Section 01332 SEISMIC DESIGN CRITERIA

Section 01332

_{SEISMIC DESIGN CRITERIA}

PART 1 - GENERAL

1.1 SUMMARY

A. This Section includes seismic design criteria for the following

1. Seismic design and anchorage of pre-engineered metal structures and canopies.

2. Seismic design and anchorage of mechanical and electrical equipment and items.

3. Seismic design of tanks and anchorage of tanks.

4. Seismic support of piping, cable tray, conduit, bus duct and ductwork.

5. Seismic design of other structures or items as specified or indicated on the

Drawings.

1.2 REFERENCES

A. Project Geotechnical Report: “Final Geotechnical Study Report: Proposed Sludge Thickening, Dewatering and Odor Control, P1-101”; December 7, 2010; by Converse Consultants; Project Number 05-32-115-01.

B. California Code of Regulations: Title 24, Part 2, Volume 2, 2007, California Building

Code (CBC).

C. California Building Code (CBC) 2010 Edition with references to ASCE 7 – 05, as indicated in the CBC.

1.3 SEISMIC REQUIREMENTS FOR ABCHORING EQUIPMENT

1. General: All equipment, including machinery, pumps, fans, tanks, piping, electrical panels, and their components and appurtenances, including their anchorages, supplied by manufacturers or suppliers, shall be designed for the following seismic forces in accordance with ASCE 7-05 Chapter 13 with a Seismic Importance Factor IP = 1.5

2. All liquid storage tanks, including their supports and anchorages, shall be designed as essential facilities in conformance with AWWA D100 latest edition, Section 13. Tanks shall be designed for seismic forces including hydrodynamic forces indicated in AWWA D100 or ACI 350.3-06 Seismic Liquid Containing Concrete Structures. See general structural notes for all seismic information not indicated herein.

3. Seismic forces shall be considered acting at the center of gravity of the piece under consideration.

4. Anchorage of equipment shall be coordinated with the concrete subcontractor so that anchorage may be installed at the time of concrete placement. If calculations and anchorage details are not submitted prior to placement of concrete, the Contractor shall be responsible for any strengthening of concrete elements because of superimposed seismic loading.

5. Equipment with vibration isolators shall be provided with snubbers capable of retaining the equipment in its designated location without any material failure or deformation of the snubbers when exposed to a vertical or horizontal force at the contact surface equal to 100 percent of the operating weight of the equipment. Air gaps between retainer and equipment base shall not exceed 1/4 IN. Deflection must be considered with respect to piping attached to the equipment. Equipment without vibration isolators shall be anchored directly to the supporting floor system.

6. In addition to the anchorage, all equipment shall be internally designed so that all static and moving parts are anchored to the supporting framework to resist the imposed seismic forces. All forces must be transmitted to the base in order to be anchored as required.

7. All piping, raceways, ductwork, accessories, appurtenances, and other items furnished with equipment shall be anchored to resist lateral considered acting at the center of gravity of the piece under consideration.

8. Lighting fixtures shall be provided with safety cable attached to the structure and to the fixture at each support point capable of supporting four times the vertical load.

9. All piping installed shall be anchored to the floor system(s) to resist lateral seismic forces without excessive deflection. This force shall be considered acting at the center of gravity of the pipe under consideration.

10. Piping with flexible connections and/or expansion joints shall be anchored such that the intended uses of these joints are maintained in the piping system.

11. Do not use friction to resist sliding due to seismic forces. (per CBC

requirements)

12. Do not use more than 60 percent of the operating weight of mechanical and electrical equipment for designing anchors for resisting overturning due to seismic forces. (per DISTRICT requirements)

13. Do not use more than 60 percent of the weight of tankage for resisting overturning due to seismic forces. (per DISTRICT requirements)

14. Use anchor bolts, bolts, or welded studs for anchors for resisting seismic forces. Anchor bolts embedded in concrete or masonry and used to resist seismic forces shall have a standard or heavy hex bolt head. Do not use anchor bolts fabricated from rod stock with an L or J shape. (Per DISTRICT requirements)

a. Do not use concrete anchors, flush shells, chemical anchors, powder actuated fasteners, or other types of anchors unless indicated on the Drawings or accepted in writing by the ENGINEER. (per DISTRICT requirements)

b. Seismic forces must be resisted by direct bearing shear or tension on the fasteners used to resist seismic forces. Do not use connections which use friction to resist seismic forces. (per DISTRICT requirements)

1.4 SUBMITTALS

A. Shop Drawings and Documentation: Submit complete shop drawings and documentation for equipment, fabrications and construction subjected to seismic loads, including anchorage criteria.

B. Calculations: Calculations for equipment, fabrications, construction, and anchorages subject to seismic loads shall be prepared, signed, and sealed by a civil or structural Professional Engineer licensed to practice in the State of California. These seismic calculations shall not be submitted unless specifically requested by the ENGINEER or the Building Code Official.

C. Foundation and Support Load Summaries: All foundation and support load summaries for equipment, fabrications, and construction supported on structures designed by others shall include the seismic load reactions applicable to the foundations and supporting structures.

D. Design Certification: Two (2) copies of written certification, prepared and signed by a Registered Professional Engineer licensed to practice in the State of California, shall be submitted by the building, equipment, or item supplier attesting that their tankage, mechanical and electrical equipment, pre-engineered metal structures and canopies, and their anchorage systems have been designed to meet the specified seismic requirements of the CBC and these project documents.

1.5 PROJECT CONDITIONS

A. Seismic (Earthquake) Loads:

1. Seismic use group: III

2. S_S: 1.644g

3. S₁: 0.586g

4. Fa: 1.0

5. Fv: 1.5

6. S_MS: 1.644g

7. S_M1: 0.879g

8. S_DS: 1.096g

9. S_D1: 0.586g

10. Site Class: D

11. Seismic design category: D

PART 2 - PRODUCTS

2.1 ACCEPTABLE MANUFACTURERS

A. Subject to compliance with the Contract Documents, the following manufacturers are acceptable:

1. Pre-engineered suspended bracing systems:

a. International Seismic Application Technology (ISAT) “Engineered Seismic

Bracing of Suspended Utilities”. b. Unistrut.

c. Tolco. d. B-Line.

e. Or Equal.

2. Custom engineered systems designed using specified criteria and common building materials.

2.2 EQUIPMENT ANCHORS AND SUPPORTS

A. Drilled-in-place concrete anchors shall have an approved ICC Evaluation Services

Report.

B. Cast-in-place anchors shall comply with ASTM A36, ASTM A307, or ASTM F1554,

36 ksi.

C. Anchors permanently exposed to weather or corrosive environments shall be A 316 stainless steel

D. Structural steel for supports: ASTM A992 or ASTM A36.

_{E. Cold Formed Metal and Connection Material: Unistrut or equal.}

F. Any details provided are based on assumed equipment and arrangement.

1. Contractor shall be responsible for design and acquiring approval for support and anchorage of equipment and arrangement which varies from equipment and arrangement assumed in detail provided.

PART 3 - EXECUTION

3.1 GENERAL REQUIREMENTS

A. Every run which requires bracing shall have a minimum of two (2) transverse braces and one (1) longitudinal brace.

1. A “run” is defined as suspended pipe, conduit, ductwork, cable tray, bus-duct, or trapeze rack having a minimum 5 feet straight run length.

B. Brace spacing shall not exceed the maximum allowable brace spacing as engineered by the manufacturer or custom bracing designer.

C. Bracing may be omitted from conduit, ductwork, cable tray, and bus-duct runs less than 5 feet in length.

D. Bracing may be omitted from conduit, cable tray, and bus duct runs where rod hung supports of less than 12 IN. in length are required.

1. All unbraced suspended utility systems having 2-inch conduit and larger or systems weighing more then 5 pounds/foot shall be installed with a minimum 6-inch clearance to suspended ceiling vertical hanger wires.

2. The conduit, cable tray, ductwork, or bus-duct shall be installed such that the lateral motion of the members will not cause damaging impact with other systems or structural members or loss of vertical support.

E. A longitudinal brace at a 90 degree change in direction may act as a transverse brace if it is located within 2 feet of the change in direction.

F. A transverse brace may act as a longitudinal brace if it is located within 2 feet of a change in direction and if the brace arm and anchorage have been sized to meet or exceed the requirements of the longitudinal brace.

G. When bracing equipment or a utility system that is suspended from an overhead deck, brace back to the overhead deck or to the supporting structure supporting the deck.

1. Do not brace to another element of the structure which may respond differently during a seismic event.

H. Obtain approval from the ENGINEER prior to attaching any brace elements to structural steel framing.

I. When utilizing cable bracing, tension the cable to remove slack without inducing uplift of the suspended element.

1. Tension seismic bracing system prior to system start-up and adjust if necessary after equipment start-up.

J. As a general rule, do not mix rigid bracing with cable bracing in the same run.

1. However, once bracing has transitioned a 90 degree change in run direction, the bracing may switch from rigid to cable or vice versa if required due to a significant change in overhead deck elevation or to provide an implementable bracing scheme in a congested area.

K. Install brace members at an angle of 45 degrees from horizontal within a tolerance of plus 2 1/2 degrees or minus 45 degrees provided the brace length is accounted for in design.

1. Brace angle may be increased to 60 degrees provided the brace spacing is reduced to 1/2 that required for a 45 degree brace.

L. Seismic bracing may not pass through a building separation joint.

1. Utility systems that pass through a separation joint must be seismically restrained no greater than 5 feet from the point of connection.

2. Any hardware designed to accommodate seismic movement across the span of the separation joint shall be installed per manufacturer's installation and listing instructions.

M. With approval of the ENGINEER, utility systems that are suspended from the overhead deck may be braced to load bearing concrete or CMU (concrete masonry) walls provided that the walls and the overhead decks will respond similarly during a seismic event.

N. Each layer of a multiple layer trapeze rack shall be braced individually based on the weight of the individual layer.

O. Conduit, cable tray, or bus duct constructed of non ductile material (plastic or fiberglass), shall have brace spacing reduced to 1/2 of the spacing allowed for ductile materials.

P. Where brace elements are through-bolted, the mounting hole in the element is to be no more than 1/16 inch in diameter larger then the bolt or threaded rod.

Q. Seismic braces shall directly brace the system and not the hanger.

3.2 SUSPENDED ELECTRICAL SYSTEMS

A. Install seismic bracing for all conduit 2-1/2 inches trade size or greater.

B. All trapeze assemblies supporting conduits, cable trays, or bus ducts shall be braced considering the total weight of the elements on the trapeze.

1. For the purposes of calculating weight, all conduits are to be treated as full. C. Brace all trapeze racks which support conduit 2-1/2 inches trade size or larger.

1. Brace all other conduit rack, cable tray, or bus duct trapezes having a minimum weight in excess of 10 pounds/linear foot.

2. Include a minimum 10 percent additional capacity for future additions.

D. Seismic bracing may be omitted from cable trays, conduit, and bus ducts suspended by rod hung supports 12 inches or less in length form the top of the element to the bottom of the structural attachment of the hanger provided lateral motion will not cause damaging impacts to other systems or loss of system vertical support.

E. All vertical risers involving conduit 2-1/2 inches in diameter or larger shall include lateral restraint at maximum 30 feet intervals and at the top and bottom of the riser.

3.3 FLOOR OR ROOF MOUNTED EQUIPMENT

A. Provide one (1) anchor on each leg or corner.

1. Support with a minimum of three (3) 3/8 inch diameter anchors.

B. Friction shall be neglected when designing anchors for shear.

C. Vertical seismic forces, when required, shall be presumed to act concurrently with horizontal seismic forces.