Firesafe Issue 4.pdf - OneSteel

FireSafe 

CASE STUDIES in 

Structural steel 

Fire safety engineering by design 

Issue 4, May 2007 

Alternative solutions in 

Fire Safety Engineering 

• Uncompromised safety 

• Architectural flexibility 

• Reduced construction costs 

50 Lonsdale Street, Melbourne 

www.onesteel.com

Welcome 

Welcome to FireSafe Solutions Issue 4, 

showcasing steel-framed retail projects 

that have benefited from the application of 

performance-based Fire Safety Engineering 

assessments, to provide alternative solutions 

using bare steel construction that can offer 

benefits such as: 

• INCREASED SAFETY LEVELS 

• REDUCED BUILDING COSTS 

• ARCHITECTURAL FLEXIBILITY 

• FASTER CONSTRUCTION 

Advertiser & Sunday Mail Building 

Adelaide 

THE STRUCTURAL SYSTEM INCLUDES STEEL 

HOLLOW SECTION COLUMNS, TYPICALLY 

457 MM IN DIAMETER. 

4 

3 

2 

1 

G 

B 

office 

office 

office 

office 

office 

carpark 

Figure 1 

The Advertiser office building 

incorporates 5 levels of offices above a 

basement carpark (see Figure 1). The 

floor area is approximately 3200 m 2 

per storey. It has two full-height atria 

connecting all office levels. Each 

atrium has plan dimensions of 20.2 m 

by 5.8 m. There are three fire-isolated 

stairs in addition to a non-required 

stair in an atrium. 

The structural system includes steel 

hollow section columns, typically 

457 mm in diameter, filled with 

concrete and reinforced internally. 

Floor slabs are composite profiled steel 

sheeting slabs. Steel beams include 

shear connectors to achieve composite 

action with the floor slab. 

The building is sprinkler-protected 

throughout. 

atrium 

The effective height of the building is 

approximately 19.5 m, being less than 

the height of 25 m at which sprinklers 

are required under DTS. Sprinkler 

protection is required under DTS due 

to the presence of the atria, however. 

Sprinkler protection of the carpark is 

also required under DTS, as it contains 

more than 40 car spaces. 

The building has been approved with 

structural fire protection in the office 

levels as follows: 

• all columns are protected to achieve 

an FRL of 120/-/- 

• the primary beams, which span 

across the shorter dimension of the 

building, are protected to achieve 

an FRL of 60/-/- 

• all other beams are unprotected (all 

beams have an exposed surface area 

to mass ratio of less than 30 m 2 /t) 

The sprinkler system incorporates the 

following features: 

• separate sprinkler systems for atria 

and offices; 

• monitored valves at each storey; 

• provision for end-of-line testing; and 

• fast response heads. 

In addition, a sprinkler management 

system was specified, incorporating: 

• no two zones to be isolated at any 

one time; 

• sprinkler zones to be isolated only 

for single days, reinstated a night; 

• fire loads to be reduced if periods 

of extended isolation are 

unavoidable; and 

• end-of-line testing to be performed 

after any isolation. 

The above fire safety solution has 

been justified largely on the basis that 

the benefits of the sprinkler system 

enhancements provided outweigh any 

additional hazard associated with the 

reduced FRL of the floor system. 

FireSafe : Fire Safety Engineering by Design | Page 2

Furthermore, it was demonstrated 

that even a standard sprinkler system 

provides about three times the benefit 

of fire-rated construction with respect 

to limiting the rate of occurrence of 

large fires. Since the rate of deaths 

and injuries from fires correlates 

directly with the rate of occurrence 

of large fires, the BCA objectives 

are more effectively satisfied using 

sprinkler protection rather than 

protection of structural elements. 

More specifically, the impact of the 

proposed solution upon fire spread, 

detection and suppression, occupant 

avoidance and fire brigade intervention 

were considered, as follows: 

• fire spread – the enhanced sprinkler 

system provides benefits with regard 

to reduced likelihood of fire spread, 

with sprinklers being more likely to 

stop spread than fire-rated floors, 

due to the openings and free edges 

which always occur. The full-scale 

Cardington fire tests [1] 

demonstrated the robustness of the 

structural form utlilised. 

• detection and suppression – the 

enhanced sprinkler system 

increases reliability. 

• occupant avoidance – the egress 

time will be about 10 mins, 

whereas the real behaviour provides 

safety for many times that required. 

• fire brigade intervention – fire brigade 

effectiveness is assisted by the 

enhancements to the sprinkler system. 

• adjacent buildings – the 

enhancements to the sprinkler 

system reduce the probability of a 

large fire occurring, thus 

outweighing the impact of the 

reduced FRL of the floor system. 

References 

1. Kirby, B et al, “The Behaviour of 

Multi-Storey Steel Framed 

Buildings in Fire”, British Steel 

Corporation, 1999. 

CLIENT 

Advertiser Newspapers Pty 

Limited 

ARCHITECTS 

E.G.O Fender Katsalidis 

PROJECT MANAGER 

E.G.O Group 

STRUCTURAL ENGINEER 

Wallbridge & Gilbert 

BUILDING CONTRACTOR 

Baulderstone Hornibrook 

ADVERTISER BUILDING – FIRE RESISTANCE REQUIREMENTS SUMMARY 

BUILDING ELEMENT 

ELEMENT REQUIREMENT 

DTS 

Office – beams 120/-/- 

Alternative Solution 

Primary beams: 60/-/- 

Other beams: unprotected 

Office – columns 120/-/- 120/-/- 

Carpark – beams 

60/-/- or 

30 m 2 /t 

30 m 2 /t 

Carpark – columns 60/-/- 60/-/- 

Sprinklers Yes Yes (with enhancements) 

Table 1 

FireSafe : Fire Safety Engineering by Design | Page3

Latitude East Building 

Sydney 

AN ATRIUM OF DIMENSIONS 29 M BY 14.5 M 

WILL CONNECT ALL OF LEVELS 12 TO 22. 

OWNER 

Multiplex 

DEVELOPER 

Multiplex 

ARCHITECT 

Crone Partners 

STRUCTURAL ENGINEERS 

Taylor Thomson Whitting 

BUILDER 

Multiplex Construction 

FIRE ENGINEER 

Norman Disney & Young 

This new building forms part 

of the Latitude development. 

A podium structure comprising 8 

levels of basement carparking and 3 

levels of retail has previously been 

extended above its west side with the 

construction of the 50-storey Latitude 

building. The new Latitude East 

building currently under construction 

comprises 11 storeys above the east 

side of the podium, forming Levels 12 

to 22. The new storeys will be used 

for offices throughout. 

The external dimensions of the 

building will be approximately 67 m 

by 46 m. An atrium of dimensions 

29 m by 14.5 m will connect all of 

Levels 12 to 22. Because of this 

atrium, there will be no central core. 

Overall building stability will mainly be 

provided by two concrete structures, 

located near the north-east and 

south-west corners of the building. 

The façade of the building will be fully 

glazed on all sides, with a separation 

distance to any adjacent building of 

more than 3 m on all sides. 

There will be two fire-isolated stairs. 

These will be partially supported 

on steel beams and encased 

with masonry walls. In addition, 

there will be a non-fire-isolated 

communication stair within the 

atrium space, enclosed with glazing. 

We understand that this stair will 

not be classified as a designated or 

required exit. 

The building will be fully sprinklerprotected 

throughout, which is 

required under the deemed-to-satisfy 

(DTS) provisions of the Building Code 

of Australia. The sprinkler system 

will be enhanced by the provision of 

monitored floor-by-floor valving and 

end-of-line testing. 

The structure of the new building will 

comprise steel beams and columns, 

composite slabs and shear studs 

providing composite action between 

the beams and the slab. Columns will 

generally be steel hollow sections of 

610 mm diameter, concrete-filled, 

containing longitudinal reinforcement 

with 40 mm cover and designed 

for ambient strength, ignoring the 

contribution of the external steel. 

FireSafe: Fire Safety Engineering by Design | Page

The building structure will be fireprotected 

as follows: 

• all columns will be protected to 

achieve an FRL of 120/-/-; 

• all beams framing directly into 

columns at the floor between 

Levels 18 and 19 and below will 

be protected to achieve an FRL 

of 60/-/-; 

• secondary beams spanning only 

between other beams will not be 

protected; 

• cantilever beams will not be 

protected; and 

• transfer beams supporting columns 

(if any) will be protected to achieve 

an FRL of 120/-/-. 

In addition, any beams which support 

fire-isolated stairs (either directly or 

indirectly) will be protected to achieve 

an FRL of 120/-/-. 

All steel beams will be left 

unprotected at the following levels: 

• the floor between Levels 19 and 

20, which supports the top office 

level; and 

• the floor between Levels 20 and 

21, which supports the rooftop 

plant room. 

The plant room will not contain any 

equipment required for fire brigade 

intervention. 

The columns will be required to 

achieve an FRL of at least 120/-/-, but 

in practice the typical columns being 

used are likely to achieve an FRL 

between 180/-/- and 240/-/-. 

The structural protection solution 

was approved on the basis of the 

beneficial effect of the enhancements 

to the sprinkler system in 

substantially reducing the probability 

of sprinkler failure, in addition to the 

understanding of whole-structure 

behaviour gained through full-scale 

fire testing conducted at Cardington in 

the UK and BHP Research in Australia. 

The most likely cause of sprinkler 

failure is deliberate isolation of parts 

of the system for the purpose of 

refurbishment. The proposed sprinkler 

design measures will directly mitigate 

the effects of this hazard. 

Given the large atrium and 

consequent lack of a central core 

structure (a building feature not 

included in the Cardington tests), it 

was necessary to protect all beams 

framing directly into columns and 

thus enhance the stability of the 

columns. 

The philosophy for not protecting the 

floor of the top habitable level was 

that the columns passing through this 

level are not critical in terms of the 

fire safety objectives. Thus, if a fire 

occurs in the second top habitable 

level (Level 19), the floor of the top 

level may deflect and the occupants 

will have strong cues to evacuate. If 

these columns should fail, only the 

roof above would be affected, which 

is of limited importance with respect 

to life safety. In the current case, the 

plant room may also be affected, 

but this also is extremely unlikely 

to have any impact upon life safety. 

Furthermore, regarding fire brigade 

safety, any deformations will occur in 

a gradual manner, providing adequate 

warning to firefighters to enable 

escape as necessary. 

LATITUDE EAST BUILDING – FIRE RESISTANCE REQUIREMENTS SUMMARY 


DTS 

office beams 120/-/- 



Beams framing directly into 

columns: 60/-/- 


Top two levels: all beams 

unprotected 

office columns 120/-/- 120/-/- 

sprinklers Yes Yes (with enhancements) 

Table 2 

FireSafe: Fire Safety Engineering by Design | Page

Flinder's Link Building 

Adelaide 

Figure 2: Cross-Section Elevation of 

Flinders Link Building 

DEVELOPER / BUILDER 

PT Building Services, 

Kambitsis Group and 

Hindmarsh Group 

ARCHITECT 

HASSELL 


Wallbridge & Gilbert 

The Flinders Link project incorporates 

two adjoining buildings, currently 

known as Stage 2 and Stage 5. The 

Stage 2 building incorporates 9 storeys 

of carparks with 2 storeys of offices 

above, while the Stage 5 building 

incorporates a retail storey, a carpark 

storey and 7 storeys of offices above. 

The top two storeys of offices in each 

building are linked (see Figure 2). 

The buildings have been constructed 

using a structural steel frame with 

composite floor slabs and composite 

action between the floor slabs and the 

steel beams. 

The buildings are sprinkler-protected 

throughout. As they are both over 25 m 

in effective height, these sprinklers are 

required under DTS. 

In the Stage 2 building, the carpark 

storeys at Levels 5 and below were 

protected in accordance with DTS, 

resulting in unprotected steel beams 

throughout and concrete-filled steel 

hollow section columns achieving an 

FRL of 60/-/-. 

The structural fire protection at Level 

6 has been approved as follows: 

• all columns are protected to 

achieve an FRL of 60/-/- 

• all beams in the floor above Level 6 

which span directly into columns 

are protected to achieve an FRL of 

60/-/- 

• all other beams are unprotected. 

In the Stage 5 building, the following 

protection has been used: 

• all columns are concrete-filled 

steel hollow sections achieving an 

FRL of 120/-/- 

• all beams which span directly into 

columns are protected to achieve 

an FRL of 60/-/- 

• all other beams are unprotected. 

The sprinkler system incorporates the 

following features: 

• monitored valves at each storey; 

• provision for end-of-line testing; and 

• fast response heads. 

In addition, a sprinkler management 

system was specified, incorporating: 

• no two adjoining zones to be 

isolated at any one time; 

• sprinkler zones to be isolated only 

for single days, reinstated a night; 

• wood-equivalent fire loads per unit 

floor area to be reduced below 

10 kg/m 2 if periods of extended 

isolation are unavoidable; and 

• end-of-line testing to be performed 

after any isolation. 

Table 3 

Approval for this solution was 

obtained on the basis that the 

benefits of the enhanced sprinkler 

system outweighed any additional 

hazard due to the reduction in FRL. 

Also discussed was the greater 

effectiveness of sprinklers in 

comparison with FRLs in satisfying 

the BCA objectives. 

Test evidence was also presented 

from the Cardington fire tests [1] 

and further work demonstrating the 

robustness of partially protected floor 

systems by Bailey [2] was used. 

References 

1. Kirby, B et al, “The Behaviour of 

Multi-Storey Steel Framed 

Buildings in Fire”, British Steel 

Corporation, 1999. 

2. Bailey, C G and Toh, W S, 

“Experimental Behaviour of 

Concrete Floor Slabs at Ambient 

and Elevated Temperatures”, 

Fourth International Workshop on 

Structures in Fire, Portugal, 2006. 

FLINDERS LINK BUILDING – FIRE RESISTANCE REQUIREMENTS SUMMARY 


DTS 




Beams framing directly into columns: 

Stage 2, Level 6: 60/-/- Stage 5: 120/-/- 


Office – columns 120/-/- Stage 2, Level 6: 60/-/- Stage 5: 120/-/- 

Retail – beams 180/-/- 

Retail – columns 180/-/- 120/-/- 


60/-/- or 

30 m 2 /t 

Beams framing directly into columns: 120/-/- 


30 m 2 /t 



FireSafe : Fire Safety Engineering by Design | Page

50 Londsdale Street 

Melbourne 

5 LEVELS OF BASEMENT 

CARPARK AND 33 STOREYS 

ABOVE GROUND. 

The new office building at 50 

Lonsdale Street is known as The 

Urban Workshop. It incorporates 5 

levels of basement carpark and 33 

storeys above ground. A 5-storey 

atrium connects all levels between 

Ground Floor and Level 4. There are 

retail spaces at Ground Floor, Level 

1 and Level 2. The remainder of the 

building is generally office space. 

The below-ground part of the building 

is reinforced concrete construction, 

while the above-ground part is steelframe 

with composite floor slabs and 

has composite action between the 

beams and the slab. 

All primary and secondary steel 

beams are unprotected throughout 

the building, with the exception of 

beams passing through the atrium. 

All columns and transfer beams are 

protected in accordance with DTS, ie 

120/-/- FRL in offices and 180/-/- FRL 

in retail spaces. 


throughout. Enhancements to the 

sprinkler system have been included 

to provide increased reliability in 

comparison with a DTS-compliant 

design. These enhancements include 

floor-by-floor monitored valves, 

end-of-line testing and specific 

management procedures. 

with the structural engineers for the 

project to evaluate the performance 

of both the connections and the 

columns when the unprotected 

beams are at elevated temperatures. 

This scenario assumes sprinkler 

failure and is thus a low-probability 

event. 

A risk assessment has been 

performed and it has been shown 

that, given the enhancements 

to be included in the design, the 

probability of structural failure of the 

unprotected steel beams in fire will 

be no greater than that of the beams 

at ambient temperature. 

DEVELOPER 

ISPT 

ARCHITECT 

John Wardle Architects in 

association with Hassell 

and NH Architecture 


Connell Mott MacDonald 

BUILDER 

Multiplex Constructions 

FIRE ENGINEERING 

Norman Disney & Young 

Use has been made of the results of 

the large-scale fire tests conducted 

on a similar structural system, 

being the 140 William Street tests in 

Australia and the Cardington tests in 

the UK. In addition, consideration has 

been given to the robustness of the 

structural system in the event of a 

fully-developed fire at any one storey. 

The fire safety engineers have worked 

50 LONDSDALE STREET – FIRE RESISTANCE REQUIREMENTS SUMMARY 



DTS 



Office – columns, 

transfer beams 

Retail – beams 180/-/- 

Retail – columns, 

transfer beams 

120/-/- 120/-/- 

180/-/- 180/-/- 

Atrium: 120/-/- 

Other: unprotected 

Atrium: 120/-/- 

Other: unprotected 


Table 4 

FireSafe : Fire Safety Engineering by Design | Page

Forum Apartments 

Adelaide 

THE BUILDING INCLUDES SOME 2-STOREY 

AND 3-STOREY APARTMENTS BETWEEN 

GROUND FLOOR AND LEVEL 2. 

5 

4 

3 

2 

1 

G 

B1 

apartments 

apartments 

apartments 

apartments 

apartments 

carpark / office / retail 

carpark 

light well / walkways 

internal 

windows 

2-storey & 

3-storey 

apartments 

The structural protection is as follows: 

• the basement carpark is constructed 

using reinforced concrete and 

achieves an FRL complying with DTS 

(ie 60/60/60 FRL) 

• columns and primary beams at 

Ground Floor are protected to 

achieve an FRL of 60/-/- 

• secondary beams at Ground Floor 

are unprotected 

• steel beams and columns are 

unprotected in apartment storeys. 

The solution was approved on the basis 

that, in the apartment storeys, sprinklers 

are more effective in achieving the BCA 

objectives than FRLs. At Ground Floor, 

the required FRL of 60/-/- has been 

determined by consideration of the 

likely maximum fire size and duration 

and estimation of the FRL necessary to 

survive burnout. 

Figure 3: Cross-Section Elevation of Forum Apartments Building 

DEVELOPER/BUILDER 

Commercial & General 

ARCHITECT 

David Dawson Architects 


KBR 

FABRICATOR 

MWS Group of Companies 

The Forum Stage 2 building has a 

basement carpark, mixed uses at 

Ground Floor and five storeys of 

apartments above. Ground Floor 

includes small areas of carpark, 

office, retail and apartment uses. 

The building includes some 2-storey 

and 3-storey apartments between 

Ground Floor and Level 2. 

The building has a light well connecting 

Levels 1 to 5. The apartments have 

internal windows facing this light well. 


throughout. It has an effective height of 

less than 25 m. The carpark contains 

more than 40 car spaces. 

FORUM APARTMENTS – FIRE RESISTANCE REQUIREMENTS SUMMARY 


DTS 


Apartments – beams 90/-/- Unprotected 

Apartments – columns 90/-/- Unprotected 

Retail / office – beams 180/-/- 


60/-/- or 

30 m 2 /t 


Primary beams: 60/-/- 


Retail / office – columns 180/-/- 60/-/- 

60/-/- 



Table 5 

9 3 2 0 0 7 5 0 4 5 6 3 0 

This publication has been prepared by OneSteel Market Mills an operating business group of which OneSteel Manufacturing Pty Limited ABN 42 004 651 325, OneSteel NSW Pty 

Limited ABN 59 003 312 892, OneSteel Wire Pty Limited ABN 59 000 010 873, OneSteel Trading Pty Limited ABN 50 007 519 646, OneSteel MBS Pty Limited ABN 76 096 273 

979 are a part. Please note that any specifications or technical data referred to in this publication are subject to change and/or variation or improvement without notice and no 

warranty as to their suitability for any use is made. Users of this publication - to ensure accuracy and adequacy for their purposes - are requested to check the information provided 

in this publication to satisfy themselves as to its appropriateness and not to rely on the information without first doing so. Unless required by law, the company cannot accept any 

responsibility for any loss, damage or consequence resulting from the use of this publication. Photographs shown are representative only of typical applications, current at May 2007. 

This publication is not an offer to trade and shall not form any part of the trading terms in any transaction. © Copyright 2002-2007. OneSteel Market Manufacturing Pty Limited, 

ABN 42 004 651 325. Registered Trademarks of OneSteel Market Mills: 300PLUS ® and FireSafe. Issue 4 Printed May 2007. 17530 

ONESTEEL DIRECT Freecall 1800 178 335 Website www.onesteel.com Freefax 1800 101 141 Email onesteeldirect@onesteel.com

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