In-Situ Measurement of Wind Performanceof Roof Edge Systems

Dr A Baskaran PEng and Sudhakar MolletiNational Research Council Canada

1200 Montreal Road ottawa on K1a 0R6

Phone 613-990-3616 bull e-mail basbaskarannrcca

Tony MallingerMetal-Era Inc

1600 airport Road Waukesha WI 53188

B Martiacuten-PeacuterezDepartment of Civil Engineering University of Ottawa

161 louis-Pasteur ottawa on K1n 6n5

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7 B a S k a R a n e t a l bull 8 9

Abstract

In commercial roofing metal edges are the first line of defense against the effects of wind As part of the Roofing Industry Committee on Weather Issuesrsquo (RICOWIrsquos) Wind Investigation Program (WIP) North American roofing professionals completed a major fact-finding inves-tigation immediately following the landfall of Hurricanes Charley Ike Ivan and Katrina Field data clearly supported that the majority of the roof failures were due to the failure of metal roof edges These findings suggest that current building codes (ie NBCC and ASCE) do not accurately specify wind design loads acting on roof edge metal systems The speaker will present the findings of measured wind-induced pressure acting on all surfaces of three different edge configurations

Speaker

Dr Appupillai Baskaran PEng ndash National Research Council of Canada Ottawa ON

DR BASKARAN is a group leader with the NRC He is a member of technical committees with RCI RICOWI ASCE SPRI ICBEST ASCE and CIB and a research advisor to various task groups of the National Building Code of Canada Baskaran has authored andor coau-thored over 200 research articles and received over 25 awards including the Frank Lander award from the Canadian Roofing Contractors Association and the Carl Cash Award from ASTM Dr Baskaran was recognized by Queen Elizabeth II with a Diamond Jubilee medal for his contribution to his fellow Canadians

Nonpresenting Coauthors

Sudhakar Molleti ndash National Research Council Canada Ottawa ON

Tony Mallinger ndash Metal-Era Inc Waukesha WI

B Martiacuten-Peacuterez ndash Department of Civil Engineering University of Ottawa Ottawa ON

9 0 bull B a S k a R a n e t a l 3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7

In-Situ Measurement of Wind Performanceof Roof Edge Systems

ABSTR AC T In commercial roofing metal edges are

the first line of defense against wind effects As part of the Roofing Industry Committee on Weather Issuesrsquo (RICOWIrsquos) Wind Investigation Program (WIP) several North American roofing professionals completed a major fact-finding investigation for the cause of wind failures WIP collected factual data immediately following the landfalls of Hurricanes Charley Ike Ivan and Katrina Field data clearly supported that the majority of the roof failures were due to the failure of metal roof edges These findings suggest two major contributing factors causing failures are 1) cur-rent building codes and standards in North America (ie NBCC and IBCASCE) do not accurately specify wind design load criteria for roof edge metal systems and 2) there is failure of attachments (nails) due to inadequate design or appli-cation error The objectives of this paper are

1 Give a brief sum-mary of the in-situ measurement site(the Canada Postbuilding locat-ed in VancouverCanada)

2 Compare the mea-sured wind-induced pressuressuctionsacting on all sur-faces of the three different edge con-figurationsmdashname-ly the anchor clip configuration (ACC) continuous cleat configuration (CCC) and discontinuous cleat configura-tion (DCC) with the current ASCE 7-10

wind load criteria for parapets 3 Correlate the design pressure coef-

ficients of edge metal to that of the roof design pressure coefficient to simplify the cladding and compo-nents design process

INTRODUC TION Many commercial roofs with parapets

are often covered by metal components The parapet can be constructed with vari-

ous types of substrates including wood concrete masonry and steel Normally the metal components cover the parapet by means of an inner layer namely a cleat (nailed to the substrate) and an outer layer namely coping (typically mechanically engaged to the cleat on the exterior side of the parapet and attached to the roof side of the parapet with exposed fasteners) As part of the roofrsquos perimeter the roof edge acts as an effective termination and transition

A B

C D

Figure 1 ndash Typical roof edge failures during high wind events A) coping disengagement from the cleat failure B) cleat fastener failure C) partial failure and D) complete failure

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7 B a S k a R a n e t a l bull 9 1

between the roof and the wall An adequate involving built-up roof systems occurred edge termination is required to ensure the due to failure of the roof edges Reports integrity of the roof and the contents of the from RICOWI13 -15 and observations made by building against the natural elements Baskaran et al5 also point out that a sig-

According to a study derived from FM nificant number of roof failures originated Global loss claims6 59 of the losses from the poor performance of roof edges In

A

C

B

Figure 2 ndash A) Front view of the Canada Post building showing B) the instrumented Penthouse 6 and details of the configuration positioning C) ACC CCC and DCC

1990 Smith16 documented the failure mode of edge metal flashings after Hurricane Hugo Also several FEMA publications pro-vide guidelines for edge metal design fol-lowing Hurricanes Charley (P-488)7 Ivan (P-489)8 Katrina (P-549)9 and Ike (P-757)10

ANSISPRI ES-11 is widely used by the roofing industry This standard has two parts 1) it provides wind load criteria for the design of edge metals and 2) it specifies three different test methods for the resis-tance evaluation of the edge metals The former is mainly based on ASCE 7-102 Thus there is a lack of design specifications for wind loads acting on roof edge metal systems in current building codes and standards

In practice there is a large variability in manufacturing and installation of roof edge metals As wind separates from the roof edge it breaks down into vortices which create high-pressure differences at the roofrsquos perimeter The roof edge is par-ticularly susceptible to the effects of wind because it can be fully immersed in the separation bubble These areas are char-acterized by significant wind-induced pres-sure fluctuations that can potentially dam-age roof edges

The three most common failure mecha-nisms of roof edges are illustrated in Figure 1 The mode of failure caused by a billow-ing membrane originates with the repeated pulling force of a membrane that is partially detached in the vicinity of the roof edge (F igure 1A) It has been observed that bil-lowing membranes can actually pull out fasteners or damage the coping-membrane connection A second type of failure arises when the wind suction on the roof edges is strong enough to pull out the frontal fas-teners that keep the flashings in place as depicted in F igure 1B F igure 1C represents the third mechanism of failure that occurs when wind suction overcomes the resistance provided by the connection between the coping and its supporting element (known as a cleat or clip) For instance a failure in the cleat can cause coping failure billowing of the membrane can induce failure of any roof edge component Improper nail attach-ment can also cause failure[17 ]

To understand roof edge wind perfor-mance and to incorporate wind load criteria in the North America building codes (NBCC and IBCASCE 7) a project namely Roof Edge Systems and Technologies (REST) was formulated as explained in previous papers by the authors[3 and 4] The objective

9 2 bull B a S k a R a n e t a l 3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7

Figure 3 ndash Typical pressure distribution on the front face of ACC and the corresponding wind speed and wind direction

of this paper is to give a summary of the in-situ measurement site the Canada Post building in Vancouver and compare the measured data of all three edge configu-rations In addition this paper intends to correlate design pressure coefficients of edge metal to the measured roof pressure coefficients

The Canada Post mail distribution facility located on the south side of the Vancouver International Airport was iden-tified as a suitable field-monitoring site (Figure 2) Positioned at an airport location the building can be categorized as having an open terrain exposure (ie exposure C from ASCE 7) The climatic wind data for the airport obtained from Environment Canada reveals that the predominant wind direction ranges from southwest to north-west In order to be exposed to the critical wind direction range instrumentation was placed on penthouse 6 located on the west side of the building with a parapet facing the incoming west wind This arrangement exposes the instrumented roof edge to perpendicular and oblique wind flow condi-tions The roof elevation was 18 m (58 ft)

RESULTS AND DISCUSSION The period of October 2013 to September

2014 was selected for the present analysis Only one-hour data segments for which

the wind direction statistical mode was in the interval SWndashNW and the hourly peak wind speed was greater than 48 kph (30 mph) were considered The above proce-dure yielded 16 wind speed and pressure data records during the one-year monitor-ing period Taking November 15 2013 as a typical windy day Figure 3 shows the wind pressuresuction acting on the three faces (front top and back) of the ACC metal edge

The presented data represent the maxi-mum measured pressuresuction for each minute The westerly peak winds of 97 kph (60 mph) attack the instrumented edge con-figuration with perpendicular wind direc-tion The X axis shows the time in minutes whereas the measured wind and pressure suctions are displayed in the Y axis At the front face wind induces both pressure (positive) and suction (negative) whereas the other two faces are subjected to only suction The design value for the day can be labelled as peak The corresponding peak suction values are -335 -646 and -416 Pa (-7 -135 and -87 psf ) for the front top and back faces respectively Even though there is a difference in the peak magni-tudes all three peaks occur at the middle of the hour at about 30 minutes The range of the suction fluctuations is another observa-tion of interest In the case of the front and back faces during the represented hour

the suction fluctuates in the range of -192 to -431 Pa (-4 to -9 psf ) This is significantly different on the top surface which experi-ences higher fluctuations ranging from -192 to -670 Pa (-4 to -14 psf ) This clearly shows that in designing roof edges the outward negative pull force is higher at the top sur-face This is due to wind flow separation from the leading edge To understand the performance of CCC ACC and DCC the measured data are plotted in Figure 4[4]

The X axis shows the roof height wind speed squared (VR

2) Measured data from the top and front surfaces of the edge metal are shown in the Y axis When observing the effects of wind speed on the CCC it can be seen that both pressure and suction on each face increase as wind speed increases And the rate of suction increase is greater on the top face of the CCC compared to the front face As the top face is fully immersed in the separation bubble it is not expe-riencing any pressures Even though the front face is subjected to pressure and suc-tions the magnitude of pressure is only approximately half of the induced suction Moreover when the edge metals are consid-ered as components and cladding for wind design the design for suction forces is more critical than that of pressure Hence the suction that is acting away from the para-pet surface tends to pull the cladding metal

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7 B a S k a R a n e t a l bull 9 3

Figure 4 ndash Effect of wind speed on CCC DCC and ACC

elements away from its substrates and the attachment locations This can lead to cop-ing disengagement from the cleat andor fastener pullout from the cleat or the cleat pulling over the fastener Examples of such failures are shown in Figure 2

Due to lack of wind load criteria for prop-er roof edge design process in the Canadian building code it has been decided to per-

9 4 bull B a S k a R a n e t a l

Figure 5 ndash Codification of wind load pressure coefficient of low-slope membrane roof edge metals

Windward Parapet Load Case A

1 Windward parapet pressure (p1) is determined using the positive wall pressure (p5) zones or from the applicable figure

2 Leeward parapet pressure (p2) is determined using the negative roof pressure (p7) zones or from the applicable figure

Leeward Parapet Load Case B

1 Windward parapet pressure (p3) is determined using the positive wall pressure (p5) zones or from the applicable figure

2 Leeward parapet pressure (p4) is determined using the negative wall pressure (p6) zones or from the applicable figure

Component Covering Parapet Pressure (pe) is determined using the negative roof pressure (p7 x 14) zones or from the applicable figure

form further data Peterka amp Shahid 1998[12]) are -51 and -76 analysis such that for the front and top legs respectively as a pressure coefficients design pressure coefficient Note that these that are unique to coefficients are limited to low-rise buildings the metal edges H lt18 m (60 ft) and are not suitable for can be specified use with ASCE 7 Additional data process-Inspired by available ing is needed to develop ASCE 7 pressure

engineering approaches in developing pres- coefficients These pressure coefficients are sure coefficients the authors developed a higher than ES-1 coefficients procedure for pressure coefficient calcula- Discussions with industrial partners tions as explained in a companion paper revealed that without sacrificing the tech-[3] The design pressure coefficients based nical merit of the acquired field data sim-on the Gumbel distribution are -31 and plifications are needed in specifying the de--46 for the front and top legs respectively sign pressure coefficient This is mainly to The code-comparable pressure coefficients avoid a separate set of calculations for the with a 50-year return period (obtained from front top and back faces of the edge metal

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7

Based on industry input and consider-ing the variability and complexity of the wind dynamics at the separation bubble it has been decided to propose a representa-tive design pressure coefficient for the edge metals by taking the worst-case scenario between top and front legs This resulted in a design pressure coefficient of -76 cor-responding to the top leg

Also to account for practicality in the design process it has been decided to corre-late the proposed coefficient with the exist-ing roof cladding and component pressure coefficient A correlation factor of 14 can be obtained by dividing the above-calculated pressure coefficient of -76 for edge metals by -54 where -54 is the maximum exter-nal CpCg value corresponding to low-slope roof components and cladding design speci-fication in accordance with the NBCC 2015 (refer to the Figure 4176 of NBCC 2015)[11]

Based on the above discussions and roofing industry consultations the proposed CpCg for edge metals are shown in Figure 5

For completeness of the design wind-ward and leeward loads that are directly taken from ASCE 7 are also shown This present proposal only enhances the existing parapet wind load specification of ASCE SEI 7-10[2] Edge metal pressure (Pe) is determined using 14 times the negative roof pressure (P7) corresponding to zone C or S from the appropriate figure of the NBCC This explicit specification will facilitate proper design and the attach-ment mechanism to transfer the edge metal load to the parapet structure Doing so not only simplifies the design process but also provides an explicit wind load specification for the component that offers the first line of defense against commercial roof failures due to wind effects A similar attempt has also been made to develop a pressure coeffi-cient suitable for the ASCE 7 by considering necessary transformations as the ASCE 7 pressure coefficient (GCp) values refer to a velocity pressure based on a three-second gust wind speed However only recently major changes were balloted for the com-ponents and cladding sections to the ASCE 7-2016 Hence for the time being it has been decided to limit the proposal to the NBCC 2020

CONCLUSIONS This paper developed appropriate design

pressure coefficients for possible incorpora-tion into NBCC During this process the

following observations were made bull Comparison of the in-situ measured

pressures with the existing ANSI ES-1[1] wind standards suggested that the ES-1 wind load criteria are inadequate

bull Based on consultation with the roof-ing industry it is proposed that the edge metal pressure (Pe) be deter-mined using a factor of 14 applied to the negative roof pressure (P7) corresponding to zone C or S from the appropriate figure of the NBCC This simplifies the components and cladding design process

This explicit specification will facilitate proper design and implicitly facilitate the design of attachment mechanism to trans-fer the metal load to the parapet structure This load path transfer depends on the capacity of the metal and pullout resistance of the fasteners with the substrate This will simplify the design process and clearly state a wind load specification for the com-ponent that offers the first line of defense against commercial roof failures due to wind effects

ACKNOWLEDGEMENT This research and development work

was carried out under the auspices of the Natural Sciences and Engineering Research Council of Canadarsquos (NSERCrsquos) Collaborative Research Grant (CDR ndash 395869) Industrial partners were Firestone Building Products JRS Engineering Group Menzies Metal Products Metal-Era Inc the Roofing Contractors Association of BC and Soprema Inc whom we thank for the contribu-tions including coping configurations The authors also acknowledge the assistance of NRC technical officers Steven Ko Amor Duric David Van Reenen Aarti Singla and Maha Dabas Material requirements were coordinated by Carlisle Syntech and sen-sor installation and repairs were completed by Larry Lemke of Marine Roofing Access to the building was graciously given by the Canada Post and we appreciate the help of Michael Bryson Alan Shopland and Reyes Ronald of JLL for coordinating the access

REFERENCES 1 ANSISPRI 2011 Wind Design

Standard for Edge Systems Used With Low Slope Roofing Systems ANSISPRIFM 4435ES-1

2 ASCE 2010 Minimum Design Loads of Buildings and Other Structures ASCESEI 7-10

3 A Baskaran J Bysice B Martin-Perez ldquoIn-Situ Measurement of Wind Performance of Roof Edge Systems ndash Effect of Edge Metal Configurationsrdquo Journal of Testing and Evaluation ASTM International (JAI) under review

4 A Baskaran S Molleti N Martins B Martin-Perez 2016 ldquoDevelopment of Wind Load Specifications for Commercial Roof Edge Metalsrdquo Journal of Architectural Engineering (ASCE) under review

5 A Baskaran S Molleti and D Roodvoets 2007 ldquoUnderstanding Low-sloped Roofs Under Hurricane Charley From Field to Practicerdquo Journal of ASTM International Vol 4 No 10

6 Factory Mutual Research Corpor-ation 2016 Loss Prevention Data Sheet 1-49 Factory Mutual Research Corporation Norwood MA 2016

7 FEMA 488 2005 ldquoHurricane Charley in Florida Mitigation Assessment Team Report Observations Recom-mendations and Technical Gui-dance Hurricane Recovery Adviso-riesrdquo httpwwwfemagovlibrary viewRecorddoid=1444

8 FEMA 489 2005 ldquoHurricane Ivan in Alabama and Florida Miti-gation Assessment Team Report Observations Recommendations and Technical Guidancerdquo http wwwfemagovlibraryviewRecord doid=1569

9 FEMA 549 2006 ldquoHurricane Katrina in the Gulf Coast Mitigation Assessment Team Report Building Performance Observations Rec-ommendations and Technical Guid-ancerdquo httpwwwfemagov libraryviewRecorddoid=1857

10 FEMA 757 2009 ldquoHurricane Ike in Texas and Louisiana Miti-gation Assessment Team Report Building Performance Observations Recommendations and Techni-cal Guidancerdquo httpswww f e m a g o v m e d i a - l i b r a r y -data20130726-1648-20490-9826 fema757pdf

11 NBCC 2015 National Building Code of Canada Institute for Research

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7 B a S k a R a n e t a l bull 9 5

In-Situ Measurement of Wind Performanceof Roof Edge Systems

ABSTR AC T In commercial roofing metal edges are

the first line of defense against wind effects As part of the Roofing Industry Committee on Weather Issuesrsquo (RICOWIrsquos) Wind Investigation Program (WIP) several North American roofing professionals completed a major fact-finding investigation for the cause of wind failures WIP collected factual data immediately following the landfalls of Hurricanes Charley Ike Ivan and Katrina Field data clearly supported that the majority of the roof failures were due to the failure of metal roof edges These findings suggest two major contributing factors causing failures are 1) cur-rent building codes and standards in North America (ie NBCC and IBCASCE) do not accurately specify wind design load criteria for roof edge metal systems and 2) there is failure of attachments (nails) due to inadequate design or appli-cation error The objectives of this paper are

1 Give a brief sum-mary of the in-situ measurement site(the Canada Postbuilding locat-ed in VancouverCanada)

2 Compare the mea-sured wind-induced pressuressuctionsacting on all sur-faces of the three different edge con-figurationsmdashname-ly the anchor clip configuration (ACC) continuous cleat configuration (CCC) and discontinuous cleat configura-tion (DCC) with the current ASCE 7-10

wind load criteria for parapets 3 Correlate the design pressure coef-

ficients of edge metal to that of the roof design pressure coefficient to simplify the cladding and compo-nents design process

INTRODUC TION Many commercial roofs with parapets

are often covered by metal components The parapet can be constructed with vari-

ous types of substrates including wood concrete masonry and steel Normally the metal components cover the parapet by means of an inner layer namely a cleat (nailed to the substrate) and an outer layer namely coping (typically mechanically engaged to the cleat on the exterior side of the parapet and attached to the roof side of the parapet with exposed fasteners) As part of the roofrsquos perimeter the roof edge acts as an effective termination and transition

A B

C D

Figure 1 ndash Typical roof edge failures during high wind events A) coping disengagement from the cleat failure B) cleat fastener failure C) partial failure and D) complete failure

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7 B a S k a R a n e t a l bull 9 1

between the roof and the wall An adequate involving built-up roof systems occurred edge termination is required to ensure the due to failure of the roof edges Reports integrity of the roof and the contents of the from RICOWI13 -15 and observations made by building against the natural elements Baskaran et al5 also point out that a sig-

According to a study derived from FM nificant number of roof failures originated Global loss claims6 59 of the losses from the poor performance of roof edges In

A

C

B

Figure 2 ndash A) Front view of the Canada Post building showing B) the instrumented Penthouse 6 and details of the configuration positioning C) ACC CCC and DCC

1990 Smith16 documented the failure mode of edge metal flashings after Hurricane Hugo Also several FEMA publications pro-vide guidelines for edge metal design fol-lowing Hurricanes Charley (P-488)7 Ivan (P-489)8 Katrina (P-549)9 and Ike (P-757)10

ANSISPRI ES-11 is widely used by the roofing industry This standard has two parts 1) it provides wind load criteria for the design of edge metals and 2) it specifies three different test methods for the resis-tance evaluation of the edge metals The former is mainly based on ASCE 7-102 Thus there is a lack of design specifications for wind loads acting on roof edge metal systems in current building codes and standards

In practice there is a large variability in manufacturing and installation of roof edge metals As wind separates from the roof edge it breaks down into vortices which create high-pressure differences at the roofrsquos perimeter The roof edge is par-ticularly susceptible to the effects of wind because it can be fully immersed in the separation bubble These areas are char-acterized by significant wind-induced pres-sure fluctuations that can potentially dam-age roof edges

The three most common failure mecha-nisms of roof edges are illustrated in Figure 1 The mode of failure caused by a billow-ing membrane originates with the repeated pulling force of a membrane that is partially detached in the vicinity of the roof edge (F igure 1A) It has been observed that bil-lowing membranes can actually pull out fasteners or damage the coping-membrane connection A second type of failure arises when the wind suction on the roof edges is strong enough to pull out the frontal fas-teners that keep the flashings in place as depicted in F igure 1B F igure 1C represents the third mechanism of failure that occurs when wind suction overcomes the resistance provided by the connection between the coping and its supporting element (known as a cleat or clip) For instance a failure in the cleat can cause coping failure billowing of the membrane can induce failure of any roof edge component Improper nail attach-ment can also cause failure[17 ]

To understand roof edge wind perfor-mance and to incorporate wind load criteria in the North America building codes (NBCC and IBCASCE 7) a project namely Roof Edge Systems and Technologies (REST) was formulated as explained in previous papers by the authors[3 and 4] The objective

9 2 bull B a S k a R a n e t a l 3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7

Figure 3 ndash Typical pressure distribution on the front face of ACC and the corresponding wind speed and wind direction

of this paper is to give a summary of the in-situ measurement site the Canada Post building in Vancouver and compare the measured data of all three edge configu-rations In addition this paper intends to correlate design pressure coefficients of edge metal to the measured roof pressure coefficients

The Canada Post mail distribution facility located on the south side of the Vancouver International Airport was iden-tified as a suitable field-monitoring site (Figure 2) Positioned at an airport location the building can be categorized as having an open terrain exposure (ie exposure C from ASCE 7) The climatic wind data for the airport obtained from Environment Canada reveals that the predominant wind direction ranges from southwest to north-west In order to be exposed to the critical wind direction range instrumentation was placed on penthouse 6 located on the west side of the building with a parapet facing the incoming west wind This arrangement exposes the instrumented roof edge to perpendicular and oblique wind flow condi-tions The roof elevation was 18 m (58 ft)

RESULTS AND DISCUSSION The period of October 2013 to September

2014 was selected for the present analysis Only one-hour data segments for which

the wind direction statistical mode was in the interval SWndashNW and the hourly peak wind speed was greater than 48 kph (30 mph) were considered The above proce-dure yielded 16 wind speed and pressure data records during the one-year monitor-ing period Taking November 15 2013 as a typical windy day Figure 3 shows the wind pressuresuction acting on the three faces (front top and back) of the ACC metal edge

The presented data represent the maxi-mum measured pressuresuction for each minute The westerly peak winds of 97 kph (60 mph) attack the instrumented edge con-figuration with perpendicular wind direc-tion The X axis shows the time in minutes whereas the measured wind and pressure suctions are displayed in the Y axis At the front face wind induces both pressure (positive) and suction (negative) whereas the other two faces are subjected to only suction The design value for the day can be labelled as peak The corresponding peak suction values are -335 -646 and -416 Pa (-7 -135 and -87 psf ) for the front top and back faces respectively Even though there is a difference in the peak magni-tudes all three peaks occur at the middle of the hour at about 30 minutes The range of the suction fluctuations is another observa-tion of interest In the case of the front and back faces during the represented hour

the suction fluctuates in the range of -192 to -431 Pa (-4 to -9 psf ) This is significantly different on the top surface which experi-ences higher fluctuations ranging from -192 to -670 Pa (-4 to -14 psf ) This clearly shows that in designing roof edges the outward negative pull force is higher at the top sur-face This is due to wind flow separation from the leading edge To understand the performance of CCC ACC and DCC the measured data are plotted in Figure 4[4]

The X axis shows the roof height wind speed squared (VR

2) Measured data from the top and front surfaces of the edge metal are shown in the Y axis When observing the effects of wind speed on the CCC it can be seen that both pressure and suction on each face increase as wind speed increases And the rate of suction increase is greater on the top face of the CCC compared to the front face As the top face is fully immersed in the separation bubble it is not expe-riencing any pressures Even though the front face is subjected to pressure and suc-tions the magnitude of pressure is only approximately half of the induced suction Moreover when the edge metals are consid-ered as components and cladding for wind design the design for suction forces is more critical than that of pressure Hence the suction that is acting away from the para-pet surface tends to pull the cladding metal

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7 B a S k a R a n e t a l bull 9 3

Figure 4 ndash Effect of wind speed on CCC DCC and ACC

elements away from its substrates and the attachment locations This can lead to cop-ing disengagement from the cleat andor fastener pullout from the cleat or the cleat pulling over the fastener Examples of such failures are shown in Figure 2

Due to lack of wind load criteria for prop-er roof edge design process in the Canadian building code it has been decided to per-

9 4 bull B a S k a R a n e t a l

Figure 5 ndash Codification of wind load pressure coefficient of low-slope membrane roof edge metals

Windward Parapet Load Case A

1 Windward parapet pressure (p1) is determined using the positive wall pressure (p5) zones or from the applicable figure

2 Leeward parapet pressure (p2) is determined using the negative roof pressure (p7) zones or from the applicable figure

Leeward Parapet Load Case B

1 Windward parapet pressure (p3) is determined using the positive wall pressure (p5) zones or from the applicable figure

2 Leeward parapet pressure (p4) is determined using the negative wall pressure (p6) zones or from the applicable figure

Component Covering Parapet Pressure (pe) is determined using the negative roof pressure (p7 x 14) zones or from the applicable figure

form further data Peterka amp Shahid 1998[12]) are -51 and -76 analysis such that for the front and top legs respectively as a pressure coefficients design pressure coefficient Note that these that are unique to coefficients are limited to low-rise buildings the metal edges H lt18 m (60 ft) and are not suitable for can be specified use with ASCE 7 Additional data process-Inspired by available ing is needed to develop ASCE 7 pressure

engineering approaches in developing pres- coefficients These pressure coefficients are sure coefficients the authors developed a higher than ES-1 coefficients procedure for pressure coefficient calcula- Discussions with industrial partners tions as explained in a companion paper revealed that without sacrificing the tech-[3] The design pressure coefficients based nical merit of the acquired field data sim-on the Gumbel distribution are -31 and plifications are needed in specifying the de--46 for the front and top legs respectively sign pressure coefficient This is mainly to The code-comparable pressure coefficients avoid a separate set of calculations for the with a 50-year return period (obtained from front top and back faces of the edge metal

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7

Based on industry input and consider-ing the variability and complexity of the wind dynamics at the separation bubble it has been decided to propose a representa-tive design pressure coefficient for the edge metals by taking the worst-case scenario between top and front legs This resulted in a design pressure coefficient of -76 cor-responding to the top leg

Also to account for practicality in the design process it has been decided to corre-late the proposed coefficient with the exist-ing roof cladding and component pressure coefficient A correlation factor of 14 can be obtained by dividing the above-calculated pressure coefficient of -76 for edge metals by -54 where -54 is the maximum exter-nal CpCg value corresponding to low-slope roof components and cladding design speci-fication in accordance with the NBCC 2015 (refer to the Figure 4176 of NBCC 2015)[11]

Based on the above discussions and roofing industry consultations the proposed CpCg for edge metals are shown in Figure 5

For completeness of the design wind-ward and leeward loads that are directly taken from ASCE 7 are also shown This present proposal only enhances the existing parapet wind load specification of ASCE SEI 7-10[2] Edge metal pressure (Pe) is determined using 14 times the negative roof pressure (P7) corresponding to zone C or S from the appropriate figure of the NBCC This explicit specification will facilitate proper design and the attach-ment mechanism to transfer the edge metal load to the parapet structure Doing so not only simplifies the design process but also provides an explicit wind load specification for the component that offers the first line of defense against commercial roof failures due to wind effects A similar attempt has also been made to develop a pressure coeffi-cient suitable for the ASCE 7 by considering necessary transformations as the ASCE 7 pressure coefficient (GCp) values refer to a velocity pressure based on a three-second gust wind speed However only recently major changes were balloted for the com-ponents and cladding sections to the ASCE 7-2016 Hence for the time being it has been decided to limit the proposal to the NBCC 2020

CONCLUSIONS This paper developed appropriate design

pressure coefficients for possible incorpora-tion into NBCC During this process the

following observations were made bull Comparison of the in-situ measured

pressures with the existing ANSI ES-1[1] wind standards suggested that the ES-1 wind load criteria are inadequate

bull Based on consultation with the roof-ing industry it is proposed that the edge metal pressure (Pe) be deter-mined using a factor of 14 applied to the negative roof pressure (P7) corresponding to zone C or S from the appropriate figure of the NBCC This simplifies the components and cladding design process

This explicit specification will facilitate proper design and implicitly facilitate the design of attachment mechanism to trans-fer the metal load to the parapet structure This load path transfer depends on the capacity of the metal and pullout resistance of the fasteners with the substrate This will simplify the design process and clearly state a wind load specification for the com-ponent that offers the first line of defense against commercial roof failures due to wind effects

ACKNOWLEDGEMENT This research and development work

was carried out under the auspices of the Natural Sciences and Engineering Research Council of Canadarsquos (NSERCrsquos) Collaborative Research Grant (CDR ndash 395869) Industrial partners were Firestone Building Products JRS Engineering Group Menzies Metal Products Metal-Era Inc the Roofing Contractors Association of BC and Soprema Inc whom we thank for the contribu-tions including coping configurations The authors also acknowledge the assistance of NRC technical officers Steven Ko Amor Duric David Van Reenen Aarti Singla and Maha Dabas Material requirements were coordinated by Carlisle Syntech and sen-sor installation and repairs were completed by Larry Lemke of Marine Roofing Access to the building was graciously given by the Canada Post and we appreciate the help of Michael Bryson Alan Shopland and Reyes Ronald of JLL for coordinating the access

REFERENCES 1 ANSISPRI 2011 Wind Design

Standard for Edge Systems Used With Low Slope Roofing Systems ANSISPRIFM 4435ES-1

2 ASCE 2010 Minimum Design Loads of Buildings and Other Structures ASCESEI 7-10

3 A Baskaran J Bysice B Martin-Perez ldquoIn-Situ Measurement of Wind Performance of Roof Edge Systems ndash Effect of Edge Metal Configurationsrdquo Journal of Testing and Evaluation ASTM International (JAI) under review

4 A Baskaran S Molleti N Martins B Martin-Perez 2016 ldquoDevelopment of Wind Load Specifications for Commercial Roof Edge Metalsrdquo Journal of Architectural Engineering (ASCE) under review

5 A Baskaran S Molleti and D Roodvoets 2007 ldquoUnderstanding Low-sloped Roofs Under Hurricane Charley From Field to Practicerdquo Journal of ASTM International Vol 4 No 10

6 Factory Mutual Research Corpor-ation 2016 Loss Prevention Data Sheet 1-49 Factory Mutual Research Corporation Norwood MA 2016

7 FEMA 488 2005 ldquoHurricane Charley in Florida Mitigation Assessment Team Report Observations Recom-mendations and Technical Gui-dance Hurricane Recovery Adviso-riesrdquo httpwwwfemagovlibrary viewRecorddoid=1444

8 FEMA 489 2005 ldquoHurricane Ivan in Alabama and Florida Miti-gation Assessment Team Report Observations Recommendations and Technical Guidancerdquo http wwwfemagovlibraryviewRecord doid=1569

9 FEMA 549 2006 ldquoHurricane Katrina in the Gulf Coast Mitigation Assessment Team Report Building Performance Observations Rec-ommendations and Technical Guid-ancerdquo httpwwwfemagov libraryviewRecorddoid=1857

10 FEMA 757 2009 ldquoHurricane Ike in Texas and Louisiana Miti-gation Assessment Team Report Building Performance Observations Recommendations and Techni-cal Guidancerdquo httpswww f e m a g o v m e d i a - l i b r a r y -data20130726-1648-20490-9826 fema757pdf

11 NBCC 2015 National Building Code of Canada Institute for Research

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7 B a S k a R a n e t a l bull 9 5

between the roof and the wall An adequate involving built-up roof systems occurred edge termination is required to ensure the due to failure of the roof edges Reports integrity of the roof and the contents of the from RICOWI13 -15 and observations made by building against the natural elements Baskaran et al5 also point out that a sig-

According to a study derived from FM nificant number of roof failures originated Global loss claims6 59 of the losses from the poor performance of roof edges In

A

C

B

Figure 2 ndash A) Front view of the Canada Post building showing B) the instrumented Penthouse 6 and details of the configuration positioning C) ACC CCC and DCC

1990 Smith16 documented the failure mode of edge metal flashings after Hurricane Hugo Also several FEMA publications pro-vide guidelines for edge metal design fol-lowing Hurricanes Charley (P-488)7 Ivan (P-489)8 Katrina (P-549)9 and Ike (P-757)10

ANSISPRI ES-11 is widely used by the roofing industry This standard has two parts 1) it provides wind load criteria for the design of edge metals and 2) it specifies three different test methods for the resis-tance evaluation of the edge metals The former is mainly based on ASCE 7-102 Thus there is a lack of design specifications for wind loads acting on roof edge metal systems in current building codes and standards

In practice there is a large variability in manufacturing and installation of roof edge metals As wind separates from the roof edge it breaks down into vortices which create high-pressure differences at the roofrsquos perimeter The roof edge is par-ticularly susceptible to the effects of wind because it can be fully immersed in the separation bubble These areas are char-acterized by significant wind-induced pres-sure fluctuations that can potentially dam-age roof edges

The three most common failure mecha-nisms of roof edges are illustrated in Figure 1 The mode of failure caused by a billow-ing membrane originates with the repeated pulling force of a membrane that is partially detached in the vicinity of the roof edge (F igure 1A) It has been observed that bil-lowing membranes can actually pull out fasteners or damage the coping-membrane connection A second type of failure arises when the wind suction on the roof edges is strong enough to pull out the frontal fas-teners that keep the flashings in place as depicted in F igure 1B F igure 1C represents the third mechanism of failure that occurs when wind suction overcomes the resistance provided by the connection between the coping and its supporting element (known as a cleat or clip) For instance a failure in the cleat can cause coping failure billowing of the membrane can induce failure of any roof edge component Improper nail attach-ment can also cause failure[17 ]

To understand roof edge wind perfor-mance and to incorporate wind load criteria in the North America building codes (NBCC and IBCASCE 7) a project namely Roof Edge Systems and Technologies (REST) was formulated as explained in previous papers by the authors[3 and 4] The objective

9 2 bull B a S k a R a n e t a l 3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7

Figure 3 ndash Typical pressure distribution on the front face of ACC and the corresponding wind speed and wind direction

of this paper is to give a summary of the in-situ measurement site the Canada Post building in Vancouver and compare the measured data of all three edge configu-rations In addition this paper intends to correlate design pressure coefficients of edge metal to the measured roof pressure coefficients

The Canada Post mail distribution facility located on the south side of the Vancouver International Airport was iden-tified as a suitable field-monitoring site (Figure 2) Positioned at an airport location the building can be categorized as having an open terrain exposure (ie exposure C from ASCE 7) The climatic wind data for the airport obtained from Environment Canada reveals that the predominant wind direction ranges from southwest to north-west In order to be exposed to the critical wind direction range instrumentation was placed on penthouse 6 located on the west side of the building with a parapet facing the incoming west wind This arrangement exposes the instrumented roof edge to perpendicular and oblique wind flow condi-tions The roof elevation was 18 m (58 ft)

RESULTS AND DISCUSSION The period of October 2013 to September

2014 was selected for the present analysis Only one-hour data segments for which

the wind direction statistical mode was in the interval SWndashNW and the hourly peak wind speed was greater than 48 kph (30 mph) were considered The above proce-dure yielded 16 wind speed and pressure data records during the one-year monitor-ing period Taking November 15 2013 as a typical windy day Figure 3 shows the wind pressuresuction acting on the three faces (front top and back) of the ACC metal edge

The presented data represent the maxi-mum measured pressuresuction for each minute The westerly peak winds of 97 kph (60 mph) attack the instrumented edge con-figuration with perpendicular wind direc-tion The X axis shows the time in minutes whereas the measured wind and pressure suctions are displayed in the Y axis At the front face wind induces both pressure (positive) and suction (negative) whereas the other two faces are subjected to only suction The design value for the day can be labelled as peak The corresponding peak suction values are -335 -646 and -416 Pa (-7 -135 and -87 psf ) for the front top and back faces respectively Even though there is a difference in the peak magni-tudes all three peaks occur at the middle of the hour at about 30 minutes The range of the suction fluctuations is another observa-tion of interest In the case of the front and back faces during the represented hour

the suction fluctuates in the range of -192 to -431 Pa (-4 to -9 psf ) This is significantly different on the top surface which experi-ences higher fluctuations ranging from -192 to -670 Pa (-4 to -14 psf ) This clearly shows that in designing roof edges the outward negative pull force is higher at the top sur-face This is due to wind flow separation from the leading edge To understand the performance of CCC ACC and DCC the measured data are plotted in Figure 4[4]

The X axis shows the roof height wind speed squared (VR

2) Measured data from the top and front surfaces of the edge metal are shown in the Y axis When observing the effects of wind speed on the CCC it can be seen that both pressure and suction on each face increase as wind speed increases And the rate of suction increase is greater on the top face of the CCC compared to the front face As the top face is fully immersed in the separation bubble it is not expe-riencing any pressures Even though the front face is subjected to pressure and suc-tions the magnitude of pressure is only approximately half of the induced suction Moreover when the edge metals are consid-ered as components and cladding for wind design the design for suction forces is more critical than that of pressure Hence the suction that is acting away from the para-pet surface tends to pull the cladding metal

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7 B a S k a R a n e t a l bull 9 3

Figure 4 ndash Effect of wind speed on CCC DCC and ACC

elements away from its substrates and the attachment locations This can lead to cop-ing disengagement from the cleat andor fastener pullout from the cleat or the cleat pulling over the fastener Examples of such failures are shown in Figure 2

Due to lack of wind load criteria for prop-er roof edge design process in the Canadian building code it has been decided to per-

9 4 bull B a S k a R a n e t a l

Figure 5 ndash Codification of wind load pressure coefficient of low-slope membrane roof edge metals

Windward Parapet Load Case A

1 Windward parapet pressure (p1) is determined using the positive wall pressure (p5) zones or from the applicable figure

2 Leeward parapet pressure (p2) is determined using the negative roof pressure (p7) zones or from the applicable figure

Leeward Parapet Load Case B

1 Windward parapet pressure (p3) is determined using the positive wall pressure (p5) zones or from the applicable figure

2 Leeward parapet pressure (p4) is determined using the negative wall pressure (p6) zones or from the applicable figure

Component Covering Parapet Pressure (pe) is determined using the negative roof pressure (p7 x 14) zones or from the applicable figure

form further data Peterka amp Shahid 1998[12]) are -51 and -76 analysis such that for the front and top legs respectively as a pressure coefficients design pressure coefficient Note that these that are unique to coefficients are limited to low-rise buildings the metal edges H lt18 m (60 ft) and are not suitable for can be specified use with ASCE 7 Additional data process-Inspired by available ing is needed to develop ASCE 7 pressure

engineering approaches in developing pres- coefficients These pressure coefficients are sure coefficients the authors developed a higher than ES-1 coefficients procedure for pressure coefficient calcula- Discussions with industrial partners tions as explained in a companion paper revealed that without sacrificing the tech-[3] The design pressure coefficients based nical merit of the acquired field data sim-on the Gumbel distribution are -31 and plifications are needed in specifying the de--46 for the front and top legs respectively sign pressure coefficient This is mainly to The code-comparable pressure coefficients avoid a separate set of calculations for the with a 50-year return period (obtained from front top and back faces of the edge metal

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7

Based on industry input and consider-ing the variability and complexity of the wind dynamics at the separation bubble it has been decided to propose a representa-tive design pressure coefficient for the edge metals by taking the worst-case scenario between top and front legs This resulted in a design pressure coefficient of -76 cor-responding to the top leg

Also to account for practicality in the design process it has been decided to corre-late the proposed coefficient with the exist-ing roof cladding and component pressure coefficient A correlation factor of 14 can be obtained by dividing the above-calculated pressure coefficient of -76 for edge metals by -54 where -54 is the maximum exter-nal CpCg value corresponding to low-slope roof components and cladding design speci-fication in accordance with the NBCC 2015 (refer to the Figure 4176 of NBCC 2015)[11]

Based on the above discussions and roofing industry consultations the proposed CpCg for edge metals are shown in Figure 5

For completeness of the design wind-ward and leeward loads that are directly taken from ASCE 7 are also shown This present proposal only enhances the existing parapet wind load specification of ASCE SEI 7-10[2] Edge metal pressure (Pe) is determined using 14 times the negative roof pressure (P7) corresponding to zone C or S from the appropriate figure of the NBCC This explicit specification will facilitate proper design and the attach-ment mechanism to transfer the edge metal load to the parapet structure Doing so not only simplifies the design process but also provides an explicit wind load specification for the component that offers the first line of defense against commercial roof failures due to wind effects A similar attempt has also been made to develop a pressure coeffi-cient suitable for the ASCE 7 by considering necessary transformations as the ASCE 7 pressure coefficient (GCp) values refer to a velocity pressure based on a three-second gust wind speed However only recently major changes were balloted for the com-ponents and cladding sections to the ASCE 7-2016 Hence for the time being it has been decided to limit the proposal to the NBCC 2020

CONCLUSIONS This paper developed appropriate design

pressure coefficients for possible incorpora-tion into NBCC During this process the

following observations were made bull Comparison of the in-situ measured

pressures with the existing ANSI ES-1[1] wind standards suggested that the ES-1 wind load criteria are inadequate

bull Based on consultation with the roof-ing industry it is proposed that the edge metal pressure (Pe) be deter-mined using a factor of 14 applied to the negative roof pressure (P7) corresponding to zone C or S from the appropriate figure of the NBCC This simplifies the components and cladding design process

This explicit specification will facilitate proper design and implicitly facilitate the design of attachment mechanism to trans-fer the metal load to the parapet structure This load path transfer depends on the capacity of the metal and pullout resistance of the fasteners with the substrate This will simplify the design process and clearly state a wind load specification for the com-ponent that offers the first line of defense against commercial roof failures due to wind effects

ACKNOWLEDGEMENT This research and development work

was carried out under the auspices of the Natural Sciences and Engineering Research Council of Canadarsquos (NSERCrsquos) Collaborative Research Grant (CDR ndash 395869) Industrial partners were Firestone Building Products JRS Engineering Group Menzies Metal Products Metal-Era Inc the Roofing Contractors Association of BC and Soprema Inc whom we thank for the contribu-tions including coping configurations The authors also acknowledge the assistance of NRC technical officers Steven Ko Amor Duric David Van Reenen Aarti Singla and Maha Dabas Material requirements were coordinated by Carlisle Syntech and sen-sor installation and repairs were completed by Larry Lemke of Marine Roofing Access to the building was graciously given by the Canada Post and we appreciate the help of Michael Bryson Alan Shopland and Reyes Ronald of JLL for coordinating the access

REFERENCES 1 ANSISPRI 2011 Wind Design

Standard for Edge Systems Used With Low Slope Roofing Systems ANSISPRIFM 4435ES-1

2 ASCE 2010 Minimum Design Loads of Buildings and Other Structures ASCESEI 7-10

3 A Baskaran J Bysice B Martin-Perez ldquoIn-Situ Measurement of Wind Performance of Roof Edge Systems ndash Effect of Edge Metal Configurationsrdquo Journal of Testing and Evaluation ASTM International (JAI) under review

4 A Baskaran S Molleti N Martins B Martin-Perez 2016 ldquoDevelopment of Wind Load Specifications for Commercial Roof Edge Metalsrdquo Journal of Architectural Engineering (ASCE) under review

5 A Baskaran S Molleti and D Roodvoets 2007 ldquoUnderstanding Low-sloped Roofs Under Hurricane Charley From Field to Practicerdquo Journal of ASTM International Vol 4 No 10

6 Factory Mutual Research Corpor-ation 2016 Loss Prevention Data Sheet 1-49 Factory Mutual Research Corporation Norwood MA 2016

7 FEMA 488 2005 ldquoHurricane Charley in Florida Mitigation Assessment Team Report Observations Recom-mendations and Technical Gui-dance Hurricane Recovery Adviso-riesrdquo httpwwwfemagovlibrary viewRecorddoid=1444

8 FEMA 489 2005 ldquoHurricane Ivan in Alabama and Florida Miti-gation Assessment Team Report Observations Recommendations and Technical Guidancerdquo http wwwfemagovlibraryviewRecord doid=1569

9 FEMA 549 2006 ldquoHurricane Katrina in the Gulf Coast Mitigation Assessment Team Report Building Performance Observations Rec-ommendations and Technical Guid-ancerdquo httpwwwfemagov libraryviewRecorddoid=1857

10 FEMA 757 2009 ldquoHurricane Ike in Texas and Louisiana Miti-gation Assessment Team Report Building Performance Observations Recommendations and Techni-cal Guidancerdquo httpswww f e m a g o v m e d i a - l i b r a r y -data20130726-1648-20490-9826 fema757pdf

11 NBCC 2015 National Building Code of Canada Institute for Research

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7 B a S k a R a n e t a l bull 9 5

Figure 3 ndash Typical pressure distribution on the front face of ACC and the corresponding wind speed and wind direction

of this paper is to give a summary of the in-situ measurement site the Canada Post building in Vancouver and compare the measured data of all three edge configu-rations In addition this paper intends to correlate design pressure coefficients of edge metal to the measured roof pressure coefficients

The Canada Post mail distribution facility located on the south side of the Vancouver International Airport was iden-tified as a suitable field-monitoring site (Figure 2) Positioned at an airport location the building can be categorized as having an open terrain exposure (ie exposure C from ASCE 7) The climatic wind data for the airport obtained from Environment Canada reveals that the predominant wind direction ranges from southwest to north-west In order to be exposed to the critical wind direction range instrumentation was placed on penthouse 6 located on the west side of the building with a parapet facing the incoming west wind This arrangement exposes the instrumented roof edge to perpendicular and oblique wind flow condi-tions The roof elevation was 18 m (58 ft)

RESULTS AND DISCUSSION The period of October 2013 to September

2014 was selected for the present analysis Only one-hour data segments for which

the wind direction statistical mode was in the interval SWndashNW and the hourly peak wind speed was greater than 48 kph (30 mph) were considered The above proce-dure yielded 16 wind speed and pressure data records during the one-year monitor-ing period Taking November 15 2013 as a typical windy day Figure 3 shows the wind pressuresuction acting on the three faces (front top and back) of the ACC metal edge

The presented data represent the maxi-mum measured pressuresuction for each minute The westerly peak winds of 97 kph (60 mph) attack the instrumented edge con-figuration with perpendicular wind direc-tion The X axis shows the time in minutes whereas the measured wind and pressure suctions are displayed in the Y axis At the front face wind induces both pressure (positive) and suction (negative) whereas the other two faces are subjected to only suction The design value for the day can be labelled as peak The corresponding peak suction values are -335 -646 and -416 Pa (-7 -135 and -87 psf ) for the front top and back faces respectively Even though there is a difference in the peak magni-tudes all three peaks occur at the middle of the hour at about 30 minutes The range of the suction fluctuations is another observa-tion of interest In the case of the front and back faces during the represented hour

the suction fluctuates in the range of -192 to -431 Pa (-4 to -9 psf ) This is significantly different on the top surface which experi-ences higher fluctuations ranging from -192 to -670 Pa (-4 to -14 psf ) This clearly shows that in designing roof edges the outward negative pull force is higher at the top sur-face This is due to wind flow separation from the leading edge To understand the performance of CCC ACC and DCC the measured data are plotted in Figure 4[4]

The X axis shows the roof height wind speed squared (VR

2) Measured data from the top and front surfaces of the edge metal are shown in the Y axis When observing the effects of wind speed on the CCC it can be seen that both pressure and suction on each face increase as wind speed increases And the rate of suction increase is greater on the top face of the CCC compared to the front face As the top face is fully immersed in the separation bubble it is not expe-riencing any pressures Even though the front face is subjected to pressure and suc-tions the magnitude of pressure is only approximately half of the induced suction Moreover when the edge metals are consid-ered as components and cladding for wind design the design for suction forces is more critical than that of pressure Hence the suction that is acting away from the para-pet surface tends to pull the cladding metal

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7 B a S k a R a n e t a l bull 9 3

Figure 4 ndash Effect of wind speed on CCC DCC and ACC

elements away from its substrates and the attachment locations This can lead to cop-ing disengagement from the cleat andor fastener pullout from the cleat or the cleat pulling over the fastener Examples of such failures are shown in Figure 2

Due to lack of wind load criteria for prop-er roof edge design process in the Canadian building code it has been decided to per-

9 4 bull B a S k a R a n e t a l

Figure 5 ndash Codification of wind load pressure coefficient of low-slope membrane roof edge metals

Windward Parapet Load Case A

1 Windward parapet pressure (p1) is determined using the positive wall pressure (p5) zones or from the applicable figure

2 Leeward parapet pressure (p2) is determined using the negative roof pressure (p7) zones or from the applicable figure

Leeward Parapet Load Case B

1 Windward parapet pressure (p3) is determined using the positive wall pressure (p5) zones or from the applicable figure

2 Leeward parapet pressure (p4) is determined using the negative wall pressure (p6) zones or from the applicable figure

Component Covering Parapet Pressure (pe) is determined using the negative roof pressure (p7 x 14) zones or from the applicable figure

form further data Peterka amp Shahid 1998[12]) are -51 and -76 analysis such that for the front and top legs respectively as a pressure coefficients design pressure coefficient Note that these that are unique to coefficients are limited to low-rise buildings the metal edges H lt18 m (60 ft) and are not suitable for can be specified use with ASCE 7 Additional data process-Inspired by available ing is needed to develop ASCE 7 pressure

engineering approaches in developing pres- coefficients These pressure coefficients are sure coefficients the authors developed a higher than ES-1 coefficients procedure for pressure coefficient calcula- Discussions with industrial partners tions as explained in a companion paper revealed that without sacrificing the tech-[3] The design pressure coefficients based nical merit of the acquired field data sim-on the Gumbel distribution are -31 and plifications are needed in specifying the de--46 for the front and top legs respectively sign pressure coefficient This is mainly to The code-comparable pressure coefficients avoid a separate set of calculations for the with a 50-year return period (obtained from front top and back faces of the edge metal

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7

Based on industry input and consider-ing the variability and complexity of the wind dynamics at the separation bubble it has been decided to propose a representa-tive design pressure coefficient for the edge metals by taking the worst-case scenario between top and front legs This resulted in a design pressure coefficient of -76 cor-responding to the top leg

Also to account for practicality in the design process it has been decided to corre-late the proposed coefficient with the exist-ing roof cladding and component pressure coefficient A correlation factor of 14 can be obtained by dividing the above-calculated pressure coefficient of -76 for edge metals by -54 where -54 is the maximum exter-nal CpCg value corresponding to low-slope roof components and cladding design speci-fication in accordance with the NBCC 2015 (refer to the Figure 4176 of NBCC 2015)[11]

Based on the above discussions and roofing industry consultations the proposed CpCg for edge metals are shown in Figure 5

For completeness of the design wind-ward and leeward loads that are directly taken from ASCE 7 are also shown This present proposal only enhances the existing parapet wind load specification of ASCE SEI 7-10[2] Edge metal pressure (Pe) is determined using 14 times the negative roof pressure (P7) corresponding to zone C or S from the appropriate figure of the NBCC This explicit specification will facilitate proper design and the attach-ment mechanism to transfer the edge metal load to the parapet structure Doing so not only simplifies the design process but also provides an explicit wind load specification for the component that offers the first line of defense against commercial roof failures due to wind effects A similar attempt has also been made to develop a pressure coeffi-cient suitable for the ASCE 7 by considering necessary transformations as the ASCE 7 pressure coefficient (GCp) values refer to a velocity pressure based on a three-second gust wind speed However only recently major changes were balloted for the com-ponents and cladding sections to the ASCE 7-2016 Hence for the time being it has been decided to limit the proposal to the NBCC 2020

CONCLUSIONS This paper developed appropriate design

pressure coefficients for possible incorpora-tion into NBCC During this process the

following observations were made bull Comparison of the in-situ measured

pressures with the existing ANSI ES-1[1] wind standards suggested that the ES-1 wind load criteria are inadequate

bull Based on consultation with the roof-ing industry it is proposed that the edge metal pressure (Pe) be deter-mined using a factor of 14 applied to the negative roof pressure (P7) corresponding to zone C or S from the appropriate figure of the NBCC This simplifies the components and cladding design process

This explicit specification will facilitate proper design and implicitly facilitate the design of attachment mechanism to trans-fer the metal load to the parapet structure This load path transfer depends on the capacity of the metal and pullout resistance of the fasteners with the substrate This will simplify the design process and clearly state a wind load specification for the com-ponent that offers the first line of defense against commercial roof failures due to wind effects

ACKNOWLEDGEMENT This research and development work

was carried out under the auspices of the Natural Sciences and Engineering Research Council of Canadarsquos (NSERCrsquos) Collaborative Research Grant (CDR ndash 395869) Industrial partners were Firestone Building Products JRS Engineering Group Menzies Metal Products Metal-Era Inc the Roofing Contractors Association of BC and Soprema Inc whom we thank for the contribu-tions including coping configurations The authors also acknowledge the assistance of NRC technical officers Steven Ko Amor Duric David Van Reenen Aarti Singla and Maha Dabas Material requirements were coordinated by Carlisle Syntech and sen-sor installation and repairs were completed by Larry Lemke of Marine Roofing Access to the building was graciously given by the Canada Post and we appreciate the help of Michael Bryson Alan Shopland and Reyes Ronald of JLL for coordinating the access

REFERENCES 1 ANSISPRI 2011 Wind Design

Standard for Edge Systems Used With Low Slope Roofing Systems ANSISPRIFM 4435ES-1

2 ASCE 2010 Minimum Design Loads of Buildings and Other Structures ASCESEI 7-10

3 A Baskaran J Bysice B Martin-Perez ldquoIn-Situ Measurement of Wind Performance of Roof Edge Systems ndash Effect of Edge Metal Configurationsrdquo Journal of Testing and Evaluation ASTM International (JAI) under review

4 A Baskaran S Molleti N Martins B Martin-Perez 2016 ldquoDevelopment of Wind Load Specifications for Commercial Roof Edge Metalsrdquo Journal of Architectural Engineering (ASCE) under review

5 A Baskaran S Molleti and D Roodvoets 2007 ldquoUnderstanding Low-sloped Roofs Under Hurricane Charley From Field to Practicerdquo Journal of ASTM International Vol 4 No 10

6 Factory Mutual Research Corpor-ation 2016 Loss Prevention Data Sheet 1-49 Factory Mutual Research Corporation Norwood MA 2016

7 FEMA 488 2005 ldquoHurricane Charley in Florida Mitigation Assessment Team Report Observations Recom-mendations and Technical Gui-dance Hurricane Recovery Adviso-riesrdquo httpwwwfemagovlibrary viewRecorddoid=1444

8 FEMA 489 2005 ldquoHurricane Ivan in Alabama and Florida Miti-gation Assessment Team Report Observations Recommendations and Technical Guidancerdquo http wwwfemagovlibraryviewRecord doid=1569

9 FEMA 549 2006 ldquoHurricane Katrina in the Gulf Coast Mitigation Assessment Team Report Building Performance Observations Rec-ommendations and Technical Guid-ancerdquo httpwwwfemagov libraryviewRecorddoid=1857

10 FEMA 757 2009 ldquoHurricane Ike in Texas and Louisiana Miti-gation Assessment Team Report Building Performance Observations Recommendations and Techni-cal Guidancerdquo httpswww f e m a g o v m e d i a - l i b r a r y -data20130726-1648-20490-9826 fema757pdf

11 NBCC 2015 National Building Code of Canada Institute for Research

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7 B a S k a R a n e t a l bull 9 5

Figure 4 ndash Effect of wind speed on CCC DCC and ACC

elements away from its substrates and the attachment locations This can lead to cop-ing disengagement from the cleat andor fastener pullout from the cleat or the cleat pulling over the fastener Examples of such failures are shown in Figure 2

Due to lack of wind load criteria for prop-er roof edge design process in the Canadian building code it has been decided to per-

9 4 bull B a S k a R a n e t a l

Figure 5 ndash Codification of wind load pressure coefficient of low-slope membrane roof edge metals

Windward Parapet Load Case A

1 Windward parapet pressure (p1) is determined using the positive wall pressure (p5) zones or from the applicable figure

2 Leeward parapet pressure (p2) is determined using the negative roof pressure (p7) zones or from the applicable figure

Leeward Parapet Load Case B

1 Windward parapet pressure (p3) is determined using the positive wall pressure (p5) zones or from the applicable figure

2 Leeward parapet pressure (p4) is determined using the negative wall pressure (p6) zones or from the applicable figure

Component Covering Parapet Pressure (pe) is determined using the negative roof pressure (p7 x 14) zones or from the applicable figure

form further data Peterka amp Shahid 1998[12]) are -51 and -76 analysis such that for the front and top legs respectively as a pressure coefficients design pressure coefficient Note that these that are unique to coefficients are limited to low-rise buildings the metal edges H lt18 m (60 ft) and are not suitable for can be specified use with ASCE 7 Additional data process-Inspired by available ing is needed to develop ASCE 7 pressure

engineering approaches in developing pres- coefficients These pressure coefficients are sure coefficients the authors developed a higher than ES-1 coefficients procedure for pressure coefficient calcula- Discussions with industrial partners tions as explained in a companion paper revealed that without sacrificing the tech-[3] The design pressure coefficients based nical merit of the acquired field data sim-on the Gumbel distribution are -31 and plifications are needed in specifying the de--46 for the front and top legs respectively sign pressure coefficient This is mainly to The code-comparable pressure coefficients avoid a separate set of calculations for the with a 50-year return period (obtained from front top and back faces of the edge metal

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7

Based on industry input and consider-ing the variability and complexity of the wind dynamics at the separation bubble it has been decided to propose a representa-tive design pressure coefficient for the edge metals by taking the worst-case scenario between top and front legs This resulted in a design pressure coefficient of -76 cor-responding to the top leg

Also to account for practicality in the design process it has been decided to corre-late the proposed coefficient with the exist-ing roof cladding and component pressure coefficient A correlation factor of 14 can be obtained by dividing the above-calculated pressure coefficient of -76 for edge metals by -54 where -54 is the maximum exter-nal CpCg value corresponding to low-slope roof components and cladding design speci-fication in accordance with the NBCC 2015 (refer to the Figure 4176 of NBCC 2015)[11]

Based on the above discussions and roofing industry consultations the proposed CpCg for edge metals are shown in Figure 5

For completeness of the design wind-ward and leeward loads that are directly taken from ASCE 7 are also shown This present proposal only enhances the existing parapet wind load specification of ASCE SEI 7-10[2] Edge metal pressure (Pe) is determined using 14 times the negative roof pressure (P7) corresponding to zone C or S from the appropriate figure of the NBCC This explicit specification will facilitate proper design and the attach-ment mechanism to transfer the edge metal load to the parapet structure Doing so not only simplifies the design process but also provides an explicit wind load specification for the component that offers the first line of defense against commercial roof failures due to wind effects A similar attempt has also been made to develop a pressure coeffi-cient suitable for the ASCE 7 by considering necessary transformations as the ASCE 7 pressure coefficient (GCp) values refer to a velocity pressure based on a three-second gust wind speed However only recently major changes were balloted for the com-ponents and cladding sections to the ASCE 7-2016 Hence for the time being it has been decided to limit the proposal to the NBCC 2020

CONCLUSIONS This paper developed appropriate design

pressure coefficients for possible incorpora-tion into NBCC During this process the

following observations were made bull Comparison of the in-situ measured

pressures with the existing ANSI ES-1[1] wind standards suggested that the ES-1 wind load criteria are inadequate

bull Based on consultation with the roof-ing industry it is proposed that the edge metal pressure (Pe) be deter-mined using a factor of 14 applied to the negative roof pressure (P7) corresponding to zone C or S from the appropriate figure of the NBCC This simplifies the components and cladding design process

This explicit specification will facilitate proper design and implicitly facilitate the design of attachment mechanism to trans-fer the metal load to the parapet structure This load path transfer depends on the capacity of the metal and pullout resistance of the fasteners with the substrate This will simplify the design process and clearly state a wind load specification for the com-ponent that offers the first line of defense against commercial roof failures due to wind effects

ACKNOWLEDGEMENT This research and development work

was carried out under the auspices of the Natural Sciences and Engineering Research Council of Canadarsquos (NSERCrsquos) Collaborative Research Grant (CDR ndash 395869) Industrial partners were Firestone Building Products JRS Engineering Group Menzies Metal Products Metal-Era Inc the Roofing Contractors Association of BC and Soprema Inc whom we thank for the contribu-tions including coping configurations The authors also acknowledge the assistance of NRC technical officers Steven Ko Amor Duric David Van Reenen Aarti Singla and Maha Dabas Material requirements were coordinated by Carlisle Syntech and sen-sor installation and repairs were completed by Larry Lemke of Marine Roofing Access to the building was graciously given by the Canada Post and we appreciate the help of Michael Bryson Alan Shopland and Reyes Ronald of JLL for coordinating the access

REFERENCES 1 ANSISPRI 2011 Wind Design

Standard for Edge Systems Used With Low Slope Roofing Systems ANSISPRIFM 4435ES-1

2 ASCE 2010 Minimum Design Loads of Buildings and Other Structures ASCESEI 7-10

3 A Baskaran J Bysice B Martin-Perez ldquoIn-Situ Measurement of Wind Performance of Roof Edge Systems ndash Effect of Edge Metal Configurationsrdquo Journal of Testing and Evaluation ASTM International (JAI) under review

4 A Baskaran S Molleti N Martins B Martin-Perez 2016 ldquoDevelopment of Wind Load Specifications for Commercial Roof Edge Metalsrdquo Journal of Architectural Engineering (ASCE) under review

5 A Baskaran S Molleti and D Roodvoets 2007 ldquoUnderstanding Low-sloped Roofs Under Hurricane Charley From Field to Practicerdquo Journal of ASTM International Vol 4 No 10

6 Factory Mutual Research Corpor-ation 2016 Loss Prevention Data Sheet 1-49 Factory Mutual Research Corporation Norwood MA 2016

7 FEMA 488 2005 ldquoHurricane Charley in Florida Mitigation Assessment Team Report Observations Recom-mendations and Technical Gui-dance Hurricane Recovery Adviso-riesrdquo httpwwwfemagovlibrary viewRecorddoid=1444

8 FEMA 489 2005 ldquoHurricane Ivan in Alabama and Florida Miti-gation Assessment Team Report Observations Recommendations and Technical Guidancerdquo http wwwfemagovlibraryviewRecord doid=1569

9 FEMA 549 2006 ldquoHurricane Katrina in the Gulf Coast Mitigation Assessment Team Report Building Performance Observations Rec-ommendations and Technical Guid-ancerdquo httpwwwfemagov libraryviewRecorddoid=1857

10 FEMA 757 2009 ldquoHurricane Ike in Texas and Louisiana Miti-gation Assessment Team Report Building Performance Observations Recommendations and Techni-cal Guidancerdquo httpswww f e m a g o v m e d i a - l i b r a r y -data20130726-1648-20490-9826 fema757pdf

11 NBCC 2015 National Building Code of Canada Institute for Research

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7 B a S k a R a n e t a l bull 9 5

Based on industry input and consider-ing the variability and complexity of the wind dynamics at the separation bubble it has been decided to propose a representa-tive design pressure coefficient for the edge metals by taking the worst-case scenario between top and front legs This resulted in a design pressure coefficient of -76 cor-responding to the top leg

Also to account for practicality in the design process it has been decided to corre-late the proposed coefficient with the exist-ing roof cladding and component pressure coefficient A correlation factor of 14 can be obtained by dividing the above-calculated pressure coefficient of -76 for edge metals by -54 where -54 is the maximum exter-nal CpCg value corresponding to low-slope roof components and cladding design speci-fication in accordance with the NBCC 2015 (refer to the Figure 4176 of NBCC 2015)[11]

Based on the above discussions and roofing industry consultations the proposed CpCg for edge metals are shown in Figure 5

For completeness of the design wind-ward and leeward loads that are directly taken from ASCE 7 are also shown This present proposal only enhances the existing parapet wind load specification of ASCE SEI 7-10[2] Edge metal pressure (Pe) is determined using 14 times the negative roof pressure (P7) corresponding to zone C or S from the appropriate figure of the NBCC This explicit specification will facilitate proper design and the attach-ment mechanism to transfer the edge metal load to the parapet structure Doing so not only simplifies the design process but also provides an explicit wind load specification for the component that offers the first line of defense against commercial roof failures due to wind effects A similar attempt has also been made to develop a pressure coeffi-cient suitable for the ASCE 7 by considering necessary transformations as the ASCE 7 pressure coefficient (GCp) values refer to a velocity pressure based on a three-second gust wind speed However only recently major changes were balloted for the com-ponents and cladding sections to the ASCE 7-2016 Hence for the time being it has been decided to limit the proposal to the NBCC 2020

CONCLUSIONS This paper developed appropriate design

pressure coefficients for possible incorpora-tion into NBCC During this process the

following observations were made bull Comparison of the in-situ measured

pressures with the existing ANSI ES-1[1] wind standards suggested that the ES-1 wind load criteria are inadequate

bull Based on consultation with the roof-ing industry it is proposed that the edge metal pressure (Pe) be deter-mined using a factor of 14 applied to the negative roof pressure (P7) corresponding to zone C or S from the appropriate figure of the NBCC This simplifies the components and cladding design process

This explicit specification will facilitate proper design and implicitly facilitate the design of attachment mechanism to trans-fer the metal load to the parapet structure This load path transfer depends on the capacity of the metal and pullout resistance of the fasteners with the substrate This will simplify the design process and clearly state a wind load specification for the com-ponent that offers the first line of defense against commercial roof failures due to wind effects

ACKNOWLEDGEMENT This research and development work

was carried out under the auspices of the Natural Sciences and Engineering Research Council of Canadarsquos (NSERCrsquos) Collaborative Research Grant (CDR ndash 395869) Industrial partners were Firestone Building Products JRS Engineering Group Menzies Metal Products Metal-Era Inc the Roofing Contractors Association of BC and Soprema Inc whom we thank for the contribu-tions including coping configurations The authors also acknowledge the assistance of NRC technical officers Steven Ko Amor Duric David Van Reenen Aarti Singla and Maha Dabas Material requirements were coordinated by Carlisle Syntech and sen-sor installation and repairs were completed by Larry Lemke of Marine Roofing Access to the building was graciously given by the Canada Post and we appreciate the help of Michael Bryson Alan Shopland and Reyes Ronald of JLL for coordinating the access

REFERENCES 1 ANSISPRI 2011 Wind Design

Standard for Edge Systems Used With Low Slope Roofing Systems ANSISPRIFM 4435ES-1

2 ASCE 2010 Minimum Design Loads of Buildings and Other Structures ASCESEI 7-10

3 A Baskaran J Bysice B Martin-Perez ldquoIn-Situ Measurement of Wind Performance of Roof Edge Systems ndash Effect of Edge Metal Configurationsrdquo Journal of Testing and Evaluation ASTM International (JAI) under review

4 A Baskaran S Molleti N Martins B Martin-Perez 2016 ldquoDevelopment of Wind Load Specifications for Commercial Roof Edge Metalsrdquo Journal of Architectural Engineering (ASCE) under review

5 A Baskaran S Molleti and D Roodvoets 2007 ldquoUnderstanding Low-sloped Roofs Under Hurricane Charley From Field to Practicerdquo Journal of ASTM International Vol 4 No 10

6 Factory Mutual Research Corpor-ation 2016 Loss Prevention Data Sheet 1-49 Factory Mutual Research Corporation Norwood MA 2016

7 FEMA 488 2005 ldquoHurricane Charley in Florida Mitigation Assessment Team Report Observations Recom-mendations and Technical Gui-dance Hurricane Recovery Adviso-riesrdquo httpwwwfemagovlibrary viewRecorddoid=1444

8 FEMA 489 2005 ldquoHurricane Ivan in Alabama and Florida Miti-gation Assessment Team Report Observations Recommendations and Technical Guidancerdquo http wwwfemagovlibraryviewRecord doid=1569

9 FEMA 549 2006 ldquoHurricane Katrina in the Gulf Coast Mitigation Assessment Team Report Building Performance Observations Rec-ommendations and Technical Guid-ancerdquo httpwwwfemagov libraryviewRecorddoid=1857

10 FEMA 757 2009 ldquoHurricane Ike in Texas and Louisiana Miti-gation Assessment Team Report Building Performance Observations Recommendations and Techni-cal Guidancerdquo httpswww f e m a g o v m e d i a - l i b r a r y -data20130726-1648-20490-9826 fema757pdf

11 NBCC 2015 National Building Code of Canada Institute for Research

3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7 B a S k a R a n e t a l bull 9 5

in Construction National Research Georgia 16 T Smith 1990 ldquoHurricane Hugorsquos Council of Canada (NRCC) 14 RICOWI Inc 2007 ldquoHurricane Effects on Metal Edge Flashingsrdquo

12 JA Peterka and S Shahid 1998 Katrina Wind Investigation Reportrdquo International Journal of Roofing ldquoDesign Gust Wind Speeds in the Roofing Industry Committee on Technology United Statesrdquo Journal of Structural Weather Issues Inc Powder Springs 17 T Smith 2015 ldquoNailer Attachment Engineering 124(2) 207ndash214 Georgia is One Key to Achieving Wind-Uplift

13 RICOWI Inc 2006 ldquoHurricanes 15 RICOWI Inc 2007 ldquoHurricane Ike Performancerdquo Professional Roofing Charley and Ivan Wind Investigation Wind Investigation Reportrdquo Roofing NRCA page 65-70 Reportrdquo Roofing Industry Committee Industry Committee on Weather on Weather Issues Inc McDonough Issues Inc Powder Springs Georgia

9 6 bull B a S k a R a n e t a l 3 2 n d R C I I n t e R n a t I o n a l C o n v e n t I o n a n d t R a d e S h o w bull M a R C h 1 6 - 2 1 2 0 1 7