Structural Engineering Design Criteria – American Codes and Standards

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April 27, 2025

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In the United States, structural engineering design is governed by a robust framework of codes, standards, and guidelines to ensure safety, functionality, and durability of buildings and infrastructure. Understanding and applying the right standards is essential for engineers to deliver code-compliant and efficient designs.

B.1 INTRODUCTION

This appendix summari zes the codes, standards, criteri a, and practices that will be generally used in th e design and construction o f structural engineeri ng s ystems.

More specific project information will be developed during execution of the projects to support detail design, engineering, material procurement specification and construction specifications.

B.2 CODES AND STANDARDS

The design of structural engineering s ystems for th e project will be in accordance with the laws and regulations of the federal government, the State of C alifornia, Contra Costa County, and City of Antioch, California ordinances, and the industr y standards. T he current issue or edition of the documents at the time of filing of this Application for Certificati on (AFC) will ap ply, unless otherwise noted. In cases where conflicts between the cited documents exist, re quirements of the more conservative document will be used.

The following codes and standards have been identi fied as applicable, in whole or in part, t o structural engineering design and construction of power plants.

California Building Code (CBC), 2007 Edition, including all Supplements
Internal Building Code (IBC), 2007 Edition
American Institute of Steel Construction (AISC):
- Manual of Steel Construction – 13th Edition
- Specification for the Design, Fabrication and Erection of Structural Steel fo r Buildings – ASD
- Specification for Structural Joints Using ASTM A325 or A490 Bolts
- Code of Standard Practice for Steel Buildings and Bridges
American Concrete Institute (ACI):
- ACI 318-05, Building Code Requirements for Structural Concrete
- ACI 301-05, Specifications for Structural Concrete for Buildings
- ACI 543R-00, Design, Manufacture, and Installation of Concrete Piles
American Society of Civil Engineers (ASCE):
- ASCE 7-05, Minimum Design Loads for Buildings and Other Structures
American Society of Mechanical Engineers – ASME STS-1, 2000 – Steel Stacks
American Welding Society (AWS):
- D1.1 – Structural Welding Code – Steel
- D1.3 – Structural Welding Code – Sheet Steel
Code of Federal Regulatio ns, Title 29 – La bor, Chapter XVII, Occupational Safety and Health Administration (OSHA).
- Part 1905 – Rules of practice for va riances, lim itations, va riations, tolera nces, a nd exemptions under the Williams-Steiger Occupational Safety and Health Act of 1970
- Part 1910 – Occupational Safety and Health Standards
- Part 1926 – Construction Safety and Health Regulations

National As sociation of Architectural Metal M anufacturers ( NAAMM) – Metal B ar Grating Manual
Hoist Manufacturers Insti tute (HMI), Standard Spe cifications for Electric W ire Rope Hoists (HMI 100)
National Electric Safety Code (NESC), C2-2005
National Fire Protection Association (NFPA Standards)
- NFPA 850 Fire Protection for Electric Generating Plants
Steel Deck Institute (SDI) – Design Manual for Floor Decks and Roof Decks

B.2.1 California Energy Commission Special Requirements

Prior to the start of any increment of construction, the proposed lateral-force procedures for project structures and the applicable designs, plans and drawings for project structures will be submitted for approval.

Proposed lateral-force procedures, designs, plans, and drawings shall be those for:

Major project structures
- Major foundations, equipment supports, and anchorage
- Large, field-fabricated tanks
- Switchyard structures

B.3 STRUCTURAL DESIGN CRITERIA

B.3.1 Datum

Site topogra phic elevations will be based on an elevation survey conducte d using known elevation benchmarks.

B.3.2 Frost Penetration

The site is in an area fre e of frost penetration. Bottom el evation of all foundations for structures an d equipment, however, will be maintained at a minimum of 12 inches below the finished grade.

B.3.3 Temperatures

The design basis temperatures for civil and structural engineering systems will be as follows: Maximum 104°F

Minimum 20°F

B.3.4 Design Loads

General

Design loads for structures and foundat ions will com ply with all applicable build ing code requirements. The State of California has agreed to adopt the 2006 International Building Code (IBC) effective January 2008. The building code in effect in Contra Costa County is the 2007 California Building Code (CBC).

B.3.4.2 Dead Loads

Dead loads will consist of the weights of structure and all equipment of a permanent or sem i-permanent nature including tanks, bins, wall panels, partitions, roofing, drains, piping, cable trays, bus ducts, and the contents of tanks and bins measured at full operating capacity . The contents of the tank s and bins, however, will not be considered as effective in resist ing structure uplift due to wind forces; but will be considered as effective for seismic forces.

B.3.4.3 Live Loads

Live loads will consist of uniform floor live loads and equipment live loads. Uniform l ive loads are assumed equivalent unit loads that are considered sufficient to provide for m ovable and transitory loads, such as the weights of people, portable equip ment a nd tools, small equipment or parts, which may be moved over or placed on the floors during maintenance operations, and planking. The uniform live load s will not be applied to floor areas that will be permanently occupied by equipment.

Lateral earth pressures, h ydrostatic pressures, and wheel loads from trucks, will be consi dered as live loads.

Uniform live loads will be in accordance with ASCE Standard 7, but will not be less than the following:

Roofs 20 pounds per square foot (psf)
- Floors and Platforms

(steel grating and checkered plates) 100 psf

In addition, a uniform load of 50 psf will be used to account for piping and cable trays, except that where the piping and cable loads exceed 50 psf, the actual loads will be used.

Furthermore, a concentrated load of 5 kips will be applied concurrently to the supporting beams of the floors to m aximize stresses in the m embers, but th e reactions from the concentrated loads will not be carried to the columns.

Floors (elevated concrete floors) 100 psf

In addition, elevated concrete slabs will be designed to support an alternate concentrated load of 2 kips in lieu of the uniform loads, whichever governs. The concentrated load will be treated as uniform ly distributed load acting over an area of 2.5 square feet, and will be located in a manner to produce the maximum stress conditions in the slabs.

Control Room Floor 150 psf
- Stairs, Landings, and Walkways 100 psf

In addition, a concentrated load of 2 kips will be applied concurr ently to t he supporting beams for the walkways to maximize the stresses in the members, but the reactions from the concentrated loads will not be carried to the columns.

Pipe Racks 50 psf

Where the pi ping and cable tray loads e xceed the de sign uniform load, the actu al loads will be used. In addition, a c oncentrated load of 8 kips will be applied concurr ently to the supporting beams for the

walkways to maximize the stresses in the members, but the reactions from the concentrated loads will not be carried to the columns.

Hand Railings

Hand railings will be designed fo r a 200-pou nd concentrated load applied at any poi nt and in any direction.

Slabs on Grade 250 psf
- Truck Loading Surcharge Adjacent to Structures 250 psf
  - Truck Support Structures AASHTO-HS-20-44
  - Special Loading Conditions Actual loadings

Laydown loads from equipment components during maintenance and floor areas where trucks, forklifts or other transports have access will be considered in the design of live loads.

Live loads may be reduced in accordance with the provisions of CBC Section 1607.

Posting of the floor load capacity signs for all roofs, elevated flo ors, platforms and walkway s will be in compliance with the OS HA Occupational Safety and Health Standard, Walking and Working Surfaces, Subpart D. Floor load capacity for slabs on grade will not be posted.

B.3.4.4 Earth Pressures

Earth pressures will be in accordance with the r ecommendations contained in the project-specifi c geotechnical report.

B.3.4.5 Groundwater Pressures

Hydrostatic pressures due to groundwater or temporary water loads will be considered.

B.3.4.6 Wind Loads

The wind forces will be calculated in accordance with CBC 2007 with a basic wind speed of 80 miles per hour (mph) and an exposure category of “C.”

B.3.4.7 Seismic Loads

Structures will be designed and constructed to resist the effects of earthquake loads as determined in CBC 2007, section 1630. The site is located in Seism ic Design Cat egory D, per th e CBC. The occupancy category of the structure is 3 (Special Occupancy Structure) and corresponding im portance factor (I) is

1.25. Other seismic parameters will be obtained from the geotechnical report.

B.3.4.8 Snow Loads

The ground snow load for design is 0 to 5 psf b ased on Figure A-16-1 of Appendix Chapter 16 of the CBC 2007. Conservatively, we will use 5 psf for the d esign. There is no cost impact to using the high end of the range for the design value.

B.3.4.9 Turbine-Generator Loads

The combustion turbine-generator and steam turbine- generator loads for pedestal and found ation design will be furnished by the equipm ent manufacturers, and will be applied in accordance with the equipm ent manufacturers’ specifications, criteria, and recommendations.

B.3.4.10 Special Considerations for Steel Stacks

Steel stacks will be designed to w ithstand the normal and abnormal ope rating conditions in combination with wind loads and seismic loads, and will include the along-wind and across-wind effects on the stacks. The design will meet the requirem ents of ASME/ ANSI STS-1-2000, “Steel Stacks,” using allowable stress design method, except that i ncreased allowable stress for wind loads as permitted by AISC will not be used.

B.3.4.11 Special Considerations for Structures and Loads during Construction

For tem porary struct ures, or permanent structures le ft tem porarily incomplete to facilitate equipm ent installations, or tem porary loads im posed on perm anent structures during construction, th e allowable stresses may be increased by 33 percent.

Structural backfill may be placed again st walls, retaining walls, and sim ilar structures when the concrete strength attains 80 percent of the design com pressive strength (f’ _c), as determined by sa mple cy linder tests. Restrictions on structural backfill, if any, will be shown on the engineering design drawings.

Design restrictions im posed on cons truction shorin g rem oval that are different from normal practices recommended by the ACI Codes will be shown on engineering design drawings.

Metal decking used as fo rms for elev ated concrete slabs will b e evaluated to adequately support the weight of concrete plus a uniform construction load of 50 psf, without increase in allowable stresses.

B.4 DESIGN BASES

B.4.1 General

Reinforced concrete struct ures will be designed by the strength design method, in accordance with the California Building Code and the ACI 318, “Building Code Requirements for Structural Concrete.”

Steel structures will be d esigned by the working stress method, in accordance with the California Building Code and the AISC Specification for the Design, Fabrication and Erection of Structural Steel for Buildings.

Allowable soil bearing pressures for foundation design will be in accordance with the “Final Subsurface Investigation and Foundation Report” for the facility.

B.4.2 Factors of Safety

The factor of safety for all structures, tanks, and equipment supports will be as follows: Against Overturning 1.50

Against Sliding 1.50 for Wind Loads

1.50 for Seismic Loads

Against Uplift Due to Wind 1.50

Against Buoyancy 1.50

Allowable Stresses

Calculated stresses from the governing loading combinations for structures and equipment supports will not exceed the allowable limits permitted by the applicable codes, standards, and specifications.

B.4.4 Load Factors and Load Combinations

For reinforced concrete structures and equipment supports, using the strength method, the strength design equations wil l be determ ined based on CBC 2007, Sections 1612.2, 1612. 4, 1909.2 and ACI-318-05 Eqn.s (9-2), (9-3). The Al lowable Stress Design load combinations of CBC 2007 section 1612.3 will be used to assess soil bearin g pressure and stabilit y of s tructures per CBC 2007 sections 1805 and 1629.1, respectively.

Steel-framed structures will be designed in accordan ce with CBC 2007, Chapter 22, Divisions I, III and IV and the AISC Specific ation for the Structural Steel Buildings, Allowable Stress Design and Plastic Design, June 1, 1989. Connections will conform to Research Council on Structural Connections of the Engineering Foundation Specification for Structural Joints.

B.5 CONSTRUCTION MATERIALS

B.5.1 Concrete and Grout

The design compressive strength (f’_c) of concrete and grout, as measured at 28 days, will be as follows:

Electrical ductbank encasement 2,000 psi and lean concrete backfill (Class L-1)

Structural concrete (Class S-1) 3,000 psi

Structural concrete (Class S-2) 4,000 psi

Structural concrete (Class S-3) 5,000 psi (applies to cooling tower basins)

Grout (Class G-1) 5,000 psi

The classes of concrete and grout to be used will be shown on engineering design drawings or indicated in design specifications.

B.5.2 Reinforcing Steel

Reinforcing steel bars for concrete will be deformed bars of bill et steel, conform ing to ASTM A615, Grade 60.

Welded wire fabric for concrete will conform to ASTM A185.

B.5.3 Structural and Miscellaneous Steel

Structural and miscellaneous steel will generally conform to ASTM A36, ASTM A572, or ASTM A992 except in special situations where higher strength steel is required.

High-strength structural bolts, including nuts and washers, will conform to ASTM A325 or ASTM A490. Bolts other than high-strength structural bolts will conform to ASTM A307, Grade A.

B.5.4 Concrete Masonry

Concrete masonry materials will comply with Section 21 of CBC.

B.5.5 Other Materials

Other materials for construction, such as anchor bolts, shear connectors, concrete expansion anchors, and embedded metal will conform to industry standards and will be identified on engineering design drawings or specifications.

📘 Major American Codes and Standards for Structural Design

Standard	Description
ASCE 7	Minimum Design Loads for Buildings and Other Structures
IBC (International Building Code)	Unified building regulation adopted by most U.S. states
ACI 318	Structural Concrete Building Code
AISC 360	Steel Building Structures Design Specification
AISI S100	Cold-Formed Steel Design Standard
TMS 402/602	Masonry Structures Code and Specification
AWS D1.1	Welding Code for Structural Steel
NDS (National Design Specification)	Wood Construction Design Code
AASHTO LRFD	Bridge Design Specifications

🔹 Key Structural Design Criteria Based on American Standards

1. Load Considerations (ASCE 7)

Dead Loads (self-weight)
Live Loads (occupancy)
Roof Live Loads
Snow Loads
Wind Loads (ASCE 7-16 / 7-22)
Seismic Loads (Earthquake forces)
Rain and Flood Loads
Ice Loads
Special Loads (impact, blast, vehicular collision)

2. Material Strength and Selection

Concrete – ACI 318 (Design strength fc′f’_cfc′)
Steel – AISC 360 (Yield stress fyf_yfy)
Wood – NDS (Allowable stresses and durability)
Masonry – TMS 402 (Unit strength method or prism strength method)

3. Load Combinations

Based on Strength Design (LRFD) and Allowable Stress Design (ASD) principles.
Example (Strength Design): 1.2D+1.6L+0.5S1.2D + 1.6L + 0.5S1.2D+1.6L+0.5S
Example (ASD): D+L+SD + L + SD+L+S

4. Serviceability Requirements

Limiting deflections (e.g., L/240 for beams)
Vibration control (especially in pedestrian structures)
Crack width control (in concrete)
Drift limits (for seismic design)

5. Seismic Design (ASCE 7, Chapter 12-21)

Site classification based on soil profile
Seismic Design Category (SDC)
Response Spectrum Analysis or Equivalent Lateral Force method
Special detailing for ductility (per ACI, AISC Seismic Provisions)

6. Wind Design (ASCE 7, Chapters 26-31)

Determination of basic wind speed (V) from maps
Exposure category (B, C, or D)
Importance factor and topographic effects
Main Wind Force Resisting System (MWFRS) and Components & Cladding (C&C) calculations

📚 Important References

Document	Latest Edition
ASCE 7	ASCE 7-16 or ASCE 7-22
ACI 318	ACI 318-19
AISC 360	AISC 360-16
IBC	IBC 2021
TMS 402/602	TMS 402/602-22

🧩 Integration with Building Codes

Most U.S. states and jurisdictions adopt the IBC, which references ASCE 7 for loads and material-specific standards like ACI, AISC, TMS, NDS, and others. Hence, a complete structural design is typically a coordinated application of multiple standards together.

✅ Conclusion

In the U.S., structural engineering design criteria are set through a network of codes and standards that ensure buildings are safe, sustainable, and serviceable. Mastery of these documents is essential for engineers to create compliant and high-performing structures