RISA Webinar€¦ · LoadCategoriescreated:Load Categories created: WLX, WLZ WLX+R, WLX rR WLZ+R, WLZ rR Image Courtesy of ASCE Wind Loads ageCou tesyo SC. Automated Seismic loading

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!