Formwork - Suspended Slabs

NATIONAL TRAINING MATERIALS CONSTRUCTION STUDIES

AUSTRALIAN NATIONAL TRAINING AUTHORITY

CCC348 - FORMWORK: SUSPENDED DEVELOPED IN COLLABORATION BETWEEN INDUSTRY AND TAFE QUEENSLAND WITH THE SUPPORT OF THE AUSTRALIAN NATIONAL TRAINING AUTHORITY

ACKNOWLEDGEMENTS Produced by the Construction Curriculum Consortium, TAFE Queensland. Managing Agent :

Recognition Directorate, Vocational Education, Training And Employment Commission (VETEC)

© Australian National Training Authority (ANTA) 1997 All rights rights reserved. This work has been p rodu ced ced initiall initially y w ith the assistance assistance of fund fund ing pr ovided by the Commonw ealth Government thr ough ANTA. This This work is copyright, but p ermission ermission is given to trainers and teachers teachers to make copies copies by p hotocopying hotocopying or other d up licati licating ng p rocesses rocesses for for use w ithin their own training organisation or in a wor kplace where the training is being cond cond ucted. This This permission permission d oes not extend extend to the m aking of copies copies for for u se outside the immed iate training training environm ent for wh ich ich they are mad e, nor the m aking of copies copies for for h ire or resale to third p arties. arties. For For p ermission ermission ou tside these guidelines, apply in writing to Australian Training Prod ucts Ltd.(formerly Ltd.(formerly ACTRAC ACTRAC Products Ltd). The views views expressed in th is version version of the w ork d o not n ecessari ecessarily ly represent the views of AN TA. ANTA does not give w arranty nor accept accept an y liabili liability ty in relation to the content of this work.

Published by Australian Training Products Pty (formerly ACTRAC Products Ltd), Australian National Training Authority. GPO Box 5347BB, MELBOURNE, Victoria 3001, Australia Te le le p h o n e + 6 1 0 3 9 6 3 0 9 8 3 6 o r 9 6 3 0 9 8 3 7 ; Facsimile Facsimile +61 +61 0 3 963 9 46 84 First Published October 1997 DP2120348LRG Printed by Document Printing Australia

NATIONAL CONSTRUCTION STUDIES RESOURCE PROJECT

STAGE 3

FIELD OF WORK SKILLS

LEARNING PACKAGE

CCC348 - FORMWORK: SUSPENDED SLAB AND BEAM

PUBLISHED:

1997

ACKNOWLEDGMENTS: AUTHOR: Holmesglen Institute of TAFE Batesfsford Road CHADSTONE, Victoria

INSTRUCTIONAL DESIGNER: Construction Curriculum Consortium TAFE Queensland

This learning package was developed as part of the AVTS Training Program in Construction Studies This project was managed by the Construction Curriculum Consortium, TAFE Queensland For further details contact: Noel Ryan Manager Construction Curriculum Consortium Yeronga Institute of TAFE PO Box 6045 FAIRFIELD GARDENS QLD 4103 Telephone: Facsimile:

(07) 3892 0457 (07) 3892 0457

4

TABLE OF CONTENTS Page INTRODUCTION ..................................................................................................................... 11 OVERVIEW............................................................................................................................... 14 WHAT IS PROVIDED ............................................................................................................. 15 WHAT YOU PROVIDE?......................................................................................................... 15 HOW TO USE THIS PACKAGE ........................................................................................... 16 GETTING TO “KNOW THE PACKAGE”.......................................................................... 17 KEY TO SYMBOLS .............................................................................................................. 18 MODULE INFORMATION: FROM THE TRAINING SPECIFICATION................... 19 ASSESSMENT INFORMATION............................................................................................ 21 ASSESSMENT SPECIFICATION.......................................................................................... 22 ASSESSMENT TASKS............................................................................................................. 24 ASSESSMENT TASK 1:........................................................................................................ 24 ASSESSMENT TASK 2:........................................................................................................ 26 SECTION 1 - THE PRINCIPLES OF FORMWORK DESIGN, PLANNING AND QUALITY CONTROL ............................................................................................................. 27 INTRODUCTION................................................................................................................... 27 1. FORMWORK MEMBER SIZES AND SPACINGS ........................................................ 28 2. FALSEWORK MEMBER SIZES AND SPACINGS........................................................ 28 3. LOADS ON FORMWORK.............................................................................................. 30 EXERCISE 1: FORMWORK CALCULATIONS................................................................ 32 ACTIVITY 1: BASIC INFORMATION................................................................................ 32 4. USE OF TABLES AND GRAPHS TO DESIGN FORMWORK..................................... 33 EXERCISE 2: FALSEWORK ................................................................................................ 38 5. DROP PANELS AND HOPPER HEADS AS COLUMN CAPITALS............................ 39 EXERCISE 3: CAPITALS AND COLUMNS....................................................................... 41 6. CONSTRUCTION WORKERS’ DUTIES....................................................................... 42 EXERCISE 4: CONCRETE WORKERS DUTIES............................................................... 43 7. QUALITY CONTROL PROCEDURES TO ENSURE CORRECT SHAPE, SIZE AND ALIGNMENT ...................................................................................................................... 44 EXERCISE 5: QUALITY ....................................................................................................... 45 8. WORKING DRAWINGS ................................................................................................. 46 EXERCISE 6: WORKING DRAWINGS .............................................................................. 47 ACTIVITY 2: DESIGN FORMWORK ................................................................................. 48 9. CALCULATION OF MATERIAL QUANTITIES ........................................................... 49 EXERCISE 7: CONCRETE CALCULATIONS ................................................................... 52 10. WORKING PLATFORMS FOR WALLS AND COLUMNS......................................... 53 EXERCISE 8: PLATFORMS................................................................................................. 56 SUMMARY............................................................................................................................. 57

SECTION 2 - SETTING OUT, CONSTRUCTING AND ASSEMBLING ........................59 INTRODUCTION....................................................................................................................59 1. SETTING OUT FALSEWORK AND FORMWORK.......................................................59 EXERCISE 9: SETTING OUT ...............................................................................................61 2. CONSTRUCTING FALSEWORK AND FORMWORK FOR A SUSPENDED SLAB AND BEAMS........................................................................................................................62 EXERCISE 10: SLAB AND BEAM FORMWORK .............................................................69 3 LOCATE, CONSTRUCT AND FIX LIFT AND SERVICE PENETRATIONS ................70 EXERCISE 11: SERVICE PENETRATIONS .......................................................................72 4. STAIRS AND LANDINGS ...............................................................................................73 SUMMARY ........................................................................................................................ .....74 SECTION 3 - STRIPPING, CLEANING AND STORING FORMWORK AND FALSEWORK ............................................................................................................................75 INTRODUCTION....................................................................................................................75 1. STRIPPING FORMWORK..............................................................................................75 2. STRIPPING SEQUENCE AND EQUIPMENT REMOVAL...........................................78 3. BACKING OFF OF FALSEWORK AND ADJUSTMENT HARDWARE......................80 4. REMOVAL, DENAILING, CLEANING AND STORING OF FORMWORK.................81 SUMMARY ........................................................................................................................ .....83 EXERCISE 12: STRIPPING, CLEANING AND STORING................................................84 ACTIVITY 3: ERECT AND STRIP FORMWORK.............................................................85 CONCLUSION ........................................................................................................................ 86 ANSWERS............................................................................................................................... 87 EXERCISE 1: FORMWORK CALCULATIONS .................................................................87 EXERCISE 2: FALSEWORK.................................................................................................87 EXERCISE 3: CAPITALS AND COLUMNS .......................................................................89 EXERCISE 4: CONCRETE WORKERS DUTIES ...............................................................91 EXERCISE 5: QUALITY........................................................................................................93 EXERCISE 6: WORKING DRAWINGS...............................................................................95 EXERCISE 7: CONCRETE CALCULATIONS....................................................................97 EXERCISE 8: PLATFORMS..................................................................................................97 EXERCISE 9: SETTING OUT ...............................................................................................99 EXERCISE 10: SLAB AND BEAM FORMWORK ...........................................................101 EXERCISE 11: SERVICE PENETRATIONS .....................................................................101 EXERCISE 12: STRIPPING, CLEANING AND STORING..............................................103

2

LIST OF ILLUSTRATIONS Page

Figure 1 SLABS AND BEAMS ..................................................................................... 28 Figure 2 SCHEMATIC DIAGRAM OF FORMWORK AND FALSE WORK FOR A SUSPENDED SLAB.............................................................................................. 29 Figure 3 OPEN SPANDREL ARCH 1 AND ARCH 2 ................................................. 29 Figure 4 SAFE LOADS FOR PROPS IN DIFFERENT LENGTHS............................ 33 Figure 5 PLAN FOR SUSPENDED SLAB AND BEAM STRUCTURE SHOWING THE LAYOUT OF PROPS AND FORMWORK FOR BEAM........................... 35 Figure 6 MAXIMUM SAFE AREA FOR PROPS........................................................ 36 Figure 7 LAYOUT OF JOISTS AND BEAMS............................................................. 37 Figure 8 DROP PANEL AND HOPPER HEAD........................................................... 39 Figure 9 PARTS OF A COLUMN................................................................................. 39 Figure 10 SQUARE AND RECTANGULAR PRISM.................................................. 40 Figure 11 FORM FACING LAYOUT FOR RECTANGULAR COLUMN................ 40 Figure 12 HOPPER HEAD TOGETHER WITH DROP PANEL ................................ 40 Figure 13 CORRECT DIRECTION FOR PLACING SLAB CONCRETE ................. 42 Figure 14 ALLOWABLE VARIATION IN SURFACE OF CONCRETE (EXAGGERATED)................................................................................................ 44 Figure 15 SECTION SHOWING SLAB AND BEAM CONSTRUCTION................. 46 Figure 16 RECTANGULAR PRISM............................................................................. 49 Figure 17 RECTANGULAR PRISM............................................................................. 50 Figure 18 CYLINDRICAL PRISM ................................................................................ 50 Figure 19 CIRCULAR COLUMN ................................................................................. 51 Figure 20 WORK PLATFORM AT TOP OF SCAFFOLD TOWER .......................... 53 Figure 21 TUBULAR METAL MOBILE TOWER ...................................................... 54 Figure 22 ANCHORAGE OF TALL PLATFORMS .................................................... 55 Figure 23 WORK PLATFORM CONSTRUCTED ALONGSIDE EDGE BEAM OF A SLAB....................................................................................................................... 55 Figure 24 CENTRE LINE............................................................................................... 60

Figure 25 GRID LINES USED TO SHOW LOCATIONS ...........................................60 Figure 26 SLABS AND BEAMS ...................................................................................62 Figure 27 WORK PLATFORM AT EDGE OF SLAB SUPPORTED BY PROPS .....63 Figure 28 BEAM SUPPORTS IN THIS EXAMPLE ALLOW DANGEROUS UNBALANCE TO EXIST .....................................................................................63 Figure 29 THE PROBLEM OF ECCENTRICITY IS AVOIDED IF THE LOAD IS ALWAYS INSIDE THE SUPPORTS ...................................................................64 Figure 30 STRIPPING BAND AT BEAM SIDE ALLOWS SLAB SOFFIT TO BE STRIPPED WITHOUT DISTURBING THE BEAM ...........................................64 Figure 31 TOLERANCE GAP WITH CLOSURE ANGLE AT BEAM SIDE ALLOWS EASY STRIPPING OF BEAM SIDE WITHOUT DISTURBING SOFFITS..................................................................................................................65 Figure 32 TYPICAL DEEP BEAM FORMWORK WITH TIES..................................65 Figure 33 TYPICAL DEEP EDGE BEAM FORMWORK SHOWING TIES AND THE USE OF SPREADER BAR AND STRUT TO KEEP THE BEAM PLUMB66 Figure 34 TYPICAL TIES ARE THE ‘HE BOLT’ SYSTEM ......................................66 Figure 35 THE EFFECTS OF MOUNDING .................................................................67 Figure 36 TYPICAL PENETRATIONS.........................................................................70 Figure 37 STRUCTURE OF RECTANGULAR PENETRATION ..............................71 Figure 38 DETAIL OF STAIR FORMS.........................................................................73 Figure 39 DETAIL OF WHOLE STAIRCASE .............................................................73 Figure 40 FORMWORK INCORPORATING PROPS WITH COLLARS TO STRIP WITHOUT REMOVING PROPS..........................................................................76 Figure 41 UNDESIRABLE DISTORTION OF SLAB LIKELY WHEN BEAMS ARE STRIPPED FIRST...................................................................................................77 Figure 42 THE BACKPROPPING PROCEDURE........................................................78

4

CONSTRUCTION INDUSTRY COMPETENCY FRAMEWORK ALL STREAMS STAGE 4 (& BEYOND) SPECIALISED SKILLS • • • • •

Advanced Technical Skills Supervisory Skills Management Skills Para-professional Skills Professional Skills

(Currently under development)

Õ

BASE TRADE

×

×

×

FIELD OF WORK SKILLS CIVIL OPERATIONS

STRUCTURES

FITOUT AND FINISH

SERVICES (NON-TRADE)

SERVICE TRADES

OFF-SITE

×××

Currently Under Development

× BASIC STREAM SKILLS CIVIL OPERATIONS

STRUCTURES

FITOUT & FINISH

SERVICES

× BASIC INDUSTRY SKILLS CIVIL OPERATIONS

STRUCTURES

FITOUT & FINISH

SERVICES

INCORPORATING INDUSTRY INDUCTION

Every stage produces a range of practical skills Endorsed by Standards Committee 13/12/95

CCC348 - Formwork: Suspended Slab and Beam

INTRODUCTION

INTRODUCTION

CCC348 - Formwork: Suspended Slab and Beam is a module intended for use by those completing Stage 3 of a specific FIELD OF WORK within a SKILL STREAM of the National Construction Industry Competency Framework.

The theoretical components of this package will enable you to complete the practical requirements of this module All set tasks, including the activities and demonstrations, will show how the theory or content can be applied in a practical manner in on-site or simulated on-site conditions Formwork: Suspended Slab and Beam is a module which deals with the knowledge and skills required to set out a simple building structure and so includes specific details on: • • • • • • • • • • • • • •

formwork details and drawings; formwork systems; material quantities; tools, equipment and personal protective equipment; set out points and datum lines; erection of scaffolding, falsework and handrails ; penetrations and blockouts; formwork and falsework for safety and quality; formwork: selection, cleaning and release agent; supervision during concrete pour; formwork stripping methods; falsework and formwork: cleaning, storage and removal from site; falsework alignment techniques; and back propping methods.

Two Assessment Tasks meet the requirements of the three Learning Outcomes: Assessment Task 1 Assessment of Knowledge

You will be given an assignment for assessment and asked to provide working drawings to demonstrate your knowledge related to the principles, planning and quality assurance procedures for construction of suspended slab and beam formwork.

Australian National Training Authority

11

INTRODUCTION


Task

Complete a graphics presentation, approximately 4 hours in duration, to develop working drawings that cover the formwork and falsework required for suspended slab and beam construction. Complete an assignment, approximately 4 hours in duration, that covers suspended slab and beam formwork including: < < <

plan and specification interpretation; design spacings; and working drawings.

Complete a written assignment, approximately 1 hour, that covers slab and beam formwork to cover: < < <

<

strength, safety and economy; material quantities; concrete workers’ duties before, during and after concrete placement; and erection and stripping sequences. sequences.

Assessment Task 2 Assessment of Skills

You will be required to construct a formwork for a suspended slab and beam structure. You will be working in a team with a maximum of four people, and you must demonstrate your individual skills and knowledge as part of that team. Task

Set out, fabricate and position formwork for a reinforced concrete slab with intersecting and perimeter beams, that encompasses encompasses the following specifications: <

<

< <

a slab of minimum size 6000mm long x 6000mm wide and 300mm thick; intersecting and perimeter beams, minimum end section size 300mm wide x 400mm deep or similar; Soffit height minimum two unit frames f rames from floor datum point; and perimeter working platform – minimum 450mm.

This learning package has therefore been developed with three sequential sections, each being closely aligned with one or more of the two Assessment Tasks:

12



INTRODUCTION

SECTION 1:

This contains learning resource material, self-checks and practical exercises required for the successful completion of the Assessment Criteria as shown in the Assessment Specification for Task 1.

SECTION 2:

This section contains the information and practical work that will help you successfully complete complete part of Task 2.

SECTION 3:

In a similar manner, this section will cover material, self-checks and practical work that wil willl help you successfully complete Task 2.

As well as self-check exercises and practical activities, your instructor will schedule additional oral and/or written tests which may be similar to the self-check exercises. These tests will satisfy specific Assessment Criteria in the Assessment Tasks and will apply to your work environment. environment. When you have achieved all the Assessment Criteria in all the Assessment Tasks, and your work has been checked and certified by your instructor, you will have successfully completed the Learning Outcomes which make up the total off-the-job component of the whole module CCC348 Formwork - Suspended Slab and Beam.


13

INTRODUCTION


OVERVIEW CCC348 - Formwork: Suspended Slab and Beam - A Stage 3 Module

The overall competencies for this module are summed up in the purpose statement:

PURPOSE:

To provide building and construction workers with the knowledge and skills required to construct formwork for reinforced concrete suspended slab and beam structures including column capitals.

In the next section on Module Details, you will find specific details about the Training Specification and how you will be assessed In general terms, CCC348 - Formwork: Suspended Slab and Beam covers: The Skills/Competencies required for this module •

•

•

The ability to apply the principles of formwork in the design, planning and quality control

The ability to set out, construct and assemble falsework and formwork.

The ability to strip, clean and store falsework and formwork.

The Theory/Content required to achieve these skills/competencies • Formwork Member Sizes and Spacings • Falsework Member Sizes and Spacings • Loads on Formwork • Use of Tables and Graphs to Design Formwork • Drop Panels and Hopper Heads • Construction Workers’ Duties • Quality Control Procedures • Working Drawings • Calculation of Material Quantities Working Platforms • Setting Out Falsework and Formwork • Constructing Falsework and Formwork • • Locate, Construct and Fix Penetrations Stairs and Landings • Stripping Formwork • Stripping Sequence and Equipment • Removal • Backing-Off of Falsework • Removal, Denailing, Cleaning and Storing Formwork

When you have successfully achieved all the Assessment Criteria for the Assessment Tasks, you will have completed the requirements for this module.

14



INTRODUCTION

WHAT IS PROVIDED You will be provided with the essentials to successfully complete this module, including: • • • •

plans and specifications; equipment; timber and plywood; and falsework.

WHAT YOU PROVIDE? •

appropriate personal protective clothing etc - to be advised by your instructor;


15

INTRODUCTION


HOW TO USE THIS PACKAGE This package has been designed so that you can work and learn at your own pace, incorporating into your own learning program. • • • •

demonstrations of practical skills by your instructor or experienced tradesperson; planned and supervised practical application of your knowledge and skills; instruction in, and application of, safe working practices; and personal progress indicators through self-check exercises and practical activities.

It is suggested that you work through the three sections as they are presented. By all means, fast-track any aspects/areas where you feel confident. Self-Check Exercises have been included so that you can measure your own progress. These exercises, however, are not part of the formal assessment of competency.

The module Formwork: Suspended Slab and Beam, has a nominal duration of 54 66 hours, but you may take more or less time working at your own pace.

16



INTRODUCTION

GETTING TO “KNOW THE PACKAGE” Here is a strategy which may help you become familiar with the contents of this package. •

Survey

Scan the whole package Read the contents page and the introduction, then flip through the pages glance at the headings. Notice that there are set tasks to be completed. The content relates to these tasks.

Ask

Ask about any topics, terms or details that are not clear to you at this stage.

Read

Read through the material, but do it actively. Jot down points, underline or highlight . Link the information with what you know already.

Let the headings and sub-headings help you organise information. Remember that you will need the content to complete the tasks. Review

At various stages, you will be directed to review the main points or complete a Self-Check Exercise to indicate how you are progressing. Make your own notes as well.

Instructor

Throughout this package, you will be required to attend practical demonstrations and receive instruction in the use of materials, tools and equipment. Ask your instructor if you have any problems with: < < <


interpretation of content; procedures or processes; or availability of resources

17

INTRODUCTION


KEY TO SYMBOLS Symbols are placed in the left hand margin to draw attention to the type of information commencing at that point. The symbols used in this package are:

READ

DEMONSTRATION

SELF-CHECK

PRACTICAL ACTIVITY

SITE VISIT

18

This is the essential information for the module.

Read

Instructor Demonstration At times, your instructor will give practical advice and demonstrate the use of tools/equipment.

Self-Check Exercise

These are your progress indicators. Typical answers are also included.

Practical Activity

The seven activities allow for the application of the theory components.

Site Visit

Your instructor will schedule visits to appropriate sites.


MODULE DETAILS


MODULE INFORMATION: from the Training Specification MODULE TITLE

Formwork: Suspended Slab and Beam

Nominal Duration

54 - 66 Hours

Module Number

CCC348

Purpose

To provide building and construction workers with the knowledge and skills required to construct formwork for reinforced concrete suspended slab and beam structures including column capitals.

Relationship to Competency Standards

National Building and Construction Industry Competency Standards: •

Pre-requisites

•

ST 3046

Erect and Dismantle Formwork

Basic Stream Skills

A trainee may seek recognition through the R.P.L. process for competencies already held. Summary of Content

•

The Principles of formwork design, planning and quality control.

•

Setting out, constructing and assembling falsework and formwork.

Delivery

Delivery methods must provide for the demonstration of competence in skills specified in all learning outcomes, either in on-site or simulated on-site conditions.

Suggested Learning Resources

• • • • •


AS 1657–1992 Fixed Platforms, Walkways, Stairways and Ladders – Design, Construction and Installation. AS 3610–1995 Formwork for Concrete. AS 3610 Supplement 2 (1992). The Concrete Society, London 1989 Formwork, A Guide to Good Practice. Fletcher, B. G. and Lavan S. A. Civil Engineering Construction Heinemann, London, 1987.

19


Suggested Learning Resources (conti)

• • • •

20

MODULE DETAILS

McAdam, P.S. (1993) Formwork: A Practical Approach . Stuart Publications, Brisbane. Walsh, P. Use of the Australian Standard for Concrete Structures Inkata Press, Melbourne, 1988. Wilshere, C.J. (1989) Formwork Thomas Telford Ltd, London. Wynn, A.E. & Manning, G.P. (1974) Design of Formwork for Concrete Structures Cement and Concrete Association, London.



MODULE DETAILS

ASSESSMENT INFORMATION CCC348 - Formwork: Suspended Slab and Beam is a module in the National Construction Industry Competency Framework.

The program focuses on the achievement of learning outcomes measured against assessment criteria based on National Competency Standards . All learning outcomes must be successfully achieved if you are to be awarded competence in this module. Your assessment will be recorded as: • •

Competent; or Not Yet Competent.

You will have completed the learning outcomes when you have successfully achieved all the Assessment Criteria in Assessment Tasks. One or more of the following assessment methods will be used: • • •

supervised assessment in the demonstration of techniques; a number of written and/or oral assessments; practical activities, allowing for demonstrations of your ability in the assessment tasks.

All projects are to be carried out on-site or in simulated on-site conditions.


21

MODULE DETAILS


ASSESSMENT SPECIFICATION

MODULE TITLE

FORMWORK: SUSPENDED SLAB AND BEAM

Module Number

CCC348

Purpose of the Assessment

To demonstrate underpinning knowledge related to the principles, planning and quality assurance procedures for construction of suspended slab and beam formwork.

Instructions for the Assessee

The following procedures could be carried out in one or more projects: Assessment Task 1 •

Complete a graphics presentation, approximately 4 hours in duration, to develop working drawings that cover the formwork and falsework required for suspended slab and beam construction.

•

Complete an assignment, approximately 4 hours in duration, that covers suspended slab and beam formwork including: < < <

•

plan and specification interpretation design spacings working drawings.


plan and specification interpretation; design spacings; and working drawings.

Assessment Task 2 •

Set out, fabricate and position formwork for a reinforced concrete slab with intersecting and perimeter beams, that encompasses the following specifications:

<

22

a slab of minimum size 6000mm long x 6000mm wide and 300mm thick.


MODULE DETAILS


<

<

<

Guidelines for the Assessor

intersecting and perimeter beams, minimum end section size 300mm wide x 400mm deep or similar soffit height minimum two unit frames from floor datum point perimeter working platform - minimum 450mm

This is a supervised assessment. This is an assessment of the final product. However some observation of the process will be involved, this is detailed on the checklist.

Learning Outcome

CCC348.1

Assessment Task 1

Assessment Task 2

Yes

CCC348.2

Yes

CCC348.3

Yes


23

MODULE DETAILS


ASSESSMENT TASKS ASSESSMENT TASK 1: Complete a graphics presentation, approximately 4 hours in duration, to develop working drawings that cover the formwork and falsework required for suspended slab and beam construction. Complete an assignment, approximately 4 hours in duration, that covers suspended slab and beam formwork including: < < <

plan and specification interpretation design spacings working drawings


<

strength, safety and economy material quantities concrete workers’ duties before, during and after concrete placement erection and stripping sequences .

The procedures above could be carried out in one or more projects. Assessment Task 1 incorporates Learning Outcome 1: Apply the Principles of Formwork in the Design, Planning and Quality Control.

Item

Assessment Criteria

1.

Suspended slab and beam formwork member sizes and spacings are selected to withstand dead and live loads and wind forces, from basic formwork span tables.

2.

Falsework members and their spacings are incorporated into the design of suspended slab and beam structures.

3.

Construction workers duties before and after concrete placement are stated.

4.

Drop panels and hopper heads which act as column capitals are designed as an integral part of suspended slab and beam formwork.

5.

Quality control procedures are incorporated into the construction process to ensure correct shape, size and alignment of concrete structures.

24

Achieved



MODULE DETAILS

6.

Working drawings for suspended slab, beam and capital formwork are produced from plans and specifications.

7.

Material quantities are calculated for suspended slab and beam formwork.

8.

Working platforms are incorporated into wall and column formwork.

All work practices must ensure that current OH&S requirements are adopted. •

Items 1 to 8 must be performed fully.


25

MODULE DETAILS


ASSESSMENT TASK 2: Set out, fabricate and position formwork for a reinforced concrete slab with intersecting and perimeter beams, that encompasses the following specifications: < <

< <

a slab of minimum size 6000 mm long x 6000 mm wide and 300 mm thick intersecting and perimeter beams, minimum end section size 300 mm wide x 400 mm deep or similar Soffit height minimum two unit frames from floor datum point perimeter working platform – minimum 450 mm.

Assessment Task 2 incorporates Learning Outcomes: 2. 3.

Set Out, Construct and Assemble Falsework and Formwork. Strip, Clean and Store Falsework and Formwork.

Item

Assessment Criteria

1.

Falsework and formwork for suspended slab and beam structures are set out using centre lines, off set grids, datums and reduced levels.

2.

Falsework and formwork for suspended slab , beam and capital components are constructed using both timber and proprietary forms.

3.

Lift and service penetrations are located, constructed and fixed in accordance with plans and specifications.

4.

Beam sides are constructed, located and braced to lines and heights specified in the plans and specifications.

5.

Hand rails and toe boards are erected in accordance with statutory regulations.

6.

Plans and specifications are checked for designed stripping times.

7.

Stripping sequence and equipment removal is planned.

8.

Falsework and adjustment hardware are backed off to allow ease of stripping. Falsework and formwork is safely and sequentially removed, denailed, cleaned and relocated.

9.

Achieved

All work practices must ensure that current OH&S requirements are adopted. •

26

Items 1 to 9 must be performed fully.



SECTION 1

SECTION 1 - THE PRINCIPLES OF FORMWORK DESIGN, PLANNING AND QUALITY CONTROL

READ

INTRODUCTION This first section of this package deals with four main aspects: design and planning; quality control; calculation of materials; and working platforms.

These areas include the essential information you will need to complete Assessment Task 1 which addresses the first learning outcome: Apply the principles of formwork design, planning and quality control.

The details required for this section will be presented under ten topics: • • • •

Formwork Member Sizes and Spacings Falsework Member Sizes and Spacings Loads on Formwork Use of Tables and Graphs to Design Formwork Drop Panels and Hopper Heads as Column Capitals Construction Workers’ Duties Quality Control Procedures to Ensure Correct Shape, Size and Alignment Working Drawings Calculation of Material Quantities Working Platforms for Walls and Columns


27

SECTION 1


1.

FORMWORK MEMBER SIZES AND SPACINGS

In concrete construction two important structural elements are slabs and beams. A slab is a large, flat piece of concrete usually in the shape of a square or a rectangle which usually forms the main part of a floor or a roof. A beam, on the other hand, is a long, thinner part of a structure used as support for some other structure such as a slab. Beams can also be built to stand alone.

Figure 1

SLABS AND BEAMS

The size and spacing of beams and formwork are carefully designed by engineers who take into account the loads the slabs and beams will have to support. All slab and beam dimensions and spacing dimensions are given in full in the engineer’s working drawings for the building project. Size and spacing will therefore vary from one job to the next and will fit in with what is known as standard good practice. Size and spacing of slabs and beams will also follow the formwork code as laid out in AS 3610. 2.

FALSEWORK MEMBER SIZES AND SPACINGS

Falsework is the temporary structure needed to support the permanent structure while it is being erected. Falsework actually includes the formwork. Usually when we speak of falsework, we usually refer to the structure that supports the formwork - that is, the structure on which the formwork rests. We mean the joists, bearers, props, and any other stabilising structures such as wedges, soleplates. Falsework also includes scaffolding and work platforms. Figure 2 shows formwork for a suspended slab. The diagram does not show formwork for the edges, scaffolding or work platforms.

28



Figure 2

SECTION 1

SCHEMATIC DIAGRAM OF FORMWORK AND FALSE WORK FOR A SUSPENDED SLAB

Falsework may be constructed from round or sawn timbers, steel joists, or scaffold tubing. In bridge construction, falsework can take the form of temporary piles. Sometimes wedges and jacks are incorporated in falsework. This is done to make it easier to dismantle a job once it is completed. Falsework designed to carry heavy loads is sometimes made up of metal cylinders filled with dry sand supporting a plunger. These cylinders are known as sandboxes. Falsework is mostly used in river and harbour works and in the construction of arches. Two styles of arch bridge are illustrated here.

Figure 3 OPEN SPANDREL ARCH 1 AND ARCH 2


29

SECTION 1


3.

LOADS ON FORMWORK

Loads are expressed as pressures which are measured in units called Pascals. The symbol is Pa. One Pascal is about 100 grams (roughly the weight of a Mars bar) spread over an area of one square metre. It’s a small unit, and when we talk of concrete it makes better sense to talk in terms of thousands of Pascals - Kilopascals (kPa). Loads on formwork come from a number of sources: Self weight - is the weight of all materials used to construct the form. Concrete loads - because the concrete acts like a liquid the forces can be assumed to increase in the same way as liquid in a column. That is, the pressure of the liquid increases the deeper you go. The pressure on the form due to concrete can be easily calculated. Live loads - are the weight of the workers, their equipment and building materials. If the formwork is to be used as a place to store materials then it must be designed to accept it. If the formwork needs to support further work above it such as a multi-level building then it must be strong enough. Extra loads may be produced by mounding of concrete or by starting the pour at the wrong position, where there is no prop directly underneath. The formwork should include some margin of strength to cope with these errors. Wind and water loads - wind will catch the formwork. The loads due to wind can be high. They will vary with climate and location. Rain and run off can add loads on formwork and can soften the foundations or remove soil, causing footings to shift. Impact loads from concrete buckets, trucks or other objects could cause damage to the formwork. If this happens the pour should be terminated and repairs undertaken. The formwork should be braced so that in the event of a serious impact it will not collapse totally. The formwork should not only be strong but also cross braced so that damage is minimised. Earthquake loads - are considered important only if the formwork is likely to be erected 6 months or more. Other loads may come from things like shrinkage of concrete or shifting of footings. Loads must be considered at three stages of the building process: Stage 1 - before placing the concrete Stage 2 - during placement of concrete Stage 3 - After placement of concrete, until concrete is able to support the applied loads. Some of the loads described above can be calculated. Others are estimated because they are constantly changing and no accurate calculation can be made.

30



SECTION 1

The concrete load is calculated with the knowledge that concrete weighs about 2500 Kg per cubic metre. (Sometimes the figure 2400 is used). This is called it’s density and it’s symbol is r (the Greek letter ‘rho’). The self weight of formwork is normally fairly predictable. It is estimated to be 0.1 kPa. The live loads are estimated to be 1.0 kPa for the workers and their equipment, 3.0 kPa for concrete mounding and 4.0 kPa for building materials. These are obtained from Australian Standard 3610. All of the loads are added to obtain the total load. Calculation of concrete load Formula used : Load = (rho) x h / 100 Where rho is 2500 and h is the depth of the concrete Example 1:

(a) Calculate the load due to a concrete slab 200 mm thick L = rho x h / 100 = 2500 x 0.2 / 100 = 5.0 kPa Calculate the total load on the props Total load = 5.0 (concrete) + 0.1 (self load) + 1.0 (workers and equipment) + 3.0 Mounding + 4.0 Materials = 13.1 kPa


31

SECTION 1


SELF-CHECK

EXERCISE 1: 1.

FORMWORK CALCULATIONS

Calculate the concrete load due to a slab 250 mm thick. ____________________________________________________________________ ____________________________________________________________________

2.

Assume that the slab is to be suspended by formwork and props. Calculate the total load on the props due to the formwork, live loads, concrete and stacked materials. ____________________________________________________________________ ____________________________________________________________________

PRACTICAL ACTIVITY

ACTIVITY 1: 1.

Draw small pictorial sketches of: • • •

2.

BASIC INFORMATION

a slab a beam a slab supported by two beams

In your own words tell what is meant by standard good practice . ____________________________________________________________________ ____________________________________________________________________

32



4.

SECTION 1

USE OF TABLES AND GRAPHS TO DESIGN FORMWORK

There are ways of deciding on the spacing of supporting falsework beams and joists. One way of doing it is to use tables which show the safe loads that can be carried by joists and props at given spacing. Figure 4 shows the safe loads that can be carried by props of given length. Table 1 gives the spacing of joists required to support given loads. On the job, props used to support the formwork are often hired, and the supplier may provide a design service which sets out the spacing of the props. Figure 5 Shows a section of a plan for a slab and beams which shows the set out of props and working drawings for the formwork to support the beams.

Figure 4

SAFE LOADS FOR PROPS IN DIFFERENT LENGTHS


33

SECTION 1


ID Code 12-10-5

12-10-7

12-13-5

12-16-5

12-25-5

15-32-5

17-10-7

17-13-7

17-14-7

Stress Grade F11 F14 F17 F22 F27 F11 F14 F17 F22 F27 F11 F14 F17 F22 F27 F11 F14 F17 F22 F27 F11 F14 F17 F22 F27 F11 F14 F17 F22 F27 F11 F14 F17 F22 F27 F11 F14 F17 F22 F27 F11 F14 F17 F22 F27

225 39.4 50.2 61.0 78.9 86.4 44.8 57.0 69.3 87.8 87.8 44.8 57.0 69.3 85.6 85.6 53.8 68.4 83.1 87.8 87.8 67.6 77.0 86.4 86.4 86.4 84.5 96.2 108.0 108.0 108.0 78.9 100.0 122.0 122.0 122.0 89.6 112.0 125.0 125.0 125.0 86.0 108.0 122.0 122.0 122.0

300 22.2 28.2 34.3 44.4 55.5 25.2 32.1 39.0 50.4 63.0 25.2 32.1 39.0 50.4 63.0 30.3 38.5 46.8 60.5 65.9 38.3 48.8 59.2 64.8 64.8 59.5 72.2 81.0 81.0 81.0 44.4 56.5 68.6 88.7 91.8 50.4 64.2 77.9 93.9 93.9 48.4 61.6 74.8 91.2 91.2

Face grain parallel to span Span (l) mm 400 450 480 600 12.5 9.9 7.7 3.2 15.9 11.4 8.8 3.6 19.3 13.3 10.3 4.2 24.3 15.2 11.7 4.8 28.1 17.5 13.5 5.6 14.2 10.7 8.2 3.4 18.1 12.2 9.4 3.9 21.9 14.2 11.0 4.5 26.0 16.2 12.6 5.1 30.1 18.8 14.5 5.9 14.2 10.7 8.2 3.2 18.1 12.2 9.4 3.9 21.9 14.2 11.0 4.5 26.0 16.2 12.6 5.1 30.1 18.8 14.5 5.9 17.0 13.4 10.4 4.3 21.7 15.4 11.9 4.9 26.3 18.0 13.9 5.7 33.0 20.6 15.9 6.5 38.1 23.8 18.4 7.5 21.6 16.3 12.6 5.2 27.4 18.7 14.4 5.9 33.3 21.8 16.8 6.9 39.9 24.9 19.2 7.5 46.1 28.8 22.2 9.1 33.5 26.4 23.2 10.1 42.6 33.7 28.2 11.6 51.7 40.9 32.9 13.5 60.7 48.7 37.6 15.4 60.7 54.0 43.5 17.8 25.0 19.7 17.3 8.8 31.8 25.1 22.1 10.0 38.6 30.5 26.6 11.7 49.9 39.4 32.6 13.4 62.4 48.8 37.7 15.5 28.4 22.4 19.7 10.1 36.1 28.5 25.1 11.6 43.8 34.6 30.4 13.5 56.7 44.8 37.6 15.4 70.4 56.0 43.5 17.8 27.2 21.5 18.9 9.4 34.7 27.4 24.1 10.8 42.1 33.2 29.2 12.6 54.5 43.0 35.1 14.4 68.1 52.6 40.6 16.6

800 900

2.1 2.4

2.2 2.4 2.0 3.2 2.2 3.7 2.5 4.3 3.0 4.9 3.4 5.6 3.9 2.8 3.2 2.2 3.7 2.6 4.2 2.9 4.9 3.4 3.2 2.2 3.7 2.5 4.3 3.0 4.9 3.4 5.6 3.9 3.0 2.1 3.4 2.4 4.0 2.8 4.6 3.2 5.3 3.7

225 55.6 70.7 85.9 86.4 86.4 53.8 68.4 83.1 87.8 87.8 52.0 66.2 80.3 85.6 85.6 48.4 61.6 74.8 87.8 87.8 30.5 38.8 47.1 61.0 76.2 46.6 59.3 72.0 93.2 108.0 95.7 109.0 122.0 122.0 122.0 98.0 112.0 125.0 125.0 125.0 95.2 108.0 122.0 122.0 122.0

Face grain perpendicular to span Span (l) mm 300 400 450 480 600 800 31.3 17.6 11.4 8.8 3.6 39.8 20.8 13.0 10.0 4.1 48.3 24.3 15.2 11.7 4.8 62.5 27.8 17.3 13.4 5.5 64.8 32.1 20.0 15.5 6.3 2.0 30.3 17.0 11.4 8.8 3.6 38.5 20.8 13.0 10.0 4.1 46.8 24.3 15.2 11.7 4.8 60.5 27.8 17.3 13.4 5.5 65.9 32.1 20.0 15.5 6.3 2.0 29.2 15.9 10.0 7.7 3.2 37.2 18.2 11.4 8.8 3.6 45.2 21.3 13.3 10.3 4.2 58.5 24.3 15.2 11.7 4.8 64.2 28.1 17.5 13.5 5.6 27.2 14.8 9.2 7.1 2.9 34.7 16.9 10.6 8.1 3.3 42.1 19.7 12.3 9.5 3.9 54.5 22.6 14.1 10.9 4.5 65.9 26.1 16.3 12.6 5.2 17.1 8.0 5.0 3.8 21.8 9.1 5.7 4.4 26.5 10.6 6.6 5.1 2.1 34.3 12.1 7.6 5.9 2.4 42.9 14.0 8.8 6.8 2.8 26.2 14.8 9.2 7.1 2.9 33.4 16.9 10.6 8.1 3.3 40.5 19.7 12.3 9.5 3.9 52.4 22.6 14.1 10.9 4.5 65.5 26.1 16.3 12.6 5.2 59.5 33.5 26.4 23.2 10.3 3.3 75.7 42.6 33.7 28.9 11.8 3.7 91.8 51.7 40.9 33.7 13.8 4.4 91.8 66.9 49.8 38.5 15.8 5.0 91.8 68.8 57.6 44.5 18.2 5.8 59.5 33.5 26.4 23.2 10.3 3.3 75.7 42.6 33.7 28.9 11.8 3.7 91.9 51.7 40.9 33.7 13.8 4.4 93.9 66.9 49.8 38.5 15.8 5.0 93.9 70.4 57.6 44.5 18.2 5.8 56.5 31.8 25.1 22.1 9.2 2.9 71.9 40.4 31.9 25.7 10.5 3.3 87.3 49.1 38.8 30.0 12.3 3.9 91.2 63.5 44.4 34.3 14.1 4.4 91.2 68.4 51.3 39.7 16.2 5.1

Table 1 SPACING OF JOISTS FOR A SUSPENDED SLAB

34


900

2.3 2.6 3.0 3.5 4.0 2.3 2.6 3.0 3.5 4.0 2.0 2.3 2.7 3.1 3.6


SECTION 1

Figure 5 PLAN FOR SUSPENDED SLAB AND BEAM STRUCTURE SHOWING THE LAYOUT OF PROPS AND FORMWORK FOR BEAM


35

SECTION 1


The graphs and table are used in the following example. Example 2: A suspended slab 200 mm thick is to be poured. The height will be 2.6 m. Decide with the use of tables and graphs;

the spacing of props the spacing of joists Answer :

Step 1: Calculate the load on the props. We know from example 1 that a slab of 200 mm will have a total load of 13.1 KPa, so we don’t need to calculate the load. Step 2: Go to Figure 4, and find 2.6 m prop height. Step 3: Find 200 mm slab depth on the horizontal axis. Step 4: Find the point where the two lines from the axes intersect Step 5: Choose the nearest curved line to the right of the point of intersection. Read the figure at the end of the line. This is the area that the prop will safely support. Answer = 1.5 square metres What does the answer mean? It means that the area supported by the prop must not be more than 1.5 square metres. From that information we can decide how far to space the props. To decide on the spacing, we choose one prop and look at the nearest two props and form a rectangle. So if distance from prop 1 to 2 is 1 m, then distance 1 to 3 cannot be more than 1.5 m. Combinations of distances in both directions can be used. If stronger props are chosen the distances between props can be increased.

Figure 6

36

MAXIMUM SAFE AREA FOR PROPS



SECTION 1

Spacing of Joists

Plastic coated plywood is commonly used as the formface material. This is made in different thicknesses and strengths. Tables such as those supplied by the Plywood Association (Table 1) can be used to work out the spacing of joists. Example 3: The 200 mm slab in example 2 is to be poured on 19 mm plywood identified by the code number 19-13-7, stress grade F11. Use the tables to decide how far apart the joists should be placed. Step 1:

Calculate the pressure of the concrete. (we already know this from previous calculation, 13.1 KPa.)

Step 2:

Use Table 1 to decide on the spacing of the joists. Find 19-13-7 and F11 in the table. Then look across the table to find a figure just greater than 13.1 you should see the figure 17.6 which will be in the column under 480 mm. That means that the plywood should have joists spaced no more than 480 mm apart to avoid deflections.

Now we know the Prop spacing and the joist spacing and we can begin to design the formwork.

Figure 7

LAYOUT OF JOISTS AND BEAMS


37

SECTION 1


SELF-CHECK

EXERCISE 2:

FALSEWORK

Write brief answers to these. Add sketches where appropriate: 1.

What is falsework? ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________

2.

What materials are used for the construction of falsework? ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________

38



5.

SECTION 1

DROP PANELS AND HOPPER HEADS AS COLUMN CAPITALS

A drop panel is one placed to carry a high load. It is a part of a slab that is made thicker. Typically, a drop panel might be 100 mm thick. A hopper head is a funnel shaped capital for a column.

Figure 8

DROP PANEL AND HOPPER HEAD

A column is an upright pillar, usually with a shaft often in the shape of a cylinder and with a bottom piece known as a base. The top of a column is called a capital. These components are shown in the following diagram.

Figure 9

PARTS OF A COLUMN


39

SECTION 1


Columns can also be in the form of square or rectangular prisms.

Figure 10 PRISM

SQUARE AND RECTANGULAR

Formwork for square or rectangular columns is usually made from plywood sheeting with timber bearers spaced at intervals along the sheeting. Two sides of the column will have formwork the same width as the column while the formwork for the other two sides will be the width of the column plus the width of two plywood sheets to allow for overlapping as is shown below.

Figure 11 FORM FACING LAYOUT FOR RECTANGULAR COLUMN

In construction, column capitals will be placed to support drop panels. A drop panel and hopper head may be used together.

Figure 12 PANEL

40

HOPPER HEAD TOGETHER WITH DROP



SECTION 1

SELF-CHECK

EXERCISE 3:

CAPITALS AND COLUMNS

Write brief answers to these: 1.

What is a capital? _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

2.

What are the usual shapes of columns? _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

3.

Make a sketch of a hopper head.


41

SECTION 1


6.

CONSTRUCTION WORKERS’ DUTIES

The quality of concrete work depends very much on the quality of the formwork and the care taken a the time of the pour. The smoothness of surfaces in contact with the formwork for example depends on the formwork staying rigid as the concrete is poured. Even if the formwork is of the right strength, it could be overloaded and produce stress bulges. Tightness of the props and ties need to be checked before and during the pour. Before Concrete Placement

All workers must be on duty and in place. They must all have appropriate clothing including steel-capped boots, gloves, goggles, long-sleeved shirts, sun protection and safety helmets. Workers must all have immediate access to necessary equipment such as trowels, levelling implements and vibrators. Compressors used for operating the vibrators will need to have been checked to see that they are operating properly. During Concrete Placement

Workers must again observe all occupational health and safety requirements. Cranes, buckets, winches, pulleys must all be watched carefully. The formwork should be watched for movement. Ties and props in important positions should be checked for tightness. The pour must be managed so that mounds are minimised and that the pour is in the right direction.

Figure 13 CORRECT DIRECTION FOR PLACING SLAB CONCRETE

Special care must be taken near concrete trucks particularly when they are backing and turning. After Concrete Placement

The major tasks to be performed are levelling and smoothing.

42



SECTION 1

SELF-CHECK

EXERCISE 4:

CONCRETE WORKERS DUTIES

Prepare a chart and on it list six duties to be performed on each of these occasions: (a)

Before a concrete pour

(b)

During a concrete pour

(c)

At the completion of a concrete pour


43

SECTION 1


7. QUALITY CONTROL PROCEDURES TO ENSURE CORRECT SHAPE, SIZE AND ALIGNMENT

Quality is an important thing to think about when placing and shaping concrete forms. When we speak of quality in concrete work we speak of two main things: • •

correct shape, and quality of surface

The concrete must be formed in its designed shape. It must also have a suitably highquality finish with proper smoothness and be the right colour. Smoothness is affected by the smoothness of the form face (any rubbish left on the form will be mirrored in the surface of the concrete). It is also affected by the weight of the concrete itself - if the concrete overstresses the formwork and makes it buckle, the result will be a ripply surface. The Australian Standard sets maximum limits on surface irregularity. Typically surface ripple should be no more than about 1mm per metre of length.

Figure 14 ALLOWABLE VARIATION IN SURFACE OF CONCRETE (EXAGGERATED)

The colour could vary from one panel of formwork to another. This could happen if different panels are used, or the release agent is changed. It could also happen because of slight changes in the concrete used or the setting time. The concrete must be placed in its proper position. In other words, it must be aligned correctly. The dimensions of the slab or beam must be right. To make sure that concrete is of a proper standard or quality, tests will take place. Samples will be taken in the form of cores of concrete which will be allowed to cure or set and then be tested in a laboratory. Cores will be tested for what is known as compressive strength which is strength when compressed under load. Tests of compressive strength are usually undertaken at the end of seven days when the concrete is at sixty per cent of its final strength and at twentyeight days when the concrete is expected to have reached its final strength. In special cases - particularly with a large job being finished quickly - sample cores for testing may be taken at the end of three or four days.

44



SECTION 1

SELF-CHECK

EXERCISE 5:

QUALITY

Write TRUE of FALSE after each of these statements: 1.

Alignment is where the concrete is positioned __________.

2.

At the end of seven days concrete has reached its final strength __________.

3.

Concrete is usually tested at the end of ten days and at the end of sixty days _________.

4.

Concrete for testing is taken in sample cores __________.

5.

Sample cores are often taken earlier on large jobs __________.


45

SECTION 1


8.

WORKING DRAWINGS

When a building is being designed the designers and draftsmen will produce a set of drawings which will show how every part of the building will be constructed. These drawings will be exact and very detailed. They will also be extensive. All building workers will need to be able to refer to and understand the working drawings that are being used in a building project. Figure 15 shows a section through a suspended slab including beams. You need to be able to find the location of slab edges and beams. For specialised formwork the detail might be drawn, but often the design of formwork for simple slabs and beams is up to the formworkers.

Figure 15

SECTION SHOWING SLAB AND BEAM CONSTRUCTION

Drawing skills are required as is basic knowledge and ability with computer assisted drafting (CAD).

46



SECTION 1

SELF-CHECK

EXERCISE 6:

WORKING DRAWINGS

From Figure 15, identify the following: 1.

slab area

2.

perimeter beam

3.

intersecting beams

You should be able to draw working drawings for formwork. This will be checked by your instructor.


47

SECTION 1


PRACTICAL ACTIVITY

ACTIVITY 2:

DESIGN FORMWORK

1.

Design the formwork for a section of the plan in Figure 15. Your instructor will choose the part of the plan for you. The section should contain both beams and slab and the beam forms should be designed for easy stripping.

2.

Your instructor may ask you to construct the formwork.

48



9.

SECTION 1

CALCULATION OF MATERIAL QUANTITIES

Quantities of materials used in major building projects are calculated by special workers called quantity surveyors and estimators who are highly trained specialists. However you must be able to calculate approximate quantities of materials so that you know what to expect and know when there is too little or too much. Material quantities are calculated by basic arithmetic. To assess the quantity of pre-mixed concrete for a slab or a beam, for instance, you follow this method: The basic method for any slab or beam is to calculate the area of one end and multiply it by the depth or length. This works for any regular shape.

For a rectangular prism, the area of any side is length times width .

Figure 16

RECTANGULAR PRISM

Formula used is:

Volume (V) = Length (L) x Width (W) x Depth (D) All measurements are metric. Example:

Calculate the quantity of concrete required for a slab length 20 m, width 10m, and thickness 250 mm.

Volume = Length (20 m) x Width (10 m) x Depth (0.25 m) = 20 x 10 x 0.25 cubic metres = 50 cubic metres The same formula will be used for measuring square and rectangular beams and columns.


49

SECTION 1


Example:

Calculate the volume of concrete in a beam of width 400 mm, depth 300 mm and length 5 m.

Figure 17

RECTANGULAR PRISM

Volume = area of the end x length V=LxWxD = 0.3 x 0.4 x 5.0 = 0.60 cubic metres The same method is used for circular columns but the formula is different. The volume of a circular column will be calculated by multiplying the area of the end (radius of the column squared by 3.142 or pi (∏) by the height. Volume = Area of end x height The formula used is: 2 Volume = (∏) x R x H

Figure 18

50

CYLINDRICAL PRISM



Example:

SECTION 1

Calculate the volume of concrete required for a circular column of diameter 600 mm and 4 m high.

Figure 19 COLUMN

CIRCULAR

2

Volume = (∏) x R x H = 3.142 x 0.3 x 0.3 x 4 = 1.13 cubic metres


51

SECTION 1


SELF-CHECK

EXERCISE 7: 1.

CONCRETE CALCULATIONS

Calculate the amounts of concrete required for these slabs: 7m x 12m x 300mm 8m x 20m x 250mm 15m x 30m x 500mm

2.

Calculate the concrete required for these columns: 6m high x 1m in diameter 4m high x 600mm in diameter 10m high x 2m in diameter

52



10.

SECTION 1

WORKING PLATFORMS FOR WALLS AND COLUMNS

The simplest kind of platform used with concrete construction is on a simple scaffolding frame or tower. At the level of the platform, a plank flooring is fitted. The platform is fitted with a handrail and a toe board and an access ladder is fitted either inside or outside the tower. (See Figure 20).

Figure 20

WORK PLATFORM AT TOP OF SCAFFOLD TOWER

Working platforms can be part of towers that can be mobile or static.


53

SECTION 1


A mobile platform will be set on wheels and contain a single working platform. This kind of platform is used mainly for light work such as inspection and painting. A typical mobile platform is shown in the following diagram. Note the ladder which, in this case, is on the outside. Ladders are also sometimes internal. Note too, the handrail and the toe board. Both of these are necessary for safety as are the locking devices fitted to the wheels.

Figure 21

TUBULAR METAL MOBILE TOWER

Static platforms are held permanently in place and will not be moved. They are used as working or observation platforms. If a tower is more than ten metres high it must be tied to the main structure. It must also be braced so that it remains rigid. Other steps are taken to make sure that the towers supporting static towers remain rigid.

54



SECTION 1

Tie wires are fitted for every ten metres in height. These are set at 45º from the ground and fixed to anchorage points as shown below.

Figure 22

ANCHORAGE OF TALL PLATFORMS

Note that sometimes working platforms are attached to hoists. Cherry pickers can also be used. Work platforms are often included as part of the formwork, especially at the edge of slabs. The figure below shows a work platform constructed next to the edge beam of a slab. Note that it does not show a toe board which is required in order to meet the requirements of AS 1657.

Figure 23 WORK PLATFORM CONSTRUCTED ALONGSIDE EDGE BEAM OF A SLAB


55

SECTION 1


SELF-CHECK

EXERCISE 8:

PLATFORMS

Read the section carefully and find the words missing from the following sentences: 1.

A tower designed not to be moved is said to be _______________.

2.

Mobile towers and platforms are usually used for ___________ work.

3.

Bracing is used so that a tower remains __________.

4.

Tie ropes are attached to ____________ points.

5.

Tie ropes are set at an angle of ______________ from the ground.

56



SECTION 1

SUMMARY So far you have covered the information required to complete Assessment Task 1. The knowledge you have gained so far will be used each time you begin work on a building site. The importance of this information will become more evident when you begin work on various sites. Self-check exercises in this package are on yellow pages. This exercise has been designed to test your understanding of the information you have covered so far. Answers to the self-check exercises are on the blue pages at the end of the package. You may find it useful to make your own brief summary below on the following topics:

Formwork Member Sizes and Spacings:

Falsework Member Sizes and Spacings:

Loads on Formwork:

Use of Tables and Graphs to Design Formwork:


57

SECTION 1


Drop Panels and Hopper Heads:

Construction Workers’ Duties:

Quality Control Procedures:

Working Drawings:

Calculation of Material Quantities:

Working Platforms for Walls and Columns:

58



SECTION 2

SECTION 2 - SETTING OUT, CONSTRUCTING AND ASSEMBLING FALSEWORK AND FORMWORK

READ

INTRODUCTION This section of this package deals with two main aspects: • •

set out falsework and formwork; and construct and assemble falsework and formwork.

These areas contain essential information you will need to partly complete Assessment Task 2 which addresses learning outcome 2: Set out, construct and assemble formwork.

The information relating to set out and construct formwork will be presented under four topics: • • • •

1.

Setting Out Falsework and Formwork Constructing Falsework and Formwork for a Suspended Slab and Beams Locate, Construct and Fix Lift and Service Penetrations Stairs and Landings

SETTING OUT FALSEWORK AND FORMWORK

Before formwork and falsework are commenced a job has to be set or marked out. This is done using: • • • • •

centre lines; off sets; grids; datums; and reduced levels.

A centre line is a line across the centre of a project. Measurements are made from this centre line. The measurements are not made from an external side or what is called a face.


59

SECTION 2


Figure 24

CENTRE LINE

A datum or datum point is a reference point used in measuring. Distances, in other words, are calculated from a datum. A datum can be horizontal or vertical and will be fixed or immoveable. Vertical datums are set with reference to sea level and what are known as the Australian Height Datum (AHD). The AHD will be marked at the commencement of the job by a land surveyor. Reduced levels are height levels expressed in terms of relation to AHD. Heights on a structure or a building are measured from an AHD. They are not necessarily measured from ground level.

The surveyor will also mark horizontal datums which are measured from grids or coordinates of longitude and latitude. These coordinates are recorded as the Australian Grid System or AGS . Grids are used, too, in working drawings. The drawings are over a grid with lines marked with numbers and letters just as in a suburban road map. Points in a project can be identified using the grid. A column, for instance, might be set at F5 while a tower may be located at D7.

Figure 25 GRID LINES USED TO SHOW LOCATIONS

60



SECTION 2

SELF-CHECK

EXERCISE 9:

SETTING OUT

Give a brief explanation of each of the following: 1.

Centre line _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

2.

Datum _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

3.

AHD _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

4.

AGS _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

5.

Coordinates _____________________________________________________________________


61

SECTION 2


2. CONSTRUCTING FALSEWORK AND FORMWORK FOR A SUSPENDED SLAB AND BEAMS

Slabs and beams are usually constructed together. The beams add strength to the slab. Therefore the formwork for a slab is often constructed at the same time as the formwork for beams. Usually a slab will have an edge beam and internal beams. The formwork and falsework for these is different.

Figure 26

SLABS AND BEAMS

Formwork for a beam is usually supported by a soffit form. Soffit forms are those used for the underside of concrete structures like slabs and beams. Generally soffit forms are designed to be level or near level. They will always incorporate safety rails for workers. Generally a small section of a soffit form will be completed. This section will then be used as a base for further work with tools and equipment stored on the section that is completed first. The formwork for beams and slabs is commonly constructed using plywood. The beam however is usually less wide than the sheet of plywood. The plywood can be cut to fit but this means that the plywood might not be reusable and some will be wasted. For economy, the plywood is not cut. Instead, the formwork is built up on a whole sheet of ply which can then be reused. The formwork for edge beams usually includes a work platform which is cantilevered off the edge of the beam. This is unsafe if it is not properly supported and could distort the formwork. There is more than one way of supporting the work platform. If the formwork can be extended to include the platform, that may be safe enough but sometimes that cannot be done. Extra props might be needed as shown in Figure 27.

62



SECTION 2

Figure 27 WORK PLATFORM AT EDGE OF SLAB SUPPORTED BY PROPS Beam Forms

Beams are deeper and heavier than the surrounding slab. Therefore the pressure of the concrete will be greater as it is poured. This will tend to push the sides of the beam forms out of shape. The formwork has to be strong at the bottom edges and it must be constructed so that it resists tipping over as the concrete is poured. Beam forms must be correctly supported by props widely spaced. An unstable design can be improved by moving the supports beyond the edges of the beam.

Figure 28 BEAM SUPPORTS IN THIS EXAMPLE ALLOW DANGEROUS UNBALANCE TO EXIST


63

SECTION 2


Figure 29 THE PROBLEM OF ECCENTRICITY IS AVOIDED IF THE LOAD IS ALWAYS INSIDE THE SUPPORTS

The detail of formwork can also include features which make stripping easy (a stripping band, Figure 30, and tolerance gap, Figure 31).

Figure 30 STRIPPING BAND AT BEAM SIDE ALLOWS SLAB SOFFIT TO BE STRIPPED WITHOUT DISTURBING THE BEAM 64


SECTION 2


Figure 31 TOLERANCE GAP WITH CLOSURE ANGLE AT BEAM SIDE ALLOWS EASY STRIPPING OF BEAM SIDE WITHOUT DISTURBING SOFFITS

Deep beams need ties to hold the sides in place. Typical beam formwork with ties are shown below.

Figure 32

TYPICAL DEEP BEAM FORMWORK WITH TIES


65

SECTION 2


Figure 33 TYPICAL DEEP EDGE BEAM FORMWORK SHOWING TIES AND THE USE OF SPREADER BAR AND STRUT TO KEEP THE BEAM PLUMB

Figure 34 TYPICAL TIES ARE THE ‘HE BOLT’ SYSTEM

66



SECTION 2

Soffit form construction proceeds in three stages -- the formwork construction stage , the pouring stage and the strengthening stage. At the formwork construction stage the major problem lies with keeping the soffit rigid. This is particularly important with high level forms which can be subject to strong wind forces. To deal with these strong wind forces soffit forms can be tied with guy ropes. Supporting scaffolds are also braced. The pouring stage is when the soffit form must bear its heaviest load. This load should not be increased by mounding – that is allowing a mound of concrete to be gathered in a small area (Figure 35). Extra stress on a form can also be caused by allowing buckets to swing against the structure.

Figure 35

THE EFFECTS OF MOUNDING

Every care MUST be taken to avoid mounding and heavy contact from swinging buckets. Both of these can cause serious damage to a form. At the strengthening stage the concrete gradually becomes able to support itself and other loads and structures. Loads that bear down on the newly laid slab or beam will include: • • • • • •

self weight; construction activity ; concrete; materials; mounded concrete; and impact.


67

SECTION 2


Each of these loads is accounted for in design of the formwork. AS 3610 provides standard figures for some of them. The concrete pressure is dependent on the thickness of the concrete. Forces that will cause lateral or sideways load or stress will include: • • • •

68

wind; construction activity; impact; and water.



SECTION 2

SELF-CHECK

EXERCISE 10:

SLAB AND BEAM FORMWORK

Prepare rough sketches with appropriate notes to explain the following: 1.

Soffit form

2.

Mounding

3.

Guy ropes

4.

Scaffold bracing


69

SECTION 2


3 LOCATE, CONSTRUCT AND FIX LIFT AND SERVICE PENETRATIONS

In constructing slabs and beams allowance must be made for what are known as penetrations which are, in fact, holes left in a structure for pipes, stairwells, lift wells and so on. These are marked on the working drawings and located from drawing grid references. Formwork is constructed so that concrete will not cover a penetration. This is done simply by forming edges around where the penetration is to be located. Edges are often made from plywood braced with metal or timber. For small penetrations plastic foam or plastic tubes can be used. The figure below shows what they might look like.

Figure 36

70

TYPICAL PENETRATIONS



SECTION 2

Larger, rectangular penetrations can be made from plywood as shown below. Overlapping like this makes stripping or removal easier.

Figure 37 STRUCTURE OF RECTANGULAR PENETRATION


71

SECTION 2


SELF-CHECK

EXERCISE 11:

SERVICE PENETRATIONS

Write TRUE or FALSE after each of these sentences: (a)

A penetration is a place in a beam or slab where concrete is laid.____________

(b)

Penetrations are located from working drawings from grid points.

____________ (c)

Edges of penetrations in formwork are always constructed from

wood._________ (d)

Plywood forms are always braced with timber.__________

(e)

Timber penetration forms have overlapped edges so they can be dismantled easily.___________

72



4.

SECTION 2

STAIRS AND LANDINGS

Stairs can be cast off site and placed in position or cast on site. Formwork must be constructed for the soffit, the sides of the stair and the risers. The detail of riser forms and sides is shown below.

Figure 38

DETAIL OF STAIR FORMS

The soffit to the stair must be propped adequately. One method of propping is shown below.

Figure 39

DETAIL OF WHOLE STAIRCASE


73

SECTION 2


SUMMARY In this section of Formwork - Suspended Slab and Beam you have covered: • •

set out and construction of falsework and formwork location of lift and service penetrations

A practical activity at the end of Section 3 will cover: • •

set out, fabrication and erection of slab and beam formwork; and stripping, cleaning and storing formwork and falsework.

Before progressing to Section 3, you may like to make some notes on the following topics covered in this section: Setting Out Falsework and Formwork:

Constructing Falsework and Formwork for a Suspended Slab and Beams:

Locate, Construct and Fix Lift and Service Penetrations:

Stairs and Landings:

74



SECTION 3

SECTION 3 - STRIPPING, CLEANING AND STORING FORMWORK AND FALSEWORK

READ

INTRODUCTION In this final section of Formwork - Suspended Slabs and Beams, you will cover stripping, cleaning and storing formwork and falsework These areas contain the essential information you will need to complete Assessment Task 2 which addresses learning outcome 3: Strip, clean and store formwork and falsework.

The information covered will be presented under four topics: • • • •

1.

Stripping Formwork Stripping Sequence and Equipment Removal Backing off of False\work and Adjustment Hardware Removal, Denailing, Cleaning and Storing of Formwork

STRIPPING FORMWORK

The stripping or ‘striking’ of formwork can only be done when concrete is able to support itself and the loads that are to be placed on it. As stripping or striking takes place, the entire weight of the concrete and the structure transfers to the concrete. As McAdam points out: “The general rule in stripping is that it will be done so there is no thermal or physical shock, and there shall be a gradual transfer of the load.” What this means is that stripping should be avoided if extreme weather changes are expected and on days that are expected to be either extremely hot or extremely cold. Stripping should take place without knocks or jolts. It should also be done so sudden transfers of load don’t happen. One way of protecting the concrete from shock is to remove some of the formwork but leave the props in place. This is especially important for the stripping of beams, which are heavier than slabs. After the formwork is removed from a beam the props can be put back, or preferably, the formwork is designed so that the props stay in place without being moved.


75

SECTION 3


Special props can be used, which have collars to support the formwork beams as well as platforms to bear directly on the plywood. With these props in place the beams can be dropped and the plywood removed without moving the props. Figure 40 shows the detail of this kind of setup.

Figure 40 FORMWORK INCORPORATING PROPS WITH COLLARS TO STRIP WITHOUT REMOVING PROPS

The time for removing formwork is set out in AS 1509 but on the job no formwork may be removed without the written permission of the site engineer. The minimum periods for striking formwork used with Portland cement are as follows: Formwork

Surface temperature of concrete

16º C Vertical forms to columns, walls and large beams Slab soffits Beam soffits (beams left under) Props to slabs Props to beams

7º C

12 hours

18 hours

4 days 10 days

6 days 15 days

10 days 14 days

15 days 21 days

Note carefully that the colder the weather, the longer the formwork must stay in position. In general slabs, as the table indicates, will be stripped before beams. Because beams are heavier than slabs, they may cause the slab to bend, therefore it is better to strip the slab first, then the beam.

76



SECTION 3

Figu Figure re 41 UNDE UNDESI SIRA RABL BLE E DIST DISTOR ORTI TION ON OF SL SLAB AB LIKE LIKELY LY WHEN BEAMS ARE STRIPPED FIRST

Checking plans and specifications for stripping times

The conditions to be met for stripping will be written out by the design engineer for the project. Documentation or written instructions i nstructions should specify: • • • •

concrete age and minimum strength at time of stripping; the effectiveness with which the curing procedures are carried out; limits on the loads that can be placed on the structure; and the method and order of stripping.


77

SECTION 3


2.

STRIP TRIPP PING ING SEQ SEQU UENC ENCE AND AND EQ EQUI UIPM PMEN ENT T REMO REMOVA VAL L

Stripping is usually a two stage process. The first or preliminary stage, stage, involves removing the relatively short spans spans between the props, and can usually be done well before the development of the full concrete strength. The second or final stage is the removal of all remaining formwork. Backpropping

Sometimes in stripping sections of formwork backpropping is used. Backpropping involves using a jack or other support under a beam or slab after the formwork has been removed.

Figu igure 42 42

THE BA BACKPROPPING ING PR PROCEDURE

Stripping plywood and timber formwork takes place in the following sequence: 1.

The The sof soffi fitt fra frami ming ng is lowe lowere red d 50 50 mm mm or or more more..

2.

The The ply plywo wood od and and met metal al edgi edging ng stri strips ps will will com comee dow down. n.

3.

The The joi joist stss can can then then be lowe lowere red d ont onto o bea beams ms..

4.

The plywoo plywood d can can now now be full fully y remo removed ved by slidin sliding g it out out from from the the edge edgess of the the form

78



5.

The jo joists ists are th then re removed

6.

The bearer bearerss are are remove removed d – taking taking care care part particu icular larly ly with with tele telesco scopic pic stee steell posts posts which by now will have become unstable and potentially dangerous.

SECTION 3

Note that in following this procedure care should be taken to protect plywood and other timbers from falls. These can either smash the timbers t imbers or cause damage that may be hard to detect but may cause difficulties when the timber is used on a new project. Reshoring

Reshoring is simple - all the formwork and falsework is removed and then props are replaced at specified spacings. These are called reshores and they protect the uncured concrete from damage damage.. This method is not preferred when large beams beams and slabs are involved. Reshoring is usually carried out on small sections at a time.


79

SECTION 3


3.

BACKING OFF OF FALSEWORK AND ADJUSTMENT HARDWARE

A number of metal appliances are used in formwork. These include what is known as adjustment hardware. Invariably adjustment hardware is built so that it can be adjusted for fitting and removal. Sometimes it is made from aluminium and often it is made from steel. Removing adjustment hardware is generally a matter involving unbolting or unlocking rotary locks. Adjustment hardware must be backed off, (that is loosened) and removed, giving attention to the rules that apply for other stripping. In other words, backing off and stripping must be done in such a way as to avoid shocks and sudden transfers of load, and to make sure that as little damage as possible occurs to the equipment.

80


SECTION 3


4. REMOVAL, DENAILING, CLEANING AND STORING OF FORMWORK

Release agents are painted on to formwork so that it will move away easily from the completed concrete surface. Different kinds of formwork require different kinds of release agent and it is important to see that the correct release agent is used. It is also important to make sure that the release agent that is used does not contaminate the reinforcement. Some release agent types are shown in the table below, adapted from Fletcher and Lavan. Release Agent Type

Comments

Neat oil with surfactant

A useful general purpose release agent for all kinds of formwork, including steel. Over application may result in the staining of the concrete. Oil film may be affected by heavy rain.

Mould cream emulsion (oil phased)

Widely used agent recommended for all formwork except steel. Especially recommended for use with timber. Suitable for high quality finishes. Storage life may be limited.

Chemical release agent

For use with all kinds of formwork. Suitable for high-quality finishes. Resistant to washing off by rain. Safer to walk on than oily film and will not be carried on shoes from the formwork onto concrete. Coverage greater than for oils. Expensive if not used carefully.

Wax

Recommended for moulds made of concrete. Difficult to apply evenly.

Barrier paint

Becomes scratched. Needs to be used with a release agent.

Neat oil (without surfactant)

Not to be used where appearance is important; encourages the use of blowholes. Inexpensive. Can be used where concrete is later to be covered.

Water-phased emulsion (oil-in-water)

Not to be used for visual concrete. Causes severe retardation and discolouration. Cheap and easy to apply. Can be used if concrete is not exposed to view.


81

SECTION 3


Some formwork components such as the cardboard forms used especially under floor slabs are not destined for re-use or recovery. Most formwork components, however, can be removed, cleaned and stored for re-use. As soon as the formwork has been struck, it should be cleaned to remove grout and dust. In the case of steel forms these should also be lightly oiled before storage. With all wooden form components it is essential to remove all nails. Unremoved nails can be extremely dangerous to workers. As they rust they can damage timber. They can also cause fitting difficulties when being used in new forms. With nails removed, formwork must be cleaned thoroughly generally using water and heavy brooms. Metal components must also have all dirt and traces of concrete removed. For storage, all formwork components need to be dry and properly waterproofed. Steel and iron components should be lightly oiled. Plywood can be treated with sealing compounds. Storage should be in weatherproof sheds or containers. Panels and plywood sheets should be stored horizontally on a flat level base. Large panels are best stored vertically with the concrete faces together. Soldiers and waling, which are loose, are best stored in boxes or drums.

82



SECTION 3

SUMMARY You now have the necessary information to complete the Practical Activity 3 which relates to Assessment Task 2. Self-check exercises in this package are on yellow pages. This exercise has been designed to test your understanding of the information you have covered so far. Answers to the self-check exercises are on the blue pages at the end of the package. You may find it useful to make your own brief summary below on the following topics: Stripping Formwork:

Stripping Sequence and Equipment Removal:

Backing Off of Falsework and Adjustment Hardware:

Removal, Denailing, Cleaning And Storing of Falsework, Formwork and Related Equipment:


83

SECTION 3


SELF-CHECK

EXERCISE 12:

STRIPPING, CLEANING AND STORING

Write brief notes to explain what is meant by each of these. Add sketches where you think they are necessary: 1.

Backpropping

2.

Backing off

3.

Release agents

84



SECTION 3

PRACTICAL ACTIVITY

ACTIVITY 3:

ERECT AND STRIP FORMWORK

To carry out this activity, you will need a partner to assist you in the construction, erection stripping and handling of the falsework and formwork. All work must be carried out according to the criteria and tolerances specified in Assessment Task 2 on pages 16 and 17 and AS 3610. 1.

SET OUT, FABRICATE AND ERECT FORMWORK

Set out, fabricate and position formwork for a reinforced concrete suspended slab, with intersecting and perimeter beams, that encompasses the following specifications: • • • •

NOTE:

2.

A minimum slab size of 6000mm long x 6000mm wide x 300mm thick. Intersecting and perimeter beams, minimum end section size 300mm wide x 400mm deep or similar. Soffit height minimum two unit frames from floor datum point. Perimeter working platform - minimum 450mm wide. All tolerances are to comply to AS 3610 or those specified on the plans and specifications for the project. Specifically concrete surface deflection ± 3mm and formwork member position ± 10mm.

STRIP, CLEAN AND STORE FORMWORK AND FALSEWORK

The structure is to be dismantled to demonstrate safe and effective stripping and storing procedures. 1.

Falsework and adjustment hardware are backed off to allow ease of stripping.

2. and

Falsework and formwork is safely and sequentially removed, denailed, cleaned stored.


85

SECTION 3


CONCLUSION This learning package has combined the theoretical and practical components for the module CCC348 Formwork - Suspended Slab and Beam . Having successfully completed the requirements of this module, you now understand: • • •

applying the principles of formwork in the design, planning and quality control; setting out, constructing and assembling formwork; and stripping, cleaning and storing falsework and formwork.

You can expect to apply your knowledge and skills again and again on a range of building sites. Those who developed this package hope that you have found its style and preparation easy to use.

Congratulations you have successfully completed the Module CCC348 Formwork - Suspended Slab and Beam

86


SECTION 1


ANSWERS

SELF-CHECK

EXERCISE 1: 1.

FORMWORK CALCULATIONS

Calculate the concrete load due to a slab 250 mm thick.

__________________________________________________________________ 6.25 kPa

2.

Assume that the slab is to be suspended by formwork and props. Calculate the total load on the props due to the formwork, live loads, concrete and stacked materials.

_________________________________________________________________ 14.35 kPa

EXERCISE 2: 1.

FALSEWORK

What is falsework? Falsework is support for concrete forms. The name is particularly used in bridge and harbour work and longer construction work.

2.

What materials are used for the construction of falsework? Falsework is constructed from timber, ply and various kinds of metals and fabricated metal components.


87

SECTION 1


SELF-CHECK

ANSWERS

EXERCISE 3:

CAPITALS AND COLUMNS

1.

What is a capital? A capital is the top part of a column.

2.

What are the usual shapes of columns?

________Cross-sections across columns may be square, rectangular, circular and oval.

3.

Make a sketch of a hopper head.

Sketch. _________________________________________ Show your instructor for verification.


89

SECTION 1


ANSWERS

SELF-CHECK

EXERCISE 4:

CONCRETE WORKERS DUTIES

(a)

Before a concrete pour

(b)

During a concrete pour

(c)

At the completion of a concrete pour Chart Answers should stress efficiency and safety. Show your instructor for verification.


91

SECTION 1


ANSWERS

SELF-CHECK

EXERCISE 5:

QUALITY

Write TRUE or FALSE after each of these statements: 1.

Alignment is where the concrete is positioned False.

2.

At the end of seven days concrete has reached its final strength False.

3.

Concrete is usually tested at the end of ten days and at the end of sixty days

False.

4.

Concrete for testing is taken in sample cores True.

5.

Sample cores are often taken earlier on large jobs True.


93

SECTION 1

CCC348 Formwork - Suspended Slab Beam

ANSWERS

SELF-CHECK

EXERCISE 6:

WORKING DRAWINGS

From Figure 15, identify the following: 1.

slab area

2.

perimeter beam

3.

intersecting beams

You should be able to draw working drawings for formwork. This will be checked by your instructor.


95

SECTION 1


ANSWERS

SELF-CHECK

EXERCISE 7: 1.

2.

CONCRETE CALCULATIONS

Calculate the amounts of concrete required for these slabs: 7m x 12m x 300mm

=

25.2 m3

8m x 20m x 250mm

=

40 m3

15m x 30m x 500mm

=

225 m3

Calculate the concrete required for these columns: 6m high x 1m in diameter

= 4.72m3

4m high x 600mm in diameter

= 1.13m3

10m high x 2m in diameter

= 31.42m3

EXERCISE 8:

PLATFORMS

Read the section carefully and find the words missing from the following sentences: 1.

A tower designed not to be moved is said to be Static.

2.

Mobile towers and platforms are usually used for Light work.

3.

Bracing is used so that a tower remains Rigid.

4.

Tie ropes are attached to Anchorage points.

5.

Tie ropes are set at an angle of 45º from the ground.


97

SECTION 2


ANSWERS

SELF-CHECK

EXERCISE 9:

SETTING OUT

Give a brief explanation of each of the following: 1.

Centre line

____________ A centre line is a line drawn through the centre of a proposed structure. 2.

Datum

____________________________________________ A datum is any set point in height. 3.

AHD

________________________________________ AHD means Australian Height Datum. 4.

AGS

___________________________________________ AGS is the Australian Grid System. 5.

Coordinates Coordinates are grid lines.


99

SECTION 2


ANSWERS

SELF-CHECK

EXERCISE 10:

SLAB AND BEAM FORMWORK

Prepare rough sketches with appropriate notes to explain the following: 1.

Soffit form

See Figures 31, 32 and 38

2.

Mounding

See Figure 35

3.

Guy ropes

See Figure 22

4.

Scaffold bracing

See Figure 23

See your instructor for verification.

EXERCISE 11:

SERVICE PENETRATIONS

a.

A penetration is a place in a beam or slab where concrete is laid.

False

b.

Penetrations are located from working drawings from grid points.

True

c.

Edges of penetrations in formwork are always constructed from wood. False

d.

Plywood forms are always braced with timber.

False

e. Timber penetration forms have overlapped edges so they can be dismantled easily. True


101

Formwork - Suspended Slabs

Recommend Documents