Design Element: Z1 - Zigzag plate steel stringer

Zigzag plate steel stringer

Z1

design elements

Zigzag plate steel stringer

design At Arden, we believe that the zigzag steel stringer design is the basis for some of the strongest architectural statements that can be made with a feature staircase.

This is because its visual impact is related to the essential functional property of a staircase, i.e. achieving an elevation through a sequence of horizontal and vertical steps. The steps therefore create a tension between these steps and the underlying diagonal slope line. Thus, design interest is created from the natural functional properties of the staircase element.

The Z1 structure is constructed from laser cut stainless or plate steel.

The style may lend itself to either a lighter gauge open construction (typically in stainless), or a heavier style closed construction (typically ex. steel plate). In the included photos, examples are shown of each form. It should be noted that when lighter gauge stringers are selected in order to satisfy design requirements, consideration must be given to method and location of support that is provided to the stringer.

Handrail (Typically stainless steel CHS or timber over ribbon plate) Positioned at the top of stanchions

Patch fittings

Upper floor balustrade

Glass panels supported by patch fittings

Z1

Feature clad floor to floor column supporting the stringer

Stainless or mild steel zigzag stringer Glazing channel

Figure 1. Isometric overview of staircase based on Z1 zigzag stringer construction. Balustrade illustrated (W4 winged blade stanchions transforming to glass curtain wall on lower floor) is just one effective balustrade combination with the Z1.

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Glass panel extended from floor to floor supported by glazing channel Lower floor handrail supported by stanchions 1

Timber tread

Zigzag plate steel stringer

The Z1 zigzag stringer looks particularly good when contrasted with tread and riser assembly that also emphasises the stepped pattern. The stepped effect can be maximised when a stepped soffit is added that mirrors the stepped pattern of the treads, thus fully realising the zigzag concept.

Figure 2. Front elevation. Support and connection methods vary on the left and right hand side of the flight.

The stringer is supported on the LHS by feature clad floor to ceiling columns. On the RHS, the stringers are suspended from the top floor balustrade.

Glass partitioning betweenbetween Glass partitioning structural columnscolumns structural Glass partitioning Glass partitioning betweenbetween structural structural columnscolumns

Mild or stainless steel column Mild or stainless steel column extended from floor to floor floor to floor extended from to support the stringer to support the stringer

Z1

Stanchion supportsupport bracket bracket welded welded Stanchion to both to post andpost stringer both and stringer

Stanchion Stanchion supportsupport bracket bracket welded welded both and stringer to both to post andpost stringer

10mm (typical) base connection 10mm (typical) base connection plate plate

M12 or M12 M16 or bolts M16 chemically bolts chemically bonded bonded to concrete to concrete floor floor

10mm (typical) base connection 10mm (typical) base connection plate plate

A

A

B

B

M12 or M12 M16 or bolts M16 chemically bolts chemically bonded bonded to concrete to concrete floor floor

2

2

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Zigzag plate steel stringer

technical The width or depth of the stringer will vary according to span, width, and performance expectations. Narrower stringer widths will require further support by way of hangers or support columns which can be integrated into the support system.

Figure 3. Left side elevation. Because of the placement of treads, the nosing line of the staircase based on the Z1 stringer traces the outer corners of the zigzag pattern. This example shows how a light gauge stainless steel zigzag stringer works effectively with stainless steel columns, stanchions and handrail to create a complete staircase solution, both structurally and visually.

12-15mm toughened or 12.76-17.52 toughened laminated glass depending on AS1170 design load, span and glass location

Typically M12-16 chemical anchors

Overall rise

A

Aluminium glazing extrusion

M16 rods chemset into wall 10mm plate steel fixing plate rebated into floor edge and plastered over for flush finish M12 or M16 bolts chemically bonded to concrete floor, fixing aluminium glazing extrusion to floor

Line of stainless or mild steel stringer

Z1

250ď € nominal tread going Nosing Line

Glazing channel Overall going determined by tread going 3

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g lazin mg iniu Alum sion u extr

8mm steel bolted to stanchions and welded to fixing plate 6 12-1 y M chors icall n Typ ical a m e h c

or less tain inger of s tr Line steel s d il m

l nne cha ing Glaz

10mm steel fixing plate rebated into wall and plastered over for flush finish Mild or stainless steel stringer

A

rise rall Ove

M16 rods chemset into floor structure. Void edge fixing located on chemset fixings.

The fixing assembly is covered by void edge treatment structure.

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Zigzag plate steel stringer

Figure 4. Typical top floor fixing detail. Fixing plates are welded to the inner side of each stringer and fixed to concrete floor. Fixing assembly concealed by top tread or bulkhead.

rall Ove

by ined term g de goin

in d go trea

F indicated on dimensions denotes a nominal dimension that typically varies according to specific application, engineering requirements or client preferences.

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Z1 design elements

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30 Tread overlap 280

Exact dimensions of the Z1 stringer may be varied to suit variable spans and supporting arrangements. The current example uses several sources of support, allowing us to minimise the width dimension of the stringer and create a ‘lighter’ impression. In other contexts, a heavier specification may be necessary or visually desirable.

Figure 6. Plan view. With face-fixed stanchions supporting the handrail, the traversable width of the flight is maximised. In the design shown, a wide composite stainless steel and timber handrail is selected to enhance the design.

Non-slip strip

Dress timber front nosing

2mm Mild or stainless steel riser

Dress timber back nosing Ply core Mild steel support tag

110

Zigzag plate steel stringer

Figure 5. Typical tread and riser detail for Z1 stringer. Tags welded to the inside of each stringer support screw fixings to composite treads with anti-skid tread nosings. In commercial applications, some risers in the interests of modesty may be appropriate, and here a folded metal riser is shown.

Line of stringer

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227

F indicated on dimensions denotes a nominal dimension that typically varies according to specific application, engineering requirements or client preferences.

Clear space between handrails unobstructed width

Upper floor

Stainless or mild steel stringer

Z1

Stair handrail (Typically stainless steel CHS or timber over ribbon plate)

C

B

C

B

Timber tread

A

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A

Top floor handrail (Typically stainless steel CHS or timber over ribbon plate)

Zigzag plate steel stringer

Z1

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design elements

Zigzag plate steel stringer

Min 50 clearMin (AS1428.1 50 clear (AS1428.1 Compliant) Compliant)

A

A

50-75mm dependent 50-75mm dependent upon spacing andspacing and upon AS1170 design load design load AS1170

Top floor handrail Top floor (Typically handrail (Typically stainless steel stainless CHS orsteel timber CHS or timber over ribbon over plate) ribbon Min 1000 plate) Min 1000 distance is required distance from is required from top of the handrail top of the to the handrail floor to the floor

Handrail inline with stringer Handrail inline with stringer (Typically stainless steel CHS steel CHS (Typically stainless or timber over ribbon over plate) or timber ribbon plate) Min 900 distance is required Min 900 distance is required from top of from the handrail to handrail to top of the the nosing line the nosing line

Line of toughened Line of toughened or laminatedor laminated toughened glass toughened glass

Handrail Support, Handrail Support, bolted to bolted to the stanchion the stanchion

Line of stanchions Line of stanchions

A50D or A38D series A50D or A38D series patch fittings (Refer to (Refer to patch fittings A50D or A38D Arden A50D or A38D Arden System A patch fittings System A patch fittings for detail) for detail)

B

B

Timber tread Timber tread

Stainless orStainless mild steelor mild steel stringer stringer

plate steel fixing 10mm plate10mm steel fixing plate plate rebated intorebated wall into wall andover plastered over for and plastered for flush finish flush finish

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Z1 8

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8mm steel bolted into bolted into 8mm steel stanchion and weldedand welded stanchion into fixing plate into fixing plate

7

7

stanchion attached stanchion attached to post and stringer to post and stringer (50-100mm dependent (50-100mm dependent upon spacing and upon spacing and AS1170 design load) AS1170 design load)

Handrail 865 minHandrail 1000 max 865 min 1000 max above nosing lineabove (BCAnosing and line (BCA and AS1428) AS1428)

Glazing channel Glazing supporting channel supporting the glass pannelthe glass pannel

Stainless or mildStainless steel stringer or mild steel stringer supported by column supported by column Mild or stainless Mild steelorcolumn stainless steel column extended from floor to floor extended from floor to floor to support the stringer to support the stringer

Lower floor

Lower floor

Zigzag plate steel stringer

Top floor handrail Top min floor 1000 handrail min 1000 above floor(BCA above and AS1428) floor(BCA and AS1428)

Top floor handrail min 1000 Top floor handrail min 1000 floor(BCA and AS1428) above floor(BCA above and AS1428)

50-100mm 50-100mm dependent upondependent upon spacing and AS1170 design spacing and AS1170 design load load

865 min 1000 max Handrail 865 minHandrail 1000 max above nosing lineabove (BCAnosing and line (BCA and AS1428) AS1428) channel supporting Glazing channel Glazing supporting the glass pannelthe glass pannel

or mild steel stringer Stainless or mildStainless steel stringer

8-15mm toughened or toughened or 8-15mm 8.76-17.52 toughened 8.76-17.52 toughened laminated glass depending laminated glass depending on AS1170 design onload, AS1170 design load, span and glass location span and glass location

Lower floor

Lower floor

8

8

8

Figure 7. Stanchion, handrail and balustrade fixing details. The stainless steel version of Z1 is often specified with handrail and stanchions, and the visual and structural interaction between these elements is critical.

design elements

Z1

Figure 8. Comparison of support methods of the Z1. In the left hand diagram, the stringer is supported a floor to ceiling post, and is further connected to the upper floor balustrade stanchion fixing. On the right hand side diagram, the stringer is suspended by an elongated stanchion dropping from the upper floor.

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Zigzag plate steel stringer

Nosing line Applied nosing to sides of treads and risers

32

32

200

270 nominal going

10

10 180 nominal rise

200 Detail of soffit matches and mirrors detail of treads and risers

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Figure 9. Zigzag plate steel stringer with tread and riser assembly, applied nosing to sides, and mirroring soffit detail on underneath. This variant of the PS2 makes the most emphasis of the stepped diagonal progression.

When a glass balustrade is applied to this design, we encourage the client or designer to consider panels with stepped bottom edges, so that the zigzag theme is continued to the balustrade.

Z1 F indicated on dimensions denotes a nominal dimension that typically varies according to specific application, engineering requirements or client preferences.

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Laser cut mild steel zigzag stringer

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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.

Zigzag plate steel 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 Z1 system, this table shows compliance with relevant codes and standards.

Key full compliance with the code can comply (see note for details) 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

1

1. Must have opaque risers to comply with AS1428

Z1

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.

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