentage of variation dur-

ing its manufacturing process that, even when mixed with white cement, can create objectionable

changes in color or shade throughout the fabrication process. However, the use of gray cementin non-exposed areas is a key element in making precast an economically viable solution.

The designer should note that increases in cost can result from changes to a mix design. A

number of factors may influence the cost increase. In general, local aggregates are preferable

because they are less expensive. Gray cement is also more cost effective than white cement;

however, it has more variations than white cement. This can be a critical consideration when

trying to match color. In terms of pigments, earth colors such as buff and brown are typically

less expensive than red and orange. Special colors, such as blue and green, are the most costly.

The quantity of pigments will also impact cost, as will factors such as corrosion inhibitors, and

changes to aggregate quantities to meet finish requirements. When specifying particular finishes,

it is important for the designer to consider the overall cost increases associated with changes to

established mix designs. The following pages include examples of the mix designs used on Fred-erick County Public Safety Building.


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Architectural Features

COLOR, TEXTURES AND APPLIED FINISHESThe use of color and textures in precast concrete gives the designer incomparable freedom.

Through a variety of aggregates, choice of matrix colors, varying depths of exposure, and finish-

ing techniques, precast can meet almost any color, form or texture that may be specified by the

designer. Additionally, the beauty of natural aggregates is greatly accentuated when the ag-

gregates are fused with the color and texture benefits of precast. Exposed smooth form finisheswithout any applied finishes are not recommended. The resulting variations in appearance due to

form release agents, air voids, minor irregularities between form treatments and its susceptibility

to crazing all will result in a less than favorable final aesthetic appearance.

ColorIt is recommended that color selections be done in the same or similar lighting conditions as the

in-place conditions. Interior-use precast should be viewed under incandescent or fluorescent

lighting. In order to maintain matrix color uniformity, white cement should always be used (as

noted in the mix design process) along with color pigments conforming to ASTM C979. Even

when the desired matrix color is gray, the use of white cement and gray pigment is still highly

recommended.

Reliance of color based solely on natural aggregates will carry with it the same variations inherent

in nature. When reviewing cost in selections, it is important to consider the source of aggregate

if deep exposure is required (local sources are almost always more cost-effective); and to realize

that matrix colors such as blue and green are higher cost selections.

Capitol Finance Building, Richmond, Virginia

Frederick County PublicSafety Building


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articulation and configuration of the units. Final selection of the finish gradation should be made

during the mock-up phase and should include recommendations from the manufacturer. Variation

of applied finishes within the individual units can be used to enhance the overall appearance of the

building. This can be a more cost-effective means of emphasizing and accentuating key compo-

nents or areas of the facade than the use of multiple mixes. When multiple applied finishes are part

of the design, the same logic regarding profile changes and/or reveal work should be applied similar

to that of multiple mixes to ensure clean breaks.

Acid Etch FinishAcid etching is a process that dissolves the surface ce-

ment matrix to expose the sand and, to a lesser percent,

the course aggregate. Acid etching is typically used to

achieve a light- to- medium-light exposure. The end

result is similar to that of natural products such as sand-

stone or limestone. The etching process leaves a sugar-

cube appearance which is enhanced by direct sunlight.

The decision to incorporate an acid etch finish must be

made prior to or during the mix design process since

only acid-resistant siliceous aggregates (granite, quartz,

etc.) should be used. Carbonate aggregate such asdolomite and limestone, suitable for sandblasting mixes,

will dissolve or discolor through the acid-etching process

due to their calcium content. Complementary aggregate

(fine and coarse) and cement pigments should always

be chosen when an acid etch finish is selected. Design-

ers should avoid large expanses of precast without reveal work or profile changes to mask any of

the slight variations that may occur through the veining exposure of the natural sand. It is recom-

mended that expanses of unbroken precast be no larger than 4 ft x 6 ft. If an acid etch wash is to be

used on deep profile panels, these should be fabricated during the mock-up phase.

Acid etching is the crucial second step process when the building faade will include clay products

such as thin brick veneers. This process not only helps remove some of the surface latent on the

brick during the manufacturing process, but also exposes the sand between the thin brick joints to

mimic that of hand-laid brick mortar. It is also used as a safe finish around the brick veneer for in-

corporated precast features such as lintels, sills, bands, and projections that have all been integrated

within the same precast unit.

Sand Blasted Finish

Sand blast is the generic term used for the abrasive blast-

ing process. Varying gradations of blast material are used

to chip away the precast surface. Selection of a particular

gradation is dependent upon the desired depth of finish.

Sand blasting allows the designer the full range of depthsobtainable in precast (light to heavy). On final exposed

surfaces, brush blasting should be avoided because of

its inability to uniformly remove all the surface laitance,

and because it will leave the same negative effects noted

above for smooth form finishes. Light blasting provides

a similar appearance to that found in natural limestone

without the sugar cube appearance created by acid

etching. In contrast to acid etching, blasting tends to be

better suited to muting or camouflaging minor varia-

tions that occur in the manufacturing process.

Example of an acid etch finish

Example of a sand blasted finish


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This is especially true when addressing deep profile articulations. Deeper blasts have an increased

ability to ensure uniformity. However, once blasting exceeds the light level of finish and texture,

the end result is more dependent on the natural elements of the mix (aggregates). Complementary

aggregates and matrix should always be considered when specifying deeper levels of exposure. A

deeper blast can mimic other natural materials such as flamed granite, and create interesting plays

of light through its texture.

Blasting can also be a more economical means of achieving multiple variations within the same unit

rather than incorporating multiple mix designs. Blasting creates multiple variations by exposingdiffering levels of the coarse aggregate in pre-defined areas on each panel. The overall desired effect

of texture is also influenced by the type and selection of coarse aggregate in relation to the psi of the

matrix. Softer aggregates will become concave during the blasting process, while harder aggregates

will become convex, depending upon the depth of exposure.

Since the final aesthetic of sandblasting is determined mainly through the exposure of aggregates,

final depth decisions should not be made until a minimum of a 4 x 4 mock-up has been reviewed.

It is highly recommended that final depth decisions be made at the precast facility so that depth

and gradation changes can be made at the facility to allow the owner or designer to be an active

controlling participant in the process.

Exposed AggregateThis process is achieved by chemically retarding the

matrix, which provides a non-abrasive method of expos-

ing the natural beauty of the coarse aggregates. Unlike

the sand blasting process, the chemical retarder does

not mute or damage the coarse aggregates. The chemi-

cal retarder is applied to the mold surface, which delays

the cement paste from setting up. After stripping the

panel, the retarded outer surface layer of cement paste

is removed with a high-pressure washer. A variety of

depths, from shallow to deep, can be achieved depend-

ing on the type of retarder used. As with other finishes,

variations of exposure within the same unit can be

achieved with chemical retarders; however, a clear reveal

or profile change is a must for the transition points to

prevent bleeding of exposure. The choice of aggregate

size is essential when choosing depth to ensure excessive

aggregate loss bald spots do not occur. If the owner or

designers vision is to enhance the bright, natural colors of the aggregates, then chemical retarders

should be used. It is recommended that contrasting matrix and aggregate be avoided to prevent a

patchy appearance.

Form Liners

Form liners offer the designer a wide array of possibilities in terms of shapes, patterns, textures,and designs. The liner material used is dependent upon the desired effect and the number as cast

required (from metal, plastic, foam, plaster, wood or elastomeric). Any combination of applied

finishes can be utilized in conjunction with form liners. They can be implemented either as the

main aesthetic feature or as a highlight, medallion, or logo. Advances in form liner technologies

have created a design palette limited only by the imagination. When vast areas of precast will

utilize form liners, limitations of liner sizes should be incorporated with reveal work to prevent

liner butt joints. Form liners provide the highest degree of texture and will enhance the play of

light and shadows, creating a changing appearance of the faade throughout the day. Key place-

ment of night illumination can also complement the effects of the liner.

Example of exposed aggregate finish


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Form liners are a key component when implementing a thin brick veneer. The three main types

of brick liners (elastomeric, plastic grids, and snaps) each have their own positive attributes, de-

pending on project design and panel configuration. The selection of a liner should be made with

the guidance of the precast manufacturer. When a designer chooses to utilize a form liner, it is

important that the designer recognize the lead time required with form liners. Lead time will

vary by type of liner or pattern selected. Liners requiring unique artwork will require additional

time for the artisan to create the master mold.

Form liner lead times can range from between 4 to 8 weeks. When elastomeric liners are used

in conjunction with thin brick, a sample run of the actual brick being used is required in order

obtain the correct fit. The first 100 bricks from a run are measured and the form liner is based

on the average brick size. Not only does the form liner lead time need to be taken into account,

the lead time required on the brick must be considered as well. Brick manufacturing will usually

fabricate the lighter shades in the beginning of the month and the darker shades at the end (or

vice versa). Depending on the time of the month and the type and color of the brick selected, it

will normally run approximately four weeks minimum (depending on the backlog of the particu-

lar color selected) until the first run of bricks are delivered.

A custom form liner was usedby The Shockey Precast Groupto fabricate these precastmedallions for the PhiladelphiaCriminal Justice Center.


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DESIGN CONSIDERATIONSTHE SHOCKEY PRECAST GROUP, WINCHESTER, VA WWW.SHOCKEYPRECAST.COM

DESIGN CONSIDERATIONS

Through this chapter, youll gain a better understanding of the architectural, structural, and

MEP design considerations that must be taken into account when specifying total precast sys-

tems. Chapter 3 will address topics such as thermal performance, fire ratings, floor vibrations,

penetration coordination, and load criteria.

Architectural

BUILDING THERMAL PERFOMANCE

How is insulation applied?There are several ways to insulate a precast concrete building. As with other types of construc-

tion, methods vary in type and complexity. When a finished wall is required, metal studs can be

installed independent of precast panels, allowing for flexibility of installation of other features

within the walls. Typically, a one-inch air gap is provided between the concrete panel and the

metal stud to form a thermal break from the exterior concrete panel. Batt insulation is then

installed within the studs to the appropriate thickness required to achieve the desired R-Value orthermal resistance. Gypsum wallboard (GWB) can then be applied to the interior surface of the

wall to produce the finished side of the wall.

In unfinished areas, such as mechanical spaces, stick pins can be applied to the concrete panels

with the batt insulation attached directly on the interior of the precast. Although this approach

does not provide for the air gap as achieved with the metal studs, it also eliminates the cost of the

metal studs, which produce a thermal break at each stud.

Insulated sandwich precast panels offer quick installation, since the insulation is installed in the

panels during the manufacturing process; however, thermal breaks occur at the edges of the pan-

Eric

TaylorPhotography.


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56 DESIGN CONSIDERATIONS THE SHOCKEY PRECAST GROUP, WINCHESTER, VA WWW.SHOCKEYPRECAST.COM

els where the solid concrete forms a

bridge to the interior of the build-

ing. Typically, furring and GWB is

still required on the interior of the

panel to achieve a finished appear-

ance. The furring also accommo-

dates electrical and telecommunica-

tion devices that would otherwise

have to be cast into the panels.

How is thermal integritymaintained?One of the key benefits of a concrete

structure is its thermal mass. Ther-

mal mass is the ability of a material

to absorb heat. When used as an exterior skin, a high-density material like concrete requires a

large amount of heat energy to change its temperature. High thermal mass materials act as thermal

sponges, absorbing heat during the day in summer and cooling the building by storing heat from

the sun over the surface of the building, rather than allowing it to flow into the building. This

cycle reverses at night when heat is released back out into the atmosphere. Thermal mass isnot a substitute for insulation, since the heat it stores is generally re-radiated to the exterior

of the building, but also may be radiated to the interior. The function of the insulation is

to form a barrier that stops heat flowing into or out of the building. When used in the right

combination, these two elements, along with a building design that captures solar light and

heat energy, can improve the thermal performance of the buildings and lower the overall

energy requirements.

A concrete masonry unit (CMU) has less mass than a solid concrete panel. Air bubbles

within the units provide insulation value; however, they are less dense and allow moisture

into the building. CMU blocks are produced with cores and webs within the blocks, which

allow thermal breaks at each web connection. Typically, rigid insulation is applied to the

exterior of the CMU to provide the thermal integrity of the wall, eliminating the advan-tages of the thermal mass principal.

How is the integrity of moisture barrier maintained?Since concrete is inherently dense, it helps prevent water infiltration into a facility, and

eliminates the need for additional moisture proofing materials required with other veneer

systems. CMU is porous, and requires the installation of damp proofing or waterproofing

when it is used. Flashings must also be installed at openings such as windows and doors

to compensate for the possibility of water infiltration into the facility.

Controlling relative humidity can reduce vapor migration. It is typically caused from the

affinity for water molecules to be present on the surface of most common concrete build-

ing materials. This molecular film is proportionate to the relative humidity of the spacewhere the panel is located. A major contributor of relative humidity within the space is

the HVAC system and its proper operation. If the relative humidity is controlled, the

sweating problem is alleviated.

Acoustic DampeningSound transmission loss (STC) defines the ability of a barrier to reduce the intensity of

airborne sound. Precast concrete walls, floors, and roofs do not usually require additional

treatments in order to provide adequate sound insulation. Greater sound insulation can

be attained by attaching additional layers of building materials such as gypsum board.

Impact insulation class (IIC) is measured in terms of Hertz, and examples of impact


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a. Department of the Army. Structures to Resist the Effects of Accidental Explosions, Army TM

5-1300, Navy NAVFAC P-397, AFR 88-2. Washington, D.C., Departments of the Army, Navy

and Air Force. (1990)

b. Department of Energy. A Manual for the Prediction of Blast and Fragment Loading on Struc-

tures, DOE/TIC 11268. Washington, D.C., Headquarters, U.S. Department of Energy. (1992)

c. Department of the Army. Security Engineering, TM 5-853 and Air Force AFMAN 32-1071,

Volumes 1, 2, 3 and 4. Washington, D.C. Departments of the Army and Air Force. (1994)

d. Department of the Army. Fundamentals of Protective Design for Conventional Weapons, TM

5-855-1. Washington, D.C. Department of the Army. (1986)e. Naval Facilities Engineering Service Center, Guidebook on Protection Against Terrorist Vehicle

Bombs. (May 1998)

Certain structures have blast requirements to reduce the impact on the structure as a result of deto-

nated explosives typically car bombs and other terrorist attacks. These types of explosions result

in dynamic pressures applied to the structure. These explosions typically have much higher pres-

sures and shorter durations than wind or seismic loading. Minimizing impact on the structure due

to such attacks can help minimize the impact on the structures ability to be operational, maintain

immediate occupancy, ensure life safety and and mitigate the potential for progressive collapse.

The two main components of calculating blast pressure are the charge weight (pounds of TNT or

alternative explosive) and the standoff distance (distance between structure and detonated explo-sive). Minimizing dynamic pressures on structure due to blast can be achieved by increasing the

standoff distance through the use of perimeter security -- bollards, fencing, landscaped berms, or

anti-ram walls and/or decreasing charge weight.

The exterior skin (precast & glazing) should be designed to prevent the blast wave from entering

the building. Ideally, the exterior skin will behave elastically and absorb energy transferring loading

into the structural diaphragm. Cladding a total precast structure with architectural precast concrete

or building redundancies within the structural members can assist in blast resistance design. Ad-

ditionally, spanning exterior skin floor-to-floor will allow loading to transfer through the structural

diaphragm. Exposed structural columns or transferring dynamic loading using connections from

the exterior skin directly into the columns should be avoided wherever possible.

The structural diaphragm to resist blast loading can be comprised of interior shear walls, moment

frame spliced columns, or a hybridization of the two. The glazing manufacturer will also have to

consider blast resistance for such projects.

Whenever possible, the building should be oriented to minimize faade exposure to blast. Exam-

ple: Here is the same C-shaped structure oriented in two separate fashions. Option (2)

provides less faade exposure.

It is critical that the precaster, window manufacturer, and blast engineer be involved in early design

and development activities since determining the materials utilized for faade plays a large role in

the performance of the structure.

Identifying relative capacities of faade elements in conjunction with building performance level /

blast criteria helps to determine structural support elements.

Progressive Collapse

Designing for progressive collapse can be defined as the evaluation of a local failure from an

element distributed into other elements resulting in the collapse of a structure or a significant

part of the structure. The United Facilities Criteria (UFC) has published Design of Buildings

to Resist Progressive Collapse, which can be found at: http://www.wbdg.org/ccb/DOD/UFC/

ufc_4_023_03.pdf.Blast resistance diagrams -Option 1 and Option 2


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EMBED

CONSIDERATIONS

The coordination of embed locations between the

Precast Manufacturer and the Engineer of Record

is very important to ensure a smooth and uninter-

rupted project completion. The Engineer of Record

typically provides the design reactions and embed

plate footprint for the Precast Manufacturer. Items

requiring embeds include canopy structures, eleva-

tor rail mounts, stairwell railing mounts, piping and

equipment mounts, as well as any other items tied

into the precast structure. Aesthetics must also be

considered so that embeds can be hidden or made

inconspicuous.

Richmond Convention Center

Connection embed, Frederick County Public

Safety Building

UnistrutHandrail embed in stairs.

Handrail embed in stairs.


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SPECIAL CONDITIONS

Raised Floors:Access raised floors are used frequently to facilitate HVAC servicing and communications,

and electrical runs below office areas and computer rooms. Precast floor systems can easily be

adapted to raised floor systems and can be designed for this additional floor load. Variances

between floor levels can be accomplished with additional floor topping or other special detailing.

Following is an example of a typical raised floor.

Microwave towers/antennae:Concentrated loads from this type of equipment can vary substantially. Input from the manufac-

turer early in a project can be valuable information to incorporate into the precast design. Tower

frames and antenna racks should more effectively be placed over column or tee stem locations toavoid issues with slab punching shear.

Vibrations:Floor vibrations can cause perceptibility problems with building occupants and should be consid-

ered on all projects, particularly those with longer spans. Vibrations are particularly prevalent in

parking garages. Precast floor construction is inherently stiffer than some other types of construc-

tion and can be designed to mitigate vibration characteristics. A building can be perfectly sound

structurally, but if the floors vibrate excessively when groups of people walk by, those sitting still

could notice the vibration and become uncomfortable. In order to make the occupants feel at ease

in the building, the floor must be designed to be stiff enough to not flex objectionably when a mov-

ing load passes.

How stiff is stiff enough?The Precast Concrete Institute (PCI) has established guidelines regarding

the amount of stiffness necessary to negate the possibility of objectionable vibrations. Calculations

are performed based upon the size and length of the floor member, along with its loading. Based

on this calculation, a minimum natural frequency required for vibration prevention is calculated. A

floor member is then designed that has a natural frequency higher than the calculated minimum.

In addition to selecting a double tee with a natural frequency greater than the calculated minimum,

it is also recommended that the vibration frequency be kept above 3 Hz if possible. Since humans

have difficulty detecting vibrations higher than 3 Hz, any vibrations above that frequency become

essentially imperceptible.


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The ideal strategy is to avoid objectionable vibrations. If vibrations are unavoidable, then the goal

is to make all vibrations imperceptible. The Shockey Precast Group routinely spans 50 feet with

our double tees in office buildings and stores. We not only exceed the minimum values required,

but also exceed the 3 Hz recommendation as well.

Operable Partitions:Operable or hanging partitions present unique

structural challenges, but with early coordina-

tion, these challenges can be easily consideredduring the design process. It is important to

receive input from the partition manufacturer

as early as possible to obtain partition loads and

preferred structural support systems. Specific

deflection criteria should also be obtained early,

to facilitate the design of precast in the areas

where operable partitions will be used.

MEP equipment/piping:Large hanging or equipment loads should be provided to the precast manufacturer as early as

possible for incorporation into the design. When carefully coordinated, embeds may be pro-

vided to support special framing for this equipment

Heavy Office Equipment:High density filing or storage systems, computer server rooms containing multiple fully loaded

equipment rack and other areas containing special equipment can place tremendous loads on the

structural system. Typically, structural load requirements for these types of office equipment may

range between 100 to 300 psf (pounds per square foot). Equipment locations and areas of poten-

tial heavy load concentration, such as the carriage wheel rails beneath high density filing systems,

must be identified as early as possible in the design phase. Coordination with the structural precast

fabricator is imperative in order to accommodate these loads in the precast member design.

Large Openings:The flexibility of precast allows for the ac-

commodation of large openings. Embedded

concrete connections can be used to facilitate

attachment of windows and curtain walls.

Unlike steel construction, large window wall

openings typically do not require supplemental

steel framing above and below the window to

provide support. Substantial savings can be

gained by the elimination of miscellaneous steel

framing; however, careful detailing with the inte-

rior finishes is recommended to assure a proper

appearance within the space.

Expansion Joints/Building Movement:Concrete does not expand and contract thermally as much as steel, but jointing between concrete

materials and other building materials must be carefully detailed during design. Particular care

should be considered at junctions between structural and non-structural elements and also between

dissimilar materials such as concrete and masonry or steel. Thermal, structural, and moisture re-

lated movements can all cause cracking and should be addressed early by the manufacturer and de-

signer. Typically, metal studs and gypsum wall board are used to frame the interior spaces so these

can be separated from the precast panels to keep each system independent. This allows the window

system to be detailed with a flexible joint material to allow the material to move independently.

Interior partition details.

Punched windows detail.


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Access to Connections:Sequencing of erection of precast members

should carefully consider access to connec-

tions. When concrete panels are tied-back to

steel construction, field issues can arise if the

General Contractor cannot perform the con-

nection work.

Stairs:Modular precast stairs serve to simplify the

stair erection process on building projects.

The overall project schedule can be expedited

through the inclusion of modular precast stairs

because there is then no need for a separate stair

framing subcontractor or concrete filled pans.

Stair attachments can easily be made in the field

and hidden from view from the public. Special

care should be considered when stairs are on the

exterior walls to account for the thickness of any

interior wall insulation. Connection details should be concealed or filled to allow the precast panels

to serve as the finish wall inside these spaces.

Roof Drains:One thing to consider when design-

ing any structure is how the roof will

drain. This can be accomplished in a

number of ways. The use of internal

roof drains is a common practice;

however, this can lead to roof leaks or

pipe leaks within the space. A better

solution is to slope the structure to

the rear of the building and allowsheet flow to scuppers that can direct

the rain water to downspouts strate-

gically placed on the exterior face of

the building. However, when using

this technique, one must always be

aware of clear height requirements

within the building, since the entire

slope of the roof is towards one

direction, making a deeper cut in

the rear of the building. Careful

coordination is required with the

exterior panels to assure that thescuppers line up with the top of the

roof and overflow scuppers are placed

correctly. Another consideration is

the clearance requirements for the

downspouts below grade and above

the footings.

Post-Completion ModificationsThere is flexibility in the removal of portions of the double-tee flanges to facilitate MEP pen-

etrations to enable intercommunicating stairs or other changing building uses.

Top to bottom: HVAC, con-duits, window coordination,and stairs.

Rooftop screenwall

Access to connections detail.


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MEP

COORDINATION OF PENETRATIONS

During design of the mechanical system, careful consideration must be given to the placement

of mechanical equipment and the location of ductwork and piping penetrations. Placement of

large equipment on the roof should also be given special consideration during the design process.

Placement of packaged rooftop air handling units is

probably the most critical item to consider during the

design of the facility. Centrally locating the air handling

units in the middle of the area to be served allows for

the shortest and most economical HVAC ductwork

runs. Placement of the packaged air handling units

should be closely coordinated with the precast system

utilized for the roof construction. The location and size

of supply and return air openings vary between manu-

facturers. Some are in close proximity to one another,

while others have a greater distance between them.

Some are parallel, while others are at right angles toeach other. The size of the required supply or return

duct opening may limit the capacity of the rooftop

unit, if the duct size can not be accommodated in the

roof slab.

Physical sizes and

weights of units vary

with the conditioning

tonnage of the unit.

Unit weights vary

from around 1,000lbsto over 17,000lbs for

the largest air han-

dling units. A prop-

erly designed precast

roofing system can

easily carry this load

while also allowing for

the proper sized holes

to allow the ductwork

to pass through.

ASHRAE 90.1 andInternational Energy

Code. The Shockey

Precast Group meets

the requirements in

90 % of the United

States with precast

wall panels with 2

insulation having a

minimum R-value of

9.5 hft2F/Btu.

Example of penetration in double tee.


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Design for Economy

There are several areas that have the potential to significantly increase precast production and

erection costs. By being aware of these areas, and by considering the guidelines outlined below,

the architect and owner can design a building that is both striking and economical.

COMPONENT SIZE AND GEOMETRY

When designing for economy, the designer should be aware of component size and geometry.

It is generally more economical to use a lesser number of large pieces than a greater number of

smaller pieces. A lesser number of large pieces equals less total set-up time to produce the mate-

rial, fewer trips required to ship the material to the job site, and fewer operations to erect the

material. All of these save time, labor, and money.

In addition to size, the geometry of the pieces can play a large role in cost savings. Pieces that are

shaped to serve multiple functions can reduce the overall piece count, which saves money. An

example would be a shear wall that has a corbel built into the wall to carry a beam (as opposed to

a column standing beside the wall and the column supports the beam). By using the wall with a

corbel, the column can be eliminated, which then eliminates the work of designing, producing,

shipping, and erecting the column. The result is a substantial savings.

DUAL-USE COMPONENTS AND ARCHITECTURAL FEATURES

Dual-use components as they relate to total precast structures can be defined as structural com-

ponents that have architectural features.

Architectural features are created using a variety of shapes, colors, textures, and applied finishes.

When selecting accent reveals or rustication lines, it is important to tie them in to the chosen

joint size. Triangular reveals are to be avoided where possible because they are difficult to affix to

the forms. Instead, a trapezoidal reveal will provide a flat nailing surface to the form builders and

help minimize possible nail-hole irregularities. Be sure to include reveals between any and all col-

or breaks - when two separate architectural mixes are utilized within the same panel, it is strongly

recommended that designers include a reveal between the two mixes to provide the casting crew

a distinct stopping point and to help reduce color bleed. This will help ensure an unwavering

and smooth break line as illustrated in the figure below. When choosing reveal sizes also consider

limiting depth to 3/4. Deep reveals decrease the effective section of the panel, thereby reducing

panel strength and increasing the chance for panel cracking. Additionally, in dual-use compo-

nents, deep reveals may hinder the optimal reinforcing and or strand configuration.

Color #1

Color #2

Trapezoidal

Reveal

Caulk with

backer rod

Panel Joint Reveal


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Facial projections can add a unique accent to your building project. Because these features are

cast with panels bottom-in-form (exposed architectural finished face towards the ground), a

minimum draft dimension is necessary in order to strip panels out of the form. Without proper

draft, suction forces generated between the concrete and the form may cause the pieces to bind

up during stripping and possibly damage the piece and or the forms. To ensure this does not

occur, Shockey recommends a minimum draft of 1:6 on facial projections as noted on the sketch

below. It should also be kept in mind that facial projections tend to increase production costs,

since forms need to be built-up to accommodate the features.

Loops for stripping

MODULARITY

When designing for economy, it is important for the designer to understand that significant

changes to profiles and other architectural features such as reveals will adversely affect the project

schedule in terms of design, drawing, and forming changes. In addition to minimizing variations

in profile changes or architectural features, the designer should also consider minimizing changes

in panel heights and widths as too much variation in panel sizes will increase total piece-count

and add substantially to production and shipping costs, as well as add time to the overall pro-

duction schedule. Finally, the designer should attempt to match interior component sizes with

exterior component sizes. For example, if using 12 double tees, dont design for 30 exterior

bays. Maintaining consistency and a relative degree of simplicity will result in a structure that is

truly designed for economy.

Forms built up to create

facial projections

Facial projection

Panel in final

erected positionPanel as cast

Minimum draft


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COMPONENTS & CONNECTIONSTHE SHOCKEY PRECAST GROUP, WINCHESTER, VA WWW.SHOCKEYPRECAST.COM

COMPONENTS AND CONNECTIONS

In this chapter we will examine typical precast components utilized in total precast systems, and

gain a better understanding of the unique connection considerations that must be taken into

account when building with precast. This section will highlight the various components and

connections used in construction of the Frederick County Public Safety Building, as well as their

interaction with other building materials. Ideally, this chapter will give you a clearer picture of

the relationship between precast components and the surrounding construction elements.

Insulated Wall Panel to Double TeeConnection of a double tee with cast in place topping to an insulated wall panel. Connection

types, and styles of embeds vary as conditions require. This is detail is usually at the roof

condition.


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70 COMPONENTS & CONNECTIONS THE SHOCKEY PRECAST GROUP, WINCHESTER, VA WWW.SHOCKEYPRECAST.COM

Insulated Wall Panel to L-Beam

Connection of a double tee to an inverted tee-beam to an insulated wall panel. Connection types,

and styles of embeds vary as conditions require. This detail illustrates conditions at the roof condi-

tion. Similar condition can occur at the floor. This condition could allow for building addition-

expansion by removing and or possibly relocating the wall panel at a future date.


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Roll Restraint Corbel

Variation of a roll restraint corbel these types of connections are hidden from view because they

normally occur above the finished ceiling line where AC/MECH/PLUMB occur.


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Rectangular Beam to Column

Dap of rectangular beam permits reduced floor to floor height requirements.


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Double Tee Flange to Flat Slab w/2 Offset

This detail illustrates the flexibility needed when the floor system must depress in portions of a

double tee floor area in order to accommodate depress systems.


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Wall to Column

This plan view at the corner of a structure shows how a column accommodates the assembly of

load bearing beam, doubl

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