CALCS PROC001
WEB PATCH LOADING

NOTATION

ssymbol
tfthick, flange
twthick, web
Bfwidth, flange
ddepth, web
aspacing, interstiffener
Wwidth, patch force
lambdaslenderness parameter
K22factor, web strength, bs5400pt3fig22(a), curve 1or2
ffstress, direct, flange
Pforce, patch
Fy'stress, yield, modified
Kw
be
j
Kaspect
P1
P2

APPLICATION

Web subject to in-plane compressive stress over a local part of one edge between stiffeners. While this detail is not good design practice, it is quite common, particularly at the interface of structural assemblies.

OUTPUT

Patch load based on web allowable compressive stress. Fcr will be less than for an equivalent force distributed across the plate full width between stiffeners.

SEE ALSO

other porcs & progs

THEORY

BS5400

GUIDANCE

In the present formulation, it is necessary to pick a stability constant from fig22 in the bs - will represent the curve as a ploynomial in a future revision.

INPUT FORMAT

Nm=:Nk=:Fr=3.5:tf=:tw=:Bf=:d=:a=:w=:P=:ff=:Fr=3.55:PROC001

EXAMPLE

Input

LET Nm=1:Nk=1:tf=1.4:tw=.8:Bf=5.9:d=41.7:a=45.3:w=17:K22=.78:P=18.4:ff=1.4:Fr=3.55:PROC001

Output

PROC001: WEB; PATCH LOADING: Rev Date: 180796
FY= Fy(Nm)*(1-(ff/Fy(Nm))^2)= 2.94
Kw= (3.4+2.2*d/a)*(.4+w/(2*a))= 3.188
be= 1.9*SQR(w*d/Kw)= 28.33
lambda= (be/tw)*SQR(FY/Fr)= 32.23
Kc= (24/lambda)^.75= 0.8016
j= SQR(Bf*tf^2/(2*Kc*tw))= 3.003
Kaspect= (tf/tw)/(1.2*SQR((w+2*j)/Bf))= 0.7385
P1= (Bf*tf^2*Fy(Nm)/j+Kc*tw*FY*(2*j+w))*Kcr(Nk)= 38.09
P2= (Kc*tw*FY*w)*Kcr(Nk)= 21.47
k= (tf/tw)/(1.2*SQR((w+2*j)/Bf))= 0.7385
UF= P/P1= 0.483
UF= P/P2= 0.8568
END001