E.1 General References
E.2 Load Requirements
E.3 General Requirements

E.1 General References

During the planning and design phase, the most cost-effective, functional, and aesthetic structural design should be developed. NIH campus buildings should meet all current building codes and ordinances. These include, but are not limited to, the latest editions of the following:

• International Building Code, International Code Council, 5203 Leesburg Pike, Suite 708, Falls Church, VA 22041-3401
• Building Code Requirements for Reinforced Concrete, ACI 318, American Concrete Institute, Detroit, MI
• Manual of Steel Construction ASD, American Institute of Steel Construction, Chicago, IL
• Building Code Requirements for Masonry Structures, ACI 530; and Specifications for Masonry Structures, ACI 530.1, American Concrete Institute, Detroit, MI
• Minimum Design Loads for Buildings and Other Structures, ASCE 7, American Society of Civil Engineers, New York, NY
• National Design Specification for Wood Construction; and National Design Specification Supplement, American Forest and Paper Association/American Wood Council, Washington, DC

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E.2 Load Requirements

E.2.1 Live Loads: Floor design live loads should be simplified to accommodate future load occupancy changes. Generalized live load categories should be applied to large areas; preferably one category to any one floor. Indicate the design live loads on all structural plans. For renovation projects, the live loads of adjacent existing areas should be noted on the structural plans to aid the contractor in determining construction live loads in staging areas or areas to be accessed during construction or demolition. Specialized equipment loads and requirements should be verified with the equipment manufacturer.

The following minimum live loads should be used except where higher loads for specific projects are required to meet program requirements.

Table E.2.1 Minimum Loads

Ensure that the occupancy/use minimum concentrated live loads dictated in the International Building Code also can be met by the design.

E.2.2 Live-Load Reduction: Columns supporting a building roof level shall not be subjected to live-load reduction. For new construction, the designer may apply the International Building Code for live-load reduction, or the current model building code for the area, whichever contains the more stringent requirements. For the structural design evaluation of sound existing buildings for renovation and re-use, the designer may use the
allowable live-load reduction allowed by the building code of the year during which the building was originally constructed, unless engineering judgment views the live-load reductions as being too liberal.

E.2.3 Wind Loads: The building shall be designed for the geographic basic wind and exposure category dictated in the International Building Code.

E.2.4 Seismic Loads: The building shall be designed to comply with the International Building Code for the seismic area in which the project is located.

E.2.5 Snow Loads: The building shall be designed for the geographic ground snow load for the area indicated by the International Building Code. The effects of sliding and drifting snow shall be incorporated in the design.

E.2.6 Dead Loads: The building shall be designed to support the actual weights of all materials. These include structural materials, finishes, ceilings, partitions, shielding, piping, and ductwork. Assumed weights shall be indicated on the design documents.

E.2.7 Hanging Loads: Loads exceeding 20 kg shall not be suspended from metal decking. All ductwork, piping, and so on should be suspended directly from the structural steel framing or supplementary steel members. Loads suspended from steel joists shall be suspended from the top chords unless structural analysis is furnished that allows otherwise.

For new concrete construction, cast-in inserts should be considered for hanging items in mechanical rooms, attaching overhead lights and equipment in operating rooms, or hanging any heavy loads. For existing construction, expansion anchors shall not be used to carry significant load in tension, except with written approval of a registered professional engineer for the specific use requested. Install anchors only with drill bits and equipment recommended by the manufacturer of the anchors. Evidence should be available indicating that contractor personnel were instructed in the correct installation procedures of that manufacturer’s anchors.

For plaster ceiling panels, an area of 14 m² shall not be exceeded without a structural separation from an adjoining panel section. Suspend loads exceeding 2 kPa independently of suspended ceiling construction.

E.2.8 Thrust Blocks: The structural engineer and the HVAC/plumbing engineers, in close coordination, should design the thrust blocks needed for the piping systems inside the building.

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E.3 General Requirements

E.3.1 Future Expansion: Any specific plans for future vertical or horizontal expansion must be accommodated. Provision should be made for the addition of future floors and additions as determined by the NIH on a project-by-project basis. Future expansion plans, including assumed type of construction and live loads, should be shown on the drawings.

E.3.2 Geotechnical: A comprehensive geotechnical investigation will be required. This will include test borings in soil, and rock coring, if rock is encountered. The investigation will provide information as to the types of soil encountered, allowable bearing pressures, differential and absolute settlements, lateral soil pressures, suggested types of foundations, water table, drainage requirements, and special foundation problems. The geotechnical report should be included in the construction documents. A geotechnical consultant should be retained to verify materials encountered during construction and monitor earthwork operations. Use of a registered geotechnical consultant in the State of Maryland, or where the project is located, is required.

E.3.3 Alternative Systems: For major new projects, a minimum of two feasible alternative structural systems should be evaluated. Provide a narrative describing the advantages and disadvantages of each system and indicate a recommended system. Include comparative cost estimates. The structural system selected should be the one that best combines overall economy with suitability of design. It must be compatible with the architectural, mechanical, electrical, and fire protection systems and accommodate vibration limitation requirements.

E.3.4 Peer Review: An independent, licensed structural engineer, if requested and contracted for by the NIH, shall perform a review of all final calculations, specifications, and drawings of the structural engineer of record.

E.3.5 Parking Garages: In addition to evaluation of at least two feasible structural systems, indicate the recommended maintenance systems and procedures to promote durability. Designs should incorporate the specification of parking garage wearing-surface systems, reinforcing materials, and concrete additives to decrease permeability and help the prevention of deterioration of the structure from de-icing salts. Life-cycle cost estimates comparing high first costs for a long-lived wearing surface to low first costs for a frequently replaced wearing surface should be included. The use of a consultant who specializes in the design of parking garages is required.

E.3.6 Loading Docks: A continuous galvanized steel angle should be embedded into the edge of the loading dock to protect the corner. A concrete apron should be constructed when paving the area adjacent to the loading dock. In addition to concrete additives designed to decrease permeability through the concrete, epoxy-coated reinforcing in the loading dock and apron concrete for protection against deterioration due to de-icing salts should be provided.

E.3.7 Vibration: Areas required to be sensitive against vibration transmission should be designed considering the effects of adjacent equipment, other sources of vibration, and operations. The use of a consultant specializing in vibration analysis and control is required for all hospital, laboratory, and animal research facility construction for both new construction and renovations. The consultant should address issues relative to vibrationsensitive equipment and specialized functions such as nuclear magnetic resonance (NMR), neurosurgery, eye surgery, mass spectrometry, and fitness centers. Specialized equipment requirements should be verified with the equipment manufacturer.

E.3.7.1 Floor Vibration Velocity Limits for New Floor Construction: The following table indicates the recommended floor vibration velocity limits, in micrometers per second, for various sensitive space usages. The manufacturer of equipment sensitive to vibration should verify that these limits are acceptable for their equipment to work within these guideline limits.

Table E.3.7.1 Recommended Floor Vibration Velocity Limits

E.3.8 Post-tensioned Concrete: Inadvertent cutting of post-tensioned concrete is a safety hazard. The tensioned steel strands within the concrete, if cut, may eject from the ends of the tubes into which they were placed or otherwise create danger to personnel. No holes should be cored or other demolition should occur before ground-penetrating radar and pacometer testing (both non-dangerous procedures) are conducted and recorded under the supervision of a registered professional structural engineer. These procedures are to be used to locate the tensioned strands in the area of interest and the information is to be provided to the registered professional engineer to design the procedure under which the demolition work is to be done. Demolition should be performed under the supervision of the design professional.

At the NIH, Buildings 40, 50, and the Clinical Research Center have floor construction of post-tensioned concrete. Building 36 has a floor area created by post-tensioned concrete construction.

E.3.9 Level of Concrete Finished Floors: Unless otherwise specified, a concrete floor shall be level, ±3 mm in height in 3 050 mm in any direction, measured at any point of the floor. Floor flatness (F_F) and floor levelness (F_L) numbers shall be specified when the installations of finish materials, functional conditions, or equipment dictate tight control of concrete slab substrates.

E.3.10 Use of Recycled Materials in Concrete: The NIH encourages the use of recycled materials in concrete unless a product is not available competitively within a reasonable timeframe, does not meet appropriate performance standards, or is available at only an unreasonable price. Concrete containing coal fly ash or ground granulated blast furnace slag should be considered for NIH projects.