5.6
Weld size Pr 2 w≥ 2 BcFw
(5-16)
where K
4b Fyp p
(5-17)
a distance from the bolt centerline to the edge of the fitting, in. db a ae (5-18) 2 ae = a ≤ 1.25b
(5-19)
db t 2
(5-20)
b b
n number of bolts
K Pr n tp
1
2
1
(5-21)
dh p
(5-22)
The available tensile strength of a bolt is checked using AISC Manual Table 7-2 as shown below. LRFD c = φ = 0.90 Pu Rn Tr rn
ASD 1 where 1.67 Rn Pa rn Tr
c
From AISC Specification Section J2.4, the available weld strength based on the limit state of shear rupture is: LRFD Fwc w Fw where Fw = 0.60 FEXX w 0.75
ASD Fw Fwc = w where Fw = 0.60 FEXX
END PLATE ON RECTANGULAR HSS WITH BOLTS ON FOUR SIDES
End-plate connections with bolts on all four sides are more common than with bolts on just two sides. The limit states for the end-plate connection bolted on four sides as shown in Figure 5-8 are: 1. Yielding of the end plate 2. Tensile strength of the bolts, including prying action 3. Strength of the weld connecting the end plate to the HSS Due to the complexity of the analysis accounting for prying action and the position of yield lines in the plate, it is difficult to directly determine nominal capacities according to the AISC Specification provisions. However, equations are presented to determine the thickness of the plate, tp, the number of bolts, n, and the weld size, w. The design procedure is based on the AISC design procedure for hanger connections. For the following design criteria to be valid, the centers of the bolt holes should not be positioned beyond the corners of the HSS. The details of the design procedure are presented by Willibald et al. (2003). In the design procedures, the flange-plate material strength is taken as Fyp, as validated experimentally for HSS end-plate connections by Willibald et al. (2003), rather than the higher capacity Fup as in the AISC Manual (pages 9-10 to 9-12). The following simplified equation from AISC Manual Part 9, gives the minimum plate thickness, tmin, required for no prying action to occur: LRFD t p t min
ASD
4.44 Pu n b pFyp
(5-23a) t p t min
6.66 Pa n b pFyp
(5-23b)
where p length of end plate tributary to each bolt, in. flange height/width divided by the number of bolts to the flange height/width on one side, in. (see Figure 5-8)
p
w 2.00
p
a b
p'
p' tp
Bolt hole diameter, dh
Fig. 5-8. Rectangular end plate with bolts on four sides. AISC DESIGN GUIDE 24 / HOLLOW STRUCTURAL SECTION CONNECTIONS / 53