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These are lecture notes from a Bridge Engineering course at the University of Anbar. The notes cover topics such as girder-slab analysis, transverse load distribution, and distribution factors for bending moment and shear. The notes also include information on effective flange width for interior and exterior beams, as well as properties of BT-72 girders and cast-in-place RC decks. The notes are likely intended for students studying civil engineering or a related field.
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Lecture 6 University Of A nbar Dr.Yousif A. Mansoor
University Of A nbar Dr.Yousif A. Mansoor Girder- Slab Analysis The principal function of the slab is to provide the roadway surface and to transmit the applied loads to the girders. This load path is illustrated in Figure below.
University Of A nbar Dr.Yousif A. Mansoor Transverse Section of Slab-Girder Bridge University Of A nbar Dr.Yousif A. Mansoor
AASHTO DF Requirements Cont. (Sect. 4. 6. 2. 2. 1 )
University Of A nbar Dr.Yousif A. Mansoor
Review AASHTO LRFD DF for P/S Bridges (k) xxxxxxxxxxxxxxxxxxxxx
Review AASHTO Review AASHTO DF (Sect. 4.6.2.2.1) Multiple presence factors not used. For fatigue design moments and shears divided by 1. 20 to eliminate multiple presence effect included in DF. Controlling moment or shear from a) HL- 93 + lane loading or b) tandem + lane loading multiplied by appropriate AASHTO DF to get design moment or shear in an individual girder. AASHTO DF can be used with other loadings (I.e., permit or rating vehicles) in design.
Multiple presences factors are incorporated into the above distribution factors (Sect.
Exterior girders shall not have less resistance than an interior girder (Sect.
DF for Bending Moment – two or more lanes loaded DF for Bending Moment – one lane loaded University Of A nbar Dr.Yousif A. Mansoor
-1.0 ≤ de ≤ 5.5, de = 1.5 ft Nb > 3, Nb = 6
University Of A nbar Dr.Yousif A. Mansoor
University Of A nbar Dr.Yousif A. Mansoor
-1.0 ≤ de ≤ 5.5, d e = 1.5 ft Nb > 3, Nb = 6
University Of A nbar Dr.Yousif A. Mansoor
University Of A nbar Dr.Yousif A. Mansoor
Special Analysis as per 4. 6. 2. 2. 2 d and Eq. C 4. 6. 2. 2. 2 d- 1 consider affects of diaphragms on DF of exterior girders. R = NL/Nb + [Xext ( Σe)/Σx^2 )] R = reaction on exterior beam (lanes/beam) NL = number of loaded lanes (2) Nb = number of beams (6) Xext = horizontal distance from the center of gravity of the pattern of girders to the exterior girder (22.5 ft) e = eccentricity of a design truck or a design lane load from the center of gravity of the pattern of girders (ft) (19 ft & 9 ft) x = horizontal distance from the center of gravity of the pattern of girders to each girder (ft) (4.5 ft, 13.5 ft, 22.5 ft)
22.5’ 2 ’^6 ’^4 ’^6 ’^6 ’ University Of A nbar Dr.Yousif A. Mansoor
R = NL/Nb + [Xext (Σe)/Σx 2 )] R = [2/6] + 22. (19+9)/2(4. 2 +13. 2 +22. 2 )) R = 0.333 + 22.5 (28)/1418) = 0.778 lanes/beam University Of A nbar Dr.Yousif A. Mansoor
University Of A nbar Dr.Yousif A. Mansoor
University Of A nbar Dr.Yousif A. Mansoor
Ac = 767 in^2 I = 545,894 in^4 yb = 36.60” Wt. = 150 pcf Top flange width = 42” Web width = 6” f’c = 6,500 psi & f’ci = 5,800 psi Ec = 4,888 ksi & Eci = 4617 ksi Remember Ec = 33,000 w1.5^ √f ’c (Sect. 5.4.2.4) University Of A nbar Dr.Yousif A. Mansoor
