WIND LOADING FOR FOUNDATION DESIGN 1

[arrass]

Typical types of column reactions I receive from most metal building suppliers are absolutely baffling! Can anyone shed light on the basic column reactions from building manufacturers such as LWIND2_R2E, F1PAT_LL_1, WIND_R1, WIND_R2, lWIND1_L23 represent? Are they referring to Fig 6-9 (ASCE7)? Fig 6-10? Could they be a throw back to UBC? Believe it or not, I have contacted the metal building suppliers to try to understand their tables and even they can't explain it! They often tell me to just use the greatest values, but not knowing is unsettling to me. I like to know that I know. Thanks

 

[JedClampett]

I'm sure they're just different load combinations that PEMB supplies are allowed to use from the Low Rise Wind Criteria (Method 2), Figures 6-9, 6-10. They plug the basic wind speed in and the building attributes and the computer spits out the load combinations. Probably one combination controls 95% of the time.
If you're working with Metal Building Calculations, get used to not knowing. I'm sure they're adequate, but trying to prove it without the software is impossible. The best you can do is to run some cases using ASCE 7 and see if they're in the ballpark (they get 15 kips, you get 20 kips, it's OK; they get 15 kips, you get 150 kips, probably should call them).

 

[arrass]

I have been in touch with Dean T. Jorgenson, P.E., President of the Metal Building Software, Inc.
His company produces a software package that many of the PEMB manufacturers use to design and model the structures. He is sending me some commentary to further explain some of these load categories that, hopefully, will assist in relating the categories to the ASCE 7 Method 2 Basic Load Cases. I will follow up with my results. I invited him to join Eng-Tips since his knowledge and experience would greatly benefit all of us. He mentioned a new design manual that MBMA has in the works that should further help our understanding...due to come out early next year.

G.G.
Dodd & Grayson Engineering

 

[arrass]

Below are some descriptive load categories encountered in PEMB Software per Metal Building Software, Inc. Thanks to Dean T. Jorgenson for his help!

BASIC REACTION REPORT
Reactions are represented according to the type of load for each column location. The load type is represented with a short description or abbreviation. The descriptions are defined below.
DL = Dead

CL = Collateral

LL = Live

SL = Snow

Drift = Snow Drift

Slide = Sliding Snow

WL1 = Wind 1 Left [with positive internal pressure, +GCpi]

WR1 = Wind 1 Right [with positive internal pressure, +GCpi]

WL2 = Wind 2 Left [with negative internal pressure, -GCpi]

WR2 = Wind 2 Right [with negative internal pressure, -GCpi]

LnW1 = Longitudinal Wind, case 1

LnW2 = Longitudinal Wind, case 2

WP = Wind Pressure

WS = Wind Suction

SeisL = Seismic Left

SeisR = Seismic Right

LnSeis = Longitudinal Seismic

Temp = Temperature change

======================================================================
LnW1_L2E = Longitudinal Wind, case 1, Wind Left Edge Zone 2E

LnW1_R2E = Longitudinal Wind, case 1, Wind Right Edge Zone 2E

LnW2_L3E = Longitudinal Wind, case 2, Wind Left Edge Zone 3E

LnW2_R3E = Longitudinal Wind, case 2, Wind Right Edge Zone 3E

E#PAT_LL * = Endwall Pattern Live

E#PAT_SL * = Endwall Pattern Snow

E# - Endwall number
1 - Left endwall
2 - Right endwall
* - Auxiliary Load Id

F#PAT_LL * = Rigid Frame Pattern Live

F#PAT_SL * = Rigid Frame Pattern Snow

F# - Rigid Frame Id
* - Auxiliary Load Id
E#UNB_SL_L = Endwall Unbalanced Snow Left

E#UNB_SL_R = Endwall Unbalanced Snow Right

F#UNB_SL_L = Rigid Frame Unbalanced Snow Left

F#UNB_SL_R = Rigid Frame Unbalanced Snow Right


F#CRANEA* = Crane loading, single crane

F# - Frame number
A* - Auxiliary Load Id
F#CRNAM $ CRN - Crane loading

F#CRNA2 $ A2 - Two largest cranes in any aisle

F#CRNAM $$ AM - Simple maximum size in one aisle

F#CRNA $$ BM - Largest crane in each aisle for two adj. aisle

F#CRNBM $ C2 - Two largest crane in any aisle plus one crane in

F#CRNC2 $ any non-adjacent aisle. Also single crane at

F#CRNBM $ C2 location and double crane at other location

F#CRN B $$ $,$$ - Id associated with crane combinations

F#CRN C $$



G.G.
Dodd & Grayson Engineering

 

[JAE]

The biggest problem we have with this is that the building manufacturers provide you only combined loads many times. We would prefer to have the individual load cases provided to allow us to combine per the applicable code.