Feature PFC Stringer
P2
design elements
Feature PFC Stringer
design Structural steel members are surprisingly graceful and have a beauty all of their own. That is, they do if you get the design right, and we believe we have done just that with the P2 Feature PFC design. In the P1 design, the PFC members get the structural work done ‘behind the scenes’ and permit a wide variety of cladding methods. In contrast, the P2 represents a very specific design, with interlocking structural steel members being the main structural feature. This brings a source of tension into the design, as the relatively open and sparse profile contrasts with the weight and impact of the structural steel. If pure heavy metal isn’t your style, the P2 can be modified to present a more refined appearance by the installation of timber panels within each member. Figure (5) illustrates that this can accent the natural geometric lines of the staircase with timber grain and shadow line details.
P2 Figure 1. P2 Feature PFC illustrative example of RHS U shaped staircase format. Balustrade not shown. A wide variety of balustrade styles (documented in other Arden brochures) can work with the P2 stringer / staircase design.
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1
230
180
2490
2490
A-A
A-A
B-B
B-B
930
B A
A
Cross-member stringer cut intomember stringer member
A
One PFC carries through
M16 bolted connections
M16 bolted connections End plate inset into one PFC
C
End plate inset into one PFC
C
H
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Top step
Upper structural floor level
Upper floor coverings 180
0 23
H
D
0 23
E
D H
180
D E
plate inset into PFC to maintain PFC profile.
Upper structural floor level
19
E
Fixing plate and endplate inset into PFC to maintain PFC profile. Fixing plate and end-
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230
H
H-H
H-H
Upper floor coverings
Top step
E
Going (260)
Going (260)
One PFC carries through
B
B
3965
3965
A
Cross-member cut into
930
930B
230
930
Rise (170)
while upper and lower sides remain flush
1281
1281
Dimensions of major / minor PFCs (230 / 180) set somajor that minor PFCs can (230 run under tread Dimensions of / minor PFCs / 180) set support while and lower remain flush so that minor PFCs canupper run under treadsides support
Rise (170)
C
230
180
C
Feature PFC Stringer
Space between Space between upper upper lower flights and lowerand flights
Upper landing support stringer
Bulkhead plaster line Upper landing support stringer
D-D
D
Bulkhead plaster line
D-D
106
10
M16 rod chemset fixing106 to concrete
M16 rod chemset fixing to concrete
E-E
E-E
2
2
2
Figure 2. Plan view and details. Sections A-A and B-B show how the use of smaller grades of PFC for the under-landing supports integrates with the main stringer members to set the bottoms of the members flush, as well as the top face of the main members and the tread surface. Detail C shows the M16 bolted connections at the 90 degree corner intersection of main landing supports. A mitred corner detail is also possible.
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P2
As section H-H shows, the illustrative example shown here works on a 170 rise and 260 going which are quite typical in a commercial installation. Section D-D illustrates the connection of the upper flight stringer with a PFC-supported top landing structure. The 180h top landing support PFC is painted and positioned with respect to the plaster with a typical shadow line detail. Finally, section E-E details a typical bottom floor fixing to concrete slab using M16 rods at 106mm separation.
F indicated on dimensions denotes a nominal dimension that typically varies according to specific application, engineering requirements or client preferences.
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Feature PFC Stringer
technical PFC (parallel flanged channels) are a standard structural steel component, similar to more standard items such as universal beams and columns. Hot formed sections such as PFC’s offer an “off the shelf� structural solution to a number of application with staircases being one of those applications that are particularly apt. In staircases, the size of the PFC is determined by its structural duties and varies according to application from 300PFC (300x90) down to 185PFC (185x70). The major advantages of the use of PFCs as stringers are: a) Engineered structural properties including torsional and lateral strength. b) Ease in fabrication in that it is straight and provides one face for the simple welding of steel tread cleats, steel tread supports, folded steel tread and riser assemblies and the like. c) Balustrade application to a PFC typically takes advantage of the flat top of the pfc (The flange) although other, (typically more complicated) solutions are possible to the open channel side of the PFC.
P2 4
Whilst PFC stringers offer a simple engineering solution for stringers in most applications, thought needs to be applied to how this may affect the styles available for a balustrade solution.
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Minor PFC members support landing Tread / landing support tags welded to inside of stringer
Figure 4. Exploded isometric summarising structure and construction methods. Details F and G illustrate welded joins between PFC members, with cut-outs required to fit one member to another. Detail J shows the tread and landing construction in this particular example, incorporating a solid timber body, inset support plate and non-slip strip, and applied nosing. A wide variety of tread and landing designs may be combined to the P2 stringer design, please refer to the appropriate Arden brochure for details.
Feature PFC Stringer
Figure 3. Bottom plan view showing the use of welded tread-support tags and minor PFC members to support the landing. Actual number and details of support fittings depending on dimensions of staircase and type of tread design selected.
3
Solid timber tread with routing to accept non-slip strip Latham strip or similar non-slip surface Tread support tag
Precise cut to achieve join between PFC members
3
45
Applied nosing
19
J
F
F
G
J
P2
Precise cut to achieve join between PFC members
Upper flight PFC stringer
G
Landing cross-piece
4
4
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5
Feature PFC Stringer
Figure 5. Design variant of the P2 when a more refined finish is desired. Feature timber panelling installed flush with the outer face of the main PFC members, and with a shadow line between the timber and the steel flange edge.
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P2 6
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Intellectual property is copyright Š Archstairs Pty Ltd unless otherwise agreed in writing. All rights to the document are retained. Any use of the document by clients or third parties, unless specifically authorised by Archstairs Pty Ltd, are at their own risk and the user releases and indemnifies Archstairs Pty Ltd from and against all loss or damage arising from such use.
Feature PFC Stringer
About this document
compliance Arden is a BSA licensed contractor for carpentry, joinery, glass, glazing and aluminium as well as structural metal fabrication and erection. Arden supplies a Form 16 (Licensed Contractor) on all projects. In design and construct contracts, a Form 15 (Design Engineer) certification is supplied upon request. For products and services incorporating the P2 system, this table shows compliance with relevant codes and standards.
Key full compliance with the code can comply not applicable to this element
Code
Title
BCA
The Building Code of Australia
Applicability
AS NZS 1170.1-2002
Structural Design Actions – Permanent, imposed and other actions
AS 1288-2006
Glass in Buildings. Selection and installation.
AS NZS 1554.1-2004
Structural steel welding - Welding of steel structures
AS 1554.6-1994
Welding stainless steels for structural purposes
AS NZS 4586-2004
Slip resistance classification of new pedestrian surface materials
AS 1428.1-2009
Design for access and mobility
AS 1657-1992
Fixed platforms, walkways, stairways & ladders. Design, construction and installation
P2
design note For all commercial applications, it is important that sufficient space for the stairwell cavity be allowed to satisfy Australian Standards and BCA requirements. The footprint is primarily driven by the floor to floor rise, as well as the staircase configuration chosen. However, stringer and balustrade style design may increase the amount of space required. Allowing too small a cavity can restrict the design options of the staircase. Also, points at where the staircase interacts with other structures are best addressed early in the design cycle. Consultation with Arden early on will help ensure that these design issues can be addressed in a cost-effective manner.
design elements
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