Problem #4:

GIVEN: Classroom portion of a 2-story school building in Portland, Oregon with interior

columns spaced 35' apart in two perpendicular directions. Interior columns are the

typical ones inside and not those closest to the outside of the building. Floor live

loading is as specified in OSSC Table 1607.1. Roof live loading is 20 psf for this

ordinary, flat roof per Table 1607.1.

FIND: Total floor live load + roof live load (kips) for a single, typical interior column at

(a) ground floor level, and (b) 2nd floor level. Consider live load reductions for both

floor and roof.

Draw both plan (looking down) and elevation (looking sideways) views of a portion of

the building so you can better understand the problem.

Reduce the floor live loads according to Section 1607.11.1 of the 2019 OSSC. This is

similar to the discussion in the Hibbeler text.

The Hibbeler text does not discuss the reduction of roof live loads, however they can

be reduced, but using different methods than for floors. Do reduce the roof loads and

use the roof load reductions described in OSSC Section 1607.13.2.1. Section

1607.13.1 indicates what to do if roof live loads are reduced to less than 20 psf and

members being designed are continuous. Assume here that the beams are not

continuous and are simply connected to the columns. Therefore, Section 1607.13.1 is

not applicable, but 1607.13.2.1 is applicable to this problem.


Be sure to write out all of the calculations (checks) that you need to satisfy the

provisions of the 2019 OSSC. This shows explicitly that you have considered all of the

requirements and have not missed any of them. These are often inequalities that are

specified in equation form or in words. Read the code carefully (every word) and don't

skip over anything. This is very important in using building codes in general. Many of

these checks are to see which equations are relevant to your situation.