Giải thích hệ số PBN

Giải thích hệ số PBN

BridgeTech, Inc.Simplified Live Load DistributionFormulaNCHRP 12-62Research TeamJay A. Puckett, Ph.D., P.E.Dennis Mertz, Ph.D., P.E.X. Sharon Huo, Ph.D., P.E.Mark Jablin, P.E.Michael Patrick, Graduate StudentMatthew Peavy, P.E.NCHRP Manager: David Beal, P.E. BridgeTech, Inc.Objective The objective of this project is to develop newrecommended LRFD live-load distribution-factordesign equations for shear and moment that aresimpler to apply and have a wider range ofapplicability than those in the current LRFD.The need for refined methods of analysis shouldbe minimized. BridgeTech, Inc.The Problem BridgeTech, Inc.Basics BehaviorStiff Deckrelativeto Girders –betterdistribution,moreuniformAll analysis and numericalapproaches attempt to quantify thisbehaviorSomewhere between Equal (Rigidbody)andLever Rule BridgeTech, Inc.AccuracySimplicity BridgeTech, Inc.AccuracySimplicity BridgeTech, Inc.Literature ReviewCurrent Specifications & SimplifiedApproachModeling TechniquesField TestingParametric EffectsBridge TypeNonlinear effects BridgeTech, Inc.PI Bias for a Simple Method• Analytically based approach• Canadian SpecificationOrthotropic Plate Theoryspace BridgeTech, Inc.NBI 1990 - mostrecentNBI TotalInventoryNumber Skewed14275 6626330.0% 43.8%1464 30753.1% 63.4%1811 35463.8% 62.0%360 36770.8% 65.3%629 113401.3% 40.3%5329 951411.2% 53.6%933 13962.0% 49.0%40820.1% 9.2%2083000.4% 35.3%2083000.4% 35.3%141682669129.8% 50.1%1571 42133.3% 15.8%6799 2072814.3% 37.1%47587 353845 150825100.0% 42.6%Precast Solid, Voided, orCellular Concrete Boxes withShear Keys and with orwithout TransversePosttensioningOpen Steel or PrecastConcrete BoxesCast-in-Place ConcreteMulticell BoxesCast-in-Place Concrete TeeBeamPrecast Solid, Voided, orCellular Concrete Boxes withShear KeysSteel BeamCast in place concreteslab, precast concreteClosed Steel or PrecastConcrete BoxesCast in place concreteslabCast-in-place concrete orplank, glued/spiked panelsor stressed woodPrecast Concrete ChannelSections with Shear KeysPrecast Concrete DoubleTee Section with Shear Keysand with or withoutTransverse PosttensioningPrecast Concrete I or Bulb-Tee SectionsPrecast Concrete TeeSection with Shear Keys andwith or without TransverseReinforcementIntegral ConcreteIntegral ConcreteCast-in-place concreteoverlayIntegral ConcreteCast-in-place concrete,precast concreteCast-in-place concreteslab, precast concrete slabMonolithic ConcreteMonolithic ConcreteCast-in-place concreteoverlayjslab on girdersslab on girdersslab on girdersmonolithic slab and girdersmonolithic slab and girdersslab on girdersihgslab on girdersslab on girdersslab on girdersslab on girdersSupporting Components Type of DeckAASHTO Letter(see Table4.6.2.2.1-1)2848adcbfeNumber of BridgesAnalytical Group Type281061776657185633151398Q4847slab on girders53285Slabs Not Applicable Not Applicable Slabs26629lkslab on girdersWood BeamsTotal:55869895851851NBI Database BridgeTech, Inc.Summary Table (NBI Data)Type1990-present Total InventorySteel Beam30.0% 42.8%Concrete I29.8% 15.1%Precast ConcreteBoxes with Shear Keys11.2% 5.0%Slabs14.3% 15.8%85.3% 78.7%Bridge Percentages by Type 123doc.vn