BRE Test Report for Evorail Demarcation System and ... · British Standard BS EN 1991-1-4: Eurocode 1: Actions on Structures: Part 1-4: General actions – Wind actions. Buildings

High speed wind testing on Evorail Demarcation System and Evowalk PVC Membrane Walkway Prepared for: Joanne McMahon 6th November 2013

Test report number 290-351

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High speed wind testing on demarcation systems

Test report number 290-351 Commercial in confidence

© Building Research Establishment Ltd 2009 Page 2 of 19

Prepared by Name D Athwal

Position Laboratory technician, Building technology Group

Date 5th November 2013 Signature Approved on behalf of BRE Name Dr P Blackmore

Position Associate Director, Building technology Group

Date 6th November 2013 Signature

BRE Garston WD25 9XX T + 44 (0) 1923 664000 F + 44 (0) 1923 664010 E [email protected] www.bre.co.uk

This report may only be distributed in its entirety and in accordance with the terms and conditions of the contract. Test results relate only to the items tested. BRE has no responsibility for the design, materials, workmanship or performance of the product or items tested. This report does not constitute an approval, certification or endorsement of the product tested. This report is made on behalf of BRE. By receiving the report and action on it, the client – or any third party relying on it – accepts that no individual is personally liable in contract, tort or breach of statutory duty (including negligence).

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mailto:[email protected]://www.bre.co.uk




Contents 1 Introduction 4 2 Details of test specimen and test procedure 5

2.1 Test specimens 5 2.2 Test procedure 5

3 Test results 7 4 Discussion 8 5 Conclusions 9 6 Figures 10

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1 Introduction

This report describes tests carried out on the Evorail Demarcation System and PVC Membrane Walkway. The objective of the testing was to determine the resistance of the system under high speed wind conditions.

This testing is based on BRE Proposal No. 133-350 dated 4th April 2013, which was sent to Ms Joanne McMahon, AKM Fabrications, Unit 6 Yarrow Business Centre, Yarrow Road, Chorley, PR6 0LP and was accepted by Ms Joanne McMahon on 24 September 2013. This work was carried out as BRE project number CV6463.

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2 Details of test specimen and test procedure

2.1 Test specimens

Demarcation system The post and base system tested was the Evorail Demarcation System and 6mm plastic chain. The base is 410mm by 410mm and 100mm high with chamfered edge and weighs approximately 9.3Kg. It is manufactured from recycled tyres. The posts were 40mm square mild steel tube, yellow powder coated for increased visibility and were 960mm tall; they were push fitted into a tapered cast hole in the base and retained by friction. Figures 1 to 5 show the posts and the two substrates tested. The potential failure modes of the post and base systems were thought to be sliding, overturning or bouncing. Both of the substrates were tested wet and dry because a change in their coefficient of friction could influence the wind speeds at which the system fails. The test substrates were concrete paving slabs and a Sarnafil membrane fixed to the plywood boarded top of the turntable. Substrates, post and bases are shown in Figures 1 to 5. A pair of posts with bases was tested on a turntable directly in front of the wind tunnel with two lengths of chain midpoint and top of the post. Walkway system

The walkway system consisted of two main components, the top which consist of six PVC rectangular hollow tubes with a spikey top surface to aid grip to the user. The second component being the base rail that goes across the six top rails that holds them together and the bottom that is in contact with the roof membrane, see Figure 6, The potential failure modes of the walkway system were thought to be sliding, or flipping up and blowing away when the leading edge lifted in the wind. The walkway was tested on a Sarnafil membrane dry and wetted because a change in their coefficients of friction could influence the wind speeds at which the walkway system fails.

2.2 Test procedure

There are no British or European test methods for assessing the stability or wind resistance of the two systems being tested. The wind speeds they will have to resist depend on many factors, which are discussed in Section 4 of this report, in most cases the minimum wind speed they will need to resist will be of the order of 25m/s to 30m/s when close to the edge of a roof. The walkways will probably experience lower windspeeds than this.

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In order to test the performance of the two systems they were set up on a platform at the end of the BRE number 3 wind tunnel and the wind speed slowly increased until the systems ‘failed’, which for the purposes of these tests was defined as significant movement of the bases sufficient to cause them to become unstable, likely to blow over or move away from their original positions. The bases were tested with a straight edge facing into the wind, with a corner facing into the wind and with the substrates both dry and wetted. The walkway was tested with its long side to the wind and the membrane dry and wetted. For these tests the wind speed was measured using a Pitot tube and calibrated manometer.

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3 Test results

The results from each test are shown in full in Annex A and are summarised in Table 1 below.

Table 1 Failure wind speeds, the point at which the system start to slide (m/s) for each test configuration

Test number

Post Substrate Substrate condition

Wind speed at failure (ms)

Wind direction, additional remarks

1 Evorail Demarcation System

Paving slabs Dry 30 Wind blowing square to edge of the base. With chain


Paving slabs Dry 45 Wind blowing square to edge of the base. No chain attached and 5.4kg of weight added.


Paving slabs Dry 33.5 Wind blowing square to edge of the base. With chain. Both bases with 5.4kg added.


Paving slabs Dry 38.2 Wind blowing to corner of the base. With chain. Turntable rotated to 45 degrees. Both bases with 5.4kg.


Sarnafil membrane Dry 35 Wind blowing square to edge of the base. With chain


Sarnafil membrane Wet 30 Wind blowing square to the side of system. With chain

7 Evowalk Sarnafil membrane Dry 27.5 Wind blowing square to the side of system.

8 Evowalk Sarnafil membrane Dry 46.5 Wind blowing square to the side of system. 24kg of ballast added.

9 Evowalk Sarnafil membrane Wet 44.7 Wind blowing square to the side of system. With 24kg of ballast.

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4 Discussion

Demarcation system Testing showed the failure mode of the demarcation system was movement induced in the post by the wind and the chain swinging in the wind causing the bases to slide across the different substrates. Not at any point of the testing did the posts slip out of the base. Walkway system

Testing showed that the failure mode for the Roof Walker system was slippage on the substrate with the increased force of the wind. The wind speeds both systems will have to resist in practice depends on the geographical location within the UK, the height and size of the building they are located on, the ground altitude, distance from the coast, distance in to town, etc. The influence of all of these parameters can be determined from British Standard BS EN 1991-1-4: Eurocode 1: Actions on Structures: Part 1-4: General actions – Wind actions. Buildings in the UK are generally designed for wind speeds with an annual probability of exceedance of 0.02 (i.e. a 1:50 year windspeed). If the demarcation systems are intended to be left on a roof for periods exceeding one year then they should also be designed to resist a wind speed with an annual probability of exceedance of 0.02. If they are intended to be in place for sub-annual periods then a reduction in wind speed might be possible through use of the seasonal factor (see BS EN 1991-1-4). The 1:50 year gust wind speed at a height of 10m on a building in the centre of London would be approximately 26m/s; this would increase to about 50m/s in the far North of Scotland. When the wind blows over a roof it will be accelerated or retarded depending on the where it is measured over the roof.

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5 Conclusions

Tests were carried out at BRE to assess the wind resistance of a demarcation system and roof walkway system on behalf of Ms Joanne McMahon of AKM Fabrications. The following main conclusions can be drawn from this testing: Demarcation system

• The most common form of failure was found to be the bases sliding on the substrate.

• There was a difference in performance between the performance on the concrete slabs and the Sarnafil membrane. The bases began sliding at 30m/s on the dry concrete paving and 35m/s on the dry membrane.

• The performance of the system increased with the addition of the ballast. On the concrete substrate the bases began sliding at 30m/s with no ballast and 33.5m/s with 5.4kg of added ballast.

Walkway system

• The failure of the bases was sliding on the substrate.

• The performance of the system increased with the addition of the ballast. On the membrane substrate the walkway system began sliding at 27.5m/s with no ballast and 46.5m/s with 24kg of added ballast.

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6 Figures

Figure 1 Evorail Demarcation System on concrete paving slabs

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Figure 2 Evorail Demarcation System on Sarnafil membrane Dr

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Figure 3 Steel plate used as ballast in the post base

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Figure 4 Ballast in place under base

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Figure 5 Turntable rotated to 45 degrees

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Figure 6 Evowalk PVC Membrane Walkway ready to test

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Figure 7 Ballast added to the walkway

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Annex A Test results

Test 1 Barrier system on concrete slabs with the wind face on. Speed m/s

Comments

5 Chains lightly swaying in the wind. No movement in the posts or base. 10 Chains swinging and lightly tugging at the posts. No visible movement in the posts or base. 15 Chains swinging and tugging at the posts. Posts now starting to move slightly from tugging

of chains, 2-3mm approximately at the top of posts. No visible movement of the base. 20 Bottom chain now pulled taut by wind and top chain still swinging. Left post shaking more

the right. 4-5mm movement in left post at top and 2-3mm on the right. No visible movement of the base.

25 Bottom chain now pulled taut by wind and top chain still swinging. Left post shaking 10-12mm movement in left post at top and 5-7mm on the right. No visible movement of the base.

30 Wind started to lever the post and lift the front of the base then catching the underside causing the base start to “walk” back. After several seconds the wind caught the underside of the base and toppled the system.

Test 2 Barrier posts on concrete slabs with the wind at face on. Three sets of plates were screwed using two self-taping wood screws to the underside of a base. One plate weighed 1.8kg, was 280mm square and 3mm thick. The base weighed 9.3kg without the plates. Left post with a 5.4kg of additional weight and right post without. No chain was attached in this test. Speed m/s

Comments

32 Right post starting to lift. Lifting approximately 2-3mm. No visible movement on left base. 34 Right base lifting approximately 5-7mm. No visible movement on left base. 35.7 Right base now starting to slip back. Moved around 50mm. No visible movement on left

base. 36 Right base with post has now toppled over. No visible movement on left base. 44 Left base now starting to lift, 2-3mm. 45 Left base and post has now toppled over.

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Test 3 Barrier system setup on concrete slabs with the wind face on. Both bases had 5.4kg added to them and two chains were installed between the posts at mid height and the top of the posts. Speed m/s

Comments

32.5 Right base starting to lift and wobble. 33.5 Right base now starting to slip back in the wind. Test 4 Barrier system setup on concrete slabs with the wind at 45 degrees. Both bases had 5.4kg added to them and two chains were installed between the posts at mid height and the top of the posts. Speed m/s

Comments

37.6 Left post and foot starting to wobble. 38.2 Left post and foot now starting to slip back. Test 5 Barrier system setup on Sarnafil membrane with the wind face on. Both bases had 5.4kg added to them and two chains were installed between the posts at mid height and the top of the posts. Speed m/s

Comments

25 Both sides post and foot starting to wobble slightly. 30 Both sides post and foot wobble more feet lifting around 5-7mm. 35 Both sides post and foot starting to slip back. Test 6 Barrier system setup on Sarnafil membrane with the wind face on. Both bases had 5.4kg added to them and two chains were installed between the posts at mid height and the top of the posts. The membrane was wetted before placing the barrier system on. Speed m/s

Comments

25 Both sides post and foot starting to wobble. 30 Right foot slipped back 300mm

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==============REPORT ENDS============= Test report number 290-351 Commercial in confidence


Test 7 Walkway set up on Sarnafil membrane with the wind face on. No ballast was added in this test. Speed m/s

Comments

24.9 Walkway lifting around 20mm on the left side. 27.5 Walkway starting to slide. Test 8 Walkway set up on Sarnafil membrane with the wind face on. Four bars of ballast added to each of the end rails at a total of 24kg in this test. One bar equals 3kg, 20mmx10mm flat mild steel bar. Speed m/s

Comments

38.9 Leading edge of the walkway is starting to vibrate. 40.5 Middle section now starting to bounce up around 10-15mm. Right side also slipping. 46.5 Right side now starting to slip in larger steps. Test 9 Walkway set up on Sarnafil membrane with the wind face on. Four bars of ballast added to each of the end rails at a total of 24kg in this test. One bar equals 3kg, 20mmx10mm flat mild steel bar. The membrane was wetted before placing the walkway on. Speed m/s

Comments

38.5 Leading edge of the walkway is starting to vibrate. 39.9 Middle section now starting to bounce up around 10-15mm. Right side also slipping. 44.7 Right side slipped back 100mm

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Documents

BRE Test Report for Evorail Demarcation System and ... · British Standard BS EN 1991-1-4: Eurocode 1: Actions on Structures: Part 1-4: General actions – Wind actions. Buildings