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Frequently
Asked Questions
What does
LatPro IBC do?
- LatPro IBC allows
the user to enter site information, building dimension and weight
inputs to simultaneously calculate wind and seismic loading for
light framed structures up to three stories.
The majority of the
building information is entered on a diaphragm by diaphragm basis.
The diaphragm loads are then assigned to gridlines by allocating
a portion of the diaphragm forces to specific gridlines. This
is done with a tributary width allocation, which is entered as
a percentage of the diaphragm between two gridlines, and is assigned
to a gridline with easy to use, pull-down menus.
Once all of the diaphragm
forces have been assigned to gridlines, the user can easily specify
the shear walls, shear wall chord (edge) members, holdown connectors
and posts that are required to resist the gridline shear forces.
When defining the shear wall chord members, connectors, and posts
supporting shear walls above, the program has inputs for live
and dead loads in order to size the member based on the code defined
allowable stress design load combinations.
LatPro IBC also allows
the user to easily calculate component and cladding design pressures
by entering the effective area and selecting from the appropriate
type, zone and location for wall and roof members.
What analysis methods
does LatPro IBC use?
- LatPro IBC utilizes
the Equivalent Lateral Force method for seismic analysis and the
Analytical Method for All Heights for wind analysis.
Do I have to redraw the
structure in LatPro to analyze it?
- No, however, when
laying out gridlines to define diaphragm boundaries and shear
wall lines, the LatPro produces a graphical representation. This
is to visually help the user with data entry and avoid mistakes.
In a future version this graphic will be included in the printed
report and will include a shear wall, edge member and connector
key.
Can I run LatPro without
Excel?
- No, LatPro requires
Excel. All data entry is done in simple-to-understand windows,
NOT in complicated spreadsheets. Excel runs in the background
and is never apparent to the user.
How
does LatPro model stacked shear walls?
- LatPro allows
the user to model stacked shear walls without having to enter
the coordinates of the shear wall. When designing a shear wall,
LatPro gives the user the ability to "link" it to a
shear wall above. Linking transfers the uplift and compression
to a shear wall below.
How
do I enter data into LatPro? Do I have redraw the structure in LatPro
to analyze it?
- No, LatPro
does not require the user to redraw the structure to model it.
LatPro allows the engineer to work directly on a set of prints
to layout diaphragms, grids, shear walls, connectors, and transfer
shear wall uplift and compression forces to the foundation. This
method simplifies the analysis, reduces errors, and does not require
a complicated, time-consuming modeling process. By working directly
on a set of prints for the project, the engineer can review any
unusual conditions including out-of-plane or in-plane offsets,
unusual dead load tributary loading, unusual wall heights, lack
of support below shear walls, etc. This method reduces errors
inherent in creating another drawing to create a model for lateral
analysis, which may not include unusual or critical information
that is shown on the design drawings. A CAD program is not necessary
to utilize LatPro.
Can
LatPro analyze Rigid Diaphragms?
- Yes, LatPro
1.7 RDA contains a rigid diaphragm analysis module that includes
torsional analysis. The RDA version contains all of the functionality
of the standard version plus RDA. The RDA is an optional feature.
If the user is satisfied with the results of a tributary area
allocation (flexible diaphragm analysis), then it is not necessary
to perform the RDA.
Is
there a sample of LatPro's output so that I can compare it against
the Lateral Analysis program I currently use?
- Yes, the
following links contain complete lateral analysis reports of example
projects from our different versions of LatPro. (Sample Report
requires Adobe Acrobat Reader. Free Download at: www.adobe.com.)
Sample Reports:
Is
LatPro IBC compliant?
- Yes, LatPro IBC 2003
and 2006 are IBC complient. LatPro 1.7 is compliant
with the 1997 UBC. LatPro is also 2007 California Building Code
(CBC) Compliant.
Can LatPro analyze
drag struts?
- Yes LatPro
version 1.7 analyzes drag struts for diaphragms.
Can LatPro analyze
building separation?
- Not yet because
building separation analysis is only required if the building
department requests it. A future version of LatPro will include
building separation.
What if I want to use
a different type of shear wall that is not in the default shear
wall schedule?
- There is a User-Defined
menu that allows the user to add site-built and pre-built shear
walls to the existing default schedule. These walls can be entered
right away or anytime while sizing a shear wall within a project.
Also shear wall holdowns may also be added to the existing database
within the same User-Defined menu.
How do I model a shear
wall that straddles two diaphragms?
- LatPro IBC allows
the user to assign the forces from multiple diaphragms to a gridline.
The shear walls are then designed to resist the resulting gridline
force. For shear walls that straddle two diaphragms, tributary
area above the shear wall can be defined with different live and
dead loads for the two different diaphragms. The live and dead
load inputs are used with the ASD load combinations to size the
shear wall chord/edge member and the holdown connector.
How does LatPro model
stacked shear walls?
- LatPro allows the
user to easily model stacked shear walls. When designing a shear
wall, LatPro gives the user the ability to "link" it
to a shear wall above. Linking transfers the uplift and compression
forces to a shear wall below.
Why do some of the items
in the story components window display items in red?
- This is to alert the
user that the entry is insufficient and needs to be corrected;
either the shear demand on the wall is greater than the capacity
or the deflection is too large for seismic drift limits.
After entering all the
building information and building design data, why are the acting
wind and acting shear wall values shown on the shear wall tab zero
on every grid line?
- On the Tributary Width
input window, if the check box for "Transfer directly into
concrete foundation wall" is checked, that specific tributary
width allocation force will not be include in the gridline force
to be resisted by shear walls. So, if this box is checked for
all allocations, the shear walls will have zero acting wind and
seismic force to resist.
The purpose of the
check box is to allow the user to model situations where floor
or roof diaphragms attach directly to a concrete foundation/retaining
walls, without a wood cripple wall in between. In these situations
the user is able to transfer the diaphragm forces directly into
the concrete foundation without having to resist the forces with
specified shear walls.
What does "Projected
Roof Area" mean?
- The projected roof
area is area that is seen on an elevation drawing. It is the same
as the total roof area (oriented towards the specified N, S, E,
or W direction) multiplied by the Sine of the roof slope.
What do I do if a diaphragm
ends on an interior wall?
- In this situation
the diaphragm edge that ends on an interior wall may have zero
projected roof area and zero exterior wall length inputs.
Does LatPro IBC include
perforated shear walls?
- No, the current version
does not include perforated shear wall design BUT we do plan to
include it in the near future (without force transfer around openings).
Users can always perform a perforated shear wall analysis and
enter nailing/ shear wall requirements in the User-Defined site-built
shear wall entry. This will need to be done on a wall by wall
basis.
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