Pre-Schematic Considerations MASTERrichardson.eng.ua.edu/Former_Courses/CE_331_fa07/...Pre-schematic...
Transcript of Pre-Schematic Considerations MASTERrichardson.eng.ua.edu/Former_Courses/CE_331_fa07/...Pre-schematic...
PrePre--schematicschematicConsiderationsConsiderations
WhoWho
WhereWhere
WhatWhat
PrePre--schematicschematicConsiderationsConsiderations
Who, What & WhereWho, What & Where
WhoWho are the users?are the users?
ChurchChurch
SchoolSchool
ManufacturersManufacturers
ResearchersResearchers
PrePre--schematicschematicConsiderationsConsiderations
Who, What & WhereWho, What & Where
WhatWhat is the purpose?is the purpose?
FellowshipFellowship
TeachingTeaching
ManufacturingManufacturing
ProductionProduction
PrePre--schematicschematicConsiderationsConsiderations
Who, What & WhereWho, What & Where
Location, Location, Location, LocationLocation, Location
PrePre--schematicschematicConsiderationsConsiderations
Who, What & WhereWho, What & Where
Where is the project locatedWhere is the project located??
Building CodeBuilding Code
Environmental ForcesEnvironmental Forces
Construction PracticesConstruction Practices
PrePre--schematicschematicConsiderationsConsiderations
Limitation of DiscussionLimitation of Discussion
Use Use Educational, Educational, Administrative and Administrative and Assembly spaceAssembly space
StructureStructureStructural Steel with typical Structural Steel with typical and long span components up and long span components up to approximately 3 floorsto approximately 3 floors
PrePre--schematicschematicConsiderationsConsiderations
Building LoadsBuilding Loads
Forces Forces experienced experienced
by by structuresstructures
PrePre--schematicschematicConsiderationsConsiderations
Building LoadsBuilding LoadsSTRUCTURESTRUCTURE
LIVE LOADSLIVE LOADS
OCCUPANCYOCCUPANCYAND USEAND USE
ROOFROOFLOADSLOADS
UNIFORMUNIFORMLOADSLOADS
CONCENTRATEDCONCENTRATEDLOADSLOADS
SPECIALSPECIALEQUIPMENTEQUIPMENT
ENVIRONMENTALENVIRONMENTALLOADSLOADS
WINDWINDLOADSLOADS
EARTHQUAKEEARTHQUAKELOADSLOADS
FLOODFLOODLOADSLOADS
SNOWSNOWLOADSLOADS
THERMALTHERMALLOADSLOADS
EARTHEARTHPRESSURESPRESSURES
SELFSELF--WEIGHTWEIGHT
STRUCTURALSTRUCTURALFRAMINGFRAMING
MEPMEPEQUIPMENTEQUIPMENT
ARCHITECTURALARCHITECTURALFINISHES &FINISHES &CLADDINGCLADDING
PrePre--schematicschematicConsiderationsConsiderations
“…“…. loads produced by the . loads produced by the use and occupancy of the buildinguse and occupancy of the building…”…”
Live LoadsLive Loads
PrePre--schematicschematicConsiderationsConsiderations
Live LoadsLive Loads
7575RetailRetail100100Stairs & ExitsStairs & Exits
4040ClassroomsClassrooms5050AdministrativeAdministrative
150150LibrariesLibraries(stack rooms)(stack rooms)
6060LibrariesLibraries(reading rooms)(reading rooms)
4040Parking DecksParking Decks100100Dinning Rooms & Dinning Rooms & RestaurantsRestaurants
100100Corridors & LobbiesCorridors & Lobbies4040CatwalksCatwalks
5050Projection & Control RoomsProjection & Control Rooms125125Stages and PlatformsStages and Platforms
100100AssemblyAssembly(movable seats)(movable seats)
6060Assembly & TheatersAssembly & Theaters(fixed seats)(fixed seats)
LiveLiveLoadLoad
Occupancy or Occupancy or UseUse
LiveLiveLoadLoad
Occupancy or Occupancy or UseUse
PrePre--schematicschematicConsiderationsConsiderations
Live Loads are ReducibleLive Loads are Reducible
•• Reduction reflects the statistical Reduction reflects the statistical probability that a floor will be probability that a floor will be fully loaded at any one time.fully loaded at any one time.
•• Reduction based on occupancy, Reduction based on occupancy, structural component and floor structural component and floor area being supported by area being supported by component.component.
•• Most floor joist or floor beams Most floor joist or floor beams do not see a reduction.do not see a reduction.
•• Girders and beams Girders and beams –– maximum maximum reduction is 40%reduction is 40%
•• Columns Columns –– maximum reduction maximum reduction is 60%is 60%
PrePre--schematicschematicConsiderationsConsiderations
Live LoadsLive Loads
Consider designing with Consider designing with
Unreduced live loads Unreduced live loads
or or
More than code required live loadsMore than code required live loads
PrePre--schematicschematicConsiderationsConsiderations
Building LoadsBuilding Loads
Environmental LoadsEnvironmental Loads•• Snow Snow •• WindWind•• FloodingFlooding•• SeismicSeismic
PrePre--schematicschematicConsiderationsConsiderations
Snow LoadsSnow Loads
Low ImpactLow Impact
ImpactImpact•• Snow drifts and slidingSnow drifts and sliding
snowsnow
Structural considerationsStructural considerations•• Local near parapetsLocal near parapets•• Mechanical EquipmentMechanical Equipment•• MultiMulti--tiered roofstiered roofs
Cost implicationsCost implications•• Some increased memberSome increased member
sizessizes
PrePre--schematicschematicConsiderationsConsiderations
Snow LoadsSnow Loads
Moderate ImpactModerate Impact
ImpactImpact•• Snow weight over entire Snow weight over entire
structurestructure
Structural considerationsStructural considerations•• Entire roofEntire roof
Cost implicationsCost implications•• Most Structural membersMost Structural members
will require increased sizeswill require increased sizes
PrePre--schematicschematicConsiderationsConsiderations
Snow LoadsSnow Loads
Severe ImpactSevere ImpactImpactImpact•• Snow weight over entireSnow weight over entire
structure structure
Structural considerationsStructural considerations•• Entire roofEntire roof
Cost implicationsCost implications•• Increased decking gaugeIncreased decking gauge•• Reduction of memberReduction of member
spacingspacing•• Significant increase in Significant increase in
member sizesmember sizes
PrePre--schematicschematicConsiderationsConsiderations
Wind LoadsWind Loads
90 - 100
100 - 110
110 - 120
120 - 130
130 - 140
140 - 150
150 - 160
Design Peak Gust Hurricane WindSpeeds (mph) in Open Terrain
PrePre--schematicschematicConsiderationsConsiderations
Wind LoadsWind Loads
Low ImpactLow Impact
ImpactImpact•• Typically limited to Typically limited to
buildings lateral systembuildings lateral system
Structural considerationsStructural considerations•• Slight increase in bracingSlight increase in bracing
and foundationsand foundations
Cost implicationsCost implications•• Some increased Some increased
member sizesmember sizes
PrePre--schematicschematicConsiderationsConsiderations
Wind LoadsWind Loads
Moderate ImpactModerate Impact
ImpactImpact•• Entire building includingEntire building includingexterior claddingexterior cladding
Structural considerationsStructural considerations•• Roof decking and Roof decking and
attachmentsattachments•• Drag strutsDrag struts•• Increased foundationIncreased foundationsizessizes
Cost implicationsCost implications•• Significant over entireSignificant over entire
building including claddingbuilding including cladding•• Stringent component Stringent component
attachment requirementsattachment requirementsSevere ImpactSevere Impact
PrePre--schematicschematicConsiderationsConsiderations
Flood LoadsFlood Loads
Low AreasLow Areas
RiversRivers
Coastal RegionsCoastal Regions
ConsiderationsConsiderations
•• BreakBreak--away wallsaway walls
•• Crawl space flowCrawl space flow--throughthrough
•• Limitation of inhabitable spaceLimitation of inhabitable space
•• Foundation scourFoundation scour
PrePre--schematicschematicConsiderationsConsiderations
Seismic LoadsSeismic Loads
Low ImpactLow Impact
Moderate ImpactModerate Impact
Severe ImpactSevere Impact
ImpactImpact•• Wide building expansion Wide building expansion
jointsjoints
•• Loads on building increaseLoads on building increaseexponentiallyexponentially
•• Attachments of all buildingAttachments of all buildingcomponentscomponents
•• Anchorage of MEP Anchorage of MEP equipment and building equipment and building fixturesfixtures
PrePre--schematicschematicConsiderationsConsiderations
Seismic LoadsSeismic Loads
LowLow
ModerateModerate
SevereSevere
Cost ImplicationsCost Implications•• Moderate and severe Moderate and severe
regions often see regions often see significant cost increasessignificant cost increases
PrePre--schematicschematicConsiderationsConsiderations
BEST PLACE TO BUILD A BUILDINGBEST PLACE TO BUILD A BUILDING
PrePre--schematicschematicConsiderationsConsiderations
Building LoadsBuilding Loads
Dead LoadsDead Loads
•• Weight of structureWeight of structure
•• Mechanical equipmentMechanical equipment
•• FinishesFinishes
PrePre--schematicschematicConsiderationsConsiderations
Dead LoadDead Load
EngineersEngineers
Design must Design must hold it uphold it up
PrePre--schematicschematicConsiderationsConsiderations
Dead LoadDead Load
Special finishes and featuresSpecial finishes and featuresBaptisteriesBaptisteries
PrePre--schematicschematicConsiderationsConsiderations
Dead LoadDead Load
Special finishes and featuresSpecial finishes and featuresBaptisteriesBaptisteries
CatwalksCatwalks
PrePre--schematicschematicConsiderationsConsiderations
Dead LoadDead Load
Special finishes and featuresSpecial finishes and featuresBaptisteriesBaptisteries
CatwalksCatwalks
PlatformsPlatforms
PrePre--schematicschematicConsiderationsConsiderations
Dead LoadDead Load
Special finishes and featuresSpecial finishes and featuresBaptisteriesBaptisteries
CatwalksCatwalks
PlatformsPlatforms
Drywall soffits and special glazingDrywall soffits and special glazing
PrePre--schematicschematicConsiderationsConsiderations
Deflections and DriftDeflections and Drift
Framing DeflectionFraming Deflection
Serviceability, Serviceability, not a strength not a strength
issueissue
PrePre--schematicschematicConsiderationsConsiderations
Deflections and DriftDeflections and Drift
““Structural Structural systems and systems and
members thereof members thereof shall be designed shall be designed to have adequate to have adequate stiffness to limit stiffness to limit deflections and deflections and
lateral drift.lateral drift.””
PrePre--schematicschematicConsiderationsConsiderations
Deflection LimitsDeflection Limits
I/120I/120GreenhousesGreenhouses
I/180I/180Farm buildingsFarm buildings
I/240I/240I/120I/120
Exterior walls and interior Exterior walls and interior partitions:partitions:
With brittle finishesWith brittle finishesWith flexible finishesWith flexible finishes
I/240I/240I/360I/360Floor MembersFloor Members
I/240I/240I/180I/180I/120I/120
I/360I/360I/240I/240I/180I/180
I/360I/360I/240I/240I/180I/180
Roof Members:Roof Members:Supporting plaster ceilingSupporting plaster ceilingSupporting nonSupporting non--plaster ceilingplaster ceilingNot supporting ceilingNot supporting ceiling
D + LD + LS or WS or WLLConstructionConstruction
IBC TABLE 1604.3IBC TABLE 1604.3
DEFLECTION LIMITSDEFLECTION LIMITS
PrePre--schematicschematicConsiderationsConsiderations
Deflections and DriftDeflections and Drift
What to look forWhat to look for•• Long spans adjacent to wallsLong spans adjacent to walls•• Detail for movement between structure,Detail for movement between structure,
cladding and finishescladding and finishes•• Long spans adjacent to windows and Long spans adjacent to windows and
brittle finishesbrittle finishes•• Walls with masonry veneerWalls with masonry veneer•• Tall wallsTall walls•• Flat roofsFlat roofs
PondingPonding –– the retention of water due tothe retention of water due tothe deflection of the roof framingthe deflection of the roof framing
•• Roofs with no free edge to drainRoofs with no free edge to drain
PrePre--schematicschematicConsiderationsConsiderations
Building DriftBuilding Drift
““The movement of the top of the building The movement of the top of the building relative to the base of the building.relative to the base of the building.””
PrePre--schematicschematicConsiderationsConsiderations
Building Expansion JointsBuilding Expansion Joints
PrePre--schematicschematicConsiderationsConsiderations
Building Expansion JointsBuilding Expansion Joints
Expansion Joint ConfigurationExpansion Joint Configuration
Overall length of buildingOverall length of building
Shape of buildingShape of building
PrePre--schematicschematicConsiderationsConsiderations
Building Expansion JointsBuilding Expansion JointsOnce it is determined an expansion joint is requiredOnce it is determined an expansion joint is required
Factors of Joint WidthFactors of Joint Width
•• Temperature changeTemperature change
Generally very small, especiallyGenerally very small, especiallyif the structure is continuously if the structure is continuously heated or cooledheated or cooled
PrePre--schematicschematicConsiderationsConsiderations
Building Expansion JointsBuilding Expansion JointsOnce it is determined an expansion joint is requiredOnce it is determined an expansion joint is required
Factors of Joint WidthFactors of Joint Width
•• Temperature changeTemperature change
Generally very smallGenerally very small
•• Wind forcesWind forces
Less than one inch dependingLess than one inch dependingon lateral systemon lateral system
PrePre--schematicschematicConsiderationsConsiderations
Building Expansion JointsBuilding Expansion JointsOnce it is determined an expansion joint is requiredOnce it is determined an expansion joint is required
Factors of Joint WidthFactors of Joint Width
•• Temperature changeTemperature change
Generally very smallGenerally very small
•• Wind forcesWind forces
Less than one inch dependingLess than one inch dependingon lateral systemon lateral system
•• Seismic forcesSeismic forcesCan require large structural Can require large structural jointsjoints
PrePre--schematicschematicConsiderationsConsiderations
Building Expansion JointsBuilding Expansion Joints
Additional ConsiderationsAdditional Considerations
Location of lateral bracingLocation of lateral bracing
Stiffness of columnsStiffness of columns
PrePre--schematicschematicConsiderationsConsiderations
Building Expansion JointsBuilding Expansion Joints
Avoid them if possibleAvoid them if possible
ExpensiveExpensive
Special cladding and finish Special cladding and finish requiredrequired
MEP system can incur special MEP system can incur special detailingdetailing
PrePre--schematicschematicConsiderationsConsiderations
Vibration Vibration
PrePre--schematicschematicConsiderationsConsiderations
VibrationVibrationWhen do structural engineers worry about vibration?When do structural engineers worry about vibration?
Large open spaces with few usersLarge open spaces with few users•• MallsMalls
•• Large classroomsLarge classrooms
•• Fellowship hallsFellowship halls
PrePre--schematicschematicConsiderationsConsiderations
VibrationVibrationWhen do structural engineers worry about vibration?When do structural engineers worry about vibration?
Theatrical and exercise spaceTheatrical and exercise space
Rhythm of dancers, athletesRhythm of dancers, athletesand music can create unacceptableand music can create unacceptablelevels of vibration.levels of vibration.
PrePre--schematicschematicConsiderationsConsiderations
VibrationVibrationWhen do structural engineers worry about vibration?When do structural engineers worry about vibration?
Laboratory, healthcare imaging Laboratory, healthcare imaging and research spaceand research space
Specialized equipment may not work if Specialized equipment may not work if vibration limits are exceeded.vibration limits are exceeded.
PrePre--schematicschematicConsiderationsConsiderations
VibrationVibrationWhat can minimize vibration worries?What can minimize vibration worries?
Stiffening the structureStiffening the structure
Increase mass of structureIncrease mass of structure
PrePre--schematicschematicConsiderationsConsiderations
VibrationVibrationWhat can minimize vibration worries?What can minimize vibration worries?
Stiffening the structureStiffening the structure
Increase mass of structureIncrease mass of structure
Will add cost to minimizeWill add cost to minimize
PrePre--schematicschematicConsiderationsConsiderations
AcousticsAcoustics
Structures do move. . .Structures do move. . .
Movement of steel results in Movement of steel results in creaking and poppingcreaking and popping
Most noticeable in large, Most noticeable in large, quiet placesquiet places
PrePre--schematicschematicConsiderationsConsiderations
The GridThe Grid
Optimization of grid=
Savings to the Owner
PrePre--schematicschematicConsiderationsConsiderations
The GridThe Grid
• Avoid grids that do not stack
• Avoid transfer girders
• Avoid irregular grids– Lose advantage of
repetitive fabrication– More beams required
to support offset conditions
PrePre--schematicschematicConsiderationsConsiderations
The Optimal GridThe Optimal Grid
Optimal Bay Size: Length to width ratio of approximately 1.25 tOptimal Bay Size: Length to width ratio of approximately 1.25 to 1.50o 1.50
PrePre--schematicschematicConsiderationsConsiderations
Preliminary Structural Preliminary Structural ComponentsComponents
BeamsBeams
Optimal Depth = Cost EffectiveOptimal Depth = Cost Effective
Depth (in) = Span (ft) / 2Depth (in) = Span (ft) / 2
Consult with structural engineer Consult with structural engineer if bay size is flexibleif bay size is flexible
PrePre--schematicschematicConsiderationsConsiderations
Preliminary Structural Preliminary Structural ComponentsComponents
JoistJoist(typical for basic wind, snow and seismic regions)(typical for basic wind, snow and seismic regions)
Roof : 6Roof : 6’’ 00””
Floor: 2Floor: 2’’ 00”” to 3to 3’’ 00””
Depth (in) = Span (ft) *3/4Depth (in) = Span (ft) *3/4
PrePre--schematicschematicConsiderationsConsiderations
Structural Steel DepthsStructural Steel DepthsAvailable Joist ProfilesAvailable Joist Profiles
PrePre--schematicschematicConsiderationsConsiderations
Structural Steel DepthsStructural Steel DepthsTruss DepthsTruss Depths
Great for large loadsGreat for large loads
Great for long spansGreat for long spans
Can be designed and Can be designed and detailed to match detailed to match architectural preferencesarchitectural preferences
Avoid arches if possibleAvoid arches if possible
Very expensiveVery expensive
PrePre--schematicschematicConsiderationsConsiderations
ColumnsColumns
TypesTypesPipesPipes
TubesTubes
Hollow Structural ShapesHollow Structural Shapes
Wide FlangesWide Flanges
PrePre--schematicschematicConsiderationsConsiderations
ColumnsColumns
Cost Cost ––
Varies based on Varies based on marketmarket
PrePre--schematicschematicConsiderationsConsiderations
ColumnsColumns
Wide flanges may be Wide flanges may be preferable in preferable in
multimulti--story constructionstory construction
PrePre--schematicschematicConsiderationsConsiderations
Preliminary Column SizesPreliminary Column Sizes
Maximum 15Maximum 15’’ 00”” Floor HeightFloor Height
Table is approximate and provides for allowance for selection ofTable is approximate and provides for allowance for selection of optimal shape and size of columnoptimal shape and size of column
13 X 12 1/413 X 12 1/410 1/2 X 10 1/410 1/2 X 10 1/48 X 88 X 840 X 4040 X 4012 1/2 X 12 1/412 1/2 X 12 1/410 1/4 X 1010 1/4 X 106 X 66 X 630 X 4030 X 4010 1/4 X 10 1/410 1/4 X 10 1/48 X 88 X 86 X 66 X 630 X 3030 X 3010 1/4 X 10 1/410 1/4 X 10 1/48 X 88 X 86 X 66 X 620 X 4020 X 40
10 X 1010 X 106 X 66 X 65 X 55 X 520 X 3020 X 3010 X 1010 X 106 X 66 X 65 X 55 X 520 X 2020 X 20
332211Bay SpacingBay Spacing
Number of StoriesNumber of Stories
PrePre--schematicschematicConsiderationsConsiderations
Lateral BracingLateral Bracing
Placement and LocationsPlacement and LocationsPreferred locations varies between Preferred locations varies between structural engineersstructural engineers
Options IncludeOptions Include
•• Core of buildingCore of building
•• Perimeter of buildingPerimeter of building
PrePre--schematicschematicConsiderationsConsiderations
Lateral BracingLateral BracingTypes ofTypes of BracesBraces
PrePre--schematicschematicConsiderationsConsiderations
Lateral BracingLateral Bracing
MaterialsMaterials•• MasonryMasonry
•• Concrete ShaftsConcrete Shafts
•• TiltTilt--up Panelsup Panels
•• Steel XSteel X--type Bracingtype Bracing
•• Steel FramesSteel Frames
PrePre--schematicschematicConsiderationsConsiderations
Lateral BracingLateral Bracing
Most Economical:Most Economical:
Typically steel XTypically steel X--type type BracingBracing
(Exception: load bearing (Exception: load bearing walls are present)walls are present)
PrePre--schematicschematicConsiderationsConsiderations
Lateral BracingLateral Bracing
ConsiderationsConsiderations•• Avoidance of openingsAvoidance of openings
•• Environmental LoadingsEnvironmental Loadings
PrePre--schematicschematicConsiderationsConsiderations
FoundationsFoundations
Coastal RegionsCoastal RegionsAnticipate PilingAnticipate Piling
•• Near coastlineNear coastline
•• For heavily loaded foundationsFor heavily loaded foundations
•• Soils with anticipated Soils with anticipated settlementssettlements
PrePre--schematicschematicConsiderationsConsiderations
FoundationsFoundations
Lowland AreasLowland AreasImproved swampland or filled valleysImproved swampland or filled valleys
•• Significant soil remediationSignificant soil remediation
•• Deep foundationsDeep foundations
PrePre--schematicschematicConsiderationsConsiderations
FoundationsFoundations
Northern ClimatesNorthern Climates•• Bottoms: below the frost elevationBottoms: below the frost elevation
•• Sidewalks: stabilized to avoid frost heaveSidewalks: stabilized to avoid frost heave
•• Perimeter insulationPerimeter insulation
PrePre--schematicschematicConsiderationsConsiderations
FoundationsFoundations
Mississippi GumboMississippi Gumbo•• Expansive clays shrink and swellExpansive clays shrink and swell
•• Combination of remedial solutions:Combination of remedial solutions:
PrePre--schematicschematicConsiderationsConsiderations
FoundationsFoundations
Mississippi GumboMississippi Gumbo•• Expansive clays shrink and swellExpansive clays shrink and swell
•• Combination of remedial solutions:Combination of remedial solutions:
•• Soil remediationSoil remediation
•• Deep foundationsDeep foundations
•• Framed slabs over carton formsFramed slabs over carton forms
•• PostPost--tensioned slabstensioned slabs
PrePre--schematicschematicConsiderationsConsiderations
FoundationsFoundations
BirminghamBirmingham•• Limestone geology presents Limestone geology presents
unique challengesunique challenges
•• Pinnacled limestonePinnacled limestone
•• Sinkhole activitySinkhole activity
•• Soft clay layer directly aboveSoft clay layer directly aboverockrock
PrePre--schematicschematicConsiderationsConsiderations
Exterior CladdingExterior Cladding
Exterior CladdingExterior Cladding•• BrickBrick
•• Other cladding typesOther cladding types
•• Moderate and severe wind Moderate and severe wind regions and seismic regionsregions and seismic regions
•• Store fronts and curtain wallsStore fronts and curtain walls
•• Force protection systemsForce protection systems
PrePre--schematicschematicConsiderationsConsiderations
Exterior CladdingExterior Cladding
BrickBrick
•• BIA provides BIA provides recommendations for backup recommendations for backup deflectiondeflection
•• Usually L / 600Usually L / 600
•• May require use of masonry or May require use of masonry or deeper studs to meet deeper studs to meet deflection requirements.deflection requirements.
PrePre--schematicschematicConsiderationsConsiderations
Exterior CladdingExterior Cladding
Other Cladding TypesOther Cladding Types
•• Allowable deflection assumed Allowable deflection assumed to be per IBCto be per IBC
•• Usually L / 240 Usually L / 240
•• Consider limitation carefullyConsider limitation carefully•• 1515’’ wall would deflect wall would deflect ¾”¾”
PrePre--schematicschematicConsiderationsConsiderations
Exterior CladdingExterior Cladding
Wind & Seismic RegionsWind & Seismic Regions
•• Anticipate stringent cladding Anticipate stringent cladding attachmentsattachments
•• Deeper backup systemsDeeper backup systems
PrePre--schematicschematicConsiderationsConsiderations
Exterior CladdingExterior Cladding
Curtain WallsCurtain Walls
•• MultiMulti--story walls require eitherstory walls require eitherinternal or external supportinternal or external support
•• Cost and coordination often not Cost and coordination often not recognized until late in therecognized until late in theproject!project!
PrePre--schematicschematicConsiderationsConsiderations