CIEG 301:CIEG 301:Structural AnalysisStructural Analysis

INTRODUCTIONINTRODUCTIONTypes of StructuresTypes of StructuresLoadsLoads

Corresponding ReadingCorresponding Reading

Chapter 1 of textbookChapter 1 of textbook

What Do Structural What Do Structural Engineers Do?Engineers Do?

Analyze and design new structuresAnalyze and design new structures Investigate the capacity and serviceability Investigate the capacity and serviceability

of existing structuresof existing structures Develop retrofit methods for existing Develop retrofit methods for existing

structures with inadequate capacitystructures with inadequate capacity Forensic investigationsForensic investigations Research and developmentResearch and development

Building TypesBuilding Types

Majority of buildings are 2 – 20 storiesMajority of buildings are 2 – 20 stories Taller office buildingsTaller office buildings Sports arenasSports arenas Low seismic / high seismicLow seismic / high seismic

Bridge TypesBridge Types

HighwayHighway RailroadRailroad

ShippingShipping CommuterCommuter

PedestrianPedestrian

Design ObjectivesDesign Objectives

StrengthStrength ConstructabilityConstructability ServiceabilityServiceability MaintainabilityMaintainability EconomyEconomy AestheticsAesthetics

Design ProcessDesign Process

Initial planningInitial planning Determination of design alternativesDetermination of design alternatives Preliminary design of alternativesPreliminary design of alternatives Evaluation of alternativesEvaluation of alternatives Design, analysis, and redesign of Design, analysis, and redesign of

selected alternativeselected alternative ConstructionConstruction

Structure TypesStructure Types

FramesFrames TrussesTrusses Slab-on-stringerSlab-on-stringer CablesCables ArchesArches Surface structuresSurface structures Complex structuresComplex structures

Member TypesMember Types

Each of these structures is comprised of hundreds or thousands of Each of these structures is comprised of hundreds or thousands of membersmembers

Some common member typesSome common member types Beams / Girders / stringers - flexural members – load applied Beams / Girders / stringers - flexural members – load applied

perpendicular to length, moment and shear are primary forcesperpendicular to length, moment and shear are primary forces Columns – compression members – load applied parallel to Columns – compression members – load applied parallel to

length at member ends, axial force dominateslength at member ends, axial force dominates Beam-columnsBeam-columns Tension membersTension members Compression membersCompression members Tie rods – tension force onlyTie rods – tension force only ArchesArches

Common connection typesCommon connection types PinnedPinned FixedFixed

Support TypesSupport Types

RollerRoller PinPin FixedFixed

How do we design How do we design structures?structures?

Conceptual Consideration:Conceptual Consideration: Determine forces (and deflections)Determine forces (and deflections)

Our focus for the semesterOur focus for the semester Determine capacity (and deflection limits)Determine capacity (and deflection limits)

Focus in Structural Design next semesterFocus in Structural Design next semester Require capacity is greater than forcesRequire capacity is greater than forces

Legal ConsiderationsLegal Considerations For most structures, owner specifies codeFor most structures, owner specifies code

e.g., AISC, PCI, AASHTO, AREMAe.g., AISC, PCI, AASHTO, AREMA

LoadsLoads

Forces in a structure are a result of loadsForces in a structure are a result of loads What types of loads do we need to consider in a civil engineering structure:What types of loads do we need to consider in a civil engineering structure:

Dead load: Dead load: Live load: building occupants, truck trafficLive load: building occupants, truck traffic Environmental loads:Environmental loads:

Snow loadSnow load Rain loadRain load Wind loadWind load Seismic load Seismic load

Bridge specificBridge specific Temperature loads (expansion and contraction of restrained members)Temperature loads (expansion and contraction of restrained members) ImpactImpact Breaking forceBreaking force Collisions (water and land traffic)Collisions (water and land traffic) Water loadsWater loads IceIce

Dead LoadsDead Loads

Self-weight of:Self-weight of: Structural components (e.g., beams, slabs)Structural components (e.g., beams, slabs) Non-structural components (e.g., decorative Non-structural components (e.g., decorative

façade, plywood subfloor, ceiling tiles, façade, plywood subfloor, ceiling tiles, asphalt wearing surface)asphalt wearing surface)

Useful Tables in textbook:Useful Tables in textbook: Table 1-2: Densities of Typical MaterialsTable 1-2: Densities of Typical Materials Table 1-3: Dead Loads of Typical MaterialsTable 1-3: Dead Loads of Typical Materials

Load Transfer and Load Transfer and Load DistributionLoad Distribution

Consider a typical building framing planConsider a typical building framing plan Work from top downWork from top down Determine tributary widths and tributary Determine tributary widths and tributary

areas as appropriateareas as appropriate