AASHTO Standard Specifications 17th Edition

5/19/2018 AASHTO Standard Specifications 17th Edition

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Section 10STRUCTURAL STEEL

Part AGENERAL REQUIREMENTS AND MATERIAI.S

10.1 APPLICATION

10.1.1 Notations

= total area of longitudinal ieinforcing steelthe interior support within the effectivfl ange width (Article 10.38.5. 1.2)

= total area of longitudinal slab reinforcemenA

A

A,,

= area of cross section (Articles l 11.37. J . l ,10.34.4, 10.48. 1.1, 10.48.2. J , 10.48.4.2,I 0.4d.5.3, and 10.55. 1)

= bending moment coefficient (Article10.50.1. l .2)

effective area of a flange r splice platewith holes or a tcnsion memher with holes (Articles 10. 12, 10.18.2.2. 1, 10. 18.2.2.3,10.18.2.2.4, an110.18.4.1)

amplification factor (Ai ticles l 0.37. 1.1 and10.55.l)

product of aren and yield point for bottomflange of steel section (Article 10.50.1.1.1) a

product of area xnd yield point of that part of aieiiiforcing which lies in the comprcssion

zone of the slab (Article 10.50. 1.1.1) B

= product of area and yield point for top langeof steel section (Article J 0.50. 1.1.1)

= product of area and yield point for web ofsteel section (Article 10.50.1. l . 1) b

= area of flange (Articles 10.39.4.4.2,10.48.2.1, 10.53.1.2, and 10.56.3)

= the sum of the area of filler plates on the top band bottom of the connected plate (Article111. 18.1.2.1)

area of compression fiange (Articles b10.48.4.1 and 10.50.1.2.1)

b

gross area of a flange, splice plate or tension membei (Articles 10.18.2.2.2, 10.18.2.2.4, band 10.18.4. l) b

= net section of a tension member (Article10.18.4.l)

= thc smaller of either the connected plate area bor the sum of the splice plate areas on the topand bottom of the connected plate (Article b10.18.1.2.1)

steel fireach beam over inteiior support (Aticle 10.38.5. 1.3)

= area of Steel section (Articles 10.38.5. 1.l 0.54. 1.1, and 10.54.2.l)

= ci oss-sectional area of a stud shearconnecto(Article 1l.38.5. 1.2)

= area of web of beam (Article 10.53.1.2) distance from center of bolt under con

si1eration t edge of plate, in. (Articl 0,32. .. tTld 10.56.2)

= spacing of transverse stiffeners (Artic10.39.4.4.2)

= depth of stress block (Figure 10.50A) = ratio of numerically smaller to the larger en

moment (Article 10.54.2.2) constant based on the number of stress cycl

(Article 10.38.5.1. l)= constant for stiffeners (Articles 10.34.4

and 10.48.5.3) compression flange width (Table 10.32.I

and Articles 10.34.2. l , 10.48, 10.48.1.10.8.2, 10.48.2. l, and 10.61.4)

= distance from center of bolt under consideation to toe of fillet of connected part, in. (Aticles 10.32.3.3.2 and 10.56.2)

= effective width of slab (Article 10.50.1.l . 1= effective flange width (Articles l 11.38.3 an

10,38.5.1.2)

widest flange width (Article 10. 15.2. 1) distance from edge of plate or edge of perfo

ration to the point of support (Artic10.35.2.3)

= unsupported distance between points of support (Article 10.35.2.7)

flange width between webs (Article10.37.3.1, 10.39.4.2, 10.51.5. l, and 10.55.3


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252 HIGHWAY BRIDGES

b' = width of stiffeners (Articles 10.34.5.2,10.34.6, 10.37.2.4, 111.39.4.5. 1, anti 111.55.2)

b = width of a projecting ilange element, angle,or stiffener (Articles 10.34.2.2, 10.34.4.7,10.37.3.2, 10.39.4.5. 1, 10.40.5.3, 10.51.5.5,and 10.55.3)

= web buckling coefficient (Artic les 10.34.4,

10.38.1.7, 10.48.5.3, and 10.48.8)= compressive forme in the slab (Articlel 0.50. 1. 1.l)

ejuivalentmoment factor (Article 10.54.2. 1) coiiipressive foice in top portion of steel sec-

tion (Article 10.50.1.1.1)= bending coefficicnt (Table 10.32.lA and Ar-ticles 1 0.48.4. 1 and 10.50.2.2)

column slenderness ratio dividing elastic andinelastic buckling (Table 10.32.IA)

coefficient about X axis (Article 10.36) coefficient about the Y axis (Article 10.36)

= buckling stress coefficient (Article

D = clear distance between flanges, in. (Article10.15.2)

D clear unsupported distance between flangecomponents (Articles 10.18.2.3.4, 10.18.2.3.7,10.18.2.3.8, 10.18.2.3.9, 10.34.3, 10.34.4,10.34.5, 10.37.2, 10.48.1, 10.48.2, 10.48.4,10.48.5, 10.48.6, 10.48.8, 10.49.2, 10.49.3.2,111.50.1.1.2, 10.50.2.1, 10.55.2, I10.61.1)

D distance from the top of the slab to the neu-tral axis at which a composite section in pos-

itive bending theoretically reaches its plastic-moment capacity when the maximum strainin the slab is at 0.003 (Article 10.50. 1.1.2)

= clear distance between the neutral axis and the compression flange (Articles 10.34.3.2.1,10.34.5.1, 10.48.4.1, 10.49.2, 10.49.3,10.50(b), 10.57, and 10.61.1)

= moments caused by dead load acting on com-porte girder (Article 10.50.1.2.2)

= depth of the web in compression at the plas-tic moment (Articles 10.50(b), 10.50.1.1.2,and 10.50.2.1)

depth of the web in compression of the non-composite steel beam or girder (Articles10.34.5, l and 10.49.3.2(a))

D, distance from the top of the slab to the plas-tic neutral axis, in. (Article 10.50.1.1.2)

D = moments caused by dead load acting on steelgirder (Article 10.50.1.2.2)

d = bolt diameter (Table 10.32.3B)d diametcr of stud, in. (Article 10.38.5. 1)

d

d

E

e

F

F

Fbx

F,

depth of beam or girder, in. (Table l 0.32. IAand Articles 10.13, 10.8.2, 10.48.4. l, and10.511. 1.1 2

= diametei f roclei or roller, in. (Aiticle10.32.4.2)

= beam depth (Article 10.56.3) column depth (Article UN.56.3)= spacing of iiitermediate stiffciier (Articles

10.34.4, 10.34.5, 10.48.5.3, 10.48.6.3, and10.48.8)

= distance from the centerline of a plate longi-tudinal stiffener or the gage line of an anglelongitudin:el stiffener t the inner surface orthe lcg of the compression f1angecomponent(Articles 10.34.3.2. 1, 10.34.5. 1, 10.48.4. 1,10.49.3.2(a), and 10.61.1)

modulus of elasticity of steel, psi (Table10.32. l A and Articles 10.IE.3, 10.36, 10.37,10.39.4.4.2, 10.54.1, and 10.55. 1)

modulus of elasticity of concrete, psi (Article

= distance from the center line of a splice to the centroid of the connection on the side of thejoint under consideration (Articles 10.18.2.3.3,10. 18.2.3.5, and 10.18.2.3.7)

= maximum induced stress in the bottomflange (Article 10.20.2. l)

maximum compressive stress, psi (Article10.41.4.6)

allowable axial unit stress (Table 10.32.lAund Articles 10.36, 10.37.1.2, and 10.55.1)

= allowable bending unit stress (Table 10.32. IA

and Articles 10.18.2.2.3, 10.37. 1.2, and10.55. 1)

compiessive bending stress permitted aboutthe X axis (Article 10.36)

= compressive bcnding stress permitted aboutthe Y axis (Article 10.36)

= buckling stress of the compression flangeplate or column (Articles 10.48.2, 10.50.2.2,10.51.l , 10.51.5, 10.54.1.1, and 10.54.2. 1)

local buckling stress of a stiffenei (Articles10.34.4.7 and 10.4P.5.3)

design stress for the conti olling flange at a

point of splice (Articles 10.18.2.2.3 and10.18.2.3.8)

design stress for the controlling flange at apoint of splice (Articles 10. J 8.2.2. 1 and10.18.2.3.4)

= maximum horizontal force (Article10.20.2.2)

Euler buckling stress (Articles 10.37.l ,10.54.2. 1, and 10.55.1)


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10.1.l

F,F,,

F.S.

DIVISION IDESIGN

= Euler stress divided by a factor ofsafety (Ar- ticle 10.36)

design stress for the noncontrolling flange ata point of splice (Article 10.18.2.2.3) fb

= design stress for the noncontrolling flange ata point of splice (Article 10.18.2.2. l)

- computed bearing stress due to design load fb(Table 10.32.3B)

= limiting bending stress (Article 10.34.4) allowable range of stress (Table 10.3.lA)= reduced allowable tensile stress on rivet or

bolt due to the applied shear stress, ksi (Ar-ticles 10.32.3.3.4 and 10.56.1.3.3)

specified minimum yield point of the rein-forcing steel (Article 10.38.5.1.2)

= factor of safety (Table 10.32.l A and Articles10.32.1 and 10.36)

25

= computed axial compression stress (Article10.35.2. 10, 10.36, 10.37, 10.55.2, an10.55.3)

computed compressive bending stress (Artcles 10.34.2, 10.34.3, 10.34.5.2, 10.3710.39, and 10.55)

= factored bending sness in the compressioflange (Articles 10.48, 10.48.2.1(b)10.48.4.1, 10.50.1.2.l , 10.50.2.2, 10.53, and10.53.1.2)

maximum factored noncomposite dead loadcompressive bending stress in the web (Articte 10.61.1)

= unit ultimate compressive strength of concrete as determined by cylinder tests at age o28 days, psi (Articles 10.38.l, 10.38.5. 1.210.45.3, and 10.50.1.1. 1)

= specified minimum tensile strength (Tables

10.2A, 10.32.lA and 10.32.3B and Article10.18.4)

= tensile strength of electrode classification(Table 10.56A and Article 10.32.2)= maximum bending strength of the flange(Articles 10.48.8.2, 10.50.1.2.1, and10.50.2.2)

= allowable shear stress (Table 10.32.1A and10.32.3B and Articles 10.18.2.3.6, 10.32.2,10.32.3, 10.34.4, 10.38.1.7, and 10.40.2.2)

= shear strength of a fastener (Article 10.56.1.3)= combined tension and shear in bearing-type

connections (Article 10.56.1.3)= design shear stress in the web at a point ofsplice (Articles 10.18.2.3.6, 10.18.2.3.7, and10.18.2.3.9)

specified minimum yield point of steel (Arti-cles 10.15.2.1, 10.15.3, 10.16.ll, 10.32.l,10.32.4, 10.34, 10.35, 10.37.1.3, 10.38.1.7,10.38.5, 10.39.4, 10.40.2.2, 10.41 .4.6, 10.46,10.48, J 0.49, 10.50, 10.51.5, 10.54, and10.61.4)

specified minimum yield strength ofthe flange(Articles 10.18.2.2. l , 10.48. 1.1, 10.53. l,10.57.1, and 10.57.2)

= specified minimum yield strength of atransverse stiffener (Articles 10.34.4.7 and10.48.5.3)

= specified minimum yield strength olthe web(Articles 10.18.2.2. l, 10.18.2.2.2, 10.18.2.3.4,10.53.1, and 10.61.1)

= specified mimimum yield strength of the web(Articles 10.34.4.7 and 10.48.5.3)

= the lesser of (f ,) or F, (Articles10.48.2. l(b), 10.48.2.2, and 10.53)

f,, maximum flexural stress at the reid-thickness

of the flange under consideration at a point osplice (Articles 10.18.2.2.3 and 10.18.2.3.8) maximum flexural stress due to the factored

loads at the reid-thickness of the controllingflange at a point ofsplice (Articles 10.18.2.2. and 10.18.2.3.4)

f,,, = noncomposite dead load stress in the com-pression flange (Articles 10.34.5.1 and10.49.3.2(a))

f,,, = top flange compressive stress due to the fac-tored noncomposite dead load divided by thefactor Rb (Article 10.61.4)

= totnl noncomposite and composite dead-load

plus composite live-load stress in the compression flange at the most highly stressedsection of the web (Articles 10.34.5.1 and10.49.3.2(a))

fu = top flange compressive stress due to noncomposite dead load (Articles 10.34.2.1 and10.34.2.2)

fy, = flexural stress at the reid-thickness of the noncontrolling flange concurrent with fq (Articles10.18.2.2.3 and 10.18.2.3.8)

= flexural stress due to the factored loads at thereid-thickness of the noncontrolling flange a

a point of splice concurrent with f,, (Articles10.18.2.2. l and 10.18.2.3.4)

= maximum flexural stress due to D + Q,(L + Iat the reid thickness of the flange undeconsideration at a point of splice (Article10.18.2.2.2 and 10.18.2.3.5)

= flexural stress due to D + bL L + I) at the midthickness of the other flange at a point ofsplice concurrent with f, in the flange underconsideration (Article 10.18.2.3.5)


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254 HIGHWAY BRIDGES 10.1.l

f,

f,

f,

f,

f,

fbx

fby

h

I

I,

range of stress due to live load plus impact,in the slab reinforcement over the support(Article 10.38.5. 1.3)

= modulus of rupture of concrete specified inArticle 8. 15.2.I .1 (Article 10.50.2.3)

= maximum longitudinal bending stress in the

flange of the panels on either side of thetransverse stiffener (Article 10.39.4.4)= factored bending stress in either the top or

bottom flange, whichever flange has thelarger ratio of (f,/F,) (Article 10.48.8.2)

= tensile stress due to applied loads (Articles 10.32.3.3.3 and 10.56.1.3.2)

= allowable tensile stress in the concrete spec-ified in Article 8.15.2. 1.l (Article 10.38.4.3)

unit shear stress (Articles 10.32.3.2.3, 10.34.4.4, and 10.34.4.7)

= maximum shear stress in the web at a point ofsplice (Article 10.18.2.3.6)

= computed compressive bending stress aboutthe x axis (Article 10.36)

- computed compressive bending stress aboutthe y axis (Article 10.36)

= gage between fasteners, in. (Articles10.16.14, 10.24.5, and 10.24.6)

= height of stud, in. (Article 10.38.5. l . l )= horizontal design force resultant in the web

at a point of splice (Articles 10.18.2.3.8 and10.18.2.3.9)

= overload horizontal design force resultant in the web at a point of splice (Article

10.18.2.3.5)= horizontal design force resultant in the webat a point of splice (Articles 10.18.2.3.4and 10.18.2.3.5)

= average flange thickness of the channelflange, in. (Article 10.38.5.1.2)

-moment of inertia, in.(Articles 10.34.4,10.34.5, 10.38.5.1.1, 10.48.5.3, and10.48.6.3)

= moment of inertia of stiffener (Articles10.37.2, 10.39.4.4. l, and 10.51.5.4)

= moment of inenia of transverse stiffeners(Article 10.39.4.4.2)

moment of inertia of member about the vertical axis in the plane of the web, in4 Article10.48.4. l)

= moment of inertia of compression flangeabout the vertical axis in the plane fthe web,in(Table 10.32.IA and Article 10.48.4.1)

required ratio of rigidity of one transversestiffener to that of the web plate (Anicles10.34.4.7 and 10.48.5.3)

= St. Venant torsional constant, in (Table10.32.lA and Article 10.48.4.1)

K effective length factor in plane of buckling(Table 10.32.1A and Articles 10.37, 10.54.1,and 10.54.2)

= effective length factor in the plane of bend-ing (Article 10.36)

k = constant: 0.75 for rivets; 0.6 for high-

strength bolts with thread excluded fromshear plane (Artie le 10.32.3.3.4)k = buckling coefficient (Articles 10.34.3.2. l,

10.34.4, 10.39.4.3, 10.48.4.1, 10.48.8,10.51.5.4, and 10.61.l)

distance from outer face of flange to toe ofweb fillet of member to be stiffened (Article10.56.3)

buckling coefficient (Article 10.39.4.4)= distance between bolts in the direction of the

applied force (Table 10.32.3B)L = actual unbraced length (Table 10.32.IA and

Articles 10.7.4, 10.15.3, and 10.55. l)L l/2 of the length of the arch rib (Article

10.37.1)L = distance between transverse beams (Article

10.41.4.6)Lb unbraced length (Table 10.48.2.1.A and Arti-

cles 10.36, 10.4b.1. l, 10.48.2. l, 10.48.4.l,and 10.53.1.3)

L, length of member between points of support,in. (Artie le 10.54.1.1)

L, = clear distance between the holes, or betweenthe hole and the edge of the material in the di-rection ofthe applied bearing force, in. (Table

10.32.3B and Article 10.56.I .3.2)= limiting unbraced length (Article 10.48.4.1)= limiting unbraced length (Article 10.48.4. l)= member length (Table 10.32. lA and Article

10.35.l)M = maximum bending moment (Articles

10.48.8, 10.54.2.1, and 10.50.1.l .2) smaller moment at the end of the unbraced

length of the member (Article 10.48.1.1(c))= moments at two adjacent braced points (Ta-

bles 10.32.lA and 10.3fA and Articles10.48.4. 1 and 10.50.2.2)

= column moment (Article 10.56.3.2)

= full plastic moment of the section (Articles10.50.l . l .2 and 10.54.2.1)

M, = lateral torsional buckling moment or yield moment (Articles 10.48.2, 10.48.4. l,10.50.1.2.1, 10.50.2.2, and 10.53. l .3)

M, = elastic pier moment for loading producingmaximum positive moment in adjacent span(Article 10.50.J . 1.2)

M, = maximum bending strength (Articles10.18.2.2.1, 10.48, 10.49, 10.50. 1, 10.50.2,10.51.1, 10.53.l, 10.54.2.1, and 10.61.3)


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DIVISION IDESfGN 25

M, = design moment due to the eccentricity of thedesign shear at a point of splice (Articles10.18.2.3.7 and 10.18.2.3.9)

overload design moment due to the eccentric-ty of the overload design shear at a point ofsplice (Article 10.18.2.3.5)

= design moment due to the eccentricity of thedesign shear at a point of splice (Articles10.18.2.3.3 and 10.18.2.3.5)

Mp = design moment at a point of splice represent-ing the portion of the flexural moment as-sumed to be resisted by the web (Articles10.18.2.3.8 and 10.18.2.3.9)

= overload design moment at a point of splice representing the portion of the flexural mo-ment assumed to be resisted by the web (Ar-ticle 10.18.2.3.5)

= design moment at a point of splice represent-

ing the portion of the flexural moment as-sumed to be resisted by the web (Articles10.18.2.3.4 and 10.18.2.3.5)

M, moment capacity at first yield (Articles10.18.2.2.1, 10.50. 1.1.2, and 10.61.3)

N, & N, number of shear connectors (Article10.38.5.1.2)

N number of additional connectors for eachbeam at point of contraflexure (Article10.38.5.1.3)

N, = number of slip planes in a slip-critical connection (Articles 10.32.3.2.1 and 10.57.3.l)

= number of roadway design lanes (ArticJe

10.39.2)

R

R

R

R

Rev

allowable slip resistance (Article 10.32.3.2.l= maximum axial compression capacity (Arti

cle 10.54.l .1)= design force for checking the strength of a

bolted splice in a tension member (Article10.18.4.l)

= allowable bearing (Article 10.32.4.2)= prying tension per bolt (Articles 10.32.3.3.2

and 10.56.2)= statical moment about the neutral axis (Arti-

cle 10.38.5. 1.l)= radius (Article 10.15.2.1) number of design lanes per box girder (Arti

cle 10.39.2.1) reduction factor for hybrid girders (Articles

10.18.2.2.l, 10.18.2.2.2, 10.18.2.2.310. 18.2.3.4, 10.18.2.3.8, 10.40.2. 1.110.53.1.2, and 10.53.1.3)

= reduction factor applied to the design sheastrength of fasteners passing through fillers(Article 10.18. l .2. l)

= bending capacity reduction factor (Articles10.48.2, 10.48.4.1, 10.50.1.2.1, 10.50.2.210.53.1.2, 10.53.1.3, and 10.61.4)

= absolute value of the ratio of Fq to f,, for thecontrolling flange at a point of splice (Articles10.18.2.2.3 and 10.18.2.3.8)

= the absolute value of the ratio of F,, to fu fothe controlling flange at a point of splice(Articles 10.18.2.2.l and 10.18.2.3.4)

= a range of stress involving both tension and

compression during a stress cycle (Table10.3.lB)n = ratio of modulus of elasticity of steel to that R,

of concrete (Anicle 10.38.1)n number of longitudinal stiffeners (Articles

10.39.4.3, 10.39.4.4, and 10.51.5.4)= allowable compressive axial load on mean-

bers (Article 10.35.l)= axial compression on the member (Articles

10.48.1.1, 10.48.2. l, and 1tJ.54.2.1) rbP, P,, Pp, = force in the slab (Article 10.38.5.1.2)& PP , design force in the controlling flange at a point

of splice (Article 10.18.2.2.3) r'= design force for the controlling flange at a point of splice (Article 10.18.2.2. l)

Po overload design force in the flange at a point ofsplice (Article 10.18.2.2.2)

= vertical force at connections of vertical stiffeners to longitudinal stiffeners (Anicle10.39.4.4.8)

= vertical web force (Article 10.39.4.4.7)- radius ef gyration, in (Articles 10.35.l

10.37.1, 10.41.4.6, 10.48.6.3, 10.54.l . l10.54.2. 1, and 1 O.55. 1)

= radius of gyration in plane of bending, in(Article 10.36)

= radius of gyration with respect to the Y-Yaxis, in. (Article 10.48.1.l)

radius of gyration of the compression flangeabout the axis in the plane of the web, in(Table 10.32.1A and Article 10.48.4. l)

= allowable rivet or bolt unit stress in shear(Article 10.32.3.3.4)

net = ddeessiiggnn ffoorrccee ffoorr tthhee nnoonnccoonntoroolllliinng ffllaanngee aatt aapoint of splice (Article 10.18.2.2.3)

= design force in the noncontrolling flange at apoint of splice (Article 10.18.2.2. l)

= design force for checking slip ofa bolted splicein a tension member (Article 10.18.4.2)

= section modulus, in.' (Articles 10.48.2,10.51.1, 10.53.1.2, and 10.53.l .3)

= pitch of any two successive holes in the chain(Article 10.16.14.2)

range of horizontal shear (Article10.38.5.1.1)


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256 HIGHWAY BRIDGES 10.1.l

= section modulus of transverse stiffener, in.'(Articles 10.39.4.4 and 10.48.6.3)

section modulus of longitudinal or transversestiffener, in.' (Article 10.48.6.3)

ultimate strength of the shear connector (Article 10.38.5.1.2)

- section modulus with respect to the compression flange, in.' (Table 10.32. l A andArticles 10.48.2, 10.48.4. l, 10.50.1.2.l ,10.50.2.2 and 10.53.1.2)

= section modulus with respect to the tensionflange, in.' (Articles 10.48.2 and 10.53. l .2)

= computed rivet or bolt unit stress in shear(Article 10.32.3.3.4)

T = range in tensile stress (Table 10.3.l B)T = direct tension per bolt due to external load

(Articles 10.32.3 and 10.56.2)T = arch rib thrust at the quarter point from

dead+ live + impact loading (Articles10.37.l and 10.55.l)

= thickness of the thinner outside plate orshape (Article 10.35.2)

= thickness of members in compression (Articte 10.35.2)

= thickness of thinnest part connected, in (Articles 10.32.3.3.2 and 10.56.2)

= computed rivet or bolt unit stress in tension,including any stress due to prying action (Article 10.32.3.3.4)

= thickness of the wearing surface, in. (Article10.41.2)

= flange thickness, in. (Articles 10.18.2.2.4,10.34.2. 1, 10.34.2.2, 10.39.4.2, 10.48,10.48.1.1, 10.48.2, 10.48.2.1, 10.51.5. l, and10.61.4)

= thickness of a flange angle (Article 10.34.2.2)= thickness of the web of a channel, in. (Arti

cle 10.38.5.1.2)= thickness of stiffener (Articles 10.34.4.7 and

10.48.5.3)= thickness of flange delivering concentrated

force (Article 10.56.3.2)= thickness of flange of member to be stiffened

(Article J 0.56.3.2)

thickness of the flange (Articles 10.37.3,10.55.3, and 10.39.4.3)

= thickness of the concrete haunch above thebeam or girder top flange (Article 10.50.1.1.2)

10.37.2, 10.48, 10.49.2, 10.49.3, 10.55.2,10.56.3, and 10.61.l)

= thickness of top flange (Article 10.50.1.1.1)= thickness of outstanding stiffener element

(Articles 10.39.4.5. l and 10.51.5.5)V shearing force (Articles 10.35.l, 10.48.5.3,

10.48.8, and 10.51.3)V = maximum shear in the web at a point of

splice due to the factored loads (Article10.18.2.3.2)

= maximum shear in the web atthe point ofsplice due to D + , (L + I) (Article 10.18.2.3.5)

V, shear yielding strength of the web (Articles10.48.8 and 10.53.1.4)

V, = range of shear due to live loads and impact,kips (Anicle 10.38.5.1.1)

V, = maximum shear force (Articles 10.18.2.3.2,10.34.4, 10.48.5.3, 10.48.8, and 10.53.3)

V, vertical shear (Article 10.39.3.1)Vp = design shear for a web (Articles 10.39.3.1and 10.51.3)

Vp - design shear in the web at a point of splice(Articles 10.18.2.3.2, 10.18.2.3.3, and10.18.2.3.5)

Vp,, overload design shear in the web at a pointof splice (Article 10.18.2.3.5)

= design shear in the web at a point of splice(Articles 10.18.2.3.2, 10.18.2.3.3, and10.18.2.3.5)

W length ot a channel shear connector, in. (Ar- ticle 10.38.5. 1.2)

W, = roadway width between curbs in feet or bar-riers if curbs are not used (Article 10.39.2.1)

W, = least net width of a flange (Article 10.18.2.2.4)W, = fraction of a wheel load (Article 10.39.2)w = length of a channel shear connector in inches

measured in a transverse direction on theflange of a girder (Article 10.38.5.l .1)

= unit weight of concrete, lb per cu ft (Article10.38.5.1.2)

= width of flange between longitudinal stiffen-ers (Articles 10.39.4.3, 10.39.4.4, and10.51.5.4)

Y, = distance from the neutral axis to the extremeouter fiber, in. (Article 10.15.3)

y = location of steel sections from neutral axis(Article 10.50.l . 1.l)

= thickness of stiffener (Article l 0.37.2 and Z = pllaassttiicc sectiion modulluus (Articles l10.48.l,10.55.2)

= slab thickness (Articles 10.38.5.1.2,10.50.l . 1.l, and 10.50.1.1.2)

= web thickness, in. (Articles 10.15.2. 1,10.18.2.3.4, 10.18.2.3.7, 10.18.2.3.8,10. 18.2.3.9, 111.34.3, J 0.34.4, TG.34.5,

10.53. 1.l , and 10.54.2.1)Z, allowable range of horizontal shear, in

pounds on an individual connector (Article10.38.5.1)

x constant based on the number of stress cycles(Article 10.38.5. 1.l)


7/86

25DIVISION IDESIGN

minimum specified yield strength of the webdivided by the minimum specified yieldstrength of the tension flange (Articles10.40.2 and 10.40.4)

= factor for flange splice design equal to 1.0,except that a lower value equal t Me M )may be used for flanges subject to com-pression at sections where M, does not ex-ceed M, (Article 10.18.2.2. 1)

= constant equal to 1.3 for members without alongitudinal stiffener and 1.0 for memberswith a longitudinal stiffener (Article 10.61.1)

area of the web divided by the area of the ten-sion flange (Articles 10.40.2 and 10.53.1.2)

factor applied to gross area of flange, spliceplate or tension member in computing theeffective area (Articles 10.18.2.2.4 and10.18.4.1)

= the ratio of A Al (Article 10.1 8. 1.2.l)

= load factor equal to 1.3 (Article 10.61)= F,,/Fu (Article l 11.53. J .2)

angle of inclination of the web plate to thevertical (Articles 1 0.39.3. l and 10.51.3)

ratio of total cross-sectional area to the cross-sectional area of both flanges (Article 10.15.2)

distance from the outer edge of the tensionflange to the neutral axis divided by the depthof the steel section (Articles 10.40.2 and10.53.1.2)

= amount of camber, in. (Article 10. 15.3)

= dead load camber in inches at any point (Ar-

ticle 10.15.3)= maximum value of ADL. in. (Article 10.15.3)= reduction factor (Articles 10.38.5.J .2,

10.56.1.1, and 10.56. 1.3) longitudinal stiffener coefficient (Articles

10.39.4.3 anl 10.51.5.4)= slip coefficient in a slip-critical joint (Article

10.57.3)

10.2 MATERIALS

10.2.1 General

These specifications recognize steels listed in the fol-lowing subparagraphs. Other steels may be usecl; how-ever, theii properties, strengths, allowable stresses, andworkability must be established and specified.

10.2.2 Structural Steels

Structural steels shall conform to the material desig-nated in Table 10.2A. (The stresses in this table are in

pounds per square inch.) The modulus of elasticity of agrades of structural steel shall be assumed to b29,000,000 psi and the coefficient of linear expansio0.0000065 per degree Fahrenheit.

10.2.3 Steels for Pins, Rollers, and ExpansionRoclers

Steels for pins, iollers, and expansion rockers shaconform to one of the designations listed in Tables 10.2Aand 10.2B, or shall be stainless steel conforming to ASTMA 240 or ASTM A 276 HNS 21800.

10.2.4 FastenersRivets and Bolts

Fasteners may be carbon steel bolts (ASTM A 307)power-driven rivets, AASHTO M 228 Grades l or (ASTM A 502 Grades 1 or 2); or huh-strength bolts

AASHTO M 164 (ASTM A 325) or AASHTO M 253(ASTM A 490).

10.2.5 Weld Metal

Weld metal shall conform to the current require

ments of the ANSI/AASHTO/AWS DI.5 Bridge Welding

Code.

10.2.6 Cast Steel, Ductile Iron Castings, MalleableCastings, and Cast Iron

10.2.6.1 Cast Steel and Ductile Iron

Cast steel shall conform to specifications for SteeCastings for Highway Bridges, AASHTO M 192 (ASTMA 486); Mild-to-Medium-Strength Carbon-Steel Castings for General Application, AASHTO M 103 (ASTMA 27); and Corrosion-Resistant Iron-Chromium, IronChromium-Nickel and Nickel-Based Alloy Castings foGeneral Application, AASHTO M 163 (ASTIVI A743)Ductile iron castings shall conform to ASTM A536.

10.2.6.2 Malleable Castings

Malleable castings shall conform to specifications foMalleable Lon Castings, ASTM A 47, Gradc 35018 (minimum yield point 35,000 psi).

10.2.6.3 Cast Iron

Cast iron castings shall conform to specifications forGray Lon Castings, AASHTO M 105, Class 30.


8/86

258 HIGHWAY BRIDGET

TABI.E 10.2A

Minimum Material PropertiesStructural Steel

AASHTO Designation M 270Grade 36

M 270Grade 50

M 270Grade 50W

M 270Grade HPS70W'

M 270Grdes 100/100W

Equivalent ASTMDesignation A 709 A 709 A 709 A 709 A 709Grade 36 Grade 50 Grade 50W Grade HPS70W Grades l00/ l00W

Thickness of PlI1tC:s Up to 4 in.incl.

Up to 4 in.incl.

Up to 4 in.incl.

Up to 4 in.incl.

Up to 2'/i in. Over 2'/i in. toincl. 4 in. incl.

Shapes ' All group All groups All groups Not applicable Not applicable Not applicable

Minimum TnsileStrength, Fa 58,000 65,000 70,000 90,000 1 10,000 100,000

Minimum Yield Pointor Minimum YieldStrength, F, 36,00o so,000 50,000 70,000 100,000 90,000

Except for the mandatory notch toughness and weldability requirements, the ASTM designations are similar to the AASHTO designations. Steels

meeting the AASHTO requirements are prequalified for use in welded bridges. M 270 Gr. 36 and A 709 Gr. 36 are equivalent to M 183 and A 36. M 270 Gr. 50 and A 709 Gr. 50 are equivalent to M 223 Gr. 50 and A 572 Gr. 50.M 270 Gr. 50W and A 709 Gr. 50W are equivalent to M 222 and A 588. M 270 Gr. 70W and A 709 Gr. 70W are equivalent to A 852. M 270 Gr. 100/100W and A 709 Gr. 100/100W are equivalent to M 244 and A 514.

AASHTOM 270 Grade HPS70W replaces AASHTO M 270 Grade 70W. The intent of this replacement is to encourage the use of high-performancesteel (HPS) over convenonal bridge steels due to its enhanced properties. AASHTO M 270 Grade 70W steel is still availab le, but should be used

with the owners approval.Quenched and tempered aHoy steel structural shapes and seamless mechanical tubing meeting all mechanical and chemical requirements of A 709

GfdS 100/100W, except that the specified maximum tensile strength may be 140,000 psi for structural shapes and 145,000 psi for seamless mechan-ical tubing, shall be considered as A 709 Grades 100/l00W

For nonstructural applications or bearing assembly components over 4thick, use AASHTO M 270 Gr. 36 (ASTM A 709 Gr. 36).f roups l and 2 include all shapes except those in Groups 3, 4, and 5. Group 3 includes L-shapes over 3/4 inch in thickness. HP shapes over 102

pounds/foot, and the following W shapes:Designation:

W36 K 230 to 300 incl.W33 5 200 to 240 incl.W14 X 142 to 211 incl.W12 X 120 to 190 incl.

Group 4 includes the following W shapes: W14 219 to 550 incl.Group 5 includes the following W shapes: W14 605 to 730 incl.For breakdewn of Groups 1 and 2, see ASTM A 6.

TABLE 10.2B

Minimum Material PropertiesPins, Rolleis, and Rockers

Expansion Rollers Shall be Not less Than 4 Inches in Diameter

AASHTO Designation

with Size Limitations

M 169

4 in. in dia. or

M 102

to 20 in. in dia.

M 102

to 20 in. in dia.

M 102

to 10 in, in dia.

M 102

to 20 in. in dia.less

ASTM Designation A 108 A 668 A 668 A 668 A 668Grade or Class Grades 1016 to

1030 incl. Class C Class D Class F Class G

Minimum Yield Point, psiF, 36,000 37,500 50,000

May substitute rolled material of the same properties.

For design purpose only. Not a part of the A 108 specificat ions. Supplementary material requirements should provide guarantee that material will meet these values.


9/86

DIVISION IDESIGN 25

Part B

DESIGN DETAILS

10.3 REPETITIVE LOADING AND TOUGHNESSCONSIDERATIONS

10.3.1 Allowable Fatigue Stress Ranges

Members and fasteners subject to repeated variations or reversals of stress shall be designed so that the maxi-mum stress does not exceed the basic allowable stressesgwen in Article 10.32 and that the actual range of stress does not exceed the allowablc fatigue stiess range gwenin Table 1 0.3. l A for the appropriate type and locationof material gwen in Table 10.3.IB and shown in Fig-ure l 0.3. l C. For mcmbers with shear connectors providcdthroughout their entire length that also satisfy the provi-sions of Article 10.38.4.3, the range of stress may be com-puted using the composite section assuming the concrete

deck to be fully cffective for both positive and negative moment.

For unpainted weathering steel, A709, all grades, thevalues of allowable fatigue stress range, Table 10.3.IA, asinodified by footnote d, are valid only when the designand details are in accordance with the FHWA Technic ulAdvso on Uncoated Weatherng Steel in Structurvs,

dated October 3, 1989.Main load carrying components subjected to tensile

stresses that may be considered nonredundant load pathmembersthat is, where failure of a single element couldcause collapseshall be designed for the allowable stress

ranges indicate1in Table 10.3.IA for Nonredundant LoadPath Structures. Examples of nonredundant load pathmembers are flange and web plates in one or two girderbridges, main one-element truss members, hanger plates,and caps at single or two-column bents.

10.3.2 Load Cycles

10.3.2.1

The number of cycles of maximum stressrange to be considered in the design shall be selected fromTable 10.3.2A unless traffic and loadometer surveys orother considerations indicate otherwise. The fatigue live load preferably shall not exceed HS 20 loading.

10.3.2.2

Allowable fatigue stress ranges shall applyto those Group Loadings that include live load or windload.

10.3.2.3 The number of cycles of stress range to beconsidered for wind loads in combination with dead loads,

except for sti uctuies wlieie other considei ations indicata substantially diffeient number of cycles, shall b1011,000 cycles.

10.3.3 Charpy V-Notch Impact Requirements

10.3.3.1 Main load carrying member component

subjected to tensile stress iequire supplemental impacproperties as described in the Material Specificatins.*

10.3.3.2 These impact requirements vary dependin

on the type of steel, type of construction, welded or mechanically fastened, and the average minimum servictemperature to which the structure may be subjected. *'Table 10.3.3A contains the temperature zone designations

10.3.3.3 Components requiring inaiidatory impac

properties shall be dcsignated on the drawings and the appropriate zone shall be designated in the contract documents.

10.3.4 Shear

10.3.4.1 When longitudinal beam or girder member

in bridges designed for Case I roadways are investigatcfor over 2 million stress cycles produced by placing single trucl on the bridge (see footnote c of Tabl10.3.2A), the total shear force in the beam or gircler undethis single-ti ucl loading shall be limited to 0.58 F,Dt,CThe constant C, the ratio of the buckling shear stress to thshear yield stress is defined in Article 10.34.4.2 or Articl10.48.8.1.

10.4 EFFECTIVE LENGTH OF SPAN

For the calculation ol stresses, span lengths shall be assumed as the distance between centers of bearings or othe

points of support.

*AASHTO Standard Spcc ifico ti ne fcr Trcinsportcition Matericils anMethods of Scimplii g and Te.stng.

**The basis anct philosophy used to develop these requiieineiits tiegwen in a paper entitled The Development of AASH"IO FractuieToughness Requirements for Bridge Steels by John M. Barsoni, Februai y 1975, availahle roni the American Iron and 5tecl Institute, Wash-ington, D.C.


10/86

Category For For For For over(See Table 100,000 500,000 2,000,000 2,000,00010.3. lB) Cycles Cycles Cycles Cycles

D 28 16E 22 13E' 16 9. 2F 15 12

Category For For For For over(See Table 100,000 500,000 2,000,000 2,000,00010.3. lB) Cycles Cycles Cycles Cycles

HIGHWAY BRIDGES

TABLE 10.3.IA Allowable Fatigue Stress Range

Redundant Load Path Structures

Allowable Range of Stress, F,, (ksi)

A 63 (49) 37 (29) 24 (18) 24 (16)B 49 29 18 16B' 39 23 14. 5 12C 35.5 21 13 10

10 78 4. 55.8 2.69 8

Nonredundant Load Path Structures

Allowable Range of Stress, F,, (ksi)b

A 50 (39) 29 (23) 24 (16)' 24 (16)B 39 23 16 16B' 31 18 11 11C 28 16 10 9

12d 1D 22 13 8 5E 17 10 6 2.3E' 12 7 4 1.3F 12 9 7 6

Structure types with multi-load paths where a single fra cture in a

member cannot lead to the collapse. For example, a simply supportedsingle span multi-beam bridge or a multi-element eye bar truss member has redundant load paths.

The range of stress is defined as the algebraic difference between the maximum stress and the minimum stress. Tension stress isconsidered to have the opposite algebraic sign from compressionstress.

For unpainted weathering steel, A 709, all grades, when used in conforma rice with the F-HWA Technical Advisor y on UncoatedWeathering Steel in Structures , dated October 3, 1989.

d For transverse stiffener welds on girder webs or flanges.

Partial length welded cover plates shall not be used on flanges morethan 0.8 inches thick for nonredundant load path structures.

10.5 DEPTH RATIOS

10.5.1 For beams or girders, the ratio of depth to lengthof span preferably should not be less than "

10.5.2 For composite girders, the ratio of the overall

depth of girder (concrete slab plus steel girder) to thelength of span preferably should not be less than , andthe ratio of depth of steel girder alone to length of spanpreferably should not be less than

10.5.3 For trusses the ratio of depth to length of spanpreferably should nitbe less than i

10.5.4

For continuous span depth ratios the span lengthshall be considered as the distance between the dead load points of contraflexure.

111.5.5 The foregoing Requirements as they relate tobeam or girder bridget may be exceeded at the discretion of the dcsigner. '*

10.6 DEFLECTION

10.6.1 The term deflection as used herein shall bethe cleflection computed in accordance with the assump-tien madc for loading when computing the stress in themember.

10.6.2 Members having simple or continuous spanspreferably should be designed so that the deflection due toservice live load plus impact shall not exceed u of thespan, except on bridges in urban areas used in part bypedestrians whereon the ratio preferably shall not exceed?i. For checking deflection, the service live load prefer-ably shall not exceed HS 20 loading.

10.6.3 The deflection of cantilever arms due to servicelive load plus impact preferably should be limited to ?of the cantilever arre except for the case including pedes-tri:in use, where the ratio preferably should be ?

10.fi.4 When spans have cross-bracing or diaphragmssufficient in depth or sti ength to ensure lateral distribu-tion of loads, the deflection may be computed for thestandard H or HS loading (M or MS) considering all beams or stringers as acting together and having equaldeflection.

10.6.5 The moment of inertia of the gross cross-sec-tional area shall be used for computing the deflections ofbeams and girdcrs. When the beam or girder is a part of acomposite member, the service live load may be consid-ered as acting upon the composite section.

10.6.6 The gross area of each truss member shallbe used in computing defleetions of trusses. If per-forated plates are used, the effective area shall be the net

*For considerations to be taken into Account when exceeding theselimitations, iefercnce is wade to Bulletin No. 19, Criteiia forthe De-flection of Steel Bridget, availablc from the American kon anti SteelInstitute, Washington, D.C.


11/86

10.6.6 DIVISIIN IDESIGN 26

TABLE 10.3.1B

Stress IllustrativeCategory Example

Kind of (See Table (See FigureGeneral Condition Situacion Stress 10.3. IA) 10.3. IC)

Plain Member Base metal with rolled or cleaned surface. Flame-cut edges T or Rev A 1,2with ANSI smoothness of 1,O00 or less.

Built-Up Members Base rrietal and weld metal in members of built-up plates orshapes (without attachments) connected by continuous full

T or Rev B 3,4,5,7

penetration groove welds (with backing bars removed) or bycontinuous fillet welds parallel to the direction of applicd stress.

Base metal and weld metal in members of built-up plates or T or Rev B' 3,4,5,7shapes (without attachments) connected by continuous fullpenetration groove welds with backing bars not removed, orby continuous partial penetration groove welds parallel to thedirection of applied stress.

Calculated flexural stress at the toe of transverse stiffener T or Rev 6welds on girder webs or flanges.

Base metal at ends of partial length welded coverplates with

- -b

T or Rev B 22

Groove WeldedConnections

Base metal at ends of partial length welded coverplatesnarrower than the flange having square or tapered ends, withor without welds across the ends, or wider than flange with welds across the ends:

(a) Flange thickness 0. 8 in. T or Rev(b) Flange thickness V 0. 8 in. T or ReV

Base metal at ends of partial length welded coverplates wider T or Revthan the flange without welds across the ends.

Base metal and weld metal in or adjacent to full penetration T or Revgroove weld splices of rolled or welded sections having similarprofiles when welds are ground flush with grinding in thedirection of applied stress and weld soundness established by nondestructive inspection.

Base metal and weld metal in or adjacent to full penetration T or Revgroove weld splices with 2 ft radius transitions in width, when welds are ground flush with grinding in the directionof applied stress and weld soundness established bynondestructive inspection.

Base metal and weld metal in or adjacent to full penetrationgroove weld splices at transitions in width or thickness, withwelds ground to provide slopes no steeper than 1 to 2?c, withgrinding in the direction of the applied stress, and weldsoundness established by nondestructive inspection:

EE' 7

E

B 8, 10

B

(a) AASHTO M 270 Grades 100/100W (ASTM A 709)base metal

T or Rev B'

(b) Other base iiietals T or Rev B

Base metal and weld metal in or adjacent to full penetration T or Revgroove weld splices, with or without transitions having slopes no greater than 1 to 2'Ze, when the reinforcement is notremoved and weld soundness is established by nondestructiveinspection.

11, 12

8, 10, 11,12

Groove WeldedAttachmentsLongitudinallyLoaded

Base metal adjacent to details attached by full or partial penetration groove welds when the detail length, L, in thedirection of stress, is less than 2 in.

Base metal adjacent to details attached by full or partialpenetration groove welds when the detail length, L, in thedirection of stress, is between 2 in. and 12 times the platethickness but less than 4 in.

T or Rev

T or Rev

6,15

D


12/86

262 HIGHWAY BRIDGES 10.6.6

TABLE 10.3.IB (Continued)


Kind of (See Table (See FigureGeneral Condition Situation Stress 10.3. IA) 10.3. IC)

Base metal adjacent to details attached by full or partialpenetration groove welds when the detail length, L, in the

direction of stress, is greater than 12 times the plate thicknessor greater than 4 in.:

(a) Detail thickness < 1.0 in. T or Rev E(b) Detail thickness 1.0 in. T or Rev E'

Base metal adjacent to details attached by full or partialpenetration groove welds with a transition radius, R,regardless of the detail length:

With the end welds ground smooth T or Rev 16(a) Transition radius fi 24 in.(b) 24 in. > Transition radius fi 6 in.(c) 6 in. > Jransition radius 2 in.(d) 2 in. > Transition radius fi 0 in.

For all transition radii without end welds ground smooth. T or Rev E 16

Groove welded Detail base metal attached by full penetration groove weldsAttachments with a transition radius, R, regardless of the detail length andTransversely with weld soundness transverse to the direction of stressLoaded established by nondestructive inspection:

With equal plate thickness and reinforcement removed T or Rev 16(a) Transition radius 24 in.(b) 24 in. W Transition radius fi 6 in.(c) 6 in. > Transition radius 2 in.(d) 2 in. > Transition radius 0 in.

BC

D

E

With equal plate thickness and rcintorcement not removed T or Rev 16(a) Transition radius 6 in.(b) 6 in. > Transition radius 2 in.(c) 2 in. > Transition radius 0 in.

DE

With unequal plate thickness and reinforcement removed T or Rev 16(a) Transition radius 2 in. D(b) 2 in. + Transition radius 0 in. E

For all transition radii with unequal plate thickness and T or Rev E 16reinforcement not removed.

Fillct Welded Base metal at details connected with transversely loadedConnections welds, with the welds perpendicular to the direction of stress:

(a) Detail thickness 0. 5 in. T or Rev C 14(b) Detail thickness > 0. 5 in. T or Rev See Note

Base metal at intermittent fillet welds. T or Rev E

Shear stress onthroat of fillet welds. Shear F 9

Fillet Welded Base metal adjacent to details attached by fillet welds with T or Rev C IE, 17,18,20

Attachments length, L, in the direction of stress, is less than 2 in. andLongitudinally stud-type shear connectors.Loaded ,d

Base metal adjacent to details attached by fillet welds with T or Rev Dlength, L, in the dection of stress, between 2 in. and 12 times the plate thickness but less than 4 in.

Base metal adjacent to details attached by fillet welds withlength, L, in the direction of stress greater than 12 times the plate thickness or greater than 4 in..

15,17

(a) Detail thickness < 1.0 in.(b) Detail thickness l .0 in.

1or RevT or Rev

E 7,9,15,17E' 7,9,15


13/86

10.6.6 DIVISION IDESIGN

General Condition

Fillet WeldedAttachmentsTransversely Loadedwith the Weld inthe Direction ofPrincipal Stress"'

TABLE 10.3.IB (Continued)

Situacion

Base metal adjacent to details attached by fillet welds with a transition radius, R, regardless of the detail length:

With the end welds ground smooth (a) Transition radius 2 in.(b) 2 in. > Transition radius 0 in.

For all transition radii without the end welds ground smooth.

Detail base metal attached by fillet welds with a transitionradius, R, regardless of the detail length (shear stress on thethroat of fillet welds governed by Category F):

With the end welds ground smooth(a) Tlansition radius 2 in.(b) 2 in. W Transition radius 0 in.


Kind of (See Table (See FigureStress 10.3. IA) 10.3. lC)

T or Rev 16DE

T or Rev E 16

T or Rev 16DE

MechanicallyFastenedConnections

Eyebar or Pin Plates

For all transition radii without the end welds

ground smooth.Base metal at gross section of high-strength bolted slipresistant connections, except axially loaded joints whichinduce out-of-plane bending in connecting materials.

Base metal at net section of high-strength boltedbearing-type connections.

Base metal at net section of riveted connections.

Base metal at the net section of eyebar head, or pinplateBase metal in the shank of eyebars, or through the grosssection of pin plates with:

T or Rev

T or Rev

T or Rev

T or Rev

T

E 16

B

D 21

E 23, 24

(a) rolled or smoothly ground surfaces T A 23, 24(b) llame-cut edges T B 23, 24

Tsignifies range in tensile stress only, Revsignifies a range of stress involving both tension and compression during a stress cycle.See Wattar, Albrecht and Sahli, Journal of structural Engineering, ASCF:, Vol. III, No. 6, June 1985, pp. 12351249.

where S is equal to the allowable stress range for Category C gwen in Table 10.3. lA. This assumes no penetration at the weld root.

'Gusset plates attached to girder flange surfaces with only transverse fillet welds are prohibited.

volume divided by the length from center to center ofperforations.

10.6.7 The foregoing requirements as they relate tobeam or girder bridges may be exceeded at the cliscretionof the designer. *

*For considerations to be takeii inte account when exceeding theseliinitations, reference is wade to Bulletiii No. 19, Criteria for the De-flection of Steel Bridges, available fiom the American Iron and SteelInstitute, Washington, D.C.

10.7 LIMITING LENGTHS OF MEMBERS

10.7.1 For compression members, the slendernesratio, KL/r, shall not exceed 120 or main members, othose in which the majoi stresses result fi om dead or liveload, o both; and shall not excecd 140 for secondarymembers, or those whose primary purpose is to brace thestructure against lateral or longitudinal force, or to bracor reduce the unbraced length of other members, main osecondary.


14/86

10.7.1264 HIGHWAY BRIDGES

1

fin

b

9 At End of Weld, Has No Length

10 End of Weld

FIGURE 10.3.TC Illusti-ative Examples


15/86

10.7.2 DIVISION IDESIGN 26

TABLE 10.3.2A Stress Cycles

Main (Longitudinal) Load Carrying Members

TABLE 10.3.3A Tempei-ature Zone Designations forCharpy V-Notch Impact Requirements

pe of Road Case ADTTTruck

LoadingLane

Loading

MinimumService Temperature

TemperatureZone Designation

Freeways, Expressways, I 2,500 or 2,000,000 500,000 0F and above 1Major Highways, and more 1Fto 30 F 2Streets 3lFto 60 F 3

Fre ewa s , E x re sswa s , II less than 500,000 100,000Major Highways, and 2,500 length between panel point intersections or centers o

braced points or centers of end conncctions; for secondary members, the length between the ccnters of thend connections of sitch members or centers of bracepoints.

10.7.5 For tension members, except rods, eyebars, cables, and plates, the ratio of unbraced length to radius o

Other Highways and IIIStreets not included inCase I or II

Transverse Members

and Details Subjected to Wheel Loads

Freeways, Expressways, I 2,500 or overMajor Highways, and more 2,000,000Streets

Freeways, Expressways, II less than 2,000,000Major Highways, and 2,500Streets

gyration shall not exceed 200 for main members, shall noexceed 240 for bracing iiiembers. and shall not excee140 for main members subject to a reversal of stress.

10.8 MINIMUM THICKNESS OF METALOther Highways and IIIStreets

Average Daily Truck Traffic (one direction).

500,00010.8.1 Structural steel (including bracing, cross framesand all types of gusset plates), except for webs of certain

Longitudinal members should also be checked for truck loading.Members shall also be investigated for over 2 million stress

cycles produced by placing a single truck on the bridge distributed to the girders as designated in Article 3.23.2 for one traffic lane loading. The shear in steel girder webs shall not exceed 0.58 F,DC for thissingle truck loading.

10.7.2 In determining the radius of gyration, r, for the

purpose of applying the limitations of the KL/r ratio, thearea of any portion of a member may be neglected provided that the strength of the member as calculated without using the area thus neglected and the strength of themember as computed for the entirc section with the KL/riatio applicable thereto, both equal or exceed the com-puted total force that the member must sustain.

10.7.3 The radius of gyration and the effective area forcarrying stress of a member containing perforated coverplates shall be computed for a transverse section throughthe maximum width of perforation. When perforations arestaggered in opposite cover plates, the cross-sectionalarea of the member shall be considered the same as for asection having perforations in the same transverse plane.

10.7.4 Actual unbraced length, L, shall be assumed asfollows:

For the top chords of half-through trusses, the lengthbetween panel points laterally supperted as indicatedunder Article 10.16.12; for other main members, the

rolled shapes, closed ribs in orthotropic decks, fillers, andin railings, shall be not less than ? inch in thickness. Thweb thiclness of rolled beams or channels shall not bless than 0.23 inches. The thickness of closed ribs in othotropic decks shall not be less than inch.

10.8.2 Where the metal will be exposed to marked cor

rosive influences, it shall be increased in thickness or specially protected against corrosion.

10.8.3 It should be noted that there are other provisionin this section pertaining to thickness for fillers, segmentof compression members, gusset plates, etc. As stateabove, fillers need not be inch minimum.

10.8.4 For compression members, refer to Trusses(Article 10.16).

10.8.5 For stiffeners and other plates, refer to PlatGirders (Article 10.34).

10.8.6 For stiffeners and outstanding legs of angles, etcrefer to Article 10.10.

10.9 EFFECTIVE AREA OF ANGLES ANDTEE SECTIONS IN TENSION

10.9.1 The effective area of a single angle tension member, a tee section tension member, or each angle of a ilou


16/86

10.9.1266 HIGHWAY BRIDGES

ble angle tension member in which the shapes are con-nected back to back on the same side of a gusset plate shallbe assumed as the net area of the connected leg or flangeplus one-half of the area of the outstanding leg.

10.9.2 If a double angle or tee section tension memberis connected with the angles or flanges back to back on op-

posite sides of a gusset plate, the full net area of the shapcsshall be considered effective.

10.9.3 When angles connect to separate gusset plates, as in the case of a double-webbed truss, and the angles areconnected by stay plates located as near the gusset as practicable, or by other adequate means, the full net area of the angles shall be considered effective. If the angles are notso connected, only 809r of the net areas shall be consid-ered effective.

10.9.4 Lug angles may be considered as effective in

transmitting stress, provided they are connected with atleast one-third more fasteners than required by the stressto be carried by the lug angle.

10.10 OUTSTANDING LEGS OF ANGLES

The widths of outstanding legs of angles in compres-sion (except where reinforced by plates) shall not exceedthe following:

In main members carrying axial stress, 12 times thethickness.In bracing and other secondary members, 16 times thethickness.

For other limitations, see Article 10.35.2.

10.11 EXPANSION AND CONTRACTION

In all bridges, provisions shallbe wade in the design to resist thermal stresses induced, or means shall be providedfor movement caused by temperature changes. Provisionsshall be wade for changes in length of span resulting fromlive load stresses. In spans more than 300 feet long, al-

lowance shall be wade for expansion and contraction inthe floor. The expansion end shall be secured against lat-eral movement.

10.12 FLEXURAL MEMBERS

Flexural members shall be designed using the elasticsection modulus except when utilizing compact sections

under Strength Design as specified in Articles 10.48.1,10.50. 1.1, and 10.50.2.1. When computing the strength ofa flexural member at a section with holes in the tensionflange, an effective flange area, A,, specified by Equation(10-4g) shall be used for that flange in computing the elas-tic section properties. The diameter of the holes shall betaken as specified in Article 10.16.14.6. In the case of the

strength design method, the strength of compact sectionswith holes in the tension flange shall not be taken greaterthan the moment capacity at first yield.

10.13 COVER PLATES

10.13.1 The length of any cover plate added to a rolledbeam shall be not less than (2d+ 3) feet, where (d) is thedepth of the beam in feet.

10.13.2 Partial length welded cover plates shall not be

used on flanges more than 0.8 inches thick for nonredun-dant load path structures subjected to repetitive loadingsthat produce tension or reversal of stress in the member.

10.13.3 The maximum thickness of a single cover plateon a flange shall not be greater than two times the thick-ness of the flange to which the cover plate is attached. Thetotal thickness of all cover plates should not be greaterthan 2? times the flange thickness.

10.13.4 Any partial length welded cover plate shall extend beyond the theoretical end by the terminal distance,and it shall extend to a section where the stress range in

the beam flange is equal to the allowable fatigue stressrange for base metal adjacent to or connected by fillet welds. The theoretical end of the cover plate, when usingservice load design methods, is the section at which thestress in the flange without that cover plate equals the al-lowable service load stress, exclusive of fatigue consider-ations. When using strength design methods, the theoret-ical end of the covei plate is the section at which the flange strength without that cover plate equals the requiredstrength for the design loads, exclusive of fatigue require-ments. The terminal distance is two times the nominalcover plate width for cover plates not welded across their

ends, and lu times for cover plates welded across theirends. The width at ends of tapered cover plates shall benot less than 3 inches. The weld connecting the coverplate to the flange in its terminal distance shall be contin-uous and of sufficient size to develop a total stress of notless than the computed stress in the cover plate at its the-oretical end. All welds connecting cover plates to beamflanges shall be continuous and shall not be smaller thanthe minimum size permitted by Article 10.23.2.


17/86

DIVISION IDESIGN

10.13.5 Any partial length end-bolted cover plate shallextend beyond the theoretical end by a terminal distanceequal io the length of the end-bolted portion, and the coverplate shall extend to a section where the stress range in thebeam flange is equal to the allowable fatigue stress rangefor base metal at ends of partial length welded cover plates

R=

R 00b

(10 - 2

with high-strength bolted, slip-critical end connections(Table 10.3.IB). Beams with end-bolted cover plates shallbe fabricated in the following sequence: drill holes; cleanfaying surfaces; install bolts; weld. The theoretical end ofthe end-bolted cover plate is determined in the same man-ner as that of a welded cover plate, as is specified in Arti-cte 10.13.4. The bolts in the slip-critical connections ofthe cover plate ends to the flange, shall be of sufficientnumbers to develop a total force of not less than the com-puted force in the cover plate at the theoretical end. Theslip resistance of the end-bolted connection shall be de-termined in accordance with Article 10.32.3.2 for serviceload design, and Article 10.56.1.4 for load factor design.The longitudinal welds connecting the cover plate to thebeam flange shall be continuous and stop a distance equalto one bolt spacing before the first row of bolts in the end-bolted portion.

10.14 CAMBER

Girders should be cambered to compensate for dead load deflections and vertical curvature required by profilegrade.

10.15 HEAT-CURVED ROLLED BEAMS ANDWELDED PI=ATE GIRDERS

10.15.1 Scope

This section pertains to rolled beams and welded I-sec-tion plate girders heat-curved to obtain a horizontal cur-vature. Steels that are manufactured to a specified mini-mum yield point greater than 50,000 psi, except for GradeHPS70W steel, shall not be heat-cuived.

10.15.2

Minimum Radius of Curvature

10.15.2.1 For heat-curved beams and girders, the

horizontal radius of curvature measured to the center lineof the girder web shall not be less than 150 feet and shallnot be less than the larger of the values calculated (at anyand all cross sections throughout the length of thc girder)from the following two equations:

In these equations, F, is the specified minimum yieldpoint in kips per square inch of steel in the girder web, iis the ratio of the total cross-sectional area to the ci osssectional area of both flanges, b is the widest flange widthin inches, D is the clear distance between flanges ininches, tq is the web thiclness in inches, and R is the radius in inches.

10.15.2.2

In addition to the above requircments, theradius shall not be less than 1,000 feet when the flangethickness exceeds 3 inches or the flange width exceeds30 inches.

10.15.3 Camber

To compensate for possible loss of camber of heat-curved girders in service as residual stresses dissipate, theamount of camber in inches, at any section along thelength L of the girder shall be equal to:

_ DL

_ 0.02 L' 1, 000 R

EY, 850

Ay = 0 for iadii greater than l, 000

where ADis the camber in inches at any point along thelength L calculated by usual procedures to compensate fordeflection due to dead loads or any other specified loads is the maximum value of A DL in inches withiii thelength L; E is the modulus of elasticity in ksi; F , is thespecified minimum yield point in ksi of the girder flangeY, is the distance from the neutral axis to the extremeouter fiber in inches (maximum distance for nonsyminetrical sections); R is the radius of curvatura in feet; and L

is the span length for simple spans or for continuousspans, the distance between a simple end support and thedead load contraflexure point, or the distance betweenpoints of dead load contraflexure. (L is measured ininches.) Camber loss bctween dead load contraflexurepoints adjacent to piers is small and may be neglected.

Note: Part of the camber loss is attributable to construc-on loads and will occur during construction of the


18/86

268 HIGHWAY BRIDGES

bridge; total camber loss will be complete afterseveral months of in-service loads. Therefore, aportion of the camber increase (approximately509r) should be included in the bridge profile.Camber losses of this nature (but generally smallerin magnitude) ire also known to occur in straightbcums and girders.

10.16 TRUSSES

10.16.1 Cieneral

10.16.1.1 Coinpcnentparts of individual truss mem-bers may be connected by welds, rivets, or high-strengthbolts.

10.16.1.2 Preference sheuld be gwen to trusses withsingle intersection web systems. Members shall be sym-meti ical about the central plane of the truss.

10.TG.1.3 Trusses preferably shall have inclined endposts. Latei ally unsupported hip joints shall be avoided.

10.1fi.1.4 iVain trusses shall be spaced a sufficientdistance apart, center to center, to be secure against overturiiiiig by the assumed lateral forces.

10.16.1.5 For the calciilation of stresses, effectivedepths shall be assumed as follows:

Riveted and bolted trusscs, distance between centers ofgravity of the chords.

Pin-connected trusses, distance between centers ofchord pins.

10.16.2 Truss Members

10.16.2.1 Chord and web truss members shall usu-ally be wade in the following shapes:

Hsections, wade with two side segments (composedof angles or plates) with solid web, perforated web, orweb of stay plates and lacing.Channel sections, wade with two angle segmento, withsolid web, per forated web, or web of stay plates andlacing.Single Box sections, wade with side channels, beams,angles, and plates or side segmento of plates only, con-nected top and bottom with pei foi ated plates ni stayplates and lacing.

Single Box sections, wade with side channels, beams,angles and plates only, connected at top with solid

cover plates and at the bottom with perforated plates orstay plates and lacing.Double Box sections, wade with side channels, beams,angles and plates or side segments of plates only, connected with a conventional solid web, together with tpand bottom perforated cover plates or stay plates andlacing.

10.16.2.2 If the shape of the truss permits, compres-sion chords shall be continuoiis.

10.16.2.3 In chords composed of angles in channel-shaped member s, the vertical legs of the angles pr eferablyshall extend downward.

10.16.2.4 If web members are subject to reversal ofstiess, their end connections shall not be pinned. Coiintei s preferably shall be rigid. Adjustable counters, if used,shall have open turnbuckles, and in the design of these

members an itllowance of 10,000 pounds per square inch shall be wade for initial stress. Only one set of diagonaJ sin any panel shall be adjustable. Sleeve nuts and loop b:u s shall not be used.

10.16.3 Secondary Stresses

The design and details shall be such that secondarystresses will be as small in praeticable. Secondary sti esscsdue to truss distortion or floor beam deflection usuull yneed not be considei ed in any member, the width ofwhich, measured parallel to the plane of distortion, is less

than one-tenth of its length. If the secondary stress ex-ceeds 4,0011 pounds per square inch for tension membcrsand 3,000 for compression members, the excess shall betreated es a primary stress. Stresses due lo the flexuraldead load moment of the member shall be considered asadditional secondary stress.

10.1ti.4 Diaphragms

10.16.4.1 There shall be diaphragms in the trusses atthe end connections of floor beams.

10.1ti.4.2 The gusset plates engaging the pedestal pinat the end of the truss shall be connected by a diaphragm.Similarly, the webs of the pedestal shall, if practicable, beconnectelby a diapliragm.

10.16.4.3 There shall be a diaphragm between gussetplates engaging main members if the end tie plate is 4 feeto inoie from the point of intei section ot the members.


19/86

DIVISION IDESIGN

10.16.5 Camber

The length of the truss members shall be such that thecamber will be equal to er greater than the deflection pro-duced by the dead load.

10.16.f Working Lines and Gravity Axes

10.16.6.1 Main members shall be proportioned sothat their gravity axes will be as nearly as practicable inthe center of the section.

10.16.6.2 In compression members of unsymmetri-cal section, such as chord sections formed of side seg-ments and a covei plate, the gravity axis of the sectionshall coincide as nearly as practicable with the workingline, except that eccentricity may be introduced to coun-teiact dead load bending. In twoangle bottom chord or di-agonal members, the working line may be taken as the

gage line nearest the baclof the angle or at the center ofgravity for welded trusses.

10.16.7 Portal and Sway Bracing

10.16.7.1 Through truss spans shall have portal brac-ing, preferably, of the two-plane or box type, rigidly connected to the end post and the top chord flanges, and asdeep as the clearance will allow. If a single plane portal isu sed, it shall be located, prefeiably, in the central hans-verse plane of the end posts, with diaphragms between thewebs of the posts to provide for a distribution of the por

tal sti esses. The portal bracing shall be designed to takethe full end ieaction of the top chord latci al system, andthe end posts shall be designed to transfer this reaction to

the ngs.

IO.1ti.7.2 Through truss spans shall have sway brac-ing 5 feet or more deep at each intermediate panel point.Top lateral struts shall be at least as deep as the top chord.

10.16.7.3 Deck truss spans shall ha.le sway bracing

in the plane of the end posts and at all intermediate p:inelpoints. This bracing shall extend the full depth of the

trusscs below the Poor system. The end sway liracing shallbe proportioned to carry the entire upper lateral stress to the supports through the end posts of the truss.

10.16.8 Perforated Cover Plates

When ierfoiatcd cover plates are used, the following provisions shall govein their design.

10.16.8.1 The ratio of length, in direction of stress, twidth of perforation, shall not exceed two.

10.16.8.2 The clear distance between perfrationsthe direction of stress shall not be less thxn the distancbetween points of support.

10.16.8.3 The clear distance between the end perforation and the end of the cover plate shall not be less than1.25 times the distance between points of support.

10.16.8.4 The point of support shall be the inner linof fasteners or fillet welds connecting the perforated platto the flanges. For plates butt welded to the flange edge orolled segments, the point of support may be taken as thweld whenever the ratio f the outstanding flange widtto flange thickness of the rolled segment is less thaseven. Otherwise, the point of support shall be the root othe flange of the rolled segment.

10.1ti.8.5 The periphery of the perforation at apoints shall have a minimum radius of 1inches.

10.16.8.6 For thickness of metal, see Article l II.35.2

10.16.9 Stay Plates

10.16.9.1 Wheie the open sides of compressiomembers are not connected by perfoi ateil plates, sucmembers shall be provided with lacing bars and shall havstay plates as near each cnd as practicable. Stay plat

shall be provided at intermediate points wheie the lacinis interrupted. In main members, the length of the end staplates between end fasteners shall be not less than 1times the distance between points of suppit anthe length ol intermediate stay plates not less th.in .that distance. In lateral struts and other secondary members, the overall length of end and intermediate stay platshall be not less than ? of the distance between points osupport.

10.1Si.9.2 The point of support shall be the inner linof fasteners o fillet welds connecting the stay plates t

the flanges. For stay plates butt welded to the flange edgo rolled segments, the point of suppoitmay be taken athe weld whenever the ratio of outstanding fl unge widtto flange thickness of the i olled segment is less thaseven. Otherwise, the point of support shall be the root oflange of rolled segment. When stay plates arc buwelded to i olled segmento of a member, the allowabstress in the member shall be determined in accordance


20/86

270 HIGHWAY BRIDGES 10.16.9.2

with Article 10.3. Terminations of butt welds shall beground smooth.

10.16.9.3 The separate segments of tension memberscomposed of shapes may be connected by perforatedplates or by stay plates or end stay plates and lacing.End stay plates shall have the same minimum length as

specified for end stay plates on main compression mem-bers, and intermediate stay plates shall have a minimumlength of ? of that specified for intermediate stay plates onmain compression members. The clear distance betweenstay plates on tension membcrs shall not exceed 3 feet.

10.16.9.4 The thickness of stay plates shall be notless than " of the distance between points of support formain members, and ?of that distance for bracing mem-bers. Stay plates shall be connected by not less than threefasteners on each side, and in members having lacing barsthe last fastener in the stay plates preferably shall also passthrough the end of the adjacent bar.

10.16.10 Lacing Bars

When lacing bars are used, the following provisionsshall govern their design.

10.16.10.1 Lacing bars of compression membersshall be so spaced that the slenderness ratio of the portionof the flange included betwcen the lacing bar connections will be not more than 40 or more than "ol the slender-ness ratio of the member.

10.16.10.2 The section of the lacing bars shall be de-termined by the formula for axial compression in whichL is taken as the distance along the bar between its con-nections to the main segments for single lacing, and as 709o of that distance for double lacing.

10.16.10.3 If the distance across the member betweenfastener lines in the langcs is more than 15 inches and a bar with a single fastener in the connection is used, the lac-ing shall be double and astened at the intersections.

10.16.10.4 The angle between the lacing bars and the

axis of the member shall be approximately 45 for doublelacing and 60for single lacing.

10.16.10.5 Lacing bars may be shapes or flat bars.For main members, the minimum thickness of flat barsshall be ? of the distance along the bar between its con-nections for single lacing and for double lacing. Forbracing members, the limits shall be for single lacingand / for double lacing.

10.16.10.6 The diameter of fasteners in lacing bars shall not exceed one-third the width of the bar. There shall be at least two fasteners in each end of lacing bars con-nected to flanges more than 5 inches in width.

10.1ti.11 Cusset Plates

10.16.11.1 Gusset or connection plates preferablyshall be used for connecting main members, except whenthe members are pin-connected. The fasteners connectingeach member shil1 be symmetrical with the axis of the member, so far as practicable, and the full development ofthe elements of the member shall be gwen consideration.The gusset plates shall be of ample thickness to resistshear, direct stress, and fl exurc acting on the weakest orcritical section of maximum stress.

10.16.11.2 Re-entrant cuts, except curves wade forappearance, shall be avoided as far as practicable.

10.16.11.3 II the length of unsupported edge ofa gusset plate exceeds the value of the expres-sion 11,000/ , times its thickness, the edge shall bestiffened.

i0.16.11.4 Listed below are the values of the expres-sion 11,000/ ,for the following grades of steel:

36,000 psi, Y.P. Min 5850,000 psi, Y.P. Min 4970,000 psi, Y. P. Min 4290,000 psi, Y.P. Min 37

100.000 psi, Y.P. Min 35

10.16.12 Hall-Through Truss Spans

10.16.12.1 The vertical truss members and the floorbeams and their connections in half-through truss spansshall be proportioned to resist a lateral force of not less than 300 pounds per linear foot applied at the top chordpanel points of each truss.

10.16.12.2 The top chord shall be considered as a

column with elastic lateral supports at the panel points. The critical buckling force of the column, so determined,shall exceed the maximum force from dead load, live load,and impact in amy panel of the top chord by not less than

*For a dscussion of columiis with elastic lateral supports, referto Tim-oslienlo& Geie, Theoryof Elastic Stability,McGraw-Hill Boolc Co.,First Edition, p. 122.


21/86

10.16.13 DIVISION IDESIGN 27

10.16.13 Fastener Pitch in Ends of CompressionMembers

In the ends of compression members, the pitch of fas-teners connecting the component parts of the membershall not exceed four times the diameter of the fastenerfor a length equal to l ? times the maximum width of the

member. Beyond this point, the pitch shall be increased gradually for a length equal to lu times the maximumwidth of the member until the maximum pitch is reached.

10.16.14 Net Section of Riveted or High-StrengthBolted Tension Members

10.16.14.1 The net section of a riveted or high-strength bolted tension member is the sum of the net sections of its component parts. The net section of a part is

the product of the thickness of the part multiplied by itsleast net width.

10.16.14.2 The net width for any chain of holes ex-tending progressively across the part shall be obtained bydeducting from the gross width the sum of the diametersof all the holes in the chain and adding, for each gagespace in the chain, the quantity:

where:

S = pitch of any two successive holes in the chain; g gage of the same holes.

The net section of the part is obtained from the chain thatgives the least net width.

10.16.14.3 For angles, the gross width shall be thesum of the widths of the legs less the thickness. The gagefor holes in opposite legs shall be the sum of gages fromback of angle less the thickness.

10.16.14.4 At a splice, the total stress in the memberbeing spliced is transferred by fasteners to the splicematerial.

10.16.14.5 When determining the unit stress on anyleast net width of either splice material or member being spliced, the amount of the stress previously transferredby fasteners adjacent to the section being investigated

shall be considered in determining the unit stress on thnet section.

10.16.14.6 The diameter of the hole shall be taken a? inch greater than the nominal diameter of the rivet ohigh-strength bolt, unless larger holes are permitted in accordance with Article 10.24.

10.17 BENTS AND TOWERS

10.17.1 General

Bents preferably shall be composed of two supportincolumns, and the bents usually shall be united in pairs tform towers. The design of members for bents and toweris governed by applicable articles.

10.17.2 Single Bents

Single bents shall have hinged ends or else shall be de-signed to resist bending.

10.17.3 Batter

Bents preferably shall have a sufficient spread at thbase to prevent uplift under the assumed lateral loadings

In general, the width of a bent at its base shall be not lesthan one-third of its height.

10.17.4 Bracing

10.17.4.1 Towers shall be braced, both transverseland longitudinally, with stiff members having eithewelded, highstrength bolted or riveted connections. Thsections of members of longitudinal bracing in each paneshall not be less than those of the members in corresponding panels of the transverse bracing.

10.17.4.2 The bracing of long columns shall be designed to fix the column about both axes at or near thsame point.

10.17.4.3 Horizontal diagonal bracing shall bplaced in all towers having more than two vertical panelsat alternate intermediate panel points.


22/86

272 HIGHWAY BRIDGES l 0.17.5

10.17.5 Bottom Struts

The bottom struts of towers shall be strong enough to slide the movable shoes with the structure unloaded, thecoefficient of friction being assumed at 0.25. Provision forexpansion of the tower bracing shall be wade in the col-umn bearings.

10.18 SPLICES

10.18.1 General

10.18.1.1 Design Strength

Splices may be wade by rivets, by high-strength bolts orby the use of welding. In general, splices whether in tension,compression, bending, or shear, shallbe designed inthe caseof the service load design or strength design methods for a capacity based on not less than the average of the required

design strength at the point of splice and the design strengthof the member at the saine point but, in any event, not less than 15fo of the design strength of the member, except as specified herein. Bolted splices in flexural members shallsatisfy the requirements of Article 10.18.2. Bolted splices in compression members shal! satisfy the requirements of Ar-ticle 10.18.3. Bolted splices in tension members shall sat-isfy the requirements of Article 10.18.4. Welded splicesshall satisfy the rcquirements of Aiticle 10.18.5. Where asection changes at a splice, the smaher section is to be usedio satisfy the above splice requirements.

10.18.1.2

Fillers

10.18.1.2.1

1 For lillers inch and thickef inbolted or riveted axially loaded connections, includinggirder flange splices, additional fasteners shall be requiredto distribute the total stress in the member uniformlyover the combined section of the membei and the filler.The filler shall either be extended beyond the splicematerial and secured by additional bolts, or as analternate to extending the filler, an equivalent numberof bolts may be included in the connection. Fillersinch and thicker need not be extended and developed

provided that the design shear strength of thefasteners, specified in Article 10.56.1.3.2 in the case ofthe strength design method and in Table l 0.32.3B in thecase of the service load design method, is reduced by thefollowing factor R:

A = sum of the area of the fillers on the top andbottom of the connected plate

A, = smaller of either the connectccl plate area orthe sum of the splice plate areas on the topand bottom of the connected plate

The dcsign slip force, specified in Article 10.57.3. l in the

case of the strength design methocl and in Article10.32.3.2. 1 in the case of the service load design method,for slip-critical connections shall not be adjusted for theeffect of the fillers. Fillers inch or more in thicknessshall consist of not more than two plates, unless specialpermission is gwen by the Engineer.

10.18.1.2.2 For bolted web splices with thick

ness differences of inch or less, no filler plates arerequired.

10.18.1.2.3 Fillers for welded splices shall conform

to the requirements of the ANSI/AASHTO/AWS DI.5Bridge Weldng Code.

10.18.1.3 Design Force for Flange Splice Plates

For a flange splice with inner and outer splice plates, the flange design force may be assumed to be dividedequally to the inner and outer plates and their connec-tions when the areas of the inner and outer plates do not differ by more than 109o. When the areas of the inner andoutei plates differ by morc than 109o, the design force ineach splice plate and its connection shall be determined

by multiplying the flange design forcc by the ratio of thearea of the splice plate under consideration to the totalarea of the inner and outer splice plates. For this case, theshear strength of the connection shall be checked for themaximum calculated splice plate force acting on a single shear plane. The slip resistance of high-strengthbolted connections for a flange splice with innerand outer splice plates shall always be checked for theflange design force divided equally to the two slipplanes.

10.18.1.4 Truss Chords and Columns

Splices in truss chords and columns shall be locatedas near to the panel points as practicable and usually on the side where the smaller stress occurs. The arrange-

R

where: y =

(10 - 4a) ment of plates, angles, or other splice elements shall besuch as to make proper provision for the stresses, bothaxial and bending, in the coinponent parts of the mem-bers spliced.


23/86

10.I 8.2 DIVISION IDESIGN 27

10.18.2 Flexural Members

10.18.2.1 General

10.18.2.1.1 In continuous spans, splices shall prefer-

ably be wade at or near points of dead-load contraflexure.

10.18.2.1.2

2 In both flange and web splices,there shall be not less than two rows of bolts on each sideof the joint.

10.18.2.1.3 Ovnsizeor slotted holes shall not be usedin either the member or the splice plates at bolted splices.

10.18.2.1.4

4 In both flange and web splices,high- strength bolted connections shall be proportionedto prevent slip during erection of the steel and duringthe cast- ing or placing of the deck.

10.18.2.1.5

In the case of the strength designmethod, the strength of compact sections at the point ofsplice shall not be taken greater than the moment capac-ity at first yield, computed by accounting for the holes in the tension flange as specified in Article 10.12.

10.18.2. I. 6 Flange and web splices in areas of stressreversal shall be checked for both positive and negativeflexure.

10.18.2.I. 7 Riveted and bolted flange angle splicesshall include two angles, one on each side of the flexuralmember.

10.18.2.2 Flange Splices

10.18.2.2.1 As a minimum, in the case of the strengthdesign method, the splice plates on the controlling flangeshall be proportioned for a design force, P,,,. The controlling flange shall be ta1en as the top or bottom flange forthe smaller section at the point of splice, whichever flangehas the maximum ratio of the elastic flexural stress at its reid-thickness due to the factored loads to its maximumstrength P u shall be taken equal to a design stress, Fq,,times the smaller effective flange area, A , on either side

of the splice. A is defined in Article 10.18.2 2 4 Ud F u isdefined as follows:

(10 - 4b)

where:

n = 1.0 except that a lower value equal Ct Mu M )may be used for flanges in compression at sec-tions where M,, is less than M,.

M, = maximum bending strength of the section in poitive or negative flexure at the point of splicewhichever causas the maximum compressivstress due to thc factored loads at the reid-thickness of the flangc under consideration

M, moment capacity at first yield for the section athe point of splice used to comuteM,,. For com

posite sections, M, shall be calculated in accodance with Article 111.50(c). For hybricl sectionM, shall be computed in accordance with Artic10.53.

= maximum elastic flexural sti css due to the factored loads at the miel-thiclness of the controling flange at the point of splice.

R = reduction factor for hybrid girders specified Article 10.53.J .2. R shall be taken equal to 1when f,, is less than or equilto F,p, where F,, equal to the specified minimum yield strength the web. For homogeneous girders, R shall a

ways be taken equal to l .G.Fu = specified minimum yield strength of the flange

As a minimum, the splice plates for the noncontrollinflange shall be proportioned for a design 1orce,P,,,. P,shall be taken equal to a design stress, F,,,,, times thsmaller effective flange area, A,, on either side of thsplice. F,,. is defined as follows:

where:

R,, = the absolute value of the ratio of Fq, to fq, for thcontrolling flange.

flexui al stress due to the factored loads at the reidthickness of the noncontrolling flange at thepoinof splice concurrent i h f u

In calculating f u f Muy M, and R, holes in the flangsubject to tension shall be accoiinted fer as specified in Aticle 10.12. For a flange splice with inner and outer splicplates, the flange design force shall be proportioned to thinnei and outer plates and their connections as specifiein Article 10. 18.1.3. The effective area, A,, of each splicplate shall be sufficient to prevent yielding of the splicplate under its calculated portion of the design force. A, oeach splice plate shall be taken as defined in Artic10.18.2.2.4. As a minimum, the connections for both thtop and bottom flange splices shall be proportioned to develop the design force in the flange through shear in thbolts and bearing at the bolt holes, as specifielin Artic10.5G. 1.3.2. Where filler plates are required, the requirements of Article 10.18.1.2.1 shall also be satisfied.


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274 HIGHWAY BRIDGES 10.18.2.2.2

10.18.2.2.2 As a minimum, in the case of the strengthdesign method, high-strength bolted connections for bothtop and bottom flange splices shall be proportioned to pre-vent slip at an overload ilesign force, P,,. For the flangeunder consideration, P, shall be computed as follows:

(10 -4d)

where:

f, maximum flexural stress due to D +

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AASHTO Standard Specifications 17th Edition