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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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