East Anglia Construction Safety Group 21 A pril 2011
Temporary Works What’s Changed
FÉDÉ FÉ DÉRATIO RATION N EUROPÉ EUROPÉEN ENE E D’ A SS SSOC OCIATIO IATIONS NS NATION NATI ONAL ALES ES D’ IN INGÊ GÊNI NIEU EURS RS The EUR EUR ING ING titl ti tle e deli delivered vered by b y FEANI FEANI is design desi gned ed as a guarantee gu arantee of compete com petence nce for profession pro fessiona al engi enginee neers rs in Europe Europ e. The EUR EUR ING NGss are list li sted ed in i n the th e FEAN FEANII Regis Register, ter, a database maint ained by the t he Se Secre cr etariat Ge General in Brus Br ussels. sels. Cur Currentl rentlyy over ov er 29,700 Europ ur ope ean Eng Engin ine eers are listed lis ted in the th e regi regist ste er (Oct (Octob obe er 200 2007). The Eur Europ ope ean Commis Comm issi sion on,, in a statement to the Euro Europea pean n Parl Parliament iament,, has recog r ecogni nize zed d the t he FE FEANI Regis Register ter and the th e EUR EUR ING ING titl ti tle e as valuable valuable tools for f or the th e recogn recognition ition of na n ational diplomas dip lomas among among member state st ates. s. " The FE FEANI sc scheme heme is an excellent example exampl e of selfregulation by a profe prof essi ssion on at Euro Europea pean n level level and it prov p rovides ides a mod mode el for other professional groups group s in the techni technica call and scientific se s ector. The Comm Commiss issio ion n consi co nsiders ders that an an engineer engineer who wh o has obta obt ained the title tit le of Eur Ing Ing shou s hould ld not n ot norm n orma allllyy be requi required red to unde und ertake an adapta daptatio tion n perio period d or sit an an apti aptitud tude e test. ( Directive 2005/36/EC .)"
Content 11 .. IInn tt rroo dd uu cc tt iioo nn 22 .. C Chh aa nn gg ee ss 22 00 00 99 -- 22 00 11 11 ((aa )) PPrr oo cc ee dd uu rr ee ss ((bb )) FFaa ll ss e w w oo rr kk ((cc )) SScc aa ff ff oo ll dd ii nn gg 33 .. C Chh aa nn gg ee ss iinn 22 00 11 11 ((aa )) W Wiinn dd ((bb )) FFoo rr m mw w oo rr kk
PPaarrtt O Onnee -- IInnttrroodduucc ttiioonn
“T e m p o r a r y W o r k s ” Definition:
Works undertaken during construction but not required to form part of the finally completed construction works. Includes the works to stabilise or protect an existing building or structure that are not intended to be permanent.
Cofferdams
Tower
Crane
Bases
Support to Cabins over River Thames
T e m p o r a r y F a ça d e R e t e n t i o n S t r u c t u r e s
Scaffolding
Upper Forth Crossing - 2008
27,000 ton
1.2 km
Steel wall formwork - Housing
Hin indh dhe ead Tun unnel nel A3
Nov ove emb mbe er 2009
Soffit Formwork and Falsework
Typic al c osts for a reinforc ed c onc rete fram e Item
m a t e r ia l c ost
labour & plant
% of total
Co n c re t e
15 %
8 %
23 %
Re in fo rc e m e n t
14 %
6 %
20 %
9 %
30 %
39 %
12 %
6 %
18 %
50 %
50 %
100%
Fo rm w o rk a n d falsework Su n d rie s e t c Totals
Source: Source: Formwork Formwork - a guide to good practice practice
PPaarrtt TTww oo -- CChhaannggeess 22000099 -- 22001111
(a (a )) R Ree m m iinn dd ee rr oo ff
The Law
aa nn d d
TW Proc edures
CDM 2007 Approved Code of Pra c t i c e a n d t h e
CDM Regs 2007 Document L144 March 2007 124 pages
£15 Source: http://books.hse.gov.uk Tel: 01787 881 165
Construction (Design and Management) Regs 2007 Approved Code of Practice (ACOP) 104 :
The design of temporary works, such as falsework, formwork and scaffolding, falls within the scope of the CDM 2007 Regs.. CDM co-ordinators have to take reasonable steps to ensure co-operation between permanent and temporary works designers, in particular to ensure that arrangements are in place to ensure that designs are compatible and that the permanent works can support any loadings from temporary works.
CDM Regs 2007 Industry Guidance for Designers
Published May 2007 (50 pages)
(Available as free *.pdf from Construction Skills )
Guidance for Designers (CDM07/4) 2.6.8 Designers need to consider how the structure can be constructed, cleaned, maintained and decommissioned. This may involve: checking that the overall design takes full account of any temporary works needed, no matter who is to develop those works. checking that consideration has been given to the availability of sufficient space and adequate ground support for large plant required to construct or maintain the structure.
B S 59 75 : 2 00 8 Code of prac t ic e for t e m p ora ry w o rk s procedures a n d t he perm issible st ress d e s i g n o e f nf ta l s e w o r k
1 of 10
m d m n o i 1 C 1 W 0 First published 1982 c i 2 .5 .1 l : b 1 u A 7 P + 1 8 r 0 d o 0 f n P e r m i s s ib l e St r e s s 2 a : t f 5 e s a 7 r 9 D S 5 d u r B o c e r £270 P 2 n o i t c e S Chairman: Frank Marples
Typical Register used as Active Site Document
2 of 10
A p p o i n t m e n t o f T e m p o r a r y W o r k s C o -o r d i n a t o r
7.3.1 The appointment of a temporary works co-ordinator (TWC) should be the first operation in a chain of events culminating in the construction of a Temporary Works scheme. The TWC should be appointed by the designated individual of the main or principal contractor. NOTE: In large organisations the TWC may be 7.1.2 It isbyessential for the TWC /tomanager be competent proposed a Contracts Director or similar have relevant up-to-date and both but theand designated individual should training be satisfied that qualifications the abilities experience appropriate the proposed TWC and has the outlined in 7.1.2 the complexity of the ofproject. beforetoconfirming acceptance the proposal. 3 of 10
Source BS 5975:2008+A1:2011
B S 5 9 7 5 :2 0 0 8
C la u s e 7 .2 .5
A c t iv it i e s o f t h e T e m p o ra r y W o rk s Co o r din a t o r c) ensure that a design brief is prepared with full consultation, is adequate, and is in accord with the actual situation on site; d) ensure that any residual risks, (assumed construction methods or loading constraints) are included; e) ensure a satisfactory temporary works design is carried out; f)
ensure that a design check is carried out by someone not involved in original design - for concept, structural adequacy and brief compliance;
n)
after a final check, which is satisfactory, ensure a permit to load is issued by either the TWC or TWS;
o)
when it has been confirmed that the permanent structure has attained adequate strength, ensure a permit to dismantle is issued by either the TWC or TWS;
4 of 10
( Sou
BS 5975:2008+A1:2011 )
Typic al let t er o f a p p o in t m e n t of a TWC
On larger sites the appointment of a Temporary Works Supervisor is also recommended
5 of 10
A p p o in t m e n t o f T e m p o ra r y Wo r k s Su p e rv is o r
7.3.1
On larger sites or where site manager or project manager considers it necessary, or where there are one or more subcontractors carrying out temporary works operations, or where the TWC requests assistance, one or more TWS’s may be appointed. The TWS should be appointed by the designated individual of the organisation for whose work the TWS is responsible.
6 of 10
Source BS 5975:2008+A1:2011
A p p o in t m e n t o f T e m p o ra r y Wo r k s Su p e rv is o r
6.4.5 Contractors carrying out a number of small contracts may appoint a TWC with overall responsibility and a TWS, with an appropriate level of authority for each individual site. 7.3.2
It is essential for the TWSs to be competent and to have relevant up-to-date training and both qualifications and the experience appropriate to the operations for which they are responsible.
7 of 10
Source BS 5975:2008+A1:2011
B S 5 9 7 5 :2 0 0 8 Category
O 1
2 3
Design Chec k Cat egories
Scope
Restricted to standard solutions Simple design
Independence
Site issue - by another member of site team or design team
( falsework top restraint is NOT assumed )
by another member of design team
More complex design.
by individual not involved in design and not consulted by the TW designer
excavations, structural steelwork, foundations, top restrained etc.
Complex or innovative design
by another organisation
8 of 10
Typical Permit t o Load
9 of 10
10 of 10
PPaa rrtt TT w w oo -- C Chh aa nngg eess 22 00 0099 –2 –2 00 11 11
((bb))
Falsework
Any tem porary struc ture used t o s u pp o rt a p e rm a n e n t s t r uc t u r e w h ile i t i s n o t s e l f -s u p p o r t i n g .
RMD-
Support of Twin wall and Precast soffit
B S EN 1 28 12 : 2 00 8 Falsework Published J a n u a ry 2 0 1 1
L im it S t a t e De s i g n
£170 Chairman: Frank Marples
1 of 4
B S E N 1 2 8 1 2 : 2 0 0 8 Design classes for falsework C la s s A
Dimensional limitations and generally restricts application to building work. Structural performance is derived from pre-existing knowledge of the performance of the components of the structure, such as props etc.. Such information is often included in standard solutions. Source NA.4
C la s s B
Falsework where a complete design is undertaken. There are two sub-classes. 2 of 4
Design classes for falsework
C la s s A
Class B 1
Slab area < 0.3 m² (ie 300mm) Beams
< 0.5 m²
Clear span < 6.0 m Height < 3.5 m (measured to underside of permanent works)
Design in accordance with relevant EuroCodes
Class B 2 Simplified design in BS EN 12812 and/or in accordance with relevant EuroCodes Most falsework in this class But there is a m x 1.15 3 of 4
B S 59 75 : 2 00 8 Code of prac t ic e for t e m p ora ry w o rk s proc edures and the perm issible stress d e s i g n o f f a ls e w o r k First published 1982
Pe r m i s s ib l e St r e s s
£270
4 of 4
Chairman: Frank Marples
B S 5 9 7 5 :2 0 0 8 N N ee w w LL oo aa dd iinn gg ss oo nn FFaa llss ee w w oo rr kk
Co n st r u c t io n Op e ra t io n s - Wo rk in g A re a L o ad Al A l l o w f o r a Serv Ser v i c e Clas Cl asss 1 l o ad o f o n l y 0.75 kN/m k N/m²² over the entire entir e area area,, includ inc luding ing access and workin wor king g areas. reas. i.e.
only on ly 30mm ext xtra ra co conc ncrete rete !
BS 5975 - The Britis Bri tish h Standard tandard Heap - Cl 17.4.3.1
1 of 3
Work ing Area Load
Working area Servic rv ice e Class Class 1 load 0.75 kN/m² BS 5975 Clause 17.4.3.1
2 of 3
A d d i t i o n a l T r a n s i e n t I n -s i t u C o n c r e t e In-situ concrete loading 0.75 kN/m² to 1.75 kN/m²
Load
Total load equal 3m 3m to 10% concrete load
Working area Service Class 1 load 0.75 kN/m² 2 of 3
In-situ Concrete Construction Operations Loads
Summary Thickness
calcs
Up to 300mm
0.75 + 0.75
300 to 700mm
0.75 + 10% t
Over 700mm
0.75 + 1.75
Total 1.50 kN/m2 0.75 +
10% of weight of concrete
2.50 kN/m2
Slab thickness t
3 of 3
1 of 1
Permanent formwork minimum construction load of 1.50 kN/m2
Working Areas - Access for striking Wherever falsework requires removal of individual pieces, for example striking primary or secondary bearers, consideration should be given to a working platform about two metres below the underside of the permanent works. Where the formwork and falsework is handled in large areas, provision for access to make-up areas should be considered. ( Use Service Class 1 load - 0.75 kN/m2 ) 1 of 2
BS 5975 Clause 19.1.1
Co n s i d e r a c c e s s u n d e r n e a t h f o r s t r ik in g
Tall frame structure
2 of 2
B S 5 9 7 5 :2 0 0 8 TT hh e FFoo uu rr D Dee ss iigg nn C Chh ee cc kk ss ff oo rr FFaa llss ee w w oo rr kk
Fa ls e w o rk A n a ly s is I t i s re c o m m e n d e d t h a t f o r e a c h f a ls e w o rk s t r u c t u r e FO U R d e s i g n c h e c k s b e c a r ri e d o u t :
C h e c k O N E - o n t h e S T R U C T U R A L S T R E N G T H o f t h e in d iv id u a l m e m b e rs a n d t h e ir c o n n ec t i o ns t o t r a n sm it t h e a p p lie d l o a d s / f o r c e s ;
C h e c k T W O - o n t h e L A T E R A L S T A B I L I T Y o f b ot h in d iv id u a l m e m b e rs a n d t h e s t r u c t u re as a w h o le ;
C h e c k T H R E E - o n t h e O V E R A L L S T A B I L I T Y of the falsew ork struct ure;
C h e c k F O U R - o n P O S I T I O N A L S T A B I L I T Y t o ensure
t h e fa ls e w o r k d o e s n o t s l id e .
THINK THINK
VERTICAL HORIZONTAL and then,
THINK
HORIZONTAL AGAIN and again, and a gain, and a gain.
BB SS 55 99 77 55 :2 :2 00 00 88 C Chh ee cc kk O Onn ee
St ru c t u ra l St re n g t h
B S EN 1 0 6 5 A d ju s t a b l e t e l es c o p ic st eel props
Pu b l is h e d N o v e m b e r 1 9 9 9 Committee: CEN
£150.00
1 of 6
Class A 25 A 30 A 35 A 40 B 25 B 30 B 35 B 40 B 45 B 50 B 55 C 25 C 30 C 35 C 40 C 45 C 50 C 55 D 25 to D55
Max. Extension 2.50 m 3.00 m 3.50 m 4.00 m 2.50 m 3.00 m 3.50 m 4.00 m 4.50 m 5.00 m 5.50 m 2.50 m 3.00 m 3.50 m 4.00 m 4.50 m 5.00 m 5.50 m 2.50m to 5.50m
Characteristic strength 20.40 kN 17.00 kN 14.60 kN 12.80 kN 27.20 kN 22.70 kN 19.40 kN 17.00 kN 15.10 kN 13.60 kN 12.40 kN 40.80 kN 34.00 kN 29.10 kN 25.50 kN 22.70 kN 20.40 kN 18.60 kN 34.00 kN
B S EN 1 0 6 5
Props to have minimum of 1.0m adjustment, and not to be intentionally dis-engaged 2 of 6
Ch a ra c t e ris t ic s t re n g t h is t h e v alu e at w h ic h 9 5 % o f t h o s e t e s t ee dd w ill fail a b o v e v a lu e
( iiee
55 % ee % w w iillll ffaa iill bb ee ll oo w w vv aa lluu )
3 of 6
Stellenbosch
- South Africa - 2009
Removed TWO internal walls
200mm thick x 14m slab
Supplier claim 29.80kN characteristic load
5 of 6
Thin walled props 3.2m (too short)
BS5975:2008 Safe Working Load - BS EN 1065 props erected 1o out-of-plumb with 10mm eccentricity of load
6 of 6
BB SS 55 99 77 55 :2 :2 00 00 88 C Chh ee cc kk TT w w oo
L a t e ra l St a b ilit y
BS 5975 : Horizontal Disturbing Force Clause 19.2.9.1
At each phase of construction falsework should resist the applied vertical loads PLUS a horizontal disturbing force the greater of EITHER
2 ½%
W
OR the summation of wind force, erection tolerance ( 1% W) , concrete pressure force, water and wave forces, dynamic and impact forces, forces from the permanent works (e.g. stressing etc.) etc..
Falsework’s horizontal disturbing force F H
Load W
Design for m in im u m la t e ra l st abilit y load of 2 ½% W o r k n o w n la t e ra l loads P L U S 1 % W
2 of 2
L oa d Ca s e 1 - Ere c t e d b ut n o t c o n c re t ed Lateral Forces :Maximum wind load plus 1% kn known own vertic vertica al loads (BS 5975 and Class B1) B1) Increases to at least 2% of kn know own n vertic vertica al loads if Class B2 B2
L o a d Ca se 2 - Wh ile p la c i n g t h e p erm a ne n t w o rk / c o n c re t e Lateral Forces :Working wind load plus 1% kn know own n vertic vertica al lo loa ads including full concrete load (BS 5975 and Class B1) B1) Inc ncrea reases ses to 2% kn know own n vertical loads if Class B2 B2 NOTE: If the structure is not connected to a permanent structure then the full wind load might need to be considered
U K B S 5 97 5 lo a d Ca se - M in im u m s t a b ilit y
Horizontal disturbing force FH will be a minimum of 2½ % total vertical load including self weight, concrete, and full construction operations load
T o p Re st r a in ed L o ad Ca se - c o nn ec t e d t o Pe rm a n e nt W ork s Restraining force RH will be a minimum of:-
2½ %
(vertical loads) (BS 5975 and Class A) or 2 % (self weight) plus maximum wind (Class B2) or NOTE: Although bracing is not shown, the 2 % (vertical loads) structural strength still needs checking plus working wind (Cat. 2) and bracing may be required to create effective nodes. (Class B1 and B2)
Condit ions of use stated by sup plier require t op restraint
1 of 3
2 of 3
North Staffs PFI SGB GASS braced for 2½ % W
Top restrained falsework
Or is it ?
L a t era l St ab ilit y o f s t ee l b e a m s - We b s t iffe n e rs
For structural steelwork at points of reaction or concentrated load, web stiffeners should be provided at ALL loading transfer points including supports, UNLESS calculations are provided to show that such stiffeners are not required.
Web stiffeners No Calculations (BS 5975 : Annex J Cla
J.1)
BB SS 55 99 77 55 :2 :2 00 00 88
Back flat
propping slabs
Formwork
Falsework
Backpropping
E u r o p e a n C o n c r e t e B u i l d i n g P r o j e c t (E C B P ) - 4 t h f l o o r
M e t hod One
-
On e le vel o f
b ac k p rop pin g
Distribution This isLoads 70% of Distribution ofof Applied Applied Load using Props using Elastic Rigid the Props applied load
NEW Slab to be cast Falsework load (w p )
and is in addition PROP PROP to the existing 100% load on the slab 100% 100% 100%
Supporting slab (1)
70% 50% - P p
SLAB SLAB
Backprops (w b1 ) Lower slab (2)
50% 30% + P p 50% 30% + P p
Wit h preloade d props t o v a l u e P p
BS 5975 Cl 19.3.4 Table 20
M et hod One
-
T w o levels of
bac k propping
Distribution of of Applied Loads Distribution Applied Loads This is 65% of Props load using Elastic Rigid Props the applied
is in SLABand PROP
NEW Slab to be cast Falsework load (w p ) Supporting slab (1)
addition to the existing 100%load on the slab 100% 100% 33% - P p 65%
Upper Backprops (w b1 ) Lower slab (2)
67% + P p 35% 33% 23%
Lower Backprops (w b2 ) Lower slab (3)
12% 33% + P p 33%+ P 12% p
W it h p r e lo a d e d p r o p s t o v a lu e
P
BS 5975 Cl 19.3.4
PPaarrtt TT w w oo -- C Chhaannggeess ssiinncc ee 22000099
((cc))
Scaffolding
T e m p o ra ry c o n s t ru c t i on , w h ic h is re q u ire d t o p r o vid e a s a f e p la c e o f w o rk f o r t h e e r e c t io n , m a in t e n a n c e , r e p a ir o r dem olit ion o f buildings an d ot her struc tures and for t he nec essary ac c ess
B S E N 1 2 8 1 1 -1 : 2 0 0 3 Part 1: Sc affolds - Performance requirem ents and general design
Publish ed J une 2 004
£ 1 8 2 .0 0 Chairman: CEN TC 53
“ States BS 5973 withdrawn”
B S E N 1 2 8 1 1 -1 Introduces:TWO Load Combinations : In Service Condition One platform with full imposed service load and the next above or below with 50% of service load Plus in absence of wind a lateral force of 0.3 kN / bay / working area Out of Service Condition Full wind load (BS EN 1991-1-4) and imposed Service Load limited to only 25% or 50%
T G 2 0 :0 8 V o l u m e 1
N A S C Gu i d e f o r Sc a ff old in g w it h t u b e s a n d f it t in g s
November 2008 120 pages Authors: Dr M.H.R. Godley Eur Ing P.F. Pallett
Based on BS 5973 and updated to BS EN 12811-1 with simplified BS 6399 wind information Information for erection and use of standard scaffolds and includes FOUR summary tables of safe heights for scaffolds Source : NASC
£135 + p&p
Vol 1 & 2
T G 2 0 :0 8 V o l u m e 2
November 2008 128 pages TECHNICAL DATA Information on weights and properties, additional wind info., worked examples, and method for height of unclad scaffolds. Safe Height tables for :3 tables fully loaded inside boards 3 tables part ledger braced scaffolds Fuller calculation method heights: 24 tables fully ledger braced 12 tables part ledger braced (alt. ties)
£135 + p&p
Vol 1 & 2
TG20:08 Supplement 1 February 2011 16 pages Takes account of the Wind Code BS EN 1991-1- 4:2005 + A1:2010 using a simplified method to update the SAFE HEIGHT tables for Basic Scaffolds Incorporates Apprendix H for use of ties on UNCLAD scaffolds erected to open structures.
Source : NASC
TG20:08 Overview T O OL B O X T A L K
Published by National Access and Scaffolding Confederation in July 2009
Plus a FREE Powerpoint toolbox presentation from www.nasc.org.uk £ 2 .5 0 Handy Pocket Sized booklet 4 of 4
Available from NASC
SG4 : 10 Preve nt ing Falls in Scaffolding
Published by National Access and Scaffolding Confederation with Foreword by HSE in December 2010
£25 60 pages Available from NASC
No longer permitted to traverse along a platform (known as tunnelling method) Create “ scaffolders safe zones”
SG4 : 10
For scaffolds with 2m lifts use of Step-ups
Figure 39
2 of 5
Erection hop-up for next guardrail
Quick release connection
SG4 : 10
Introduces use of ‘Scaffolders Safe Zone’
Reaching below guardrail “clip-on” Figure 9 Figure 12 4 of 5
S G 4 :Y o u
User Guide
Preve nt ing Falls in Sc affolding
Published by National Access and Scaffolding Confederation with Foreword by HSE ( 84pp January 2011)
Handy Pocket Sized booklet
5 of 5
£ 5 Available from NASC
Designation of Scaffolds to TG20:08
EXAMPLE
F 3 –5 - 1 S Load Class 3 (General Purpose)
Number of boards between standards
TG20 Cl 4.2 page 19
Number of inside boards ( 0, 1 or 2)
Inside boards Specialboards case Inside assumed lightly with loaded 1.8m fully loaded length I.e.bay Load Class
BASIC Scaffolds to TG20 Guide to T&F Scaffolds Part Boarded
Fully Boarded 2 m lifts with possible 2.7m pavement lifts
Tied to the building façade: either at alternate lifts 4m or at every lift Ledger bracing at alternate bays Façade bracing fitted every SIX bays but note: Plan bracing needed every FOUR lifts, and every twelve bays if façade braced across single bay
Load Desig tion Class
T h e c o n t r o llin g
Table 1
Activity
Load kN/m²
M ax Bay
0.75
2.7m
3
Max Boards
1
1-3-0
2
2-4-0
Light duty
1.50
2.4m
4
3
3-5-0 3-4-1 3-4-2 3-5-1 3-5-2
General purpose
2.00
2.1m
5
4-5-0 4-4-1 4-4-2 4-5-1 4-5-2
Heavy Duty
4
Inspection, v. light duty
4+1 4+2 5+1 5+2
( inside boards are 0.75 ) 3.00
( inside boards are 0.75 )
1.8m
5 4+1 4+2 5+1 5+2
Typical independent
tied scaffold
Ledger bracing alternate bracing every Ties Façade shown at alternate lifts bays SIX bays - to top platform
Plan bracing NOT required Tie assembly
Plan Façade bracingbracing REQUIRED every between SIXasbays - to top platform ties façade brace is NOT between ledger braced frames
H > 8m every FOUR lifts and every twelve bays Tie assembly
ALL sheeted & debris netted - unclad over 15m One transom at every lift within 300mm of ledger braced standards fitted with right angle or swivel fittings
Ledger bracing
Tie assembly
1 of 1
PPaa rr tt TT hh rr ee ee :: C Chh aa nn gg ee ss iinn 22 00 11 11
(a (a )) (b (b ))
W Wiinn dd FFoo rr m mw w oo rr kk
PPaa rr tt TT hh rr ee ee :: C Chh aa nn gg ee ss iinn 22 00 11 11
(a (a )) TT ee m m pp oo rr aa rr yy W W oo rr kk ss W W iinn dd
St a t u s o f W in d C o d e s in t h e U K
BS 6399-2: 1997 Loading for buildings, Part 2: Code of practice for wind loads, was published in July 1997 TG20 (scaffolding) first published in 2005 a simplified method based on BS 6399-2 Supplement No. 1 uses BS EN 1991-1-4+A1 The European Code BS EN 1991-1-4:2005+A1:2010 was amended in March 2011 (£246) The UK National Application Document (£170) was also amended in March 2011 The Background Information PD 6688 (£182) to the Annex was published in December 2009
ALL British Standards superseded by European Standards were withdrawn on 31st March 2010
Wind in Temporary Works Aim:
same procedure in all temporary works
Falsework - BS 5975:2008 +A1:2011 to introduce revised simplified method based on the UK NA to BS EN 1991-1-4 +A1 Scaffolding - TG20 Supplement No. 1 now issued Formwork - Revision will include the same method extended to suit climbing formwork. Duration of work
(assume less than two years)
Simplified method will use similar factors and town descriptions as existing for structures less than 50m with “ orography” and less than 100m without “ orography” .
Information needed by designer Location of the site How far from the nearest sea? less than 0.1km, 2 km, 10 km or 100 km Is it in a town that extends more than 2 km from the site in all directions? Is the topography fairly flat around the site, or is it near the top of the hill, or part-way up ? What is the altitude of site? (in metres Duration of work
above sea level)
(normally less than two years )
Is the falsework or the scaffold to be unclad, debris netted or sheeted?
Maximum wind pressure on falsework and formwork
qp = 0.7 × 0.613 × ce(z)ce, T ×
2 S wind
Where qp
is the peak wind pressure N/m²
Ce(z)c e,T is combined exposure correction factor
Swind is the wind factor for the site Formula is for falsework erected less than TWO years Sou
BS 5975:2008 +A1:2011 (Cl 17.5.1.3) and BS EN 12812 (Cl 8.2.4.1)
The wind factor Swind
A ⎞ ⎛ Swind = v b,map × Twind × ⎜1 + ⎟ ⎝ 1000 ⎠ Where v b,map is the fundamental wind velocity (in m/s) Twind is the topography factor allowing for whether site is on a hill, cliff or on the flat. A
1 of 8
is the altitude of the site in metres above sea level.
Mean hourly wind speeds
BS 5975:2008 Figure 4
10 minute mean wind speeds v b,map
T w i n d = T o p o g r a p h i c a l f a c t o r d e p e n d s o n w h e t h e r t h e t e r ra in a ro u n d t he sit e is flat , m oderat ely s t e e p (1 : 5 ) o r v e r y s t e e p (1 : 3 ) Structures without “orography”
3 of 8
Twind = 1.00
(z < 100m)
BS 5975 Figure 5 (a)
Topography Factor Twind
Skip wind
SEA
Definition of ‘sea’ from BS 6399
BS 5975:2008 Figure 7
TOWN
Built up areas BS 5975:2008 Figure 6 (a)
“TOWN”
Woodland areas
BS 5975:2008 Figure 6 (c)
COUNTRY
You’ll like this one !
Country is all terrain which is not sea or town ! Less than 2km of built-up area around the site.
COUNTRY
Built up areas BS 5975:2008 Figure 6 (b)
PPaa rr tt TT hh rr ee ee :: C Chh aa nn gg ee ss iinn 22 00 11 11
(b (b )) FFoo rr m mw w oo rr kk A s t r u c t u r e , u s u a l ly t e m p o r a ry , b u t in s o m e c a s e s w h o lly o r p a rt l y p e rm a n e n t u s e d t o c o n t a in p o u re d c o n c re t e t o m o u ld it t o t h e r e q u ir e d d im e n s io n s a n d s u p p o r t it u nt il it is a ble t o sup p o rt it self. It c o n s is t s p rim a rily o f t h e fa c e c o n t a c t m a t e r ia l a n d t h e b e a re rs t h a t d ire c t ly s u p p o rt t h e fa c e c o n t a c t m a t e r ia l.
Published by T h e Co n c r e t e So c ie t y
Sec ond Edition:
J une 1995
d e s i v R e 2 0 1 1 e u d C h a i rm a n : P e t e r P a l le t t
Skip to TWf
M o r e e m p h a s is o n p r o p rie t a r y p a n e l f or m w o r k
More guidance on Soffit Formwork systems
New Sections on Climbing Formwork
Update on Permanent Formwork - e.g. Twin wall
Significant updates to sections on:Surface finishes and tolerances to
BS EN 13670 “ Execution of concrete structures”
Striking and Curing
BS EN 1992-1-1:2004: Eurocode 2: Design of concrete structures. General rules and rules for buildings does not cover surface finishes (replaces BS 8110)
BS EN 13670: 2010 Execution of concrete structures. Includes informative guidance (£186 Feb 2010) Annex F Table F.4 Types of surface finish Basic Finish Ordinary Finish Plain Finish Special Finish
Where no particular requirement needed Where not of visual importance. e.g. unseen areas such as lift shafts Visual effect of some importance e.g. Seen occasionally, direct painted etc. Where special requirements needed. e.g. Where surface irregularity and colour are important.
Concrete Pressure envelope when placed from top
Pmax
Concrete stiffening
Design formwork pressures for a range of new cements and self-compacting concretes DTI Contract Ref: 39/3/739 CCC2399 September 2004 133 pages Quote: “ The findings indicate that the use of CIRIA R108 was conservative for the range of new concrete types for walls and columns. There appears to be no case for change from the existing UK approach to concrete pressure determination .” NOTE: The report is confidential and NOT available to the public. Se ticle in “CONCRETE” Ma h 2009
C o n c r e t e G r o u p s a n d t h e v a l u e s o f C 2 Group
A basic
Concrete
C 2
1. Without admixture -
0.3
2. With any admixture except with retarding property
0.3
CEM I (OPC) , SRPC, CEM II A with metakaolin or with silica fume
CEM I , SRPC, CEM II A with metakaolin / silica fume
3.
B retarded
With admixtures that retard - CEM I (OPC), SRPC, CEM I I A with metakaolin or with silica fume
0.45
4. Without admixture - CEM II A, CEM II B, CEM III A
0.45
5. With any admixture except with retarding property
0.45
CEM II A, CEM II B, CEM III A Self-compacting - With any admixture except with retarding properties. ALL cements except CEM III B & CEM IVB
0.45
C o n c r e t e G r o u p s a n d t h e v a l u e s o f C 2 Group
Concrete
6. With admixtures that retard
C 2
0.6
CEM II A, CEM II B and CEM III A
7. With or without admixtures
C heavily retarded
0.6
CEM III B and CEM IVB Self-compacting - With retarding properties ALL cements
0.6
Self-compacting - With any admixture except with retarding properties. CEM III B & CEM IVB
0.6
Table AA WALLS & B A SES P m a x (kN/m²) Basic Concrete Group A (1) CEM I (OPC) or (2) CEM I with admixture
H
Rate of Rise R in metres per hour 0.5 1.0 1.5 2.0 3.0 5.0 10.0
2m 40 45 3m 50 55 5 °C 4m 55 60 5m 65 65 6m 70 75 2m 35 40 3m80 40 55 45 10°C 4m 45 50 5m 55 45 55 6m 50 55
−
=
50 50 60 65 65 70 70 75 80 80 45 45 50 55 55 % 60 45 60 60 60 65
50 50 50 70 75 75 75 85 100 80 95 110 90 100 115 50 50 50 60 70 75 65 75 90 increase 70 80 100 75 85 105
2m 3m 15°C 4m 5m 6m
30 30 35 40 40
35 40 45 45 45
40 45 50 50 50
45 50 50 55 55
50 55 60 60 65
50 65 70 70 75
50 75 90 90 95
4m 20°C 5m
30 35
35 40
45 45
45 50
50 60
65 70
85 90
Table BB WALLS & B A SES P m a x (kN/m²)
H
Rate of Rise R in metres per hour 0.5 1.0 1.5 2.0 3.0 5.0 10.0
2m 3m 4m 5m 6m
50 50 50 50 50 50 50 65 70 75 75 75 75 75 75 80 85 90 95 100 100 85 90 95 95 105 110 125 95 100 100 105 110 120 135
2m 3m 4m 5m 6m 2m 3m 4m 5m 6m
40 50 55 60 65 35 40 45 50 50
45 55 60 70 75 40 45 50 55 60
50 60 65 70 75 45 50 55 60 65
50 65 70 75 80 45 55 60 65 65
50 65 75 80 85 50 60 65 70 75
50 75 85 90 95 50 70 75 80 85
4m 20°C 5m 6m
40 40 45
45 45 50
50 50 55
55 55 60
60 65 70
70 90 75 95 80 100
5°C
Retarded Concrete Group B (3) CEM I with retarder (4) Blend with 10°C <35% pfa or <65%ggbs (5) Blend <35% pfa <65% ggbs with admixture 15°C
50 75 100 100 115 50 75 90 100 105
Sustainable Forests Where timber is used in formwork, it is recommended that only material which is certified under the Forest Stewardship Council scheme should be used. This ensures that timber is sourced from FSC certified forests which are managed sustainably. There is a “ Chain of Custody” which tracks the timber from forest to consumer. Source www.fsc.org
Safe Working Properties - Timber in Wall formwork
Formwork to precast edge forms
Safe Working Properties - WALL Formwork
aann dd
ffiinn aall llyy
T W f
Temporary Works forum Promoting Temporary Works in the Construction Industry by : Institution of Civil Engineers Institution of Structural Engineers Health and Safety Executive Standing Committee on Structural Safety Chartered Institute of Building TW Equipment Suppliers Consulting Engineers Contractors Remit: Authoritative guidance, profesional leadership, interfaces PW & TW, current trends, warnings on unacceptable risks, recommend research areas, watching brief on overseas issues www.twforum.org.uk
Thank You
