Clase Metodo de Diseno Approx - AASHTO

7/28/2019 Clase Metodo de Diseno Approx - AASHTO

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Section 3 - Loads and Load Factors (SI)SPECIFICATIONS COMMENTARY. PermanentLoads

DO = downdragDC = dead load of structural components andnonstructuralattachmentsDW = dead load of wearing surfaces andutilities

EH = horizontal earth pressure loadEL = accumulated locked-in effects resultingfrom the construction processES = earth surcharge loadEV = vertical pressure from dead load of earthfill. Transient Loads

SR = vehicularbraking forceCE = vehicular centrfugal forceCR = creepCT = vehicular collision forceCV = vessel collision forceEQ = earthquakeFR = frictionIC = ice load1M = vehicular dynamic load allowanceLL = vehicular live loadLS = live load surchargePL = pedestrian live loadSE = settlementSH = shrinkageTG = temperature gradientTU = uniform temperatureWA = water load and stream pressureWL = wind on live loadWS = wind load on structure

3.4 LOAO FACTORS ANO COMBINATIONS3.4.1 Load Factors and Load Combinations C3.4.1

The total factored force effect shall be taken as: The background for the load factors specified herand the resistance factors specified in other sectionthese Specifications is developed in Nowak (1992).Q = ~;V;Q; (3.4.1-1)where:~ = load modifier specified in Article 1.3.2Q = force effects from loads specifiedhereinVi = load factors specified in Tables 1 and 2

.)

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Section 3 -Loads and Load Factors (SI)SPECIFICATIONS COMMENTARYlieu of better information, the resistance factor,


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Section 3 -Loads and Load Factors (SI)SPECIFICATIONS COMMENTARY@..;~ Table 3.4.1-2 Load Factors or PermanentLoads,V.~-4': ' p

.Jo;\.'

I I Load FactorI Type of Load I Maximum Minimum

DC: ComDonent and Attachments 1.25 0.90DO: DowndraQ 1.80 0.45DW: Wearing Surfaces and Utilities 1.50 0.65EH: Horizontal Earth Pressure8 Active 1.50 0.908 At-Rest 1.35 0.90EL: Locked-in Erection Stresses 1.0 1.0EV: Vertical Earth Pressure8 Overall Stability 1.35 N/A8 RetainingStructure 1.35 1.008 Rigid Buried Structure 1.30 0.908 Rigid Frames 1.35 0.908 Flexible Buried Structures other 1.95 0.90than Metal Box Culverts8 Flexible Metal Box Culverts 1.50 0.90ES: Earth Surcharge 1.50 0.75

~ .~..:',,';'1':, ~..,! The load factor for temperature gradient, VTG,and The load factor for temperature gradient shsettlement, VSE' should be considered on a project- determined on the basis of the:specific basis. In lieu of project-specific information tothecontrary, VTGmay be taken as: 8 Type of structure and

8 0.0 at the strengthand extremeevent imit states, 8 Limit state being nvestigated.8 1.0 at the service limit state when live load is not Open girder construction and multiple stconsidered, and girders have traditionally, but perhaps not neccorrectly, been designed without considera8 0.50 at the service limit state when live load is temperature radient, .e.,VTG= 0.0.

considered.For segmentally constructed bridges, the followingcombination shall be investigated at the service limit

state:DC + DW + EH + EV + ES + WA + CR +SH + TG + EL (3.4.1-2)

The load factor for live load in Extreme Event Load Past editions of the Standard SpecificationCombination1, VEO' shall be determined on a project- VEO = 0.0. This issue is not resolved. The posspecific basis. partial ive load, i.e., VEO 1.0, with earthquakebe considered. Application of Turkstra's combining uncorrelated loads indicates that VEO=reasonable for a wide range of values of avera\,\.. truck traffic (ADTT)

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~.~ HIGHWAY BRIDGES C I 9 qb) 3.22.3

TARLE 3.23.1 Dstribution of Wheel Loads in m~mben w!h lh~ narTOW ~dg~s of lh~ lamlnalons ~anng on !h~ sup-

LongitudlnaJ Bums pons (se~ Anlcl~ 20 II-Oivision 11)

'In lhis cas~ !h~ load on ~ach slring~r shal be !h~ ~aclon of !h~ridge Deslgned whe~loads. assuming !h~ looring belw~~n !h~ string~rs lo acl as a sim.

Bridge Desgned for for Two or mo~ pl~ beam ..fl O 1r'8m La 1r'8m Lan '.'Deslgn of I-B~am Bndg~s by N M N~lOImark-Proc~edlngs.

KJnd of oor De c ne c es ASCE, March 1948.

'The sid~lOIaJk lv~ load (se~ Anicl~ 31S) shaJI ~ omined for inle-lmber' rior and ~xterior box gird~rs d~signed in accordance lOIi!h the IOIheeload

Pankb S/4.0 S/3.7S distributon indicated he~in.Nai aminal~d' 'Dstribution faclors for Steel Bridge Comlgaled Pank set fonh

4" thick or muluple above ~ based substantialy on!he fololOlmg ~fe~nce:layer" l oors ov~r S"!hick . S/4.S S/4.0 Journol o/ Washington Acad~my o/ Sci~nc~s. Vol 67. No. 2. 1977

NaJlammat~d< "Wheel Load Dstribution of Steel Bridge Pank." by Conrad P. Heins,6" ot mo~ !hick S/S.O , S/4.2S , Professor of Cvi Engineering, University of Maryland,

Ir S exceeds S If S exceeds ~.S These distribution faclors lOI~re developed based on studies usinguse foolnole f. use foolnote . 6" x 2'" steel comlgated plank. The faclo~ should Y eld safe resulrs for

Glued laminated' o!her comlgated configurations provided primary ~nding stiffness isPanels on glued the same as or ~ler!han Ihe 6" x 2" comlgated plank used in !he stud-

larrunated stnngers '4" !hick S/4.S S/4.0 les.

6" or more !hick S/6.0 S/S,O 3.22.4 When ong spanstructuresare being designedbyIfSexceeds6' IfSexceeds7.S' . dbe f .fiedse oolnole . use oolnote. load factor deslgn, the garnma an ta actors SpeCIOn steel tring~~ for Load Factor Design represent general conditions and4" !hick S/4S S/4.0 should be increased if, in the Engineer's judgment.6" or mo~ !hick S/S,2S S/4.S d l d . d. . ,al fr S exceeds .S' Ir S exceeds' expecte oa s. servlce con Itlons. or maten s o

use ootnote, use oolnote. construction are different from those anticipated by theConc~l~ specifications.On steell-BeamstringersC andpreslressed 3.22.5 Structures aybe analyzedor an overloadhatconc~tegirde~ sn.o , SIS.S . is selected y fue operatingagency.Size and configurationIr S exceeds 0 If S exceeds 4 .. . . .use oolnote . use ootnote. of the overload. loadmg combmatlons. and load dlstnbu-On oncrete tion will be consistenl ith proceduresefinedn pennit

T-Beams S/6.S S/6.0, poicy of that agency-The load shall be applied n GroupIrS exceeds 6' IfS exceeds 10use ootnote f. use footnote , m as defined n Table 3.22.1A, For allloadings less hanOn im~r H 20, Group lA 10adingcombinauon shall be used (see

stringe~ S/6.0 SIS.O Art ' l 3 5 )fSexceeds6' If5exceeds lO' IC e , .use footnote f use footnote f.

Concrete boxgirde~h S/80 sn.o Part C

IfS exceeds 12' IfS exceeds ]6' DISTRIBUTION OF LOADSuse footnote f. use footnote f.

On sleel box grders See Article 10.39.2.On preslressed con- 3 23 DISTRIBUTION OF LOADS TO

crele spread box .Beams SeeAnicle 3.28. STRINGERS, LONGITUDINAL BEAMS,Ste~1rid ANO FLOOR BEAMS*

(Less than 4.' lhck) S/4S S/4.0(4" or more) 5/6.0 s/s.o 3.23.1 Position of Loads for Shear

If S exceeds 6' If S exceeds 10.5'use foolnole f. use foolnote f. . .Steel bridge 3.23.1.1 In calculalmg end shearsand end reactlons

Comlgal~d plank' in transverse loor beams and longitudinal beams and(2" min depth) S/S.S 5/4.5 stringers. no longitudinal distribution of fue wheel loadshall be assumedor fue wheelor axle load adjacent o lhe

S 2 average stnnger spacng in feet h d f th I . d. _1 be1; L- d h f I h kn transverse f1oor beam or l e en o e ongltu In* arnIm""r ImenSlons s own are or nomlna t IC ess'Plank lloors conslst of piece~ of lumber laid ~dge 10 edge with the or stringer at which the stress is being detennined,wlde faces beanng on !h~ suppons (see Anicle 20 17-Divison 11)

'Nall lamlnaled lloors conSISI of peces of lum~rlad face lo face 3.23.1.2 Lateral distribullon of the wheel loads alW h !he narrolOl ~dges beanng on Ihe suppons. each plece belng naled .to Ihe pr~c~ding pece (see Anicl~ 20 IS-Dv sion 11) ends of the beams or stnngers shall be that produced by

'MlJl pl~ lav=r loor~ consist of two or more layers 01" planks, eachlav~r oclng la.d al an angle 10 th~ olh~r Ise~ Anicle 20 17-0lvlsion 11)

'(iued lamlnal~d pan~1 loor~ conSI~1 of venlcaly glu~d lamlnaled .Provislons in Ihls Anlcl~ shal no! apply to onholropic deck bridge s


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. .~ ,reoagruastressed ood (a)Closterreaol~DfonoxO I(b)

Open Steel or Precast Cast-in-place concrete slab, ~U 117 U'oncrete Boxes precast concrete deck slabI

(c)Castonool:JC:J[::::Jl~MulticellBox(~~~~~~:J[=~~~~:[~=~~~~::(d).astonoo=:=O~~::iJ==:::=i1Tee Beam

(e)Precast Salid, Voided or Cast-in-place concrete overlay ~5Ejcil~~~dCellular Concrete Boxeswith Shear Keys D D I O O O

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Section 4 - Structural Analysis and Evaluatlon (SI)SPECIFICATIONS COMMENTARY

@~~~;~~: SUPPORTING- . COMPONENTS TYPE OF DECK TYPICAL CROSS-SECTIONPrecast Salid, Voided, or Integral concreteCellular Concrete Box b lDIDIDldith Shear Keys and withor without Transverse D D D D DPost- Tensioning ( ) t9 enPrecast Conc~ete . Cast-in-place concrete overtay ~~f~r'~~~~w~~Channel Sectlons wlthShear KeysPrecast Concrete Double Integral concrete 'irl]:J'nrlFiJ'ir1eys and with or without LTransverse .Posttensioning (1) ten

f,::Ji:;~ prec.astC?ncreteTee Integralconcrete ~I==11=S=='==~wlth Shear Keys and with or without poTransverse (J) t .P tt . . ensloos enslonlngPrecast Concrete I or Cast-in-place concrete, precast ~'Ir 1r 1r 1Tee Sections concreteWood Beams Cast-in-place concrete or n

plan k, glued/spiked panels or I . stressed wood ~ ~ ~ I~I ~~ ~ 1.;1 [;J ~

462.2.2 Distribution Factor Method for Moment andShear

{!~I~i"; 4.6.2.2. 2a Interior Beams with Wood Decksl":-' The live load flexural moment and shear for interiorbeams with transverse wood decks may be determined

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Section 4 -StructuralAnalysisand Evaluation SI)Table 4.6.2.2.2b-1 Distributionof Live Loads Per Lane or Moment n Interior Beams

Type of Beams Applicable Distribution Factors Range ofCross-Section Applicabilitfrom Table4.6.2.2.1-1Wood Deck on Wood a, I See Table 4.6.2.2.2a-1or Steel Beams oncn neooawrConcrete Deck, Filled a, e, k and One DesignLane Loaded: 1100s S .s 4900Grid, or Partially Filled also i, j 0.1 110 ~ 1s.s 300Grid on Steel or if sufficiently 0.06 +(~0.~0.5..Coneaono 3tConBectsniTndouTwrLSections (80.8,KO.09tsesfhar eqbrheMultionOnea.Boxeam)()0.3)0.10.! 1.~1100 L NcTwrLI (~0.~(!0.3~ c':;onecn,Onea1Conprox.)0...'Bea~.!. 91wrL~06~O92;; Usej::;,.:. 4 0


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Section 4 -StructuralAnalyslsand Evaluation SI)Table 4.6.2.2.2d-1 Distributionof Live Loads Per Lane or Moment n ExteriorLongitudinalBeams

~ Type of Superstructure Applicable Cross- One Design Two or More RangeSection from Table Lane Loaded Design Lanes Applica4.6.2.2.1-1 LoadedWoodDeck on Wood or a, I LeverRule Lever Rule N/ASteel BeamsConcrete Deck on Wood I Lever Rule Lever Rule N/A

Concrete Deck, Filled a, e, k and Lever Rule 9 = e ginterior -300 ~ de Grid, or Partially Filled , also}, j dGrid on Steel or If sufficlently e = 0.77 + --.!.-Concrete Beams; connected to act as 2800Concrete T -Beams, T a unitand Double T Sections

use lesser of the Nb = values obtained

from the equationabove with Nb = 3or the lever rule

Concrete Box d W W We ~Beams, Box Sections g = --.!.-- g = --.!.--4300 4300

@ ConcreteDeck on b, c Lever Rule 9 = e 9b'11erior O~ de ~ Concrete Spread Box d 1800 < S eBeams e = 0.97 + -

Use Lever Rule S > 35Concrete Box Beams t, 9 Lever Rule 9 = e 9inlerior -300 ~ deUsed in Multibeam dDecks e = 1.04 + --.!.-

Concrete Beams Other h Lever Rule Lever Rule N/Athan Box Beams Usedin Multibeam Decks i, j it connected only

enough to preventrelative verticaldisplacement at the

Steel Grid Deck on Steel a Lever Rule Lever Rule N/ABeamsConcrete Deck on b, c As specified in Table b-1Multiple Steel Box~'. (','..

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Clase Metodo de Diseno Approx - AASHTO