Connection of flange plate with web

1
Chapter 8

• Connection of flange plate with web

2
7.1 Introduction The web is machined and is in
close contact with flange therefore, the
vertical loads are directly transmitted to the
web direct bearing. The bearing stress on the web
should not exceed 0.75 Fy (Clause 2.6.6, p. 22).
The connection of flange plate to web is done by
intermittent welding. If we have a very short
piece of a girder length (a) having two moments
M1M2 and nearly the same shearing force Q,
taking the moment about point m
3
M1- M2 Q?a 0 M2- M1 Q?a M1 F1
?h M2 F2 ?h ? F2 ?h - F1 ?h Q?a ?
4
Since F2 is higher than F1, there is tendency for
flange plate to slide along the web and this
tendency must be resisted by weld between web and
flange plate. ? F2 ?h - F1 ?h change in flange
stress
?
If the thickness of the weld S, the weld is
continuous and the allowable weld stress Fw,
5
Fw 0.2 Fu (Clause 5.6.3.2, p. 84)     For one
side weld,
6
For one side intermediate weld
For two sides intermediate weld,
7
5.6.3.3 Maximum effective length of fillet weld
(Not for plate girder) l eff 70 Size For
l gt l eff use reduction factor ? ? 1.2 (0.2
L) / (70 S) 5.6.3.3 One side fillet weld for any
plate thickness is allowed
8
(No Transcript)
9

• Intermittent fillet weld
  L? ? 0.75 b or 0.75 b1
• Tension
• L1 or L2 ? 16 t or 16 t1 or 200 mm
• Compression
• L1 or L2 ? 12 t or 12 t1 or 200 mm

10
-          The minimum size of fillet welds is 4
mm for building and 6 mm for bridges. -         
The maximum size of fillet weld should not exceed
the thickness of the thinner plate to be
welded. The minimum size of fillet weld depend on
the thickness of the thicker plate-
11
-   - There are no limitations for the length of
fillet weld for flange to web in weld built up
plate girder. - Single side fillet welds may be
utilized only for static loads