Steel Structures - Plate Girders

1. The web of plate girder is designed for
(a) load
(b) bending moment
(c) shear force
(d) transverse load

2. The depth of plate girder for long span is usually
(a) 1/6 of span
(b) 1/7 of span
(c) 1/8 of span
(d) 1/12 of span

3. Economical depth of plate girder, with cover plates not curtailed, is given by d = k\sqrt {\frac{M}{{{\sigma _{bt}}.t}}}  , where k is
(a) 1.0
(b) 1.1
(c) 1.2
(d) 1.21

4. In above question, if cover plates are curtailed then value of k is
(a) 1.0
(b) 1.1
(c) 1.20
(d) 1.21

5. An steel welded plate girder is subjected to a maximum bending moment of 150 tm. If the maximum permissible bending stress is 1650 kg/cm², then the most economical depth of the girder will be
(a) 60 cm
(b) 80 cm
(c) 100 cm
(d) 120 cm (IES 1994)

Hint: {d_e} = 5{\left( {M/{\sigma _{bc}}} \right)^{1/3}}

6. Average shear stress in the web ({\tau _{va,cal}}) is
(a) \frac{V}{{{d_w}x{t_w}}}
(b) \frac{{{V^2}}}{{{d_w}x{t_w}}}
(c) \frac{{{V^{1/2}}}}{{{d_w}x{t_w}}}
(d) none of these
where V is maximum shear force on the girder, {d_w} is depth of web plate, {t_w} is thickness of web.

7. In above question value of average shear stress for unstiffened webs will be
(a) 0.33{f_y}
(b) 0.40{f_y}
(c) 0.45{f_y}
(d) 0.50{f_y}

8. The minimum thickness of the web, when the web plate is exposed to weather but accessible for cleaning and repairing, is
(a) 4 mm
(b) 6 mm
(c) 8 mm
(d) 10 mm

9. In above question if web plate is exposed to weather and not accessible to repairs etc. then minimum web plate thickness is
(a) 4 mm
(b) 6 mm
(c) 8 mm
(d) 10 mm

10. The flexural buckling strength of web plate of depth “d” and thickness “t” of a plate girder is proportional to
(a) d/t
(b) t/d
(c) (d/t)²
(d) (t/d)² (IES 1992)

Answers

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

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