FORM NOMENCLATURE AND SAFETY

What have we accomplished?STRENGTH OF MATERIALS

TIMBER DESIGN

SOIL MECHANICS

STEEL DESIGN

Where do we go from here?

Chapter One- Introduction to FormingChapter Two- General Objectives in Formwork BuildingChapter Three-Overall Planning for FormworkChapter Four-Materials, Accessories, Proprietary ProductsChapter Five -Load and PressuresChapter Six- Form Design

Book Overview

What is forming and formwork?•Formwork is the total system of support for placed concrete.•It is a major cost of a concrete structure(it accounts for as much as 60% of the cost)

What is its purpose?

•to safely support the reinforced concrete in its plastic state until it has reached adequate strength

What are the objectives of any form design?

•the form design must provide the best quality, safety and at also be economical

Introduction to Forming

• the best quality entails: 1. alignment to adjacent surfaces 2. resistance to excessive deflections 3. a good surface finish 4. structural integrity to withstand service loads 5. its ability to use standard materials 6. dimensional consistency or its repetitive members

Note: Safety and Economics will be covered in more detail later on

Introduction to Forming

What kind of nomenclature or terminology is associated with forming?

Form ties- installed through the forms to resist the bursting pressure exerted by the concrete. ( has a clamping device at each end for attachment to and support of the wales

Introduction to Forming

Beam- horizontal structural load bearing memberBraces- fastened to one side of the forms to prevent shifting when concrete is placedFormwork- the total system of support for freshly placed or partially cured concrete. This includes the mold or sheathing that contacts the concrete as well as supporting members

Introduction to Forming

What kind of nomenclature or terminology is associated with forming?

joists- horizontal members which directly support sheathing

reshoring- the construction operation in which the original shoring is adjusted or replaced to support partially cured concrete and other imposed loads

Sheathing - the material forming the contactface of forms and providing the resistance tothe pressure of the freshly placed concrete

Shoring(falsework)-the elements used ,excluding the formwork, to support fresh concrete and/or structural members during construction(i.e. vertical posts, lateral bracing,etc.)

Introduction to Forming

What kind of nomenclature or terminology is associated with forming? Sill(Mud Sill)-a member, usually wood, designed to distribute the vertical shoring loadsto the ground or the slab below.Stringer(Ledgers)- horizontal structural members which directly support joists

Introduction to Forming

Studs- members to which the vertical sheathingis attached and provide support for it, it is installed verticallyWales(Walers)-installed perpendicular to thestuds in order to support the studs, to hold the studs in position, to ensure good alignmentfor the forms and to recieve the form ties

Introduction to Forming

What kind of nomenclature or terminology is associated with forming?

Cleat-small board used to connect formworkmembers or used as a braceBase Plate- a device used between post, legor screw and foundation to distribute the vertical load(mudsill)

Introduction to Forming

Strongbacks- installed perpendicular to walesto provide additional strength and rigidity to high formsBatten(Batten Strip)-a narrow strip of wood placed over the vertical joint of sheathing or paneling, or used to hold several boards together

Introduction to Forming

What kind of nomenclature or terminology is associated with forming?

Sources:Glossary refer to Appendix page A-3Pictures with spec A-16 to A-20Pictures of Vertical shoring 4-51Pictures of Ties 12-19

Introduction to Forming

What are the safety issues involving form design?

Causes for Formwork Failures:1.Improper or inadequate shoring2. Inadequate bracing of members3. Lack of control of rate of conc. placement4.Improper vibration or consolidation of conc.5.Improper or inadequate connections6. Improper or inadequate bearing details7.Premature stripping of formwork8.Errors in placement of reshoring9.Improper, or lack of, design of formwork10. Inadequate strength of form material11. Failure to follow codes and standards12. Modifications of vendor-supplied equip.13. Negligence of workers or supervisors

Introduction to Forming

What are the safety issues involving form design?

Examples Formwork Failures:1.Improper or inadequate shoring i.e wrong size(too small to carry the load or too long and buckles) 2. Inadequate bracing of members•lack of cross or horizontal bracing•the cross bracing is preferred 3. Lack of control of rate of conc. placement•This causes excessive pressures•high discharge point causes impact loads•in cold conditions the setting rate is retarded 4.Improper vibration or consolidation of conc.•internal problems- impact loads on members•external problems-liquefaction occurs, and vertical sleaves vibrate out of plumb alignment

Introduction to Forming

What are the safety issues involving form design?

Examples Formwork Failures:5.Improper or inadequate connections•Fasteners suitability (threaded vs. nails)•or inadequate number of nails6. Improper or inadequate bearing details•Shores placed directly on ground w/o plate•uncompacted or suitable soil conditions•insufficient thickness to bridge gaps7.Premature stripping of formwork•inadequate time duration to set or cure8.Errors in placement of reshoring•improper locations (introduce secondarystresses)•insufficient quantity provided

Introduction to Forming

What are the safety issues involving form design?

Examples Formwork Failures:9.Improper, or lack of, design of formwork•lack of basic design principles•use of too high allow stress values•insufficient loading consideration(i.e impact)•improper loading value(i.e. conc thickness)10. Inadequate strength of form material•i.e Construction grade vs. structural grade•damage due to use•insufficient & improper ties to multiple members 11. Failure to follow codes and standardsFailure to follow the ACI-concrete NDS-wood AISC-steel

Introduction to Forming

What are the safety issues involving form design?

Examples Formwork Failures:

12. Modifications of vendor-supplied equip.proprietary equipment- misuse

13. Negligence of workers or supervisors•untrained workers•poor supervision

Introduction to Forming

Inspection Stages recommended by ACI:1. Preliminary Inspection is after the formsare built and prior to the oiling or re-bar placement2. Semi-Final Inspection is prior to final cleanup 3. Final Inspection is immediately before concreting to make sure surface is clean and oiled

Recommendation:•During the concrete pouring listen to formsfor cracking and popping noise•look at all portions and check for displacement of elements and vertical misalignment

Introduction to Forming

What are the safety issues involving form design?

See Case Studies in 2-4 to 2-8

Introduction to Forming