Harpur Hill, Buxton SK17 9JN Telephone: +44 (0)114 289 2000Scaffold fans are described in BS 5973:...

Harpur Hill, Buxton SK17 9JN

Telephone: +44 (0)114 289 2000

Facsimile: +44 (0)114 289 2050

Scaffold Fan Testing

Report Number

HSL/2003/17

Project Leader: P D McCann

Author(s): R A Richardson

Science Group: Engineering Control

© Crown copyright 2003

iii

CONTENTS

1 Introduction..........................................................................................................11.1 Background ................................................................................................................... 1

1.2 Recommended fan structures ........................................................................................ 1

1.3 Observed fan structures................................................................................................. 2

2 Experimental procedure......................................................................................42.1 Fan configurations......................................................................................................... 4

2.2 Test items ...................................................................................................................... 6

2.3 Launch techniques......................................................................................................... 7

2.4 test procedure ................................................................................................................ 8

2.5 Instrumentation.............................................................................................................. 8

3 Results .................................................................................................................93.1 Initial testing.................................................................................................................. 9

3.2 Quick reference guide to results.................................................................................... 9

3.3 Examples of damage caused to fan ............................................................................. 15

4 Observations...................................................................................................... 174.1 Examination of trends ................................................................................................. 20

5 Further testing ................................................................................................... 225.1 Floor zero tests ............................................................................................................ 22

5.2 Guided transom ........................................................................................................... 22

5.3 Wet and dry board performance.................................................................................. 23

5.4 Double board testing ................................................................................................... 23

6 Conclusions and recommendations ................................................................ 256.1 Fan placement ............................................................................................................. 25

6.2 Pole spacing ................................................................................................................ 25

6.3 Fan and platform Gaps ................................................................................................ 25

6.4 Fan sheeting ................................................................................................................ 25

6.5 Double Boards............................................................................................................. 27

6.6 Trends.......................................................................................................................... 27

7 Appendix 1 Detailed test results tables............................................................ 288 Glossary ............................................................................................................. 40

iv

EXECUTIVE SUMMARY

HSL Field Engineering Section were contracted by HSE to carry out testing of scaffold

fans resembling those commonly used by industry. Representative fan structures were

constructed and instrumented to determine the effectiveness of these structures at

retaining typical building objects falling in likely scenarios.

�� The light duty style scaffold fans tested were not suitable for the retention of typical

building objects from drop heights of above 4.7 m.

�� Retention failure was more likely to be due to the falling object missing the fan than as a

result of structural failure.

�� Items impacting the fan directly above one of the supporting fan poles were more likely to

be retained than similar items impacting an unsupported region of the fan.

�� Many items, or parts of items, were not retained by the fan because they fell through the

gap between the fan and the working platform.

�� Some items bounced up off the fan and span through the air, landing as far as 10 m from

the centre of the fan. This could translate to a much greater distance if the fan were

mounted at a greater height, as it would be in practice.

�� An increase in the angle of incline of the fan did not appear to improve fan retention. In

fact the loss of horizontal surface area resulting from increased incline made it slightly

less likely that an object would impact the fan. With a steeper angle, it was also more

likely that objects would tumble down the fan and fall through the gap between the fan

and the working platform, or bounce off the fan onto the working platform.

�� Debris ejection extended as far as 20 m from the centre of the fan following fan impact.

�� High winds were a contributory factor to some falling objects failing to hit the fan.

�� Small items such as couplers and bricks did not generally cause much damage to the fan

structure although it was more common for them to miss, bounce off or fall through gaps.

�� The scaffold fans did not successfully retain the contents of the paint tins. The use of an

impermeable membrane covering the fan boards may help to prevent this.

�� There was little correlation between the fans that failed due to structural damage and the

peak load of the impact that caused the damage.

�� There was little relationship between the peak load and the drop height.

�� There was little relationship between the peak load and the impact board position.

�� Outer sheeting or netting could be considered to prevent falling debris missing the fan.

�� Further protection to the fan level platform should be considered where there is a

possibility of objects deflected inwards by the fan injuring personnel or building

occupants.

1

1 INTRODUCTION

1.1 BACKGROUND

Scaffold fans are structures attached to the perimeter of a building or scaffolding to prevent

objects that may accidentally fall from the structure causing damage or injury to property or

persons on the ground. The fan consists of a structure jutting out from the scaffolding, which is

fitted with boards or decking to catch falling debris. They are usually inclined towards to

scaffolding and can often be seen in towns and cities where the scaffolding is situated directly

above the pavement or road.

Following incidents of scaffold fan failure, the Health and Safety Laboratory (HSL), Field

Engineering Section (FES), Engineering Control Group were contracted by Martin Holden of

Construction Division Technology Unit to perform a series of tests to evaluate the performance

of scaffold fans in realistic situations.

1.2 RECOMMENDED FAN STRUCTURES

Scaffold fans are described in BS 5973: 1993 – Code of practice for access and working

scaffolds and special scaffold structures in steel, section 5, clause 25.1. The standard

describes four classes of fan for different applications, some examples of which have

been reproduced in figure 1 below.

Figure 1 Examples of scaffold fan classifications from BS5973

Light duty (class A) fan Medium duty (class B) fan Heavy duty (class C) fan

2

The standard defines the fans according to four classes of duty. These are as follows:

�� Class A – Light duty, maximum loading of 0.75 kN/m2 for protection from

falling paint and mortar.

�� Class B – Medium duty, maximum loading of 1 kN/m2, for protection from

aggregate and bricks falling from no more than 10 m.

�� Class C – Heavy duty, for protection from bricks falling further than 10 m or

larger heavier items.

�� Class D – (not shown) For protection from persons or similar weights falling

from less than 10 m.

1.3 OBSERVED FAN STRUCTURES

In practice, types of fan commonly used by industry are often very simple and resemble

class A most closely in their construction, though they rarely have support wires. They

appear to be used for protection against any possible falling debris that may arise from

the work being carried out on the scaffolding, its construction or decommissioning. This

may range from paint splashes to masonry and scaffolding components. There is also

generally only one fan per scaffolding, situated low down on the structure. Some typical

examples are depicted below.

A curved city centre fan with no support wires, but additional sheeted protection and toeboards

* constructors name removed

3

Steeply angled fan with trader directly beneath

Example of a fan that has collapsed under impact - note the scaffold boards forming the fan have not

been secured to the fan poles, thus when the fan collapsed, many of the boards also fell to the ground.

* constructors name removed

Unsheeted fan directly above access platform

4

2 EXPERIMENTAL PROCEDURE

A test program was specified to evaluate the performance of scaffold fans in realistic impact

scenarios. In order to observe the effects of differences in fan construction, several

configurations of fan were proposed. These were based on structures observed in industry.

Typical items that may be likely to fall from a scaffold were identified, as were the means by

which they may be likely to fall (launch technique). To represent the range of heights from

which a fan may be subjected to impacts, the Field Engineering 25 m test tower was used. The

test items were dropped onto the representative fan configurations from 2.7 m increments,

commencing from an initial height of 4.7 m above the fan.

2.1 FAN CONFIGURATIONS

The fans were constructed at a height of around 1.1 m from the ground for both configurations.

This is much lower than would be used in practice, but was necessary in order to gain frequent

access to the fan for replacement of damaged boards and poles. Boards used were those detailed

in table 1 and were stored outside under sheeting. The supporting structure was used for both

configurations and was built to a 2 m bay length, with one full lift height above the fan (2 m),

with longitudinal and ledger bracing (diagonal braces), to represent a typical scaffold structure.

Four types of typical fan construction were identified, two of which were tested.

2.1.1 Configuration D

Configuration D was the first to be built and tested. It was constructed with the fan virtually

horizontal by fixing the fan pole over the front ledger and under the rear ledger. This gave an

inclined fan angle of approximately 4 degrees. This is depicted below in figure 2.

1 2 3 4 5 6

4O

Figure 2 Side view of configuration D fan

2.1.2 Configuration A

The second fan type to be built and tested was configuration A, shown in figure 3 below. This

was built in a similar manner to configuration D but a second rear ledger was inserted, below

which the fan poles were attached. With the constraints of the surrounding tower structure, an

angle of 12 degrees was achieved which seemed to resemble many observed structures. In

addition, a toeboard was fixed to the rear of the fan, and another to the front of the working

platform, in an attempt to evaluate this technique for preventing objects from falling through the

gap between the fan and the working platform. The addition of this toeboard was to have been

configuration B, but it was decided that the effectiveness of the toeboard installation could be

assessed without the requirement of a separate set of tests.

5

12

34

56

12O

Figure 3 Side view of configuration A fan

2.1.3 Configuration C

Another type of fan, configuration C (shown in figure 4), was identified. Following testing of

configurations D and A it was decided not to test this configuration. Being of a steeper angle to

the other fans, it has a reduced horizontal surface area, which the results of configuration A

testing suggested would result in more objects missing. It was also thought to be a weaker

design to the other configurations due to the large lever effect generated by the high ratio of the

long boarded part of the fan pole to the short fixing part. Load would also be applied to the

underside of the working platform and there would be a high pivot load around the front ledger.

Since the other configurations had already failed at these pivots, it seemed unlikely that testing

this design would offer any improvement in performance.

Figure 4 Side view of configuration C Fan (not tested)

Examples of fan configurations: A D C

6

2.2 TEST ITEMS

Test items were chosen to represent typical objects that are commonly used while working on

scaffolds or during their construction. These test items are detailed in table 1 below.

Table 1 Test items used

Picture of item Specifications

10 N block

Dimensions: 440x215x100 mm

Approximate wet weight: 20 kg

Thermal block



Engineering brick


Approximate wet weight: 2.5 kg wet

5 L paint tin

Dimensions: 178 diameter x 223 mm

Approximate weight 80% full: 5.2 kg

Scaffold board



1.2m galvanised steel scaffold pole (transom)

Dimensions: 1200 x 49OD x 41ID

Weight: 5.4 kg

7

90 degree scaffold coupler

Weight: 0.9 kg

Swivel scaffold coupler

Weight: 1 kg

2.3 LAUNCH TECHNIQUES

The open structure of the test tower also allowed the fan performance to be evaluated against

different launch techniques. The launch technique for each test item was chosen to represent the

way or ways in which it may be likely to fall from the scaffold. Release methods used were:

�� Straight drop – this was the most straightforward and repeatable drop method.

The item was held, by its centre, over the handrail and dropped in an attempt to

land squarely in the centre of the fan. This method was applied in both

configurations to scaffold board (end on), 1.2 m transom (end on) and scaffold

coupler. It was applied in configuration A only to engineering brick, thermal

block, 10 N concrete block and 5 litre paint tin.

�� Pivot over handrail – the scaffold board was rested with its centre on the

handrail and pivoted upwards until it slipped over the rail. This method was

applied to both configurations, but only using scaffold board.

�� Roll off – the 1.2 m transom was aligned parallel with the edge of the working

platform and rolled until it fell from the tower. This method was applied to both

configurations, but only using the 1.2 m transom.

�� Slid off – the item was placed near the edge of the tower floor and pushed off

using the foot. This method was applied to engineering brick, thermal block and

10 N concrete block in both configurations. In configuration D, it was also

applied to the 5 litre paint tin.

�� Bounce off – a 45o

springboard was manufactured, which was placed such that

an item bounced from it would just clear, or lightly catch the edge of the tower

floor. This was achieved by placing the springboard outer edge at around 400

mm from the outer edge of the working platform. This method was applied to

scaffold coupler, engineering brick, thermal block and 10 N concrete block, in

both configurations.

8

2.4 TEST PROCEDURE

The test program covered a height range of 7.4 m to 20.9 m in increments of 2.7 m, although

some extra tests were carried out from 4.7 m in configuration D. Where quoted, the drop height

is the distance between the floor of each drop level and the centre of the fan. Each item released

from over the handrail was thus released with its centre approximately 1 m above this height.

A number board was used for identification with a unique test number for every test. The first

digit of this number identifies the release floor of the test tower. Testing was carried out from

ascending floors. If structural failure occurred, no more similar tests were carried out using that

item from subsequent floors.

Immediately prior to the test, coupler slip potentiometer amplifiers were zeroed, logger and

cameras set running. With the area clear, the test item was released using the specified method.

After impact, cameras and loggers were stopped and a detailed digital photograph was taken

from a fixed location directly above the fan. Coupler slip values, resting place of the test item,

impacted board(s), fan retention and damage were noted.

The impacted boards, if any, were replaced after every test and labelled with the test number

and their position within the fan. Replacement boards were stored outside under sheeting. The

fan structure was checked after every test and repaired or replaced if necessary. The four

couplers supporting the fan were reinstalled to a torque of 60 Nm each time they were moved or

replaced.

Many of the configuration D tests that involved sliding an item off the tower, frequently missed

the fan. In order to explore the structural limitations of the fan with these items, the tests were

repeated until contact was made. In configuration A, testing also included straight drop tests.

These were carried out until the item passed through the fan structure. This was in addition to

the slide off tests that were carried out from every floor to give an impression of debris scatter.

Similarly, bounce tests were only carried out from ascending heights until the test item was no

longer retained.

2.5 INSTRUMENTATION

The ground around the fan structure was marked with circular lines designating every 2 m from

the centre of the fan. A video camera was situated directly overhead, with a wide field of view

to pick up debris dispersion. Another camera, synchronised with the first, was situated directly

in front of the fan, focused on the structure. A detailed digital photograph of the fan was taken

after every test where fan impact had occurred.

50 kN shearbeam loadcells were attached between the base of each of the four standards

(vertical poles) and plates that were firmly secured to the ground. This method allowed both

positive and negative loading measurements to be taken. Additionally, each of the four couplers

that supported the fan structure was fitted with a 25 mm linear potentiometer to measure

slippage. Eight Fylde 379TA amplifiers were used with the transducers. Loadcell data was

logged at 10 kHz using a laptop computer fitted with a data acquisition card. Potentiometer

readings were taken manually before and after each test. Loadcell and potentiometer data was

also recorded at 3750 Hz using an Earth Data Recorder S/N 8730 as a backup and in the event

of live potentiometer data being required at a later date.

Calibration of all instrumentation was carried out against externally calibrated references in

accordance with internal procedures. Data analysis was carried out using Jandel Scientific

Sigma Plot software.

9

3 RESULTS

3.1 INITIAL TESTING

An initial period of testing was carried out from tower floor 4 (15.5 m) to evaluate the

suitability of the chosen test regime. Results gained from this testing can be found in table 2 in

the appendices.

A straight drop 21-foot scaffold pole (standard) was to have been one of the tests, but an initial

test (test D58) proved that this was difficult to manoeuvre on the tower and would pass through

the fan from all drop heights. It was substituted with the 1.2 m transom straight drop test.

The bounce test launch technique was altered to make it more realistic. The bounce board had

been situated flush with the edge of the working platform, but all of the test items bounced well

clear of the fan, even when lower levels were tried. This is a likely possibility in a working

environment with, for instance, a scaffold board propped up between the building wall and the

toe board. To gain more information and represent more scenarios it was decided that the item

should just clip the edge of the test tower floor as it bounced over the edge. To achieve this, the

springboard was moved back by 400 mm from the edge.

3.2 QUICK REFERENCE GUIDE TO RESULTS

The following figures 5, 6, 7, 8 and 9 are a quick reference guide to the tests carried out for

which the fan failed to retain the dropped item. There are two figures per configuration of

scaffold fan tested. These differentiate between those items that were not retained because they

caused structural failure to the fan, for example broke through one or more boards, and those

items that rebounded off the fan, or missed it entirely.

Each item is represented as an icon. The release method applied to it is represented by an action

mark. A key on each figure explains the designation of each symbol.

The position of the icon on the horizontal (debris scatter) scale indicates the final distance

between the centre of the fan the farthest extreme of the item, or debris from it. Scatter was not

measured beyond 12 m, so those items in the 12 m+ range could have scattered much further.

Icons, which appear below zero on the horizontal debris scatter scale, are those objects that fell

through behind the fan. This could either be the entire item, or a significant part of it, and could

also be due to the item rebounding off the fan and working platform mesh.

The position of the icon on the vertical (floor height) scale indicates, to the nearest lift, the

height above the fan from which it was released. This height was measured between the centre

of the fan and the floor of the lift, so those items released over the handrail (straight drop and

pivot release) will be centred approximately 1m higher than the indicated height.

The text adjacent to the icons on Figure 6 and Figure 8 indicates the fan board or boards were

impact occurred. Boards are numbered from the tower outwards as indicated on the fan drawing.

Similarly the red stars on Figure 5 and Figure 7 differentiate between those items that missed

the fan entirely, and those that rebounded off. Objects that were retained by the fan are not

shown. Figure 9 is a summary of the lowest failure heights for each object.

The figures are proportionally scaled. Spreadsheets giving more detailed results can be found in

Appendix 1.

10

0

2.0

4.7

7.4

10.1

12.8

15.5

18.2

20.9

6

5

4

3

2

1

0

-1

-1.1

1 2 3 4 5 6

0 2 4 6 8 10 12 +

Flo

or

He

ight

(m)

Debris Scatter (m)

Be

hin

d F

an

Be

hin

d F

an

Items

Scaffold Board

1.2m Steel Transom

Engineering Brick

Thermal Block

10N Concrete Block

Scaffold Coupler

5L Paint Tin

Release Methods

PivotedOver

Handrail

Roll Off

Slid Off

Bounced Off

Straight DropOver Handrail

Items that missed the fan

Figure 5 Items that were not contained because they missed or bounced off the fan, showing drop height, release method and debris scatter, configuration D

11

0

2.0

4.7

7.4

10.1

12.8

15.5

18.2

20.9

6

5

4

3

2

1

0

-1

-1.1

1 2 3 4 5 6

0 2 4 6 8 10 12 +

Flo

or

He

ight

(m)

Debris Scatter (m)

Items

Scaffold Board

1.2m Steel Transom

Engineering Brick

Thermal Block

10N Concrete Block

Scaffold Coupler

5L Paint Tin

Release Methods

PivotedOver

Handrail

Roll Off

Slid Off

Bounced Off


Board 6

Board 3

Boards 2 & 3

Boards 2 & 3

Figure 6 Items that were not contained due to fan structural failure, showing drop height, release method, debris scatter and impact board(s), configuration D

12

0

2.0

4.7

7.4

10.1

12.8

15.5

18.2

20.9

6

5

4

3

2

1

0

-1

-1.1

1 2 3 4 5 6

0 2 4 6 8 10 12 +

Flo

or

He

igh

t (m

)

Debris Scatter (m)

Behin

d F

an

Items

Scaffold Board

1.2m Steel Transom

Engineering Brick

Thermal Block

10N Concrete Block

Scaffold Coupler

5L Paint Tin

Release Methods

PivotedOver

Handrail

Roll Off

Slid Off

Bounced Off


Items that missed the fan

Figure 7 Items that were not contained because they missed or bounced off the fan, showing drop height, release method and debris scatter, configuration A

13

0

2.0

4.7

7.4

10.1

12.8

15.5

18.2

20.9

6

5

4

3

2

1

0

-1

-1.1

1 2 3 4 5 6

0 2 4 6 8 10 12 +

Flo

or

He

igh

t (m

)

Debris Scatter (m)

Items

Scaffold Board

1.2m Steel Transom

Engineering Brick

Thermal Block

10N Concrete Block

Scaffold Coupler

5L Paint Tin

Release Methods

PivotedOver

Handrail

Roll Off

Slid Off

Bounced Off


Board 6

Board 2

Board 6

Board 2

Board 6

Boards 3 & 4 Board 6

Board 3

Board 4

Boards 4, 5 & 6

Boards 1 & 2

Figure 8 Items that were not contained due to fan structural failure, showing drop height, release method, debris scatter and impact board(s), configuration A

14

0

2.0

4.7

7.4

10.1

12.8

15.5

18.2

20.9

6

5

4

3

2

1

0

-1

-1.1

1 2 3 4 5 6

0 2 4 6 8 10 12 +

Flo

or

Heig

ht (m

)

Debris Scatter (m)

Items

Scaffold Board

1.2m Steel Transom

Engineering Brick

Thermal Block

10N Concrete Block

Scaffold Coupler

5L Paint Tin

Release Methods

PivotedOver

Handrail

Roll Off

Slid Off

Bounced Off


Behin

d F

an

Behin

d F

an

Figure 9 Lowest height of failure for each object – click on icon for video of drop

15

3.3 EXAMPLES OF DAMAGE CAUSED TO FAN

Floor 1 (7.4 m) minimal damage caused to boards 3, 4 & 5

Floor 2 (10.1 m) block fractures board 6 and bends centre pole

Floor 3 (12.8 m) block fractures board 6 and bends centre pole

DSC_1841

DSC_1851

DSC_2058

As a comparative

example of typical fan

damage, the following

pictures were taken

immediately after

impact. They show the

damage caused by a

10 N concrete block as

it was slid from the

floor of the working

platform during

testing from ascending

floors of the tower.

16

Floor 4 (15.5 m) block destroys board 6 and significantly distorts centre pole

Floor 5 (18.2 m) boards 4,5 & 6 shattered, centre pole very distorted and half block dropped

Floor 6 (20.9 m) boards 1 & 2 shattered

DSC_2070

DSC_2077

DSC_2081

DSC_2070

17

4 OBSERVATIONS

�� Peak loads recorded at the front standard feet were positive (downwards) where those of

the rear standards were negative (upwards). This can be explained by the construction of

the fan configurations tested. The three fan poles pivot about the front ledger (supported

by the front standards) applying a downward load to the front standards and an upward

load to the rear standards. Coupler slip, where it occurred, was in the same direction as

the load.

�� The 10 N concrete block tests shattered the fan boards from the lowest scheduled drop

height (7.4 m) in both configurations (Tests D104 and A104). Further testing was carried

out from 4.7 m on configuration D to investigate this further (see section 6).

�� The 1.2 m transom, when dropped end-on in both configurations, punched through the fan

board from the 7.4 m (Tests D108 and A108). In both tests, the transom had impacted the

fan at the gap between boards two and three. Further testing was carried out to evaluate

this failure by replicating the impact (see section 6).

�� The scaffold board, dropped end-on in configuration D, (Test D507) punched through the

fan board from floor 5 (18.2 m). In configuration A (Test A307), this occurred at floor 3

(12.8 m). This is likely to have been because the board hit the area of the fan supported by

the centre pole in test D507 where it impacted on an unsupported area of board in A307.

This theory is borne out by test D307, where the board landed square on the centre of the

fan board, the centre tube again provided extra support. This caused significant damage to

the structure, but did not completely fracture the impact board.

�� Several items that were not retained by the fan bounced off to the side. On a scaffold, a

fan that was more than one bay wide may well have retained these items providing the

item had not fallen adjacent to one of the ends.

�� Some items, or parts of items, were initially retained by the fan, but rolled down the

inclined surface, or rebounded, through the small gap between the fan and the working

platform. These gaps were frequently present in the observed scaffold fans, so this effect

could present a serious problem. Even when extra toeboards were fitted to the rear of the

fan and to the front of the working platform, some items still rebounded over the fan

toeboard and fell through the gap. This effect makes it impossible to say that fan is safe

for use at any particular height below the working platform without introducing other

controls.

�� Some items, scaffold boards in particular, bounced up off the fan and span through the air,

landing as far as 10 m from the centre of the fan. This could translate to a much greater

distance if the fan were mounted higher up, as it would be in practice. Theory would

suggest that any object that falls with a long edge at an angle of less than 90 degrees off

the perpendicular will spin in the direction of that angle upon impact with the fan. This is

explained in figures 10.1, 10.2 and 10.3.

18

Figure 10.1 Board drops at a slight angle off perpendicular

Figure 10.2 Board impacts fan. Momentum acting on the board at the point of impact is taken up by bending of the fan poles and boards causing the bottom of the board to slow. Momentum acting on the top of the board remains unhindered. This is now travelling faster than the bottom of the board, causing it to rotate

Figure 10.3 Fan springs back up applying force upwards into the bottom of the board (now the left), further increasing rate of spin and/or height of bounce

19

�� The increase in the angle of incline of the fan between configuration D and A did not

appear to significantly improve the retention. In fact the loss of horizontal surface area

created by the added incline (680 cm2) made it fractionally less likely that an object

would impact the fan. Also the steeper the angle, the more likely it was that objects would

tumble down the fan and fall through the gap between the fan and the working platform,

or bounce off the fan onto the working platform.

�� Spray from 10 N blocks that missed the fan extended as far as 20 m from the centre of the

fan. Also on several occasions, some large pieces of debris dropped though board gaps.

On one occasion (Test A513) a large piece of block bounced over the top of some brick

guard that had been erected to protect the working platform to handrail height (1 m).

�� The effect of wind on falling objects such as scaffold boards and transoms was quite

considerable. Many tests had to be repeated or postponed due to high winds blowing

falling boards way off course. Some boards were blown away from the fan and missed as

a result. In test A406, the board was blown into the tower as it fell, ripping away the brick

guard from the fan level working platform and impacting a support pole in the gap

between the two toe boards. Wind effects may not have been as pronounced had the tower

not been an open structure, but it is worthy of consideration.

�� Small items such as couplers and bricks generally did not cause much damage to the fan

structure although a brick did pass through a configuration A fan board from floor 5 (18.2

m) in test A502. It was however more common for them to either miss or bounce off the

fan. They were also more likely to fall through the gap between the fan and the working

platform.

�� The scaffold fans did not successfully retain the contents of the paint tins. They were

relatively capable at retaining the tins, but some form of waterproof sheeting over the fan

would be required to retain the contents.

�� In configuration A, slide off tests were only carried out from floors where the items had

not previously been retained in configuration D tests. This was to give a comparison of

the configurations and an impression of debris scatter. These tests were in addition to the

straight drop tests that used the same item until failure. Similarly, bounce tests were

carried out in configuration D from every floor, where in configuration A, they were only

carried out until the test item was no longer retained. The combination of these

differences in test techniques largely accounts for the reduction in items shown on Figure

7 over those shown in Figure 5.

�� During scheduled testing, all fan boards were clipped to the outer fan poles using putlog

clips. No boards became detached from the fan poles due to coupler failure. During

double board testing the fan boards were clamped between parallel poles. These

frequently fell off, or opened as a result of an impact. It is likely that having the board

firmly clamped to the structure is beneficial in spreading the load.

20

Tower Floor

0 1 2 3 4 5 6 7

Pea

k L

oad

(kN

)

0

2

4

6

8

10

12

14

16

Impacts causing structural failure - Configuration DImpacts causing structural failure - Configuration AAll other Impacts - Configuration DAll other impacts - Configuration A

Figure 11 Graph showing relationship of drop height to impact load

4.1 EXAMINATION OF TRENDS

It was expected that there would be some correlation between impact load and structural failure.

The assumption being that high impact loads would be most likely to cause failure of the boards

or poles forming the fan. To examine this relationship in further detail, the greatest of the peak

loads from each impact was plotted against the tower floor from which the item was dropped.

Symbols designate which impacts had caused structural failure. See figure 11 below. The graph

shows structural failures occurring randomly though the range of loads for each tower floor.

This indicates that there is no relationship between the peak load recorded at the base of the

standards and the failure of fan boards and poles. In fact the findings also suggest that there is

no relationship between the peak load recorded at the base of the standards and the drop height.

21

It was considered that there might be a relationship between the impact board and the peak load

due to the lever action of the fan. The assumption being that objects impacting the fan at the

outer extremities would generate greater loads due to lever action. However, this could be offset

by greater elasticity in the system at the outer boards due to pole and board bending. To

examine the hypothesis, a graph showing the greatest of the peak loads from each impact was

plotted against the impact board with symbols to designate which impacts had caused structural

failure. See figure 12 below. The graph suggests a slight tendency towards a reduction in impact

load at the outer boards, which would indicate that the elastic effect is greater than the lever

effect. A greater sample density and more controlled tests would be required to evaluate this to

any degree of accuracy.

Impact Board

0 1 2 3 4 5 6 7

Pe

ak

Lo

ad

(kN

)

0

2

4

6

8

10

12

14

16

Impacts causing structural failure - Configuration D

Impacts causing structural failure - Configuration A

Other impacts - Configuration D (excluding couplers)

Other impacts - Configuration A (excluding couplers)

Average (impacts to boards 1 & 4.5 ignored)

Figure 12 Graph showing relationship of impact board to impact load

22

5 FURTHER TESTING

Some further testing was carried out as a variation from the scheduled test programme to

evaluate different aspects of scaffold fan retention.

5.1 FLOOR ZERO TESTS

For tests where items had not been retained by the fan from floor 1 (7.4 m) in configuration D,

the tests were repeated from floor 0 (4.7 m) onto a configuration D fan. The fan performed

significantly better at this height, retaining all but one item. See also 5.2 Guided Transom.

�� The slid off 10 N block test (Test D002) landed across boards 3, 4 & 5 giving a peak load

of 6.27 kN and fracturing boards 3 & 4 but not penetrating the fan.

�� The end-on 10 N block (Test D007) was retained, giving a peak of 8.7 kN. However,

given that the safe working load of a coupler is 6.25 kN these findings would suggest that

using a fan even at this height should be treated with caution.

�� The bounce test of the brick (Test D005) was retained and gave a peak load of 1.6 kN

�� The bounce test of the thermal block (Test D006) fell spinning, hit board 2 and cart

wheeled off the front of the fan. It failed to clear the 2 m ring and gave a peak of 6.2 kN.

The effect of the spin may be significant as there is nothing to suggest that it would

otherwise not have been retained at this height.

5.2 GUIDED TRANSOM

In test D308 (and also subsequently in test A308), the fan had failed to retain the 1.2m transom

with an end on drop from the lowest scheduled drop height (7.4 m). The sharp circular end of

the transom had struck the fan at the gap between boards 2 and 3, impacting the edge of board 3.

Following this failure it was decided to repeat the test from the level below, floor 0 (4.7 m).

To replicate the point of impact it was necessary to construct a wire guide mechanism for the

transom. Two nylon bushes were manufactured and inserted a few centimetres into each end the

transom so as to not affect the sharp edge of the tube. A small hole in the centre of these bushes

acted as a low friction guide when run down a taught length of Bowden cable that passed

through the fan at the gap between boards two and three. Even using this guide mechanism, five

tests were required to achieve two accurately reproduced impacts (Tests D003, D004, D008,

D009 and D010). The transom was retained in each of the five tests, giving peak loads of

between 4 and 5 kN. The closeness of these results suggested that the fan performance may be

repeatable.

23

5.3 WET AND DRY BOARD PERFORMANCE

Additional testing was carried out to compare the performance of those fans constructed from

wet boards and those using dry boards. All boards were taken from the same batch, which had

been stored outside under sheeting. The dry boards had been placed in a dry room for at least 36

hours. They were tested for moisture content prior to testing and gave an approximate indicative

average of 14% moisture. All wet boards had been left outside and soaked with a hose pipe

prior to testing. They were tested for moisture content prior to testing and all readings were

above the 25% indicative maximum moisture content that could be read by the instrument. All

tests were carried out from the top floor (20.9 m) using a 1.2 m transom that was rolled off from

the working platform.

�� The two dry boards transmitted a higher peak loading to the structure than the wet boards.

A peak of 10.0 kN in test D6dry1 and 9.5 kN in test D6dry2 compared with 9.0 kN in

D6wet1 and 7.3 kN in D6wet2.

�� Only D6dry1 retained the transom.

�� D6wet2 and D6dry2 had board penetration.

�� The greatest coupler slip occurred in test D6wet1, this was only 0.5 mm.

5.4 DOUBLE BOARD TESTING

To examine the effect of board strength on fan retention, testing was carried out using double

boards on fan configuration D. The modified configuration is shown in figure 13 below. Six

boards were placed tight against one another to form the lower level. Onto these, five boards

were placed such that they overlapped the gaps between the lower boards. The boards were

clamped using poles running parallel to the fan tubes. 10 N blocks were dropped onto the fan

from each floor using a straight drop over the handrail.

Figure 13 Double board arrangement on configuration D

�� The fan retained the block from all but the floor 3 drop.

�� Significant damage was caused to the fan poles from floors 3, 4, 5 & 6.

�� The clamping tubes were parted by the impact on all tests.

24

�� The floor 1 drop (Test D120) caused slight damage to upper boards 3, 4 & 5. Peak Load

was 9.7 kN.

�� The floor 2 drop (Test D220) caused two boards to split, one across the impact point and

one down the length. There was significant coupler slip. Peak Load was 11.7 kN.

�� The floor 3 drop (Test D320) caught the edge of the fan, grazing the edge of upper board

5, passing through lower board 6 and bending the centre fan pole. Peak Load was 8.9 kN.

�� The floor 4 drop (Test D420) caused damage to three of the upper boards, and bent all of

the poles in the fan structure. Peak Load was 10.3 kN.

�� The floor 5 drop (Test D520) caused damage to two upper boards and split two lower

boards. The left hand and centre fan poles were bent. Peak Load was 13.7 kN.

�� The floor 6 drop (Test D620) smashed two upper boards and 1 lower board, damaging

several others. Left hand and centre fan poles and the front ledger were significantly bent.

Peak Load was 21.1 kN. The centre fan pole was struck with such force that it retained

the shape of the impact item.

25

6 CONCLUSIONS AND RECOMMENDATIONS

6.1 FAN PLACEMENT

Testing of both configurations of fan revealed that the 10 N block and 1.2 m transom shattered

the fan boards and fell to the ground from all 7.4 m straight drops. All objects that had not been

retained by the fan at 7.4 m in Configuration D were retested at 4.7 m. The items that had not

previously been contained due to structural failure were all retained when further testing was

carried out. This suggests that where there is any risk of similar objects falling from the

structure, a fan should be placed no greater than 4.7 m below the working level. It should be

noted that only nine tests were performed from 4.7 m, so it is entirely possible that a falling

object may penetrate the fan from this height if more tests were carried out.

6.2 POLE SPACING

During testing it was noticed that items impacting the fan directly above one of the supporting

fan poles were more likely to be retained than similar items impacting an unsupported region of

the fan. This was often at the sacrifice of the fan pole. The fan configurations used in testing had

bay lengths of 2 m, with transoms and fan poles spaced at 1 m intervals. It may be possible that

fan retention may be improved by decreasing the fan pole spacing. However, this would greatly

increase the weight of the fan and thus increase the load on the supporting ledgers and couplers.

6.3 FAN AND PLATFORM GAPS

When constructing a scaffold fan, the location of the standards and ledgers can lead to a gap

being formed between the inner fan board and the outer board of the platform (assuming a

platform is present at fan lift). This gap can often be sufficiently large to allow smaller items,

part items, or larger items with a small impact face (for example a scaffold board falling end-on)

to pass through. Some items, or parts of items, were initially retained by the fan, but tumbled

down the inclined surface and fell or rebounded, through the gap. This still occasionally

happened when extra toe boards were fitted to the front of the working platform and to the rear

of the fan. The findings suggest that these gaps must be filled, possibly by introducing other

controls such as fan sheeting.

6.4 FAN SHEETING

Many items that impacted the fan did not penetrate the boards, but were not retained because

they bounced off the fan. This was a particular problem with scaffold boards, that bounced up

off the fan and span through the air, landing as far as 10 m from the centre of the fan. This could

translate to a much greater distance if the fan were mounted at a greater height, as it would be

on a service scaffold. An increase in the angle of the fan did not appear to improve the

performance in this situation. The only item not to be retained at 4.7 m was a bounce test using

a thermal block (test D006). The thermal block bounced off the fan and cart wheeled in a

manner similar to that depicted in figure 10.

Similarly, 10 N blocks frequently broke up into many fragments on impact with the fan or the

ground beneath. The debris scatter from these impacts extended as far as 20 m from the centre

of the fan. Also on several occasions, some large pieces of debris dropped though board gaps.

This was also a problem with the contents of paint tins. In one test, a large piece of block

bounced over the top of some debris netting that had been erected to protect the working

platform to handrail height (1 m). This suggests that the level at which the fan is mounted

26

should be further protected where there is a risk of objects deflected inwards by the fan injuring

personnel or occupants of the building.

The vast majority of items that were not retained by the fan were dropped as a result of missing

it. This became increasingly likely with height. A six-board fan is a very small target from 25

m. The effect of wind on falling objects was also quite considerable, with many larger items

missing the fan or colliding with the test tower due to strong gusts changing their direction as

they fell.

Many of these effects may possibly be reduced or prevented by the use of sheeting and/or

netting on the scaffold structure. For instance, sheeting or netting extending vertically from the

outer edge of the fan, in the plane of the building, could prevent items bouncing off the fan from

being ejected. Also the use of an impermeable membrane covering the fan boards could prevent

paint from pouring through. If the membrane was manufactured from a relatively tough

material, it could also help to retain small rebounded items or debris and help to block the fan to

platform gap. Sheeting or netting running from the outer edge of the fan up to the height of the

working platform may help to guide falling objects and prevent them from missing the fan.

Some possible methods are shown in figure 14 below although these would require further

testing to indicate if any advantage is gained from their usage.

Figure 14 Possible methods of sheeting a fan

27

6.5 DOUBLE BOARDS

It appeared from the testing of double boarded fans in configuration D, see section 5.4 that there

was an improvement in retention. The double-boarded fans were only tested with straight drop

10 N blocks. Although significant damage was caused to the structure by the impacts, the blocks

were retained from all but the third floor drop height (12.8 m). The third floor failure was due to

the block grazing the outer edge of the fan rather than landing squarely on the boards. This

testing suggests that double boards could be used to reduce the likelihood of objects not being

retained due to board failure.

6.6 TRENDS

There appeared to be little correlation between the fans that failed due to structural damage and

the peak load of the impact that caused the damage. In fact, further analysis suggested that there

was also little relationship between the peak load and the drop height.

There was a suggestion of a possible relationship between the peak load and the impact board

position. The loads plotted on figure 12 appear to tail off slightly towards outer extremities of

the fan. On closer examination though, taking the average of the values at each board position

follows a sine wave pattern. There is such a large variation in the loading at each board position

that this may be completely meaningless.

Where tests were replicated for drop height, drop item and impact position, the peak loads were

very similar.

28

7 APPENDIX 1 DETAILED TEST RESULTS TABLES

Table 2 Results of preliminary testing from floor 4 (15.5 m)

Test Item Drop method

Impact

board

Distance

from fan

Sensor

location

Positive

peak load

Negative

peak load

Coupler

slip

(m) (kN) (kN) (mm)

Loads exceeding 6.25 kN SWL of coupler

D49 Coupler Straight drop 2 Retained Rear left 1.2973 -0.8895 0

retest Rear right 1.002 -1.1723 -0.02866

Front left 3.9992 -2.1219 0.26271

Front right 3.2741 -1.658 -0.1144

D50 Brick Slid off 4 Retained Rear left 1.0074 -1.4398 -0.0574

retest Rear right 0.8316 -1.3426 0.02866

Front left 3.1953 -1.2931 0.2919

Front right 3.5256 -1.5462 0.143

D51 Thermal block Slid off 3 Retained Rear left 1.7052 -3.4546 0.1148

retest Rear right 1.6132 -3.597 0

Front left 5.9014 -2.5563 3.38604

Front right 5.6167 -2.4777 0.2574

D52 10 N block Slid off 4 Punched Rear left 1.5136 -3.6954 0

through Rear right 1.9588 -2.9858 0.05732

Front left 6.7052 -2.9008 3.47361

Front right 4.4151 -2.296 -0.3146

D54 Scaffold board Pivoted All 2 – 4 Rear left 2.1819 -3.3613 -0.2009

Rear right 1.8586 -2.2995 0.1433

Front left 6.5804 -2.6611 3.88227

Front right 4.2055 -2.3426 0.1144

D55 Scaffold board End-on 0 Retained Rear left 1.7986 -1.5136 -0.0861

(miss) Rear right 1.4178 -2.6201 0

Front left 1.9022 -1.9522 -14.7701

Front right 3.2973 -1.6114 1.2298

D56 1.2 m transom Roll off 2 Retained Rear left 2.6143 -2.4718 0.0287

Rear right 1.2224 -2.3496 -0.11464

Front left 4.8479 -1.9771 4.93311

Front right 6.1197 -1.9793 0.0858

D58 21' standard Straight drop 5 Punched Rear left 1.8477 -1.5627 -0.4305

through Rear right 0.9819 -2.029 0.31526

Front left 3.465 -1.4828 3.94065

Front right 3.6839 -2.459 0.0286

D59 Coupler Bounce Miss 4

D60 Brick Bounce Miss 5

D61 Thermal block Bounce Miss 3

D62 10 N block Bounce Miss 3 - 20

Demo1 10 N block Straight drop 3 &4 Rear left -0.7462

Rear right 0.34392

Front left -0.49623

Front right 0.4004

29

Table 3 Results of configuration D testing

Test Item Drop method

Impact

board

Distance

from fan

Sensor

location

Positive

peak load

Negative

peak load

Coupler

slip

(m) (kN) (kN) (mm)



Rear right 0.9819 -0.9769 0.02866

Front left 2.5613 -1.4629 -0.11676

Front right 1.4996 -1.0665 -0.0286

D102 Brick Slid off 4 Retained Rear left 0.7912 -1.199 -0.1435

Rear right 1.002 -1.3226 0.11464

Front left 3.2902 -1.3381 0.05838

Front right 1.7278 -1.7046 -0.143

D103 Thermal block Slid off 2, 3, 4 Retained Rear left 1.6315 -2.3293 0

Rear right 1.3927 -2.029 0.02866

Front left 5.7267 -2.6561 3.38604

Front right 5.2534 -1.5462 -0.286

D104 10 N block Slid off 6 2 - 4 Rear left 1.9902 -3.8134 -0.1722

Rear right 1.3977 -2.9107 0.20062

Front left 8.0682 -4.2189 3.67794

Front right 6.2314 -2.9993 -0.1144

D105 5 L Paint tin Slid off No Retained Rear left 1.1103 -2.0238 0

damage Rear right 0.7512 -1.6567 0

Front left 4.5584 -2.2048 0

Front right 2.5206 -1.1671 0

D106 Scaffold board Pivot 5 2 - 4 Rear left 1.8477 -4.4866 0

Rear right 1.6382 -3.1061 -0.08598

Front left 7.6788 -3.1205 12.3182

Front right 4.7504 -2.4823 0.8866

D107 Scaffold board End on 4 2 - 4 Rear left 2.688 -3.72 0.2296

To side Rear right 1.543 -3.2013 -0.1433

Front left 5.6068 -2.2417 3.29847

Front right 5.9566 -2.3659 0.7722

D108 1.2 m transom End on 3 2 Rear left 1.7494 -2.0148 -0.1148

Rear right 0.9769 -1.2725 0.05732

Front left 4.3137 -1.7325 0.23352

Front right 3.3905 -1.2947 0

D109 1.2 m transom Roll 5 2 - 4 Rear left 1.3661 -2.3293 -0.1148

To side Rear right 1.3927 -1.6883 0.02866

Front left 3.1953 -2.3666 0.61299

Front right 2.8922 -2.4777 0

D110 Coupler Bounce 1 Retained Rear left - - 0

Rear right - - 0

Front left - - 0

Front right - - 0


D112 Thermal block Bounce Miss 2 - 3

D113 10 N Block Bounce Miss 1 - 2

30


Rear right 1.4178 -1.6633 0

Front left 3.1454 -2.4165 0.11676

Front right 2.8689 -2.501 0.0858

D202 Brick Slid 2 Retained Rear left 2.8551 -2.0394 0

Rear right 1.7134 -1.8085 0

Front left 4.2189 -1.7325 0.40866

Front right 2.4125 -1.4065 0.0286

D203 Thermal block Slid off 6 2 Rear left 2.1131 -3.6709 -0.1722

Rear right 1.3226 -2.2244 0.05732

Front left 4.9278 -2.1918 2.48115

Front right 3.5488 -2.0911 0.0572

D205 5 L Paint tin Slid off 3 Retained Rear left 1.2236 -1.7789 0.0287

Rear right 1.1022 -1.7635 0

Front left 3.0456 -1.9522 0.05838

Front right 2.7292 -1.8629 0.0286

D206 Scaffold board Pivot 2 6 Rear left 2.2064 -3.145 0.4305

Rear right 2.054 -2.7654 -0.1433

Front left 5.6568 -2.1219 1.4595

Front right 5.1649 -1.7046 0.2574

D207 Scaffold board End on 2 4 Rear left 3.8379 -3.4546 0.2009

Rear right 2.1041 -3.4017 -0.05732

Front left 7.1196 -1.9022 2.01411

Front right 8.1176 -1.9793 0.3718

D209 1.2 m transom Roll 4 Retained Rear left 1.5824 -3.2384 -0.4879

Rear right 1.543 -1.6633 0.17196

Front left 6.0961 -2.8259 -0.08757

Front right 3.4138 -1.9561 -0.3432

D210 Coupler Bounce 1 Retained Rear left 0.7666 -0.6487 0

Rear right 0.6362 -0.6362 0

Front left 2.4115 -0.9286 0.05838

Front right 1.9561 -0.8197 0


D212 Thermal block Bounce 5 2 - 3 Rear left 2.6389 -4.0787 0.0861

To side Rear right 1.7134 -2.029 0

Front left 10.2401 -5.512 10.2165

Front right 3.139 -3.4324 -0.6292

D213 10 N block Bounce 4 - Rear left 3.0713 -3.9608 -0.2583

Rear right 1.2474 -3.8676 0.22928

Prop left in Front left 5.2174 -5.7267 -0.46704

Front right 8.0291 -4.3871 0.143

D214 10 N block Bounce Miss 3

D301 Coupler Straight drop No - Rear left 1.4153 -1.0565 0.0574

damage To side Rear right 1.1723 -1.1723 0

Front left 3.8744 -2.3915 0.05838

Front right 1.7511 -1.2249 0.0286

D302 Brick Slid 6 6 Rear left 0.9091 -2.0639 -0.1148

Rear right 0.9268 -1.2224 0.08598

Front left 3.415 -1.6576 0.46704

31

Front right 2.324 -1.3413 -0.1144

D303 Thermal block Slid off 5,6 2 Rear left 2.4718 -3.2384 0.1435

Rear right 1.5681 -3.0309 0.05732

Front left 6.8999 -3.1454 16.6091

Front right 4.2102 -3.0691 -0.8866

D305 5 L Paint tin Slid off 6 3 - 5 Rear left 1.6757 -2.6635 0

Rear right 1.6132 -2.57 0

Front left 5.1175 -2.9507 0.05838

Front right 4.6154 -3.1809 0

D306 Scaffold board Pivot Repeat 4 - 5 Rear left 0.3342 -0.3587 0

Rear right 0.3657 -0.511 0

Front left 0.5143 -0.679 0

Front right 0.4098 -0.34 0.0286


Rear right 2.1041 -2.7153 -0.05732

Front left 9.2116 -2.5363 1.72221

Front right 7.121 -1.9561 -0.1716

D309 1.2 m transom Roll 4,5,6 7 Rear left 1.7494 -2.403 -0.0574

Rear right 1.2975 -2.1993 0.08598

Front left 6.8251 -3.8045 1.80978

Front right 4.5688 -2.8689 -0.286

D310 Coupler Bounce 6 2 Rear left 0.2162 -0.1671 0

Rear right 0.1703 -0.2705 0

Front left 0.4144 -0.5392 0

Front right 0.5449 -0.34 0


D312 Thermal block Bounce 4 Retained Rear left 1.2973 -2.7372 -0.287

Rear right 1.7635 -3.2764 0.1433

Front left 9.5311 -2.9058 0.43785

Front right 6.8462 -2.7944 -0.143

D313 10 N Block Bounce Miss 9

D314 Scaffold board Pivot 3 7 Rear left 2.1573 -2.6635 0.2296

Rear right 1.8837 -2.8606 -0.17196

Front left 5.2873 -2.3166 0.52542

Front right 5.6632 -1.8396 0.1716

D401 Coupler Straight drop 2,3 Retained Rear left 1.1057 -0.8157 0.0574

Rear right 1.1773 -1.1222 -0.02866

Front left 2.9757 -1.3181 -0.17514

Front right 1.7744 -0.8616 -0.1716

D402 Brick Slid Miss 2

D403 Thermal block Slid off 4 Retained Rear left 1.9214 -3.0959 0.0861

Rear right 1.8586 -3.056 0.08598

Front left 8.3378 -3.1454 0.61299

Front right 7.0744 -2.9993 0.2002

D404 Brick Slid off 2 Retained Rear left 1.2567 -2.0187 0.1148

Rear right 1.2554 -2.1867 -0.05732

Front left 8.7117 -2.3023 0.17514

Front right 3.6877 -1.3297 -0.1716

D405 5 L Paint tin Slid off 4 4 Rear left 1.7986 -2.5406 0.0861

32

Rear right 1.4679 -2.2995 0

Front left 5.8015 -2.9257 0.17514

Front right 3.6373 -2.6826 0.1144

D406 Scaffold board Pivot 6 4 Rear left 1.9657 -2.806 -0.3444

Rear right 1.3727 -2.1292 0.20062

Front left 5.8015 -3.3152 0.2919

Front right 3.982 -2.7524 -0.2002


Rear right 1.6382 -3.0059 -0.20062

Front left 9.7508 -2.4364 -2.45196

Front right 6.1197 -1.7744 -3.4034

D409 1.2 m transom Roll Miss 5

D410 Coupler Bounce No Retained Rear left 0.1179 -0.1229 0


Front left 0.1448 -0.2946 0

Front right 0.1118 -0.1583 0

D411 Brick Bounce Miss 4 - 8

D412 Thermal block Bounce Miss 3.5-7


D414 Brick Slid off Miss 2

D415 Brick Slid off Miss 3

D416 1.2 m transom Roll 3 Retained Rear left 1.2482 -2.0148 -0.2583

Rear right 1.4428 -1.5631 0.2866

Front left 6.6303 -2.7061 0.35028

Front right 7.9593 -1.8629 -0.286

D501 Coupler Straight drop

2,3

floor 4 2Wrong

Floor

D502 Brick Slid 4 Retained Rear left 1.4398 -2.2556 -0.0287

Rear right 1.543 -2.8105 0.02866

Front left 4.8479 -2.0969 0

Front right 2.9807 -1.9095 0

D503 Thermal block Slid off 3,4,5 Retained Rear left 2.231 -4.5112 -0.1148

Rear right 1.543 -2.7404 0.11464

Front left 9.7758 -4.3636 0.46704

Front right 6.4363 -2.9807 -0.0572

D505 5 L Paint tin Slid off 6 2 Rear left 1.9657 -2.9731 0.0287

Rear right 1.7635 -3.2263 0.05732

Front left 5.4321 -3.3651 1.48869

Front right 5.3465 -3.4091 0

D506 Scaffold board Pivot 6 2 - 5 Rear left 0.7912 -0.8157 0.0287

Rear right 1.1022 -1.6132 0

Front left 1.4379 -1.1933 -0.02919

Front right 2.9807 -1.7278 0.0286

D507 Scaffold board End on 2,3 2 Rear left 1.032 -1.317 -0.0287

Rear right 1.1272 -1.7835 -0.02866

Front left 2.1169 -1.343 -0.14595

Front right 2.1377 -1.2481 -0.2574

D509 1.2 m transom Roll Inside 6 Rear left 2.3047 -3.0468 0.0861

mesh Rear right 1.6633 -1.9087 -0.02866

33

3 Front left 5.8764 -4.2438 0.43785

Front right 2.5475 -2.0445 0.1716

D510 Coupler Bounce Miss 4


D512 Thermal block Bounce Miss 4



Rear right 0.9819 -1.4428 0.02866

Front left 4.6832 -1.8773 0

Front right 1.821 -1.1364 -0.0858


Rear right 1.1523 -1.2975 0

Front left 4.5334 -1.9272 -0.08757

Front right 3.139 -0.7964 -0.0858

D602 Brick Slid 1,2 Retained Rear left 1.9902 -1.7052 0.0861

Rear right 1.8586 -2.0039 -0.02866

Front left 7.9484 -2.4864 0

Front right 8.1642 -2.9807 -0.0286

D603 Thermal block Slid off Miss

D605 5 L Paint tin Slid off 5,6 Retained Rear left 2.0148 -3.145 0

Rear right 1.6633 -2.3246 0.05732

Front left 5.9463 -3.44 0.93408

Front right 4.5688 -2.9108 -0.0572

D606 Scaffold board Pivot Miss 8

D609 1.2 m transom Roll 1,2,3, Retained Rear left 1.1303 -2.688 -0.3444

4,5 Rear right 1.6883 -3.2764 0.31526

Front left 8.8521 -2.072 0

Front right 5.9613 -2.4078 0.0572

D610 Coupler Bounce 3 Retained Rear left 0.6978 -0.8649 0.0287

Rear right 0.6362 -0.7064 0

Front left 2.6561 -2.3166 0

Front right 1.4112 -0.7498 0


D612 Thermal block Bounce Miss 2 - 4

D613 10 N Block Bounce 6 0-20 Rear left 0.6732 -0.6732 0

Rear right 0.9819 -1.0971 0

Front left 1.3381 -1.1234 0

Front right 2.3892 -1.318 0

D614 Thermal block Slid off 2,3 Retained Rear left 2.1376 -3.9854 0.1435

Rear right 1.6883 -3.3015 -0.17196

Front left 7.5839 -2.4364 0.23352

Front right 6.7111 -2.1377 -0.1144

D615 Scaffold board Pivot Miss 10

D616 Scaffold board Pivot Centre 3 Rear left 0.6241 -0.5258 0

pole Rear right 0.516 -0.9018 0

Front left 0.659 -0.6091 0

Front right 0.8663 -0.475 0

D6dry1 1.2 m transom Roll 4,5 Retained Rear left 2.0394 -3.8871 0.0574

Rear right 1.9338 -3.0309 -0.02866

34

Front left 10.0204 -4.3137 0.17514

Front right 5.5049 -2.2029 0.0572

D6dry2 1.2 m transom Roll 5 2 Rear left 2.3981 -3.9608 -0.0574

Rear right 1.2725 -2.1041 0

Front left 9.5311 -3.8294 0.02919

Front right 2.9574 -2.4078 -0.0572

D6wet1 1.2 m transom Roll 6 4 Rear left 2.0639 -3.7642 0

Rear right 1.1523 -2.1292 0.08598

Front left 9.0418 -4.5334 0.46704

Front right 4.0006 -2.1843 0

D6wet2 1.2 m transom Roll 5,6 0 Rear left 2.5947 -3.8871 -0.0287

Rear right 1.1272 -1.6132 0

Front left 7.2644 -5.0227 -0.02919

Front right 2.8409 -2.501 0.0572

Further testing

D001 1.2 m transom Straight drop

Not

required

D002 10 N block Slid off 3,4,5 Retained Rear left 1.7494 -2.5455 -0.0574

Rear right 1.7635 -2.7404 0

Front left 6.2659 -3.4849 -0.23352

Front right 4.7318 -2.9574 -0.0572

D003 1.2 m transom Guided 2 Retained

D004 1.2 m transom Guided 2,3 Retained Rear left 1.2236 -1.5578 0

Rear right 0.9569 -2.029 0

Front left 4.3137 -1.8523 0

Front right 3.8236 -1.3646 0

D005 Brick Bounce 3 Retained Rear left 0.7175 -1.032 -0.0287

Rear right 0.8066 -1.1472 0.05732

Front left 3.0506 -1.6077 -0.11676

Front right 2.7524 -0.7964 0.0572

D006 Thermal block Bounce 2 2 Rear left 1.6806 -2.2802 -0.2009

Rear right 1.1272 -2.1993 0.1433

Front left 6.2409 -3.0206 0

Front right 3.6606 -1.998 -0.0286

D007 10 N block End on 3,4 Retained Rear left 2.1327 -5.1598 0.3444

Rear right 2.4949 -5.2603 0

Front left 8.7023 -3.8045 17.1929

Front right 8.2993 -1.6813 -0.1144

D008 1.2 m transom Guided 2 Retained Rear left 1.2482 -1.7494 0.0287

Rear right 1.2474 -2.1492 -0.02866

Front left 4.094 -2.4614 -0.02919

Front right 5.3186 -0.9082 -0.0572

D009 1.2 m transom Guided 2 Retained Rear left 1.3661 -1.4398 0.0574

Rear right 1.1973 -2.0791 0

Front left 4.1689 -1.6077 0.02919

Front right 5.7983 -1.3413 0

D010 1.2 m transom Guided 2,3 Retained Rear left 1.1008 -1.489 -0.0861

Rear right 0.9318 -2.1292 0.02866

Front left 4.094 -1.7325 0

35

Front right 3.4371 -1.5928 0

D120 10 N block End on Upper Retained Rear left 1.6561 -4.7028 -0.1148

double board 3,4,5 Rear right 1.6633 -3.9377 0.20062

Front left 9.7258 -2.9757 0

Front right 7.2095 -3.2741 -0.0572

D220 10 N block End on Upper Retained Rear left 1.4153 -5.2778 0.3444

double board 2,3,4 Rear right 1.6883 -4.6491 -0.20062

Lower Front left 11.678 -3.1654 23.0893

3 Front right 7.2327 -2.1144 -0.0858

D320 10 N block End on Upper 4 Rear left 2.0885 -4.7274 0.1722

double board 5 Rear right 1.6633 -4.0329 -0.17196

Lower Front left 8.8521 -3.5348 0.43785

5,6 Front right 6.1197 -2.7944 0.6292


double board 3,4,5 Rear right 1.543 -4.0129 0.51588

Front left 10.285 -3.0955 -0.99246

Front right 8.7091 -2.8875 -0.3432


double board 3,4 Rear right 2.8856 -5.2603 0.2866

Lower Front left 13.6751 -4.144 16.2588

3,4,5 Front right 8.3924 -3.1809 11.0968

D620 10 N block End on Upper Retained Rear left 3.6463 -5.4006 0

double board 1,2 Rear right 4.3786 -4.6491 0.05732

Lower Front left 21.1092 -2.3166 20.0535

1,2,3 Front right 10.3485 -1.8163 -0.429

Table 4 Results of configuration A testing

Test Item Drop method Impact

board

Distance

from fan

Sensor

location

Positive

peak load

Negative

peak load

Coupler

slip

(m) (kN) (kN) (mm)


A101 Coupler Straight drop 1,2 Retained Rear left 0.6978 -0.8157 0

Rear right 0.8066 -1.0771 0

Front left 1.4179 -1.0235 0

Front right 1.0712 -0.6334 0

A102 Brick Straight drop 2,3 Retained Rear left 1.6806 -2.2064 -0.0861

Rear right 2.034 -2.2244 0

Front left 2.5563 -1.6376 -0.2335

Front right 4.6619 -1.0712 -0.2288

A103 Thermal block Straight drop 1,2 Retained Rear left 2.2556 -2.9485 0

Rear right 2.3947 -3.3015 0

Front left 5.8265 -1.9771 -0.1168

Front right 5.7098 -2.3193 -0.1716

A104 10 N block Straight drop 6 0 Rear left 0.8157 -2.6635 -0.2009

Rear right 0.6362 -2.8155 -0.7451

Front left 3.6597 -0.704 -0.4670

Front right 4.4337 -1.2714 -0.3146

A105 5 L Paint tin Straight drop 3 Retained Rear left 1.6561 -2.5898 -0.0287

Rear right 1.3927 -2.3746 0.05732

36

Front left 4.5334 -1.343 -0.1751

Front right 4.2987 -1.5229 -0.1144

A106 Scaffold board Pivot 2 6 Rear left 2.9288 -3.0222 0

Rear right 1.9588 -2.2995 0

Front left 9.1666 -2.072 -0.0292

Front right 4.2102 -2.3845 -0.0572

A107 Scaffold board End on 3 3 Rear left 2.5455 -4.0787 -0.0861

Rear right 2.1041 -3.7674 -0.3439

Front left 5.512 -1.8773 0.05838

Front right 6.3479 -2.8875 -0.143

A108 1.2 m transom End on 2 0 Rear left 2.7814 -2.8797 0

Rear right 1.2725 -2.4197 -0.0287

Front left 2.9257 -1.393 -0.0876

Front right 4.3452 -1.3879 -0.0858

A109 1.2 m transom Roll 4 Retained Rear left 3.0222 -4.8011 0

Rear right 3.2564 -3.1061 -0.0287

Front left 6.4107 -2.6312 0.14595

Front right 3.5023 -2.2075 0.0572

A110 Coupler Bounce 4,5 Retained Rear left 0.4816 -0.575 0

Rear right 0.3908 -0.6362 0

Front left 0.6341 -0.7339 -0.0292

Front right 0.9547 -0.6334 0

A111 Brick Slid off Miss 3 Rear left 0.6914 -0.8378 0.0287

Rear right 0.957 -1.3068 0

Front left 1.6511 -1.3537 0.05838

Front right 2.8268 -1.6549 0

A112 Thermal block Slid off 3,4 Retained Rear left 2.3735 -3.5284 -0.0287

Rear right 2.1292 -2.8856 -0.086

Front left 5.7017 -2.2667 -0.0584

Front right 4.3452 -1.9561 -0.0572

A113 10 N block Slid off 3,4,5 Retained Rear left 2.6635 -5.1107 0

Rear right 2.4247 -5.7212 -0.086

Front left 7.2395 -2.8059 0.20433

Front right 11.6199 -4.0937 0.2288

A201 Coupler Straight drop No Retained Rear left 0.863 -0.7116 0


Front left 1.528 -0.6256 0

Front right 1.3536 -0.5357 0

A202 Brick Straight drop 2,3 Retained Rear left 1.5578 -2.231 0

Rear right 1.5931 -1.8586 0

Front left 2.9507 -1.1733 -0.1168

Front right 4.0472 -1.7278 -0.1144

A203 Thermal block Straight drop 1,2 Retained Rear left 2.4227 -3.5284 0.0574

Rear right 2.1542 -4.2082 -0.0573

Front left 11.1388 -1.8573 0.05838

Front right 7.5727 -1.8396 -0.0286

A205 5 L Paint tin Straight drop 3,4 Rear left 1.2973 -2.5406 0

Rear right 1.4679 -2.2043 0

Front left 4.8979 -1.8273 0.08757

Front right 4.1357 -1.5276 0

37

A206 Scaffold board Pivot Miss 3

A207 Scaffold board End on 1,2 4 Rear left 1.9214 -2.9288 -0.0861

Rear right 2.034 -2.8606 -0.0287

Front left 8.8022 -2.2917 0.20433

Front right 4.8203 -2.3193 0.0572

A209 1.2 m transom Roll 3,4 Rear left 2.6849 -3.5984 0.0287

Rear right 1.559 -2.4593 -0.086

Front left 4.4558 -2.3279 -0.2043

Front right 2.9894 -1.6788 -0.1144

A210 Coupler Bounce 6 4 Rear left 0.9583 -0.8403 0

Rear right 0.6863 -0.7565 0

Front left 1.7325 -1.4629 0

Front right 1.0013 -0.8616 0

A211 Brick Slid off 6 3 Rear left 1.8231 -2.0885 0

Rear right 1.2474 -1.8336 0

Front left 3.2652 -2.2417 0.05838

Front right 2.2308 -1.7278 0

A212 Thermal block Slid off 6 4 Rear left 2.4718 -5.0861 0

Rear right 1.4178 -2.5199 -0.086

Front left 5.487 -3.7995 0.23352

Front right 3.9354 -2.6826 0.1144

A213 10 N block Slid off 6 2 Rear left 1.8969 -2.8305 0

Rear right 1.8136 -2.4448 -0.0287

Front left 5.8515 -3.8993 -0.0292

Front right 3.5023 -2.7757 0

A301 Coupler Straight drop No Retained Rear left 1.2728 -1.032 0


Front left 2.5363 -1.6825 -0.0584

Front right 2.4125 -1.1597 0

A302 Brick Straight drop 4,5 3 Rear left 2.1819 -2.3293 -0.0287

Rear right 1.4929 -2.4197 -0.0287

Front left 2.6112 -1.388 -0.0876

Front right 3.0924 -1.9561 -0.0286

A303 Thermal block Straight drop 1,2,3 Retained Rear left 2.4964 -4.3687 0

Rear right 2.7404 -2.8406 0

Front left 12.8213 -2.4165 -0.146

Front right 7.6426 -2.4078 -0.1716

A305 5 L Paint tin Straight drop 2,3 Rear left 1.8477 -3.2138 0.0287

Rear right 1.3176 -2.4247 -0.086

Front left 8.4876 -1.8723 0.08757

Front right 4.3406 -1.7046 0.1144

A306 Scaffold board Pivot Miss 7

A307 Scaffold board End on 2 0 Rear left 2.3047 -2.1573 0

Rear right 2.1542 -3.1562 0

Front left 3.8494 -1.3181 -0.0292

Front right 4.0006 -1.3879 -0.0286

A309 1.2 m transom Roll 5 Retained Rear left 2.7372 -4.9191 0.0574

Rear right 2.1542 -2.029 -0.0573

Front left 6.9948 -4.099 0.26271

Front right 3.3672 -2.8642 0.0572

38

A310 Thermal block Bounce Miss 3.8 - 20

A311 Brick Slid off 6 Retained Rear left 1.5332 -2.5947 -0.0287

Rear right 1.1723 -1.8085 0

Front left 3.8993 -2.1968 0

Front right 2.5242 -1.5229 -0.0572

A312 Thermal block Slid off No 2 Rear left 1.5578 -2.8797 0

damage Hit centre Rear right 2.1793 -1.7384 -0.172

pole only Front left 2.756 -1.6576 -0.0292

Front right 2.1377 -1.318 -0.0286

A313 10 N block Slid off 6 0 Rear left 1.3219 -1.8969 0

Rear right 1.0771 -3.2764 0.05732

Front left 3.465 -1.8523 0.14595

Front right 3.4138 -1.9561 0.2002

A401 Coupler Straight drop 2 Retained Rear left 2.0394 -1.7249 0

Rear right 1.3927 -1.5631 -0.0287

Front left 2.5613 -1.3381 0

Front right 2.161 -1.1364 -0.0286

A402 Brick Straight drop 3,4 Retained Rear left 2.0639 -3.1205 0

Rear right 1.2224 -2.57 0

Front left 3.9992 -1.6576 -0.5838

Front right 2.6826 -1.5928 -0.0286

A403 Thermal block Straight drop 1,2 Retained Rear left 3.2138 -4.5603 0

Rear right 2.8155 -3.1311 -0.1146

Front left 10.6545 -2.4864 -0.2043

Front right 6.0265 -2.0911 -0.143

A405 5 L Paint tin Straight drop 3,4 Retained Rear left 2.0394 -3.2138 -0.0287

Rear right 1.3927 -3.6471 -0.0287

Front left 7.7038 -3.7795 0

Front right 4.2754 -1.9141 0

A406 Scaffold board Pivot Retained Rear left 2.806 -2.8797 0.0287

Brickguard Rear right 1.6132 -4.083 -0.0287

damaged Front left 2.9757 -2.9008 0.17514

Front right 8.1223 -2.0678 0.1144

A409 1.2 m transom Roll 3,4 0 Rear left 1.5136 -3.5529 -0.0861

Rear right 1.2224 -2.9107 0.1433

Front left 4.6582 -1.7075 -0.4379

Front right 4.5967 -1.8629 -0.286

A410 Coupler Bounce Miss 2

A411 Brick Bounce Miss 0 - 7

A412 Thermal block Slid off 5,6 2 Rear left 2.1819 -3.9608 -0.0287

Rear right 1.9338 -2.4197 0

Front left 5.2174 -3.9492 -0.0292

Front right 4.3685 -2.6593 -0.1144

A413 10 N block Slid off 6 0 - 4 Rear left 2.1082 -4.1524 0.0861

Rear right 2.1542 -3.6672 -0.2579

Front left 5.1924 -2.3166 0.5838

Front right 4.7085 -2.8409 0.7722

A414 Brick Slid off 6 2.3 Rear left 1.5136 -2.3293 0.0574

Rear right 1.6633 -2.5951 -0.086

Front left 3.0256 -2.2168 0.08757

Front right 2.0259 -1.8396 0.0572

39

A501 Coupler Straight drop 2 Retained Rear left 1.1008 -1.5824 -0.0287

Rear right 0.7364 -1.2975 0.05732

Front left 4.7031 -0.9985 0

Front right 1.8862 -0.7731 -0.0572

A502 Brick Straight drop 3 0 Rear left 1.3907 -1.8231 0

Rear right 1.1272 -1.8085 0

Front left 2.2417 -1.6576 -0.1751

Front right 2.1377 -1.1131 -0.1144

A503 Thermal block Straight drop 4 0 Rear left 2.1131 -4.3687 -0.1148

Some over Rear right 2.1542 -3.2263 0

brickguard Front left 7.7287 -3.7046 -0.1168

Front right 5.2301 -3.0691 -0.3718

A505 5 L Paint tin Straight drop 1 Rear left 4.8257 -3.9608 0.0287

Rear right 3.9878 -3.7423 -0.0573

Front left 8.6324 -2.0969 -0.0584

Front right 7.0045 -1.7278 0.0572

A506 Scaffold board Pivot Miss 4.2

A511 Brick Slid off Miss 3

A512 Thermal block Slid off 4,5,6 Retained Rear left 2.3735 -4.3441 0

Rear right 2.1292 -2.3947 0

Front left 8.5575 -4.1689 0

Front right 4.3219 -2.4777 0

A513 10 N block Slid off 4,5,6 0 Rear left 2.231 -5.5186 0

Rear right 3.8425 -4.4287 -0.086

Front left 7.2644 -2.2917 -0.146

Front right 6.2081 -2.7944 -0.2002

A601 Coupler Straight drop 1 Retained Rear left 1.774 -1.2973 0

Rear right 1.4178 -1.3677 0

Front left 4.6582 -1.2432 0

Front right 2.0492 -1.2249 0

A605 5 L Paint tin Straight drop 3,4 Rear left 2.231 -3.8871 0.0287

Rear right 1.7134 -2.6903 0

Front left 7.6039 -2.4614 0.08757

Front right 4.6154 -2.1144 0.0572

A606 Scaffold board Pivot Miss 15 - 25

A612 Thermal block Slid off 6 7 Rear left 1.6069 -3.3858 0.0287

Rear right 1.8386 -1.6883 0

Front left 5.487 -2.1219 0.17514

Front right 2.7757 -1.8396 -0.0286

A613 10 N block Slid off 1,2 0 Rear left 5.1353 -5.8085 0.0861

Rear right 3.6471 -3.0309 -0.172

Front left 9.581 -1.8523 -0.2627

Front right 8.3458 -1.6114 -0.1716

A6dry2 1.2 m transom Rolled off 1 end Rear left 1.489 -2.0394 0

on 6 Rear right 1.1272 -1.3677 0.05732

Front left 4.5833 -2.9257 0

Front right 2.0492 -1.5881 0

40

8 GLOSSARY

Bay Space defined on a scaffold face between two adjacent

standards

Bay Length The horizontal distance between the standards forming either

side of a bay

Brick Guard Mesh used to protect working platform, fitted between

toeboard and handrail

Coupler Component used to fix scaffold tubes together

Fan Pole The poles used to form the fan platform, placed perpendicular

to the building and often inclined towards the scaffold.

Handrail A horizontal tube fixed to the structure at waist height for

protection of personnel

Ledger Horizontal tube fixed parallel to the face of the building

Ledger Bracing Diagonal bracing between standards in the perpendicular plane

to the building

Lift The horizontal levels of a scaffold

Lift height The vertical height between lifts

Longitudinal

bracing

Diagonal bracing fixed between standards generally in the

longer plane of the scaffold

Scaffold A temporary structure allowing access and working Scaffold Fan Structure attached to the perimeter of a scaffold to prevent

objects that may accidentally fall from structure causing

damage or injury to property or personnel on the ground

Scaffold Board Softwood boards used to construct working platforms,

toeboards and fans

Standard A vertical tube

SWL Safe working load

Toeboard Board fixed vertically to outer edge of working platform for

protection of personnel or from falling objects

Transom Horizontal tube perpendicular to building face

Working Platform Deck from which personnel work

Harpur Hill, Buxton SK17 9JN Telephone: +44 (0)114 289 2000Scaffold fans are described in BS 5973:...

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