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What is SMA?

"SMA" is the initials of the Storage Manufacturers Association. The SMA was formed in 1974 and operates as an Industry Group within the Material Handling Industry of America (MHI). The membership of the SMA is made up of companies which produce industrial storage equipment for customers world-wide. The SMA promotes the safe design and use of shelving, work platforms, shop furniture, cabinetry and drawer systems.

Programming includes research, development of specifications, educational programs, and meetings. The SMA is the American National Standards Institute (ANSI) accredited developer of shelving systems and work platforms.

How do I obtain copies of SMA/ANSI Specifications? Does SMA have a website?

Copies of the most recent edition of the ANSI/SMA Specifications For The Design, Testing and Utilization of Industrial Steel Storage Shelving, Metal/Wood Shelving and Industrial Work Platforms are complimentary and can be downloaded on the SMA website at www.mhi.org/sma.

What is the maximum allowable shelf deflection at maximum shelf load?

Shelving designed to the American National Standard (ANSI MH28.1) will carry a maximum capacity based on a uniformly distributed load. At that load, one should expect to see mid-span deflection no greater than L/140, where L is the maximum span of the shelf. For example, a 48" shelf should not deflect more than 48"/140 or 0.3" at maximum shelf capacity. When unloaded, the shelf should return to its level state. It is normal for shelves to deflect under load.

Can one help stabilize or stiffen the shelving or work platforms by tying to the building?

While it may be possible to tie work platforms or shelving to a building structure, this should never be done without consulting both the equipment provider and building designer to assure that each structure can receive and resist any forces that may be transferred.

Is it permissible to add vertical extensions onto existing shelving units?

To expand vertically, one will need to know if the existing installation was designed to hold increased shelf loads. A qualified design professional is the best person to answer the question. He/She can do a structural analysis of the existing shelving layout and advise on how best to expand to meet present and future needs.

Is it permissible to step on a shelf?

No. Unless notified otherwise by the manufacturer, typically, shelves are not designed for this purpose.

What are the fire code requirements for the decking used on my work platform or shelving system?

The International Code Congress (ICC) has interpreted the wood decking to be as an interior floor finish, and is not required to be noncombustible. (Reference IBC Table 601, and Sections 602, 603, 804 & 805). The building elements permissible in construction depend on the type of construction to be used. Types of construction range from Type I through Type V. Types I and II are the most restrictive concerning combustibility requirements of building elements, while type V allows any materials permitted by code to be used. In Type I and II construction of work platforms, the structural elements are normally required to be made of noncombustible materials.

Combustible decking materials may be used in all types of construction where they are not considered a structural element of the work platform. An example of this is wood decking that is installed over a noncombustible structural element, such as corrugated metal roof deck. The uniform and point loads on the structure are designed to be carried by the substructure (floor framing) and the roof deck, not the wood decking.

For more details on this subject, please contact a member of the SMA.

How do I design my work platform for point loads and for pallet jack loads?

This is an important consideration, as these loads by definition are more concentrated, may be dynamic instead of static, and often are more damaging to the floor than uniform loads. It is imperative that the end user determines what type of traffic may be on the work platform. Common types of traffic include pedestrian, rolling loads from pallet jacks or carts, and point loads from shelving units, conveyor legs, and other heavy equipment. Rolling loads may be problematic for some types of flooring. The end user needs to consult with the manufacturer of the work platform and provide the usage and loading information so that the work platform can be properly designed including deck selection. The load carrying capacity of a work platform may be limited by the decking surface type, as well as the elements of the underlying substructure.

What loading criteria should I consider when designing my work platform or shelving system with bar grating for pedestrian and light cart traffic?

Light duty steel grating is best suited for use in conjunction with pedestrian traffic, and for light, rubber pneumatic-tired rolling traffic (carts, dollies, and hand trucks,) The National Association of Architectural Metal Manufacturers (NAAMM) recommends a maximum deflection of L/240 or less for uniform loads. ¼" is considered the maximum deflection consistent for pedestrian comfort, but can be exceeded for other loading conditions at the discretion of the qualified design professional.

How do I know if my system will require seismic design?

State and local building codes, most commonly based on the International Building Code (IBC), or local building officials will provide guidance to owners/users as to appropriate considerations for your specific site. The US Geological Survey has created a spectral mapping system of the USA, USA territories, and select foreign countries that identifies seismic risk to a level as precise as specific latitude/longitude.

Storage systems, not unlike buildings, are often subject to the building code review and permitting process. Most communities face the potential of earthquakes to varying degrees, magnitudes, and probabilities. Particular seismic requirements are site-specific, and the user should bring to the attention of the manufacturer the specific local requirements, including applicable building codes, the specific installation location, any knowledge of the supporting concrete slab, and any information about the below-slab soils and their properties. Storage systems should be designed, manufactured, installed, and used in accordance with the requirements of the site; these requirements may include seismic effects and may also include the characteristics of the building in which the storage system is housed. To find the requirements for your job site, contact a structural engineer familiar with seismic requirements at the site as well as the local building authority.

What is the difference between a Qualified and Registered Design Professional?

A Qualified Design Professional is an individual with the knowledge of and the ability to apply the design principles appropriate to the specific application.

A Registered Design Professional is an individual with the knowledge of and the ability to apply the design principles appropriate to the specific application and who is registered or licensed to practice his/her design profession as defined by the statutory requirements of the professional registration laws of a state or jurisdiction. Typically, the design calculations and construction drawings submitted in order to obtain a building permit are certified by the Registered Design Professional licensed in the state where the work platform/shelving system is located.

What do I do if my shelving/work platform is damaged or if I suspect that there may be a structural problem such as overloading?

Damage can originate from a number of causes, most notably from impact. Any structural damage to the system will negatively impact capacity and performance. Structural problems, such as overloading, typically manifest themselves in such manners as excessive deflection or excessive sway.

Where any visible damage or suspected structural problems occur, isolate the area in question to minimize the risk of injury to workers, or to goods and/or property, and then notify a responsible party. The manufacturer, or their representative, should be summoned for an evaluation of the problem. If the manufacturer cannot be identified, a Qualified Design Professional, with experience in the design and implementation of shelving/work platforms, should be retained for an evaluation of the problem. The correction will generally involve an unloading protocol followed by the replacement or repair of the damaged component(s).

What should I do if I think there may be damage to my work platform and/or shelving system?

If there are any concerns about structural problems with the platform or shelving system, the first priority must be to isolate the area in question, then evaluate the damage & situation and then safely unload the area supported by the damaged component and to prevent loads from being placed into that area. Then, the manufacturer’s representative should be contacted for an engineering evaluation of the problem. If the manufacturer cannot be identified, an independent engineer, experienced in the design of platform or shelving systems, should be retained to evaluate the damage and propose the repair. The repair should be performed by an experienced installer, and the repairs should leave the storage system as strong as the original installation.

Should work platforms and/or shelving systems be periodically inspected?

Following initial installation, the work platform and/or shelving system owner should establish and implement a program of regularly scheduled work platform and/or shelving system inspections. The inspections should be performed by a qualified person familiar with the work platform or shelving design and installation requirements. Work platforms and/or shelving should be inspected periodically to check for any damage or abuse and immediately after any event that occurs that may result in damage to the structure. The frequency of inspections should be up to the discretion of the owner, depending on the conditions of use. As a minimum, inspections should be performed annually. The inspection schedule and results of the inspection should be documented and retained. Should there be any concerns as a result of the inspection, refer to the FAQ on damage, overloading or others as applicable. For your convenience, the SMA has created a generic inspection form which is available as a free download.

What are the common life safety (personnel) concerns to be considered when purchasing work platforms and/or shelving systems?

There are many life safety concerns that dictate the design of work platforms and or shelving systems. These include, but are not limited to, fire protection, travel distance, means-of-egress, commodity classification, lighting and ventilation. Because these requirements continue to evolve, these items are typically not included in the scope of work provided by the work platform and/or shelving system manufacturer. It is the responsibility of the owner or the owner’s integrator to ensure that all applicable codes are complied with in their facility.

What should I know about height-to-depth ratios for catalog shelving?

The height-to-depth ratio is an important factor used in evaluating the stability of a shelving system. The maximum height-to-depth ratio for catalog shelving located in a non-seismic region is 4-to-1 (4:1). For catalog shelving the height of the shelving is considered the top of the post. This ratio is determined by dividing the height of the unit by its depth. If the result is greater than four (4:1), then floor anchoring and/or cross-aisle top-tying may be required. It is best to check with a qualified design professional to review the installation.

What is a concentrated (point) load?

A concentrated or point load is any static load considered to act over a small or concentrated area when compared to the extent of the surface to which the load is applied. Shelving or equipment legs can be examples of concentrated/point loads. "Punch through" of the decking may be a design consideration for these types of loads.

What is a uniformly distributed load?

A uniformly distributed load is one where the load is considered evenly distributed across a defined area. Examples may be live and/or dead loads.

To what load rating should my work platform be designed?

Determining the correct load rating for a work platform is dependent on the intended use and types of equipment placed on it. The work platform may be designed based on a minimum uniform live load, maximum point load, or actual equipment weight. The International Building Code (IBC) states in Table 1607.1 that work platforms used for light manufacturing or storage applications are designed to carry a default minimum uniform live load of 125 pounds per square foot (psf). This uniform rating averages the total combined weight of racks or shelving, equipment, walkways, loading areas, and products. Due consideration must be given to verify that point loads from racks, shelving, or other equipment do not exceed the capacity of the work platform. Other types of work- platforms such as conveyor support structures, equipment support platforms and other specialty structures may be designed for the specific loads they support. Careful analysis of the loads must be done to assure proper design criteria. Consulting an SMA member company regarding work platforms will help assure a correct design.

Does deflection play an important role in the design of work platforms?

Deflection is one of five criteria that comprise serviceability design considerations, as recommended by the American Institute of Steel Construction (AISC). Serviceability deals with "the state in which the function of a building, its appearance, maintainability, durability, and comfort of its occupants are preserved under normal usage". Neglecting serviceability issues may result in a structure that is overly flexible, which could lead to unacceptable performance of the structure, or movement that is in excess of what is comfortable to people on the structures. Deflection and drift (lateral deflection) criteria need to be determined with use of the intended structure in mind. Deflection is typically measured as a relationship to the span of the member. Common live load deflection limits are L/240 and L/360 depending on flooring type and occupancy, where L is the span of the floor beams.

It is sometimes difficult to specify limits for work platforms because they can vary depending on the type of structure, its intended use, and subjective physiological reactions. For example, acceptable deflections for an office on a work platform would be different than for shelving units on a work platform. The occupants sitting at a desk would be more sensitive to floor deflections than somebody walking across a work platform. When someone can see or feel the deflection in a structure, a discomforting feeling can occur. On normal work platforms used for storage or manufacturing, L/240 limits are adequate. For a work platform with an office on it, a plaster or drywall ceiling hung from underneath, or a concrete deck, L/360 would be appropriate. Many types of conveyors may have higher limits such as L/720 or L/1000, as requested by the manufacturers. Attention must also be paid to other pieces of equipment or processes that may be on the work platform. Standard deflection criteria may not be acceptable when supporting a scale or other precision equipment. It becomes imperative that the Qualified Design Professional understand the nature of the equipment and/or application in order to ensure proper performance.

What are the life safety concerns to be considered when purchasing a work platform and/or shelving system?

There are many life safety concerns that dictate the design of a work platform and/or shelving system. These include, but are not limited to, fire protection, travel distance, means-of-egress, commodity classification, lighting and ventilation. Because these requirements continue to evolve, the initial design of the platform or shelving structure and its operation is usually a joint effort on the part of the manufacturer and the owner (or owner’s representative) to take these factors/concerns into consideration so that the requirement of the applicable building code(s) are met.

When using bar grating as an elevated decking surface for a work platform and/or shelving module, what is the recommended minimum loading for the decking?

Light-duty steel grating (bearing bar thickness of ³⁄₁₆” or less) is best suited for use in conjunction with pedestrian traffic, light floor loading, and rubber pneumatic-tired rolling traffic (carts, dollies, and hand trucks) under 500 lbs. total. For pedestrian loading, the National Association of Architectural Metal Manufacturers – Metal Bar Grating (NAAMM-MBG) recommends a minimum design load for the grating of 100 psf, with a maximum deflection of L/240 ≤ ¼” (ANSI/NAAMM-MBG-531-00). This deflection limit can be exceeded for other loading conditions at the discretion of the qualified design professional.

For light rolling loads, a bearing bar spacing less than 1” on center is recommended for proper wheel load distribution and a smooth surface for the rolling load. For a manual pallet jack carrying heavier loads (over 1,000 pounds), a bearing bar spacing of ½” or less is recommended. Other types of rolling pallet jacks (electric or walkies) may require special design considerations.

How do I compute the wheel loads on a manual pallet jack?

The wheel loads on a manual pallet jack is case-specific and needs to be figured on a job-per-job basis and is therefore beyond the scope of this FAQ; however, that being said, following is an example for computing the wheel loads for a three-point pallet jack (two separated front point loads and a single rear point load): The total weight of the pallet jack and its load rating should be used for total load. The rear steering wheel(s) is presumed to carry a point load equal to 50% of the total load and the front fork wheel(s) are each presumed to carry a point load equal to 25% of the total load. For a 3,000 lb. rated pallet jack with a self-weight of 500 lbs. equals 3,500 lbs total load. The rear steering wheel(s) will carry 1,750 lbs. and each fork wheel will carry 875 lbs.

How is the weight of an occupant or employee accounted for in the design load of the flooring system?

The recommended minimum design live loads as specified in the codes/standards (e.g. IBC, ASCE7) include both point loads and uniform loads. For stairs the weight of an occupant is generally considered a point load (minimum 300# concentrated load at the center of a tread) and for a walking/work surfaces, the occupant load is include within the minimum uniform live load (typically a minimum live load of 125 psf for light-duty storage, 60 psf for pick aisles, and 40 psf for catwalks).

What is the best initial loading protocol for a shelving storage system.

All storage systems are designed for a specified live load in any location, and it is commonly assumed by the designer that the shelves in it will be loaded and unloaded in a random fashion during its lifetime. With that said, an appropriate approach to initially loading a shelving system is to start at the bottom shelf and work upwards, working from the middle bays outwards.

How do I know if I need footings under my work platform columns?

A typical slab-on-grade has a limited capacity to carry a concentrated load from a column. The greater the column load, the greater the chance that footings will be required. The manufacturers of the work platforms typically do not provide floor analysis but will provide column loads that can be furnished to the Engineer of Record doing the floor slab evaluation based on the strength and thickness of the floor slab and the allowable soil bearing pressure.

How is the size of the base plate determined?

A base plate is one of the major engineered components of any structural system. This is typical of either industrial bin shelving, boltless shelving, storage racks or work platforms. Many factors contribute to the final design size and thickness including lateral and vertical loads, strength of the steel plate, size of the columns, size and required spacing of anchor bolts, strength and thickness of the floor slab, and the allowable soil bearing pressure. The Qualified Design Professional must account for all of these factors, as well as “fit and function” factors when finalizing the design of base plates.

What codes and standards are used in the design of work platforms?

The design of work platforms is covered in ANSI MH28.3. However, structural design, load combinations and life safety considerations can be found in the applicable state and local codes, which are typically based on the IBC, ASCE7, AISC, AISI, NFPA, OSHA, FEMA and others.

Does OSHA require handrail/guardrail to be painted a specific color?

No, OSHA does not specify that guarding or handrails be painted any specific color. Often manufacturers offer a high visibility color for these products.

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