3 What Do Structural Engineers Do? Analyze and design new structuresInvestigate the capacity and serviceability of existing structuresDevelop retrofit methods for existing structures with inadequate capacityForensic investigationsResearch and development
10 Member TypesEach of these structures is comprised of hundreds or thousands of membersSome common member typesBeams / Girders / stringers - flexural members – load applied perpendicular to length, moment and shear are primary forcesColumns – compression members – load applied parallel to length at member ends, axial force dominatesBeam-columnsTension membersCompression membersTie rods – tension force onlyArchesCommon connection typesPinnedFixed
12 How do we design structures? Conceptual Consideration:Determine forces (and deflections)Our focus for the semesterDetermine capacity (and deflection limits)Focus in Structural Design next semesterRequire capacity is greater than forcesLegal ConsiderationsFor most structures, owner specifies codee.g., AISC, PCI, AASHTO, AREMA
13 Loads Forces in a structure are a result of loads What types of loads do we need to consider in a civil engineering structure:Dead load:Live load: building occupants, truck trafficEnvironmental loads:Snow loadRain loadWind loadSeismic loadBridge specificTemperature loads (expansion and contraction of restrained members)ImpactBreaking forceCollisions (water and land traffic)Water loadsIce
14 Dead Loads Self-weight of: Structural components (e.g., beams, slabs) Non-structural components (e.g., decorative façade, plywood subfloor, ceiling tiles, asphalt wearing surface)Useful Tables in textbook:Table 1-2: Densities of Typical MaterialsTable 1-3: Dead Loads of Typical Materials
15 Load Transfer and Load Distribution Consider a typical building framing planWork from top downDetermine tributary widths and tributary areas as appropriate
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