Structure Engineering 101 For Mechanical Engineers

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Structure Engineering101For Mechanical Engineers
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Class outline

• Structural systems
• IBC 2006 Seismic provisions
• Information your structural engineer needs
• Coordination
• Building Information Modeling

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Structural Systems

• Foundations
• Drilled piers and pier caps
• Driven piles
• Footings
• Mat footings
• Perimeter grade beams
• Basement walls
• Tie beams
• Post-Tensioned slabs on grade

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Drilled pier video
Yes I know the video is side ways.I am just a
structural engineer
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So what does a mechanical engineer need to know
about a drilled pier?

• Underground coordination
• Top of pier elevation is critical
• Trenches and excavations next to piers undermine
  piers capacity
• Pier caps and tie beam coordination
• Electrical grounding
• Piers are bigger then shown on structural
• Piers are not the ideal place to put the
  geo-exchange system.

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Driven piles
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Electrical Grounding Driven Pile
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Screw Piles
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Mat Foundations
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Foundation grade beam
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• How do foundation problems effect the mechanical
  engineer?
• Expansive soils
• Soil settlement
• Void forms
• Crawl spaces and molds

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Void form
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Foundation heave/ settlements
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Structural Systems

• Steel Frame
• Beams and columns
• Gussets
• Acoustical
• Vibration

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Slab thickness see schedules and details Beam
depth see plan Camber not to worry Beam
reactions does not effect you Dimensions not
something a mechanical engineer uses..
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• Steel Beam Sizes
• Link to steel section properties look up table
  http//www.efunda.com/math/areas/RolledSteelBeamsW
  .cfm
• Commonly used steel beam sizes
• Size Depth (d) Width (bf)
• W10x19 10 4
• W10x30 10 6
• W12x22 12 4
• W12x35 12 7
• W14x26 14 5
• W14x38 14 7
• W14x53 14 8
• W16x31 16 6
• W16x57 16.5 7
• W18x46 18 6
• W18x70 18.5 7 1/2
• W21x57 21 6 1/2
• W21x68 21 8 1/4
• W24x62 24 7
• W24x84 24 9

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Cutting the metal deck
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Floor drains in the metal deck
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Hydronic Heating
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Joists and joist Girders
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Structural Systems

• Cast-in-place concrete frame
• Wide beams center on columns Concrete slabs that
  generally can be readily sleeved for piping
• Mechanical shafts and chases
• Sleeves and floor sinks.. electrical conduits

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Structural Systems

• Cast-in-place concrete core walls
• Avoid locating telecom and electrical rooms
  inside of closed in concrete core walls
• Locate shafts at ends of cores
• Coordination of openings
• Mechanical ducts
• Stair pressurization
• Piping sleeves
• Electrical conduits
• Fire house cabinets
• Recessed drinking fountains

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Do you make site visits duringstructural
construction?Ask to go along with your
structural engineer sometime It is a lot of
funcheck this video out
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Structural Systems

• Post-tensioned Cast-in-place concrete
• Most common on Residential and Hotels
• Flat thin slab
• Highly stressed cables embedded in slab
• Sleeves around columns are critical to design
• Drilled in hanger inserts limited to about 1 inch
  in depth.
• Pipe sleeves by columns

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Structural Systems

• Precast concrete
• Tee stems spaced at 4-0 or 5-0 and
• 6-inches wide at the top.
• Field concrete topped and pre-topped tees (no
  electrical conduit in pre-topped tees)
• Mechanically hang from tee flanges if hangers are
  drilled in inserts, do not drill stems.
  Pre-stress tendons are located in stems.

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• Light gage cold formed steel (Studs)

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Masonry
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Structural Systems-Wood
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Roof mechanical stacks

• SMACNA provisions.
• Guyed stacks
• Performance specifications
• Wind loads
• Anchoring locations and requirements
• Tensioning load criteria

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Roof mechanical stacks

• Large Tall Stacks.design and detail stacks and
  connections to structure or retain a structural
  engineer.
• Stack design is generally not a part of your
  structural engineers scope of service.

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IBC 2006

• SECTION 1613
• EARTHQUAKE LOADS
• 1613.1 Scope.

Every structure, and portion thereof, including
nonstructural components that are permanently
attached to structures and their supports and
attachments, shall be designed and constructed to
resist the effects of earthquake motions in
accordance with ASCE 7, excluding Chapter 14 and
Appendix 11A.
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ASCE 7 2005

• Chapter 13
• SEISMIC DESIGN REQUIREMENTS FOR NONSTRUCTURAL
  COMPONENTS
• 13.1 GENERAL
• 13.1.1 Scope. This chapter establishes minimum
  design criteria
• for nonstructural components that are
  permanently attached to
• structures and for their supports and
  attachments.
• 13.1.2 Seismic Design Category. For the purposes
  of this chapter,
• nonstructural components shall be assigned to
  the same seismic
• design category as the structure that they
  occupy or to which
• they are attached.

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ASCE 7 2005

• 13.1.3 Component Importance Factor. All
  components shall
• be assigned a component importance factor as
  indicated in this
• section. The component importance factor, Ip,
  shall be taken as
• 1.5 if any of the following conditions apply
• 1. The component is required to function for
  life-safety purposes
• after an earthquake, including fire protection
  sprinkler systems.
• 2. The component contains hazardous materials.
• 3. The component is in or attached to an
  Occupancy Category
• IV structure and it is needed for continued
  operation of the
• Facility or its failure could impair the
  continued operation of the facility.
• All other components shall be assigned a
  component importance
• factor, Ip, equal to 1.0.

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ASCE 7 2005

• 13.1.4 Exemptions. The following nonstructural
  components are exempt from the requirements of
  this section
• Architectural components in Seismic Design
  Category B other than parapets supported by
  bearing walls or shear walls provided that the
  component importance factor, Ip, is equal to 1.0.
• Mechanical and electrical components in Seismic
  Design Category B.
• Mechanical and electrical components in Seismic
  Design Category C provided that the component
  importance factor, Ip, is equal to 1.0.
• 4. Mechanical and electrical components in
  Seismic Design Categories D, E, and F where the
  component importance factor, Ip, is equal to 1.0
  and either
• a. Flexible connections between the components
  and associated ductwork, piping, and conduit are
  provided.
• b. Components are mounted at 4 ft (1.22 m) or
  less above a floor level and weigh 400 lb(1780
  N) or less.
• 5. Mechanical and electrical components in
  Seismic Design Categories D, E, and F where the
  component importance factor, Ip, is equal to 1.0
  and
• a. Flexible connections between the components
  and associated
• ductwork, piping, and conduit are provided.
• b. The components weigh 20 lb (89 N) or less
  or, for distribution
• systems, weighing 5 lb/ft (73 N/m) or less.

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Information needed

• Schematics
• Conceptual requirements of mechanical systems,
  including preliminary location and equipment
  weight
• Non Standard criteria
• Vibration
• Acoustical separation
• Under floor mechanical systems

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Take care of your structural engineerspend time
coordinating during DD!

• Or this could happen on your next joblets watch

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Information needed

• Design Development
• Establish Story heightCeiling height,
  structural depth and mechanical space
  requirements
• Equipment size and weight
• Identify heavy hanging loads due to piping
  mechanical, boiler rooms, mechanical corridor
  arenas and stadiums
• Vibration / acoustical isolation of equipment
• Structural supports for Mechanical equipment
  cooling towers, generators, chillers, boilers,
  roof top ducts, stacks

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Information needed

• Design Development
• Major shaft openings in floors and roof
• Major wall penetrations shear walls and
  structural exterior walls
• Roof top mechanical penthouses, platforms,
  mezzanines and catwalks

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Information needed

• Construction Documents ..getting down to the
  Nitty Gritty dimensions and details
• Confirmation of mechanical equipment weights from
  DD
• House keeping pad locations and thickness
• Openings in floors and roof ducts, roof drains,
  water lines, conduit, bus ducts, grease traps,
  floor sinks, etc
• Openings in exterior foundation walls and grade
  beams
• Beam web penetrations/notches
• Ducts running through bar joists
• Buried tanks
• Plumbing inverts /elevations coordinated with
  footings
• Sump pits
• Trench drains

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Information needed

• Roof top mechanical equipment screen wall
  coordinationBracing of screen walls to equipment
  and equipment that has an architectural screen
  attached.
• Louver back up structure requirements

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Information needed

• Early Structural construction packages..
• .Project specific
• ..But in simple terms we need
  everything that effects structural by the end of
  DD.

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Construction Administration

• Dimensions not set during design.Contractor and
  MEP supplier to coordinate equipment specific
  opening dimension.Always an issueHow can you
  help?
• Lets structural engineer know if contractor
  proposes to switch equipment before the Owner
  accepts the changeweight, size and opening
  requirements may change and require re-designbe
  conservative during designno savings in
  structure for equipment weights.

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Coordination

• .I do not believe it is possible for a
  mechanical or electrical engineer to fully meet
  the expectations of the contractor (and
  structural engineer) when it comes to
  coordination
• but we would appreciate your effort.
• Ralph Rempel

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Coordination List

• Structural depth and MEP systems
• Construction tolerances, structure deflection,
  fire proofing and the wrap on the Mechanical
  ducts and pipes
• Floor and roof openings
• Dimensioned opening size and dimensioned to grids
• Beam flange widths for telecom and electrical
  risers and pipes and wall locations.
• Concrete wall openings
• For concrete shear walls structural engineer
  needs to show everything that penetrates the
  wall.
• Foundation walls not as critical structural
  engineer generally has typical details
• Roof slopes
• Locate drains near columns
• Floor drains
• Coordinate with beam locations

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Coordination List

• House keeping pads
• Fire protection beam penetrations
• Louver back up frame dimensions
• Perimeter drains
• Pipes through perimeter grade beams
• Floor drains
• Embedded pipes and electrical conduits

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Coordination List

• Slabsembedded electrical conduits
• Slabs on metal deck space 1 ½ OD conduits at
  18 for slabs on metal deck unless Structural
  designs and details the slab for the conduit.
• Spacing can be reduced to 12 inches with minimal
  design effort.
• Spacing tighter than 12 inches will require
  additional engineering and may cause the slab
  thickness to increase.

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Coordination List

• Embedded electrical boxes in concrete columns
  (power and fire alarm) .try to avoid
• Avoid electrical conduits and boxes embedded in
  cast in place concrete columns Why?
• Coordination intensive..
• Difficult to build at construction joint
  interfaces.
• Electrical boxes need to be on structural column
  details
• Rebar fire-protection cover to be maintained.

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Coordination List

• Specifications
• Embedded electrical conduit
• In general prohibit embedded conduit unless as
  shown on the drawings.
• For embedded conduit specify under the submittals
  section that the contractor shall prepare shop
  drawing showing the location of the conduit.
• You may want to also specify that if the conduits
  are moved in the field that the record drawings
  show the changes.

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Coordination List

• Specifications cont.
• Hung piping
• Hang heavy pipes with a trapeze from structural
  members
• Hanging smaller pipes from the slab generally ok
• Drilled in inserts
• Cast in hangers
• Supporting piping from the floor below

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Architects and BIM
SEAC 3/2010 survey
64 of architects use BIM
71 3 years or more
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Building Information Modeling

• Interoperable software
• Shared coordinates
• Coordination
• First do it the standard old fashion way
• Second fly through techniques (navisworks)
• Last Clash detection.