1

2013/03/27Hoang Long

1. AASHTO

.

Qi is the force effects Rn is the nominal resistance. Rr is the factored resistance. 2. Limit States a. Service limit state: The service limit state shall be taken as restriction on stress, deformation, and crack width under regular service condition. b. Strength limit state: Strength limit state shall be taken to ensure that strength and stability, both local and global, are provided to resist the specified staticticaly significant load combination that a bridge is expected to experience in its design life. c. Extreme Event Limit States: The extreme event limit state shall be taken to ensure the structural of a bridge during a major earthquake or flood, or when collided by a vessel, vehicle, or ice flow, possibly under scoured conditions.d. Fatigue and Fracture limit state:3. Load, Combination Load and Load factor:a. Permanent load:

CR = force effects due to creepDD = downdrag force

DC = Dead load of structural components and non-structural attachments.DW = dead load of wearing surfaces and utilities.EH = horizontal earth pressure load

EL = miscellaneous locked-in force effects resulting from the construction progress, including jacking apart of cantilevers in segmental construction

ES = Earth surcharge load

EV = Vertical pressure from dead load of Earth fillPS = secondary forces from post-tensioningSH = force effects due to shrinkage.b. Transient Loads:

BS = vehicular braking force

CE = vehicular centrifugal force

CT = vehicular collision force

CV = Vessel collision force

EQ = Earthquake

FR = Friction Load

IC = Ice Load

IM = Vehicular dynamic load allowance

LL = Vehicular Live load

LS = live load surcharge

PL = pedestrian live load

SE = Force effect due to settlement

TG = Force effect due to temperature gradientTU = Force effect due to uniform temperature

WA = Water load and stream pressureWL = Wind on live load

WS = Wind load on structure

Table 3.4.1-1 Load Combinations and load factors

Table 3.4.1-2 : Load factors for permanent loads

P ( DD + DC + DW + CR + SH ) + 1.75 x ( LL + IM + CE + BR + PL + LS) + FR + Tu x TU + + SE

P ( DD + DC + DW + CR + SH ) + EQ x ( LL + IM + CE + BR + PL + LS) + FR + EQ

4. Steel Material

4.1 Structural Steel:

Modulus of Elasticity = 2x10^5 Mpa

Thermal Coefficient of expansion of all grades of structural steel = 11.7 x 10^(-6) mm/mm/ C.

4.2 Bolts, Nuts and Washer

4.2.1 Bolts: (6.4.3.1)

- Carbon steel bolts and studs, 414 Mpa Tensile Strength, ASTM A 307, Grade A or Grade B.

- Standard Specification for Structural Bolts, Steel, Heat-Treated, ASTM A 325

- The SS for Heat-Treated Steel Strutural Bolts, ASTM A490

Note:

ASTM A 325 Type 1 may be hot-dip galvanized in according with ASTM A153.

ASTM A 490 bolts shall not be galvanized.

- Anchor Bolts shall conform to one of the following:

+ ASTM A 307 Grade C

+ASTM F 1554

4.2.2 Nuts (6.4.3.2)

4.2.2.1 Nuts used with Structural Fasteners (6.4.3.2.1)ASTM A 325 Bolts => Nuts ASTM A 563 ( Grades DH, DH3, C, C3 and D)

ASTM A 490 bolts => Nuts ASTM A563 ( Grades DH and DH3)

4.2.2.2 Nuts used with anchor bolts (6.4.3.2.2)

ASTM F 1554 Bolts => Nuts ASTM A 563.

4.2.3 Weld Metal (6.4.5)AASHTO/AWS D1.5M/D1.5:2010 Table 4.1

Matching filler metal requirement for WPSs qualified in conformance with fillet Weld WPS Qualification.

4.2.4 Cast Steel (6.4.6)

4.2.4.1 Cast Steel and ductile Iron (6.4.6.1)

Cast steel shall conform to one of the following

+ ASTM A27/A27M, Grade 485-250, 240-450.+ASTM A 743/ A743M Grade CA15.

+Ductile iron castings: ASTM A 536, Grade 60-40-18(414-276 Mpa).

4.2.5 Stainless Steel: (6.4.7)

ASTM A 176, ASTM A240, ASTM A 276 or ASTM A666

5. 5.1 25Mpa

Where: Dp = (mm)u=

0.005+0.005+5.2 5.2.1

Where:Dp = internal diameter of pot (mm)Hu = lateral load from appliable strength and extreme event load combinations. (kN)u=maximum strength limit state design rotation angle (rad)Fy = Minimum yield strength of the weakest steel at the contact surface. (Mpa)5.2.2 The pot wall:

The minimum pot wall thickness, tw , shall satisfy:

Where:Dp = internal diameter of pot (mm)Fy = Minimum yield strength of the weakest steel at the contact surface. (Mpa)s = average compressive stress due to total load from applicable service load combinations.Hu = lateral load from appliable strength and extreme event load combinations. (kN)5.2.3 u=maximum strength limit state design rotation angle (rad)5.2.4 Height of pot:

The pot cavity depth, hp1 , may be determined as:

Where: hr = depth of elastomeric disc (mm)hw = height from top of rim to underside of piston. (mm)5.3 Piston:

5.3.1 Piston Rim:Pot bearings that transfer load through the piston shall satisfy:

hw = height from top of rim to underside of piston (mm)

Hu = lateral load from appliable strength and extreme event load combinations. (kN)Dp = internal diameter of pot (mm)Fy = Minimum yield strength of the weakest steel at the contact surface. (Mpa)5.3.2 Vertical Clearance: hp2

The vertical clearance between top of piston and top of pot wall, hp2, may be determined:

Where:u is the vertical deflection from strength load(mm)

Ro = radial distance from center of pot to object in question (e.g., pot wall, anchor bolt, etc.)u=maximum strength limit state design rotation angle (rad)5.3.3 Clearance between piston and pot wall:

The diameter of the piston rim shall be the inside diameter of the pot less a clearance, c. The clearance, c,shall be as small as possible in order to prevent escape of the elastomer but not less than 0.5mm. If the surface of the piston rim is cylindrical, the clearance shall satisfy:

Where:u=maximum strength limit state design rotation angle (rad)hw = height from top of rim to underside of piston (mm)

Dp = internal diameter of pot (mm)5.3.4 Brass Ring:

Cross Section: Rectangular

Three rectangular rings shall be used. Each ring shall be circular in plan but shall be cut at one point around its circumference. The faces of the cut shall be on a plane at 45 degrees to the vertical and to the tangent of the circumference. The rings shall be oriented so that the cuts on each of the three rings are equally spaced around the circumference of the pot. The width of each ring shall not be less than either 0.02 Dp or 6 mm and shall not exceed 19 mm. 19 mm tb 0.02 Dp (mm) and, 6.0 mm

The depth of each shall not be less than 0.2 times its width.hb 0.2 tb5.4 PTFE:

1 ksi = 6.9 Mpa

5.5 Stainless Steel: 14.7.2.3.2

The thickness of the stainless steel mating surface shall be at least 1.291 mm when the maximum dimension of the surface is less than or equal to 305 mm and at least 1.828 mm when the maximum dimension is larger than 305 mm.6. Resistance factor: ( 6.5.4.2 Resistance factor )

* For service and extreme event limit states, resistance factors shall be taken as 1.0, except for bolts.

* For the strength limit state, resistance factor shall be taken as follow:

For flexure f = 1.00

For shear v = 1.00

For axial compression, steel only c = 0.90

For axial compression, composite c = 0.90

For tension, fracture in net section u = 0.80

For tension, yielding in gross section y = 0.95

For bearing on pins in reamed, drilled or bored holes and on milled surfaces b = 1.00

For bolts bearing on material bb = 0.80

For shear connectors sc = 0.85

For A 325 and A 490 bolts in tension t = 0.80

For A 307 bolts in tension t = 0.80

For F 1554 bolts in tension t = 0.80

For A 307 bolts in shear s = 0.75

For F 1554 bolts in shear s = 0.75

For A 325 and A 490 bolts in shear s = 0.80

For block shear bs = 0.80

For shear, rupture in connection element vu = 0.80

For web crippling w = 0.80

For weld metal in complete penetration welds:

o shear on effective area e1 = 0.85

o tension or compression normal to effective area same as base metal

o tension or compression parallel to axis of the weld same as base metal

For weld metal in partial penetration welds:

o shear parallel to axis of weld e2 = 0.80

o tension or compression parallel to axis of weld

same as base metal

o compression normal to the effective area

same as base metal

o tension normal to the effective area e1 = 0.80

For weld metal in fillet welds:

o tension or compression parallel to axis of the weld same as base metal

o shear in throat of weld metal e2 = 0.80

For resistance during pile driving = 1.00

For axial resistance of piles in compression and subject to damage due to severe driving conditions where use of a pile tip is necessary:

o H-piles c = 0.50

o Pipe piles c = 0.60 For axial resistance of piles in compression under good driving conditions where use of a pile tip is not necessary:

o H-piles c = 0.60

o pipe piles c = 0.70 For combined axial and flexural resistance of undamaged piles:

o axial resistance for H-piles c = 0.70

o axial resistance for pipe piles c = 0.80

o flexural resistance f = 1.007. Section Verification:

a. Flexure:

The factored flexural resistance, Mr , shall be taken as:

where Mn = nominal flexural resistance.

f = resistance factor for flexure.

b. Shear

The factored shear resistance, Vr , shall be taken as:

where Vn = nominal shear resistance.

v = resistance factor for shear.

c. Tension 6.8.2.1

The factored tensile resistance, Pr, shall be taken as the lesser of the values given

where:

Pny = nominal tensile resistance for yielding in gross section ( kN)

Fy = specified minimum yield strength (Mpa)

Ag = gross cross-sectional area of the member (mm2)

Fu = tensile strength (Mpa)

An = net area of the member (mm2)Rp = reduction factor for holes taken equal to 0.90 for bolt holes punched full size and 1.0 for bolt holes drilled full size or subpunched and reamed to size

U = reduction factor to account for shear lag; 1.0 for components in which force effects are transmitted to all elements.y = resistance factor for yielding of tension membersu = resistance factor for fracture of tension membersd. Compression: 6.9.2.1

The factored resistance of components in compression, Pr , shall be taken as:

Pr = cPnWhere: Pn = nominal compressive resistance.

c = resistance factor for compression.

8. Verification of bolts:

a. Shear:

The nominal shear resistance a high-strength bolt (ASTM A325 or ASTM A490) or an ASTM A307 bolt (Grade A or B) at the strength limit state in joints whose length between extreme fasteners measured parallel to the line of action of the force is less than 1250mm shall be taken as:

Where threads are excluded from the shear plane:

Rn= 0.48AbFubNs

Where threads are included in the shear plane:

Rn= 0.38AbFubNsWhere:

Ab is the area of bolt corresponding to the nominal diameter (mm2)

Fub is the specified minimum tensile strength of the bolt. ( Mpa)

Ns is the number of shear plane per bolt.

The nominal shear resistance of a bolt in connections greater than 1250 mm in length shall be taken as 0.80 times the value given by above equation.

b. Bearing resistance at bolt holes:

The effective bearing area of a bolt shall be taken as its diameter multiplier by the thickness of the connected material on which it bears.

The nominal resistance of interior and end bolt holes at the strength limit state, Rn , shall be taken as:

* With Lc 2d : Rn = 2.4dtFu * With Lc < 2d : Rn = 1.2LctFuWhere: Lc is the clear distance between holes or between the hole and the end of the member in the direction of the applied bearing force

Fu is the tensile strength of the connected material

t is the thickness of the connected material

d is the nominal diameter of the bolt.c. Tension

The nominal tensile resistance of a bolt, Tn , independent of any initial force shall be taken as

Tn = 0.76AbFubWhere: Ab is the area of bolt corresponding to the nominal diameter (mm2)

Fub= specified minimum tensile strength of the bolt.

d. Shear resistance of anchor bolts:

The nominal shear resistance of an ASTM F 1554 or an ASTM A 307 Grade C anchor bolt at the strength limit state shall be taken as:

Rn=0.48AbFubNsWhere:

Ab is the area of the anchor bolt corresponding to the nominal diameter.

Fub is the specified minimum tensile strength of the anchor bolt

Ns is the number of shear planes per anchor bolt.

9. Bearing Resistance of Concrete 5.7.5In the absence of confinement reinforcement in the concrete supporting the bearing device, the factored bearing resistance shall be taken as:

in which

where:Pn is the nominal bearing resistance

A1 is the area under bearing device

m is the modification factor

A2 is a notional area where bearing laid on.

The modificatioin factor may be determined as:

where the supporting surface is wider on all sides than the loaded area.

10. Welding Verification:

(next page).

Complete Penetration Groove-WeldedPartial Penetration Groove-WeldedFillet-Welded Connection

CompressTensionShearCompressTensionShearCompressTensionShear

Parallel to the axis of weldingSame as factored resistance of base metalSame as factored resistance of base metalMin(Rr = 0.6e1Fexx; 60% of the factored resistance of base metal in tension)Same as factored resistance of base metalSame as factored resistance of base metalMin ( Rr=0.6e2Fexx ; Rr=0.58FyAvg)Same as factored resistance of base metalSame as factored resistance of base metal= Effective area Rr

= Aeff0.6e2Fexx

Normal to the effective areaSame as factored resistance of base metalSame as factored resistance of base metalSame as factored resistance of base metalMin ( Rr=0.6e1Fexx ; factored resistance of the base metal)Same as factored resistance of base metalSame as factored resistance of base metal

-THE END-

2

_1425040295.unknown

_1425040305.unknown

_1425040317.unknown

_1425040320.unknown

_1425040313.unknown

_1425040299.unknown

_1389088728.unknown

_1425040291.unknown

_1425040292.unknown

_1389090064.unknown

_1389090160.unknown

_1389088957.unknown

_1389012351.unknown

_1389012419.unknown

_1389012660.unknown

_1388299023.unknown