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Field Splices
� The main restriction on manufactured and fabricated length of steel sections is transportation.
� The contractor usually orders the required steel from the factory to his workshop where it is cut to desired lengths, drilled, tapered and welded according to workshop drawings. The fabricated steel is again transported to the site for erection and assembling.
� Hot rolled sections such as Ι-L-C and PLs (small width) are usually fabricated in lengths ranging from 12 to 14 m. It is likely to transfer such lengths from plant to workshop and then to site.
� Large widths PLs (b≥1m) are fabricated in approximately 7 m lengths, in order to prevent and instability problem in it during transportation.
� Splices are fabricated either at workshop or at field.
� Workshop splices are used to connect large-width plates (≤ 7m), which are part of a built-up section less than 14m length. Such splices are used in webs of main girders.
� Field splices are used to assemble members having lengths exceeding 12 m.
� In bridges and frames, splices in main girders and rafters are better to be symmetrical about the C.L. of the MG and to be located between the XGs or beams.
� In multistory buildings, splices in the columns are made away from the beam-column connection (1m above or below), and don’t splice adjacent columns at the same elevation, instead used staggered splices.
Example Design the F.S. for the shown built-up MG assuming:
Max. moment @ splice = 70 tm
Max. shear @ splice = 38 ton
Use St 37, H.T.Bolts M24 (Qs= 6.29 t)
tm7471100*57.3
601525*1.4M
cm 601525)(I
cm 303 A
cap
4grossx
2 gross
.==
=
=
� AASHTO specifications require that splices be designed for the average of the calculated maximum moment @ splice and the allowable capacity of the member, but not less than 75% of the allowable capacity, i.e.:
=
=+
tm 110.8147.7*0.75
tm 81082
147.770 of greater the is Msplice
.
ton 156070
8110*83V
load, to related are moment & shear since
tons 4158424011051(V
tm 110.8M
splice
cap
splice
..
.).*.**.()
==
==
=
tm
tmt
web
� Web Splice
Assume the # of bolts and the configuration as shown below.
30cm
110cm
2.3cm
1.5cm
100cm [email protected]
cm
FS
7cm
e=8cm 18M24
tm 35.54.830.65
100
81560
601525
518110
e*VI
I*MMMM
12110
splicegross
websplice ecc.webbolts
3
=+=
+=
+=+=
*.*.
*.
bolts the on shear causes that moment torsional a is Mbolts
4
22222
yxp
cm 516090
5329465342351122
II(I
.
].**[)]..(*[
)
=
++++=
+=bolts
ton 3.3418
60.15
n
VP Vto Due
ton 0.773.5*16090.5
100*35.5x*
I
M(P
ton 10.1546*16090.5
100*35.5y*
I
M(P
splice'vsplice
maxp
bv
maxp
bh
===⇒
===
===
max
max
)
)
OK tons 58122P tons 9510
3437701510R
s
22max
..
)..(.
=<=
++=
The web splice plates should be 100cmx30cmxt
.....OKt/cm 960t/cm 300100)*(1*2
60.15f
.....OKt/cm 1.4t/cm 1.0650*166667
100*35.5f
cm 166,66712
100*1*2)(I
cm 1tsay 9.522
tt Let
22v
22b
43
PLx
mmmmw
...
.
<==
<==
=
=
=→=+=
