CONCRETE FORMWORKPresented by David H. Glabe, P.E.

© 2012, DH Glabe & Associates, Westminster, CO 80031 All Rights Reserved

CONCRETE FORMWORK

Guide to Formwork for Concrete

• Chapter 1 – Introduction

• Chapter 2 – Design

• Chapter 3 – Construction

• Chapter 4 – Materials

ACI 347R-03

FORMWORK

• ACI 347, Chapter 1, Section 1.2Formwork – total system of support for freshly placed concrete, including the

mold or sheathing that contacts the concrete and all supporting members, hardware, and necessary bracing.

• CDOT, Section 601.11Falsework is defined as any temporary construction used to support vertical

loads for a structure until it becomes self-supporting. Formwork is the temporary structure or mold used to retain plastic or fluid concrete in its designated shape until it hardens.

Formwork or Falsework??

Formwork v. Falsework

• ACI - Formwork includes Falsework

• CDOT – Formwork and Falsework are separate

• Formwork is the “Jello” Mold that holds fresh concrete

• Falsework supports formwork and other structures (such as precast girders)

Formwork – the “Jello Mold”

There are two types of Formwork:

1. Vertical Forms

2. Horizontal Forms

Vertical Forms are used to hold pressure

Horizontal Forms are used to hold weight

Vertical Forms

Vertical Forms are used to form:

Walls Columns Piers Abutments Beamsides Other Vertical Concrete Surfaces

Vertical Form: Wall Form

Vertical Form: Shear Wall

Vertical Form: Retaining Wall

Vertical Form: Sidewall/Abutment

Horizontal Forms

• Horizontal Forms are used to form:

Bridge DecksFloorsOverhangsOther Horizontal Concrete Elements

Horizontal Form: Metal Bridge Deck

Horizontal Form: Bridge Overhang

Horizontal Form: Bridge Overhang(Cantilevered Beams)

Formwork or Falsework?

Pressure or Weight?

Pressure

• Vertical Forms are designed to resist pressure. Form Pressure is affected by:

The Concrete MixThe Rate of PlacementThe Temperature of the ConcreteThe Weight of the Concrete

Weight

• Horizontal Forms are designed to hold the weight of the concrete. The design weight is determined by:

The Depth of the ConcreteThe Unit Weight of ConcreteThe Amount of Reinforcing

Concrete Structures

The Quality of the finished product is determined by:

MaterialsDesignConstructionPlacement of the Concrete

Manufactured Forms

What is the Pressure Capacity?

Is it designed according to specification?Is it constructed according to the design?

Job-Built Forms

Does it meet Project Specifications?

Success?

Success is measured by how well the Jello

Mold conforms to the owner’s expectations.

Is it the right shape?Are the length, height and width correct?Is it within tolerance?Is it in the right location?

The Perfect Wall??

Blemish

Bad Joint

What do you think?

Is the concrete being placed properly?

Falsework

Falsework is used to support fresh concrete and the Jello Mold it is in. Falsework is also used to support other structures such as precast girders, steel girders, and existing bridges.

Falsework Supporting Pier Cap Formwork

Falsework Supporting Precast Concrete Girders

Formwork-the “jello” mold

Wall forms hold pressure. Deck Forms hold weight. Falsework holds formwork. Watch your tolerances. What are their qualifications? What are your qualifications?