12’

6’

6’

Brace

CE311 FALL 2018 Lesson 11: Column Design Aids

“I came here to chew bubblegum and kick ass. And I’m all out of bubblegum” – your exam attitude

LESSON 11: COMPRESSION MEMBERS IV: COLUMN DESIGN AIDSWednesday, September 19, 2018

LESSON OBJECTIVES 1. Select a standard column shape for adequate compressive strength using the ASD or LRFD method by using the

AISC Part 4 Column Tables.2. Determine the Pn or Pn/ for a standard column shape by using the AISC Part 4 Column Tables.3. State the limitations of the AISC Part 4 Column Tables.4. Identify the preferred material specifications for various steel structural shapes using Tables 2-4 through 2-6 in AISC

(reading, only. Not covered in class).

EXAM Q & A SESSION: TONIGHT, 8PM, ROOM 327.EXAM 1: THURSDAY, 9/20/18, 7PM TO 9:30PM, ROOM 200 .

REFERENCE – All AISC Part 4 Tables and AISC Tables 2-4 to 2-6READING – Segui Textbook

Section 4.5, 4.6 – Tables and Design. Students who have this book will benefit quite a bit from all of the examples in these sections.

HOMEWORK (Due Friday)UNLESS NOTED OTHERWISE, ALWAYS USE THE “PREFERRED MATERIAL SPECIFICATION” FOR THE GIVEN SHAPE (Tables 2-4 to 2-6 in AISC).

1. Select the lightest wide-flange (W) column shape for the application, shown. Dead load axial compression: 50 kipsLive load axial compression: 300 kipsSnow load axial compression: 100 kipsWind load axial compression: 5 kips

Use:A. ASD to find the lightest selectionB. LRFD to find the lightest selection

Given:

2. Use ASD to select the lightest square or rect. HSS (“hollow structural shape”) shapes for the column at grid locations B1 and B2. It is quite reasonable for the lightest shape at B1 to be a rectangular shape, rather than a square shape. If a rectangular shape is chosen, specify the orientation of the shape.Given:

All of the connections in the single-story building shown are simple pins and the foundation is pinned. All columns: HSS sectionsYou may ignore the self-weight of the columns, themselves (negligible)The roof acts as a structural diaphragm1

1 Reminder: floor and roof diaphragms are extremely important. Without a roof system that is physically attached to the beams so that the roof acts as a rigid body, this building would be highly unstable; without a roof diaphragm, the system of pin-ended beams and girders has a DOI that is much less than Zero. The roof diaphragm “locks in” all points on the roof; thus, every column is considered to be braced at its top. Without a diaphragm, only columns A1 and A4 would be considered

24’

24’

24’

24’

24’

24’

20’

3D View

CE311 FALL 2018 Lesson 11: Column Design Aids

Loads:Roof Dead Load: 20 psf. This includes the appropriate allowance for all roof beams, the roof decking, and the actual rubber roofing material (i.e., 20psf includes all of the roof dead load)Snow Load: 80 psf (location is Nome, Alaska)Roof Live Load: 20 psfRain Load: 20 psf

Dimensions:Story Height: 20 ftAll bays are 24 ft

braced and every other column would have infinite K (i.e., the building would fall down and you would get sued).