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EZ-Shear Wall for ®ETABS v1.1
INSTALLATION
Download the installation folder and run the EXE file, which will install the
program in your PC
To uninstall use windows program uninstaller via control panel
DISCLAIMER
THE USER ACCEPTS AND UNDERSTANDS THAT NO WARRANTY IS
EXPRESSED OR IMPLIED BY THE DEVELOPERS OR THE DISTRIBUTORS ON
THE ACCURACY OR THE RELIABILITY OF THIS PRODUCT.
THE USER MUST EXPLICITLY UNDERSTAND THE BASIC
ASSUMPTIONS OF THE SOFTWARE
®ETABS is a trademark of Computers and Structures Inc.
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Program Graphic User Interface
(GUI) and Use
Algorithm Notes:
The program is mainly tailored for practical design of shear walls, in which one
direction is larger than the other and detailing of reinforcement is done in a practical
and economical manner
Results from ®ETABS can be imported and wall can be analyzed and designed inside
EZ-Shear wall. Walls can be designed in a fraction of the time that it will take using
®ETABS general pier section procedure
The wall is planar and one constant thickness
Design is based on ACI 318 -08,11,14
Full iteration diagrams are created in the two principal axis of the walls at 0 and 90
degrees from X axis
This assumes wall takes little or no forces in the weak axis, as is the common
assumption in design practice
The program designs the wall as per ACI 318-08/11 Section 14.4
The program assumes that the user is entering ultimate forces including any
amplifications due to slenderness effects; however for most walls slenderness
effects can be neglected as per ACI section 10.10.1
Rebar material for wall is assumed to be ASTM grade 60 rebar (fy=60ksi)
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1.0 Input Fields
The program initializes with default values for each input field that can then be changed
by the user
Note: Make sure to click enter after each data entry, the value should be updated
below data field
Length of wall: Length of wall in inches, this should always be the longer side
Thickness of wall: Thickness of wall in inches
Rebar cover: Distance from edge of wall to center of rebar in inches, the program
assumes cover is the same around wall
Number of edge bars: Number of layers of edge bars, each layer has two bars, in figure
below the edge bar quantity should be 3. The program assumes symmetric
reinforcement at each end of wall (i.e. same number of edge bars).
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Spacing of edge bars: Spacing between edge bars in inches, program will not allow to
enter a value larger than half the wall length
Web rebar percentage: This value needs to be entered as percentage of reinforcement
to gross concrete area. This is a common and practical way to specify uniform
reinforcement as per ACI 318 14.3.2 minimum reinforcement for ordinary walls should
be 0.12% for bars #5 or less and 0.15% for larger bars. As per section 21.9.2.1 for special
walls minimum vertical reinforcement should be 0.25% (walls for buildings in SDC D or
above). The program fits web reinforcement between edge bars as is common in wall
detailing, and also assumes bar spacing of 12”, Note that change web reinforcement
spacing would have negligible effects in the overall results.
Edge bar size: Rebar size based on ASTM-US customary rebar sets from #2 to #11
f’c: Design compressive concrete strength in ksi
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File Path: This si the complete path where the XML file exoported from ETABS is located.
If the fiel path is incorrect or it doenst exist the program will dipaly a warning
Pier label: This is the pier label as defined on your ETABS model that you want to check,
if the pier label is incorrect or doesn’t exist the program will display a warning
Story: This is the story label of the prier that the sure wants to check/design, if the story
name is incorrect or doesn’t exist the program will display a warning
1.1 Import data from ETABS
In ®ETABS there are 3 ways of designing shear walls:
The simplified Tension/compression method: This is an extremely simplified 2 dimensional
method, not recognized by ACI code as a method suitable for designing shear walls
The Uniform reinforcement method: This method is compatible with ACI, however the entire
wall reinforcement is changed, and hence resulting in an uneconomical and inefficient design,
furthermore interaction diagram is not available to help the user make design decisions, or
check results
The general pier section method: This method allows the user to modify individual re-bars in the
wall, and come up with an efficient and economical design; however, it takes an extremely
large amount of time to modify rebar layout and check the wall every time. Also interaction
diagram is provided but design loads are not plotted, making check of results difficult
In Ez-ShearWall, uniform rebar and edge rebar can be modified rapidly, an adequate design can
be performed in a matter of seconds. Plotting of interaction diagram with design forces allows
the engineer to make decisions on where to add reinforcement resulting in an economical and
efficient design.
After you run the ETABS model, results including pier forces will be available. Once this data is
transferred to the program, the analysis forces information at top and bottom for all piers and
load cases/combinations at all stories will be available and the user can choose any pier and
story in the model to perform design/checks. The transfer of pier data to the program can be
done in 4 easy steps:
Step 1.- Use File>export>ETABS tables to XML
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Step 2.- Choose the Analysis>Results>Wall results>pier forces table, click OK
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Step 3.- Chose the corresponding units, which must be ft, and kip for length and force
respectively, temperature is not relevant
Step 4.- Chose the name and location where to save the XML file
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Once saved this file contains the data that will be read by the program, simply right click on
the file name, use copy path and paste(Ctrl+V) on the File path input field in the program
Additional Options:
If the user is interested in only certain load cases / combinations they can be chosen at step
2 above by right clicking on tables
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2.0 Results and Design
The program provides the following results:
No. of Combos: Number of combos and cases imported from ETABS
Rho(%)= percentage of steel in the section As/(b*d)
Max. Combo stress= The program will check maximum stress fiber as per
section 21.9.6.3 ACI 318-08/11, and report the combo/case that governs (i.e.
highest stress value)
Stress Max.(ksi)=From all load combination/combos the highest extreme
fiber maximum compressive stress in strong direction (ksi), this results can be
used to check Boundary elements requirements for Special Reinforced Concrete
walls as per section 21.9.6.3 ACI 318-08/11
Max. Combo D/C= The program will check maximum D/C ratio , and report
the combo/case that governs (i.e. highest D/C ratio)
D/C= From all load combination/combos the highest demand capacity ratio, is
determined as Mu/Mn, a value larger than 1 indicates wall is inadequate to
resist design forces
Max. Combo Neutral= The combo/case which produces the largest Neutral
axis length value.
N.A(c.max)(in)= Neutral axis of section in the strong direction(in) , for given
Pu , this information can be used to check Boundary elements requirements for
Special Reinforced Concrete walls as per section 21.9.6.2 ACI 318-08/11, and
detailing according to 21.9.6.5
Max. Shear Combo= The combo/case which produces the highest shear
demand to shear capacity ratio
Vu(kips) = The demand value for the combo that produces the highest shear
demand to shear capacity ratio Vu/phiVc
phiVc(kips)= The wall concrete shear capacity for the combo that produces
the highest shear demand to shear capacity ratio and is calculated as per section
11.9.5 of ACI 318-08/11 :
Min. of equations 11-27 and 11-28
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If the value of Abs(Mu/Vu)-Lw/2 is negative or zero, or if if Vu is zero then only
equation 11-27 is used
If any of the equations produces a negative value, which can occur due to wall
being in high tension, then conservatively zero is used as recommended by ACI
318
And phi= 0.75.
Av (in2/in)= The value is calculated as:
Where fys=fy, and phi =0.75.
Also, if Vu> 10*sqrt(f’c)*b*d, a “FAIL” value is reported as per ACI 318/08/11
section 11.9.3
The program enforces a minimum steel requirement of ρt, min = 0.0025 (ACI
11.9.9.2, 14.3.3(b), 21.9.2.1).
fy(ksi)= Rebar yield strength, 60ksi
f’c(ksi)= Input design compressive concrete strength in ksi
Pier Label= Name of pier to be analysis/designed
Story = Story name where pier to be analysis/designed is located
Results are also presented in the form of Iteration diagrams in the X and Y axis. Defined
Ultimate design forces and load combination/case names are also plotted in the
diagram.
Three curves plotted are:
=1, This is the curve without any strength factors
, This is the curve with all strength factors (varies) and where all reinforcement is
used in tension and compression
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+NoWebcomp, This curve assumes that only edge reinforcement has been
confined as per ACI 14.3.6 ; hence, web rebar can only be used in tension. This
produces a more economical and easier to detail and build wall.
The wall is considered capable of resisting the demand forces when they fall inside the
Curve , if detailed as per 14.3.6 (confined web reinforcement) and +Nowebcomp if
detailed assuming web reinforcement bars are only used in tension. Any point outside
this this curves will indicate wall fails and needs to be revised.
This is a trial and error procedure, but due to the ease of data entry an acceptable
design can be reached within a few minutes. The approach above also assume that
loads in weak axis are small enough to be considered negligible.
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3.0 Verification example
Verification Example 1
A model is created in ETABS with Dead, live and Seismic load patterns
The program automatically generates 6 load combinations if concrete code as per ACI
318-14 is chosen
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Check of the wall P1 at Story 1st is performed, a general wall design section
with #4@12 bars and 2 #10 bars at edges is defined, f’c=4ksi and fy=60ksi
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Interaction diagram for general section generated by ®ETABS along the long
and short side indicated below
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Pier results are exported to Ez-Sherwall , input screen and interaction
diagrams are indicated below:
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As it can be observed interaction diagram matches very well with the one
generated by ®ETABS
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Other program results are compared with the ones reported by ®ETABS:
ETABS EZ-Shear wall % difference Max. Stress 3.18ksi 3.18ksi 0%
D/C 0.95 0.91 4%
Neutral Axis 84.55in 94.14in 10% phiVc 72.6 72.6 0%**
Av 0.36 0.03 0%* *0.03x12=0.36in2/ft
** In ETABS When minimum shear reinforcement is required for all load
combinations, the program simply reports the one with the highest Vu, which is of
no practical use, in EZ-Shear wall the combination that produces highest shear
D/C ratio is the one reported, in this case Dwall5, if we enforce ®ETABS to design
only for this load combination by choosing this as the only design combo, then
results for shear design match.
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