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Building Design and Construction Handbook - Merritt - Ventech!

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7.94 SECTION SEVEN<br />

TABLE 7.26 <strong>Design</strong> Strength, ksi, for Bolts <strong>and</strong> Threaded Parts<br />

Fasteners<br />

a<br />

Shear in slip-critical connections Fv St<strong>and</strong>ardsize<br />

holes<br />

Oversized<br />

<strong>and</strong> shortslot<br />

holes<br />

Long-slot<br />

holes<br />

Transverse<br />

loads a<br />

Parallel<br />

load b<br />

<strong>Design</strong><br />

shear<br />

strength<br />

�P n<br />

Bearing-type connections<br />

Tension F t, including<br />

reduction for shear stress<br />

c<br />

ƒ v<br />

A307 bolts 16.2d,e 39 � 1.8ƒv � 30<br />

0.45 g Fu 0.73Fu � 1.8ƒv � 0.56 g,h Fu Threaded parts <strong>and</strong> A449<br />

bolts, threads ƒ not<br />

excluded from shear<br />

planes<br />

Threaded parts <strong>and</strong> A449<br />

bolts, threads excluded<br />

from shear planes ƒ<br />

A325 bolts, when threads<br />

are not excluded from<br />

shear planes<br />

A325 bolts, when threads<br />

are excluded from shear<br />

planes<br />

A490 bolts, when threads<br />

are not excluded from<br />

shear planes<br />

A490 bolts, when threads<br />

are excluded from shear<br />

planes<br />

0.60 g Fu 0.73Fu � 1.4ƒv � 0.56 g Fu 17.0 15.0 12.0 10.0 35.1 e 85 � 1.8ƒ v � 68<br />

17.0 15.0 12.0 10.0 46.8 e 85 � 1.4ƒ v � 68<br />

21.0 18.0 15.0 13.0 43.9 e 106 � 1.8ƒ v � 84<br />

21.0 18.0 15.0 13.0 58.5 e 106 � 1.4ƒ v � 84<br />

a Assumes clean mill scale <strong>and</strong> blast-cleaned surfaces with Class A coatings (slip coefficient 0.33). For special<br />

faying-surface conditions, see the Research Council on Structural Connections LRFD specification for structural joints.<br />

b Relative to the long axis of the slotted holes.<br />

c Static loading only. For fatigue conditions, see the AISC ASD ‘‘Specification for Structural Steel for <strong>Building</strong>s.’’<br />

d � � 0.60. Threads permitted in shear planes.<br />

e � � 0.65. Reduce design shear strength 20% for bolts in bearing-type splices of tension members if the fastener<br />

pattern has a length, parallel to the line of force, exceeding 50 in.<br />

ƒ Applicable to threaded parts meeting the requirements of ASTM A36, A242, A441, A529, A572, A588, A709, or<br />

A852 <strong>and</strong> to A449 bolts in bearing-type connections requiring bolt diameters exceeding 1 1 ⁄2 in.<br />

g Fu � minimum tensile strength, ksi, of bolts.<br />

h For the threaded portion of an upset rod, AbR n should be larger than A sF y, where A b is the area at the major thread<br />

diameter, A s is the nominal body area before upsetting, F y is the specified yield stress, ksi, <strong>and</strong> �R n is the design tensile<br />

strength, where � � 0.65.<br />

welds (Fig. 7.43) are commonly used for steel connections. Groove welds are classified<br />

as complete or partial penetration. (See Art. 7.3.5.)<br />

A significant characteristic of fillet-welded joints is that all forces, regardless of<br />

the direction in which they act, are resolved as shear on the effective throat of the<br />

weld. For instance, when joining elements such as a girder flange to a web, fillet<br />

welds are designed to carry the horizontal shear without regard to the tensile or<br />

compressive stresses in the elements.<br />

For computation of load capacity, the effective area of groove <strong>and</strong> fillet welds<br />

is the effective length times the effective throat thickness. The effective area for a<br />

plug or slot weld is the nominal cross-sectional area of the hole or slot in the plane<br />

of the faying surface.<br />

Except for fillet welds in holes or slots, the effective length of a fillet weld is<br />

the overall length of weld, including the return. For a groove weld, the effective<br />

length should be taken as the width of the part joined.

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