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RISA WebinarRISA Webinar
Lateral Loads in RISALateral Loads in RISA
Presenter:Presenter: Deborah Brisbin, P.E.Deborah Brisbin, P.E.
RISA 3D 9.1
RISAFloor 5.1RISAFloor 5.1(Buildings Design)
RISA PROGRAMSRISA PROGRAMS
Types of Lateral Loads
• Wind Loads
• Seismic Loads
• Notional Loads
Diaphragms
L d C bi tiLoad Combinations
OVERVIEWOVERVIEW
Image Courtesy of International Code Council Image Courtesy of ASCE
REFERENCED CODESREFERENCED CODES
Automated Wind loading in RISA 3D
• ASCE7 6.5.12.2.1 Main Wind Force Resisting Systems (MWFRS)Rigid Enclosed Buildings of All Heights
Wind LoadsWind Loads
Base Elevation
Wind LoadsWind Loads
DiaphragmWIND
WALL
W
Diaphragm
Foundation
WIND LOAD PATH ILLUSTRATEDWIND LOAD PATH ILLUSTRATED
Foundation
Roof Wind Loads
per ASCE7 Figure 6 6
Load Categories created:Load Categories created:
WLX, WLZ
WLX+R, WLX RWLZ+R, WLZ R
Image Courtesy of ASCE
Wind LoadsWind Loads
age Cou tesy o SC
Automated Seismic loading in RISA 3D
ASCE7 12.8 Equivalent Lateral Force calculated forBuilding Structuresg
Seismic LoadsSeismic Loads
Seismic Weight in RISAFloor
Automatically calculates Self Weight:Gravity Items, Decks, Lateral Items
Dyn Mass = Superimposed Dead Loads
Seismic LoadsSeismic Loads
Seismic Weight in RISA 3D
Select the LC from the drop down list
Seismic LoadsSeismic Loads
Diaphragm
DiaphragmyShear
Story
Diaphragm
Foundation
SEISMIC LOAD PATH ILLUSTRATEDSEISMIC LOAD PATH ILLUSTRATED
Foundation
Notional Loads
Definition L t l l d th t li d t h f i l lDefinition: Lateral loads that are applied at each framing level…
to account for the effects of geometric imperfections, inelasticity
or both.
AISC Appendix 7 Direct Analysis Method
ASCE7 2010 Required for all structures (ASCE7 1.4.3)
Notional LoadsNotional Loads
Let’s look at an example of Wind, Earthquake, NotionalLoads:Loads:
Automated LoadsAutomated Loads
Earthquake & Wind Loads without Diaphragms
• Calculate the loads outside of RISA
• Apply the wind loadsApply the wind loads
Point Loads
Distributed Line loads
dArea Loads
Lateral LoadsLateral Loads
Area Loading for Wind Walls
Di t ib tiDistribution:
• One Way (Ribbed Siding)
• Two Way (Isotropic Siding)
• Open Structure (No Siding)
Direction:
• Always Perpendicular to the member local axis (“Perp”)
Lateral LoadsLateral Loads
RISA 3D & RISAFloor automates Lateral Loads
R i Di hRequires a Diaphragm
Flexible or Rigid Diaphragm?
What is the stiffness of your diaphragm?What is the stiffness of your diaphragm?
How does it distribute the loads?How does it distribute the loads?
Lateral LoadsLateral Loads
DiaphragmWalls
hear
WSh
Wind/Seismic Uniform Load
DIAPHRAGM EXAMPLEDIAPHRAGM EXAMPLE
W/3
W/3
W/3
RIGID DIAPHRAGMRIGID DIAPHRAGM
4 4
W/4
W/2
W/4
FLEXIBLE DIAPHRAGMFLEXIBLE DIAPHRAGM
W 0 0W
0.4W
2WSTIFF=1.0
=0.5
STIFF=1.0
0.4W
0.2S
STIFF= S
RIGID DIAPHRAGMRIGID DIAPHRAGM
4 4LLEC
TOR
W/4
/2
W/4CO
L
W/
FLEXIBLE DIAPHRAGMFLEXIBLE DIAPHRAGM
Seismic Load Combinations Options:
• Reversible• Reversible
• Redundancy Factor, r
• Ev = 0.2 SDS*DL
• Include Non Orthogonal
• Overstrength Options
Load CombinationsLoad Combinations
Wind Load Combinations
Load CombinationsLoad Combinations
Additional ResourcesAdditional ResourcesRISA 3D Help File and Reference Manual
www.risanews.com
support@risa [email protected]
User’s Guides available at www.risa.com
Presenter:Presenter: Deborah Brisbin, P.E.Deborah Brisbin, P.E.
Questions?Questions?
Please let us know if you have questions.
W ill i i i d i hWe will answer as many questions as time permits during thewebinar.
Once the webinar is closed, we will post all Q&A’s, thepowerpoint slides and the models used today to our website:www risa comwww.risa.com
For further information, contact us at: [email protected]
Thank you for Attending!Thank you for Attending!