Simplified Steel Stair Design for Commercial and Institutional Buildings

Transcription

1 Simplified Steel Stair Design for Commercial and Institutional Buildings Collaborating with steel stair fabricators during the design of commercial and institutional buildings promotes integrated practice and produces streamlined results. Provided by: Lapeyre Stair Written by: Peter J. Arsenault, FAIA, NCARB, LEED-AP

2 !"!#$%&'%()#*+',-.%(/&0# McGraw-Hill Construction is a registered provider with The American Institute of Architects Continuing Education System. Credit earned on completion of this program will be reported to CES records for AIA members. Certificates of completion for non-aia members are available on request. This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product.

3 1&23%,'4.#5&/6+# This presentation is protected by US and international copyright laws. Reproduction, distribution, display and use of the presentation without written permission of the speaker is strictly prohibited.

4 7+(%0,0'#89:+6/;+-## After participating in this presentation, you will be able to:!!!! Identify and recognize the overall parameters, general code requirements, and preliminary design outcomes in a building stair design. Determine the specific requirements and options for stair treads, risers, and landings in building stair systems. Differentiate between the specific requirements and options for stair guards and handrails in commercial and institutional buildings. Formulate construction specifications for steel stair systems working in concert with recognized standards and specialty fabricators.

5 1&<%-+#8<.=,0+# Section 1: General Stair Design Overview Section 2: Stair Design Specifics: Treads, Risers and Landings Section 3: Stair Design Specifics: Guards and Handrails Section 4: Steel Stair Construction Specifications

6 Section 1 General Stair Design Overview The Architect will typically determine the following:! Building Parameters! Applicable Codes and Standards! Basic Design Decisions

7 Section 1: General Stair Design Overview General Definitions: Stair: A change in elevation, consisting of one or more risers. (International Building Code) (IBC) Step: A rest for the foot in ascending or descending as one of a series of structures consisting of a riser and tread. (Merriam Webster Dictionary) Stairway: One or more flights of stairs, either exterior or interior, with the necessary landings and platforms connecting them, to form a continuous and uninterrupted passage from one level to another. (IBC)

8 Section 1: General Stair Design Overview Building Parameters: The Architect working in concert with the Owner will always determine the overall building criteria and parameters that affect the general and specific details of stair design.

9 Section 1: General Stair Design Overview Building Parameters: 1. Building Type: Fundamentally, determining if the building is classified as a commercial, institutional, multi-family, mixed use, or other building application. Each type has obvious differences in use and code requirement calculations

10 Section 1: General Stair Design Overview Building Parameters: 2. Floor to floor or landing heights The physical vertical dimension that each building stair is servicing needs to be determined and finalized Generally, steel stair systems service up to 12 vertical rise maximum before connecting to a landing or level

11 Section 1: General Stair Design Overview Building Parameters: 3. Overall building design requirements The Architect and other design professionals determine the overall design standards for the building including:!!!! Aesthetics/Appearance Durability Materials Function

12 Section 1: General Stair Design Overview Applicable Codes and Standards Virtually all of the specific dimensions of most stair components and spaces are governed by a code or standard. Materials, surface texture, and other product specific items are also subject to regulation.

13 Section 1: General Stair Design Overview Applicable Codes and Standards 1. International Building Code (IBC) Means of Egress: A continuous and unobstructed path of vertical and horizontal egress travel from any occupied portion of a building or structure to a public way. (IBC) Enclosed stairways are typically a critical part of a means of egress and exit and regulated with many very prescriptive details.

14 Section 1: General Stair Design Overview Applicable Codes and Standards 1. International Building Code (IBC) Some recent updates include details of:! Minimum egress width! Open riser changes! Handrail graspability! Required locations for guards! Limitations on guard openings! Luminous markings in egress path! Required areas of refuge

15 Section 1: General Stair Design Overview Applicable Codes and Standards 2. Handicapped Accessibility Requirements Area of Refuge: An area where persons unable to use stairways can remain temporarily to await instruction or assistance during emergency evacuation. (IBC) Stairways often include these areas within their enclosure.

16 Section 1: General Stair Design Overview Applicable Codes and Standards 2. Handicapped Accessibility Requirements IBC, ANSI and ADA all impose requirements for stairways and components to be accessible for non-wheelchair based handicaps including:! Treads and Risers! Nosings! Handrails

17 Section 1: General Stair Design Overview Applicable Codes and Standards 3. General Safety Standards Workplace safety governed by OSHA standards that address stairs, handrails, guardrails, and slip resistance. ASTM Standard F1637 addresses Standard Practice for Safe Walking Surfaces.

18 Section 1: General Stair Design Overview General Design Decisions Architects and Designers determine:! Stair Configuration to fit with building design: straight run, switch back, angled, scissor stair, custom, etc.! Presence of other allowable items in stairwells such as sprinklers, standpipes, openings, etc. and clearances required! Applicable Code and Standard requirements to determine design features such as occupancy load for stair, stair width and handicapped accessibility requirements.

19 Section 1: General Stair Design Overview General Design Decisions Steel Stair Fabricators/Manufacturers can use the General Design Decisions from architects to develop the specific details of the fabricated stair design. In the spirit of integrated practice, the fabricator or manufacturer can provide a preliminary or trial shop drawing for the architect s review and input to coordinate the overall building design and stair design together.

20 Section 2 Stair Design Specifics: Treads, Risers, and Landings The Stair fabricator / manufacturer can provide the specialty details of the following under the direction of the Architect:! Treads! Risers! Landings! Nosings

21 Section 2: Stair Design Specifics: Treads, Risers, and Landings Treads 1. Tread Definition: The upper horizontal part of a step (Merriam-Webster Dictionary) Codes and standards assume common understanding and don t define differently.

22 Section 2: Stair Design Specifics: Treads, Risers, and Landings Treads 2. Specific Code and Standard Requirements for Treads: Depth: 11 minimum with less than 3/8 variation between treads in a single run of stairs (IBC) Width: to match stair width requirements (IBC) Profile: Leading edge or nosing shall be less than! curve or bevel (ANSI 117.1) Slip resistance: Stable, planar, level, flush & slip resistant (ASTM F1637)

23 Section 2: Stair Design Specifics: Treads, Risers, and Landings Treads 3. Tread Design Options:! Steel pan filled with concrete on site! Fabricated smooth plate steel! Fabricated diamond plate patterned steel! Primed steel for separate field finish! Pre-finished in standard or custom colors! Galvanized steel

24 Section 2: Stair Design Specifics: Treads, Risers, and Landings Risers 1. Riser Definition: The upright member between two stair treads (Merriam-Webster Dictionary) Codes and standards also assume common understanding and don t define differently.

25 Section 2: Stair Design Specifics: Treads, Risers, and Landings Risers 2. Specific Code and Standard Requirements for Risers: Height: 4 7 with less than 3/8 variation along a run of stairs (IBC) Open or closed: Closed most common and required for accessible stairs (ANSI 117.1). Open risers allowed only in limited situations (IBC & OSHA) Flat or sloped: vertical or up to 30 degrees slope (ANSI 117.1)

26 Section 2: Stair Design Specifics: Treads, Risers, and Landings Risers 3. Riser Design Options:! Open or closed! Flat or sloped if closed! Material choice! Pre-finished or field-finished

27 Section 2: Stair Design Specifics: Treads, Risers, and Landings Landings 1. Landings Definition: A level part of a staircase (as at the end of a flight of stairs). (Merriam-Webster Dictionary) Codes and standards assume understanding and don t define differently. Sometimes referred to as a stair platform

28 Section 2: Stair Design Specifics: Treads, Risers, and Landings Landings 2. Specific Code and Standard Requirements for Landings: Location: Required at the top and bottom of each stairway (IBC) Width: to match stair width requirements (IBC) Slip resistance: Stable, planar, level, flush, and slip resistant (ASTM F1637) Stair level identification (ANSI 117.1)

29 Section 2: Stair Design Specifics: Treads, Risers, and Landings Landings 3. Landing Design Options (could be same or different than treads)! Steel pan filled on site with concrete! Fabricated smooth plate steel! Fabricated diamond plate patterned steel! Primed steel for field-finish! Pre-finished in standard or custom colors! Galvanized steel

30 Section 2: Stair Design Specifics: Treads, Risers, and Landings Nosings 1. Nosing Definition: The leading edge of treads of stairs and of landings at the top of stairway flights (IBC)

31 Section 2: Stair Design Specifics: Treads, Risers, and Landings Nosings 2. Specific Code and Standard Requirements for Nosings: Projection from vertical: 1-1/4 (IBC ) or 1-1/2 max. (ANSI 117.1) Differentiation: Visual contrast across front 2 inches of tread. (ANSI 117.1, ASTM F1637) Slip resistance: tactile difference along nosings are a common safety feature (ASTM F1637)

32 Section 2: Stair Design Specifics: Treads, Risers, and Landings Nosings 3. Nosing Design Options (could be same or different than treads and landings)! Integral to stair tread! Integral to stair riser! Additional add-on treatment

33 Section 3 Stair Design Specifics: Guards and Handrails The Stair fabricator / manufacturer can provide the specialty details of the following under the direction of the Architect:! Guards! Handrails! Stringers

34 Section 3: Stair Design Specifics: Guards and Handrails Guards 1.!Guard Definition: A building component or a system of building components located at or near the open sides of elevated walking surfaces that minimizes the possibility of a fall from the walking surface to a lower level (IBC)

35 Section 3: Stair Design Specifics: Guards and Handrails Guards 2. Specific Guard Code and Standard Requirements: Required: Anywhere above 30 above floor or grade below (IBC) Height: 42 high measured vertically above the leading edge of the tread or adjacent walking surface. (IBC) Opening restrictions: a 4 sphere shall not pass through any opening up to a height of 34 inches or an 8 sphere between height of inches (IBC)

36 Section 3: Stair Design Specifics: Guards and Handrails Guards 3. Guard Design Options Architects need to specify if guards are needed or if stairway walls are present and negate the need:! One side! Both sides! Neither side

37 Section 3: Stair Design Specifics: Guards and Handrails Guards 3. Guard Design Options! Rails or pickets! Solid filler panels! Wire mesh panels! Pre-finished in standard or custom colors! Primed for field-finish! Galvanized! Welded or bolted pre-assembled or field assembled

38 Section 3: Stair Design Specifics: Guards and Handrails Handrails 1.!Definition: A horizontal or sloping rail intended for grasping by the hand for guidance or support (IBC)

39 Handrails Section 3: Stair Design Specifics: Guards and Handrails 2. Specific Handrail Code and Standard Requirements: Required: On both sides of all stairs and ramps. Intermediate (center) rail if more than 60 stair width (IBC & ANSI 117.1) Continuity: Handrails shall be continuous without interruption at ends or supports (IBC & ANSI 117.1) Height: Uniform height that is no less than 34 and no higher than 38 measured vertically above stair tread nosing (IBC & ANSI 117.1)

40 Section 3: Stair Design Specifics: Guards and Handrails Handrails 2. Specific Handrail Code and Standard Requirements (cont d): Graspability for Circular handrails: Outside diameter of at least 1.25 inches but less than 2 inches. (IBC & ANSI 117.1) Graspability for Non-Circular handrails: Perimeter dimension of at least 4 inches but less than 6.25 inches and maximum cross section of 2.25 inches. (IBC & ANSI 117.1)

41 Section 3: Stair Design Specifics: Guards and Handrails Handrails 2. Specific Handrail Code and Standard Requirements (cont d): Clearance: 1-1/2 inches minimum clearance between handrail and wall or guard (IBC & ANSI 117.1) Surfaces: Smooth with rounded edges (IBC & ANSI 117.1) Handrail Extensions: 12 inches or depth of tread past the last top and bottom tread (IBC & ANSI 117.1)

42 Section 3: Stair Design Specifics: Guards and Handrails Handrails 3. Handrail Design Options Architects need to specify if handrails are intended to be installed as:! Guard mounted! Stair mounted! Wall mounted

43 Section 3: Stair Design Specifics: Guards and Handrails Handrails 3. Handrail Design Options! Pre-finished in standard or custom colors! Primed for field finish! Galvanized! Pre-assembled or field assembled! Welded or bolted

44 Section 3: Stair Design Specifics: Guards and Handrails Stringers 1. Stringer Definition: The structural member that supports the treads and risers.

45 Section 3: Stair Design Specifics: Guards and Handrails Stringers 1. Stringer Design Options:! Flat Plate! C- Channel! Tube! Z-Channel

46 Section 3: Stair Design Specifics: Guards and Handrails Stringers 3. Structural Requirements for Stringers! Size and Number of stringers are determined by the stair design and load requirements! Center stringers may be required for wide stairs in excess of 6 0 in width (NAAM 4.4)! Stair manufacturer can help determine the appropriate stringer sizes to meet design requirements

47 Section 4 Steel Stair Construction Specifications The Stair fabricator / manufacturer and the Architect can work together to fashion appropriate specifications for the construction and installation of the steel stair system.

48 Section 4: Steel Stair Construction Specifications Part 1: General Relevant Fabrication standards:! AISC Manual of Steel Construction Code of Standard Practice! ASTM Select relevant standard based on type of steel product and treatment! NAAM Metal Stairs Manual ANSI/NAAM Metal bar Grating Manual

49 Section 4: Steel Stair Construction Specifications Part 1: General Performance and Construction Requirements:! Components to meet concentrated and distributed load requirements code minimum or above! Fabrication of components to be of single piece material! Specify welded or bolted conditions where appropriate

50 Section 4: Steel Stair Construction Specifications Part 1: General Submittals! Manufacturer s installation instructions! Dimensioned drawings for approval before fabrication! Full shop drawings! In the spirit of integrated practice, the submittal process can be drastically simplified if the stair fabricator provides trial drawings during design for coordination and integration in building

51 Section 4: Steel Stair Construction Specifications Part 1: General Delivery, Storage and Handling! Reference AISC Code of Standard Practice, Sections 6 and 7! Clean, dry, location away from damaging chemicals or substances! Lay out on firm material to avoid bending! Do not stack! Protect finishes

52 Section 4: Steel Stair Construction Specifications Part 2: Products Manufacturer! Select a single manufacturer for all components for a complete, coordinated system! Assure availability to project location

53 Section 4: Steel Stair Construction Specifications Part 2: Products Materials! Steel stair components! Brackets or mounting devices! Fasteners! Miscellaneous materials

54 Section 4: Steel Stair Construction Specifications Part 2: Products Finishes Pick one for each component. Powder coat baked enamel:!gray primer!safety yellow paint!standard or custom colors!hot dip galvanized

55 Section 4: Steel Stair Construction Specifications Part 2: Products Fabrication Per final approved shop drawings, determine assembly type:! Welded! Field bolted! Pre-assembled! Partially assembled

56 Section 4: Steel Stair Construction Specifications Part 2: Products Packaging Pack and ship in a manner to protect the final products and minimize the potential for damage during shipping and handling

57 Section 4: Steel Stair Construction Specifications Part 3: Execution Preparation! Coordinate with other trades and work! Weather and operations protection! Verify enclosure dimensions! Verify substrate! Make any needed corrections prior to stair installation

58 Section 4: Steel Stair Construction Specifications Part 3: Execution Installation! Field check steel components! Handle to avoid bending or deforming! Inspect, replace, or repair any damaged pieces! Pre-assemble per instructions! Prepare mounting holes! Install square, level, and plumb! Tighten all fasteners to torque level

59 Section 4: Steel Stair Construction Specifications Part 3: Execution Cleaning! Touch up finishes! Clean finished assembly

60 Section 4: Steel Stair Construction Specifications Final Installation Examples

61 Final Installation Examples Section 4: Steel Stair Construction Specifications

62 Section 4: Steel Stair Construction Specifications Final Installation Examples

63 Thank you! Please take the test to receive your AIA credits This concludes the American Institute of Architects Continuing Education System Program