Precast Concrete 101...tension and bending capacity. Precast Concrete 101 Precast vs. Prestressed Concrete •National Precast Concrete Association (NPCA) is the ... •Box Culvert

Precast Concrete 101Precast Concrete 101

Precast Concrete 101

Prepared By:Ralph Verrastro, PE, Principal Engineer, Bridging Solutions, LLC

E-mail: [email protected]: 239-216-1370

mailto:[email protected]


Agenda• History

• Advantages of Precast Concrete

• Precast vs. Cast-in-Place Concrete

• Precast vs. Prestressed Concrete

• Wet Cast vs. Dry Cast Concrete

• Utility/Drainage Products

• Transportation Products

• Structural Design Process

• Shop Drawings

• Manufacturing

• Handling, Storage, Shipping & Installation

• Case Study


History

• Ancient Romans

– Aqueducts

– Culverts

– Tunnels

• Liverpool England in 1905

– Precast panels for buildings

• United States in 1950s

– Many small companies

– Many started with burial vaults (Wilbert)

– Mergers and acquisitions prevalent today

• Oldcastle (CRH in Ireland)

• Hanson Pipe and Precast


Advantages of Precast Concrete

• Manufactured in a controlled environment

• Quality is controlled and monitored

• Weather is not a factor

• Products may be cast and installed 24/7/365

• Less labor required compared to cast in place concrete

• Structures are installed quickly on site



• Concrete is formed, poured and cured out of the critical path

• Repeatability—easy to make many of the same products

• Precaster can buy materials for multiple projects, quantity discounts can lower costs

• Concrete is more durable due to controlled environment

• Concrete strengths are higher than design requirements



Precast vs. Cast-in-Place Concrete

• Which approach is most cost effective? Answer: It depends!

• Here is an approach to consider if you are not sure:

– Design and detail a CIP structure in contract plans

– Provide design criteria for a precast option

– Precaster’s specialty engineer designs precast elements

– Precaster provides bidders cost for precast elements

– Contractor determines which is more cost effective


Precast vs. Cast-in-Place ConcreteConsiderations

• Crane size requirements

• Site access requirements

• Schedule – critical path

• Dewatering requirements

• Overhead wires/trees



• Contractor availability/preferences

• Precaster availability/proximity

• Owner preferences

• Engineer preferences

• Cold weather (not in Florida!)



Precast vs. Prestressed Concrete

• Concrete is strong in compression-weak in tension

• Steel bars added to precast

• Steel cables added to prestressed

• Cables tensioned using jacks

• Concrete is poured

• Jacks released after concrete hardens

• Bonded cables transfers forces to concrete

• Compression force/stress adds tension and bending capacity


Precast vs. Prestressed Concrete

• National Precast Concrete Association (NPCA) is the industry association for these markets:

– Utility

– Underground

– Drainage

– Box culverts

– Retaining walls

• Precast/Prestressed Concrete Institute (PCI) is the industry association for these markets:

– Buildings

– Parking structures

– Bridges


Wet Cast vs. Dry Cast Concrete

• Wet cast has a W/C ratio of 0.4 or greater

• Dry cast has a W/C ratio of 0.3 to 0.36 or what is referred to zero slump concrete

• Wet cast is cast and cured in forms for at least 24 hours

• Dry cast may have the forms stripped very quickly


Wet Cast vs. Dry Cast Concrete

• Another term for dry casting is slip forming

• Expensive machines are required for dry casting

• Typical dry cast products are pipe, round manholes, block and hollow core slabs for buildings

• The remainder of this presentation will focus on wet cast


Utility/Drainage Products

• Manholes

• Catch Basins

• Drop Inlets

• Pump Stations

• Grease Traps

• Septic Tanks


Utility/Drainage Products

• Electrical Manholes

• Pull Boxes

• Light/Sign Pole Bases

• Utility/Storage Sheds

• Latrines


• Box Culverts– Wingwalls

– Toe Walls

– Head Walls

Transportation Products


• Bridge Elements– 3 Sided Frames

Transportation ProductsTransportation Products


• Bridge Elements– Arches



• Bridge Elements– Prestressed Beams

– Prestressed Slabs

– Prestressed Piles



• Retaining Walls



• Sound/Privacy Walls



• Light/Sign Pole Bases

• Traffic Barriers



Structural Design Process

• Per Industry Standards

– ASTM

– FDOT Standard Indexes

• Structural Design is Provided



• ASTM C27

– Underground precast utility structures

– Underground precast water and wastewater containers

– Architectural and structural products

– Glass fiber reinforced concrete

– Precast autoclaved aerated concrete

– Precast for stormwater management

• Box Culvert -

– ASTM C1433 – monolithic - per LFD

– ASTM C1577 – monolithic – per LRFD

– ASTM 1786 – 2 pieces - LRFD




• Job Specific Designs

– Design Criteria

– Soil Conditions

– Water Table Depth

– Structural Design is Required




• Civil Engineer-of-Record (EOR)

– Develops Geometry

– Establishes Performance Criteria

– Coordinates with Owner

– Determines if ASTM or Index Structures Applicable

– Consults with Structural Engineer if Required

– Develops Civil Plans & Specifications



• If Structure per ASTM or Standard Index

– ASTM or Index Referenced in Civil Plans

– Civil EOR Reviews and Approves Submittals




• If Bridge Structure or if NO ASTM/Index for Structure

– Structural EOR Coordinates with Civil EOR

– Structural EOR Defines Design Criteria

– Structural EOR Defines Permissible Alternatives

– Structural EOR Reviews and Approves

• Specialty Structural Engineer Calculations

• Structural Shop Drawings




• Specialty Structural Engineer

– Works for Precast Supplier - In-house or Consultant

– Design Criteria Provided by SER

– Designs Prefabricated Components

– Prepares Erection Drawings

– Prepares Shop Drawings

– If no SER on team – Civil EOR is responsible as SER



Shop Drawings

• Erection Plans

– Mark Numbers for Each Element

– Connection Details

– Typical Reinforcing


• Shop Tickets or Production Details

– Detailed Bar Lists

– Lifting Devices

– Joints/Inserts/Embeds

– Pipe Openings

– Work Sheets

Shop Drawings


Manufacturing

• Plant Quality Control

– DOT Certification

– Industry Certification

• PCI for Bridges

• NPCA for

Utility/Drainage

Structures

• Manufacturing Specs

– DOT Specs

– ASTM


Manufacturing

• Molds or Forms

– Steel Molds

• Collapsible or Tapered Core

• Adjustable

– Tilt Tables

Catch Basin Form Tilt Table

Manufacturing


Manufacturing

– Hand Set Forms (e.g. Symons Panels)

– Custom Built Forms

The more specialized

the product, the more

it will cost to produce.

3 Sided Bridge Form

Manufacturing


Automated Manufacturing

• In the USA, the materials are delivered to the mold which is at a fixed work station.

• In Europe and most other countries, the mold moves along an assembly line to various work stations and robots do most of the work.



Product Handling


Product HandlingProduct Handling


Product StorageProduct Storage


Product Shipping


Product ShippingProduct Shipping


Product Installation


Product InstallationProduct Installation


Case Study

Kingswood Mobile Home

Community Bridge Replacement

Riverview, Florida

Project Team

Bridge EOR: Bridging Solutions

Civil EOR: Aurora Civil Engineering

Geotech EOR: Pinnacle Engineering

Contractor: Thomas Marine Construction

Precast Supplier: CONTECH

Specialty Engineer: CONTECH


Case StudyCase Study




















Case Study


















QUESTIONS???Case Study

Documents

Precast Concrete 101...tension and bending capacity. Precast Concrete 101 Precast vs. Prestressed Concrete •National Precast Concrete Association (NPCA) is the ... •Box Culvert