Steel Structures - Plate Girders

1. Web crippling and web buckling may be prevented by
1. Increasing the length of the bearing plate
2. Increasing the thickness of web
3. Decreasing thickness of web
4. Decreasing length of bearing plate
Which is/are true
(a) 1, 2
(b) 1, 3
(c) 2, 3
(d) 2, 4 (IES 1992)

2. The thickness of web for unstiffened plate girder with clear distance d between the flanges shall not be less than
(a) d/200
(b) d/85
(c) d/100
(d) d/160 (IES 1996)

3. In a plate girder bridge the thickness of web is less than d’/200 where d’ is the unsupported depth of web. The web plate should be provided with
(a) vertical stiffness
(b) horizontal stiffness
(c) end stiffness
(d) both vertical and horizontal stiffness (IES 2001)

4. Flanges are designed for
(a) shear force
(b) maximum bending moment
(c) average bending moment
(d) axial load

5. The extension of flange cover plates, in a plate girder, from the stiffening edge is limited to 16T to account for
(a) local buckling
(b) buckling
(c) crippling
(d) shear

6. Consider following plate girder section.
The moment of resistance (M) of this section would be (assuming D \approx {d_w} \approx {d_f})
(a) {\sigma _{bc\,or\,bt}}D\left( {{A_f} + \frac{{{A_w}}}{3}} \right)
(b) {\sigma _{bc\,or\,bt}}D\left( {{A_f} + \frac{{{A_w}}}{4}} \right)
(c) {\sigma _{bc\,or\,bt}}D\left( {{A_f} + \frac{{{A_w}}}{6}} \right) 
(d) none of these
where {A_f} is gross area of one flange, df is distance of cg of flanges, {d_w} is depth of web plate, and {A_w} is gross area of web = {t_w}{\rm{ }}x{\rm{ }}{d_w}

7. According to IS: 800-1984, moment of resistance of a plate girder shown in above question is
(a) {\sigma _{bc\,or\,bt}}D({A_f} + {A_{we}})
(b) {\sigma _{bc\,or\,bt}}D\left( {{A_f} + {A_w}} \right)  
(c) 1.44{\sigma _{bc\,or\,bt}}D\left( {{A_f} + \frac{{{A_w}}}{6}} \right)  
(d) none of these
where {A_{we}} is effective web area in flange.

8. The effective flange area in tension of a plate girder is equal to
(a) {A_f}
(b) {A_f} + \frac{{{A_w}}}{2}  
(c) {A_f} + \frac{{{A_w}}}{8}
(d) {A_f} + \frac{{{A_w}}}{6} (IES 2002)

9. Intermediate vertical stiffeners are provided in plate girders to
(a) eliminate web buckling
(b) eliminate local buckling
(c) transfer concentrated loads
(d) prevent excessive deflection (IES 1995)

10. Maximum spacing between vertical stiffeners is
(a) d₁
(b) 1.5d₁
(c) 2.0 d₁
(d) 2.5d₁
where d₁ is clear distance between flange angles.

Answers

    1. (a)    2. (b)    3. (a)    4. (b)    5. (a)
    6. (c)    7. (a)    8. (c)    9. (a)    10. (b)

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