PROJECT: STEEL BUILDING DESIGN CASE STUDYSUBJECT: BASE PLATE DESIGN SHEET 106 of 131

INVESTIGATE THE BASE PLATE SIZE NEEDED

Design a base plate for column B-2.Refer to LRFD 3rd edition, p.14-21 example 14-2 for design ofaxially loaded base plates.Column B-2 loads at column base.

Pu = (kips) After Live Load Reduction, interior column design.

Shear Pu = (kips) Since column B-2 footing carries column and brace, there are 2 governing load cases, one foraxial load only and the second for combined axial load and shear. The shear would be transferredto the footing through either shear lugs (bars welded to the bottom of the base plate andtransferring shear to the concrete through bearing) or through anchor bolts. Since problem is to design a base plate, do not consider brace gusset plate, shear lugs, or anchor bolts.

AnalysisAssume concrete f"c = ksi

Column =d = bf = tw = tf =

A req'd = Pu =

OPTIMIZE BASE PLATE DIMENSIONS 0.95*d - 0.8*bf =

2

N =

Try - N (in)= B (in)=

CALCULATE REQUIRED BASE PLATE THICKNESSm = N-0.95*d =

2

n = B-0.8*bf =2

0.6*(0.85*f'c*A1*2) = kips

(4d*bf) Pu =

= > 1 If greater than 1 use 1

=4 Red font indicates user input

Assume Spread footing with (A2/A1)1/2 >

f(0.85 * f'c)*2

D =

(A req'd)1/2 + D = > bf? --->

fcPp =

C =

(d+bf)2 fcPp

l = 2*x0.5

1+(1-x)0.5

ln'= l*(d*bf)0.5

PROJECT: STEEL BUILDING DESIGN CASE STUDYSUBJECT: BASE PLATE DESIGN SHEET 107 of 131

INVESTIGATE THE BASE PLATE SIZE NEEDED, CONT.

l = m =n = MAX =

MAX =

t req'd = =

fy = 36 ksi

USE -

Red font indicates user input

max (m, n, ln') =

ln'=

l*(2*Pu/0.9*fy*B*N)0.5