Chapter 9 - Column Base Plates.pdf

7/26/2019 Chapter 9 - Column Base Plates.pdf

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CE134

-

STRUCTURAL STEEL

DESIGN

J. Berlin P. Juanzon PhD



Column Base Plates

The main purpose of column base platesis to distribute a concentrated load to thesupporting material.

Column base plates are shop welded tothe bottom of a column to provide bearing forthe column usually and to help in transferring

the column axial loads to the concrete pier orfooting.







Column loads transmitted to masonry adconcrete foundations must meet the bearingpressure limitations as beam loads. The

required base plate area is:

=

Pu = Ultimate column loadFp = Allowable bearing stress of concrete



On sandstone and limestone Fp=2.76MPa

On brick in cement motar Fp=1.75MPa

On full area of a concrete

Support Fp= 0.35f’c

On less than the full area of

concrete support Fp =0.35f’c√ 2

1≤0.70f’c





The critical base plate cantilever length, l , is thelargest of the cantilever lengths , m, n , and n’

where



λ is conservatively taken as 1.0



Anchor rods are used to safely anchorcolumn bases and to prevent theoverturning of columns during erection.They are also used to resist the basemoments and the uplift forces that acolumn base may be subjected to due to

lateral wind or earthquake forces.





A W10 x 49 is used as a column and issupported by a concrete pier as shown. The topsurface of the pier is 18in x 18in. Find the minimumthickness of the base plate for a column dead load of

98kips and a live load of 145kips. The concretestrength is f’c = 3000psi, fy = 36ksi. Pu

18in

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Chapter 9 - Column Base Plates.pdf