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Autodesk
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Robot Structural Analysis
Professional
VERIFICATION MANUAL
FOR INDIAN CODES
March 2014
Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
INTRODUCTION ..............................................................................................................................................................................1
STEEL ..............................................................................................................................................................................................2
1. IS 800:2007 - GENERAL CONSTRUCTION IN STEEL (THIRD REVISION) ............................................................................3
GENERAL REMARKS ..................................................................................................................................................................5
VERIFICATION EXAMPLE 1 - DESIGN OF MEMBERS FOR COMPRESSION ....................................................................................10
VERIFICATION EXAMPLE 2 - COMBINED COMPRESSION AND BENDING ABOUT BOTH AXES (LATERAL-TORSIONAL BUCKLING) ........18
CONCRETE ...................................................................................................................................................................................27
1. IS 456:2000 – RC BEAMS .........................................................................................................................................................28
VERIFICATION EXAMPLE 1 - DIMENSIONING OF SIMPLY SUPPORTED BEAM ...............................................................................29
VERIFICATION EXAMPLE 2 - DETERMINATION OF CAPACITY OF A BEAM ....................................................................................32
LITERATURE .............................................................................................................................................................................33
2. IS 456:2000 – RC COLUMNS ...................................................................................................................................................34
VERIFICATION EXAMPLE 1 - UNIAXIALLY ECCENTRICALLY LOADED BRACED RECTANGULAR COLUMN .........................................35
VERIFICATION EXAMPLE 2 - COLUMN SUBJECTED TO AXIAL LOAD AND BIAXIAL BENDING ...........................................................38
LITERATURE .............................................................................................................................................................................41
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
INTRODUCTION
This verification manual contains numerical examples for elements of steel structures prepared and
originally calculated by Autodesk Robot Structural Analysis Professional version 2013. The
comparison of results is still valid for the next versions.
All examples have been taken from handbooks that include benchmark tests covering fundamental
types of behaviour encountered in structural analysis. Benchmark results (signed as “Handbook”) are
recalled, and compared with results of Autodesk Robot Structural Analysis Professional (signed further
as “Robot”).
Each example contains the following parts:
- Title of the problem
- Specification of the problem
- Robot solution of the problem
- Outputs with calculation results and calculation notes
- Comparison between Robot results and exact solution
- Conclusions.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
STEEL
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
1. IS 800:2007 - General
Construction in Steel
(third revision)
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
IMPLEMENTED CHAPTERS of IS 800: 2007 (third revision)
List of Indian Standard General Construction in Steel – Code of Practice chapters, implemented to
Autodesk RSA program:
1. Mechanical properties of structural steel (Table 1)
2. Classification of cross-sections - § 3.7 and Table 2
3. Partial Safety Factor for Loads f ( Table 4)
4. Partial Safety Factor for Materials M ( Table 5)
for Limit State Design
5. Design of tension members - § 6
6. Design of compression members - § 7
7. Design of members subjected to bending
 Laterally supported beam - § 8.2.1
 Laterally unsupported beams - § 8.2.2
 Effective length for simply supported beams – Table 15
8. Shear - § 8.4
9. Combined axial force and bending moment - § 9.3
10. Limit State of serviceability - § 5.6 and Table 6
11. Working Stress Design § 11
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
GENERAL REMARKS
A.
Job Preferences
If you make first step in RSA program  specify your job preferences in JOB PREFERENCES dialog
box (click Menu/ Tools/ Job Preferences). Default JOB PREFERENCES dialog box opens:
You can define a new type of Job Preferences to make it easier for future.
First of all, make selection of documents and parameters appropriate for India from tabs of the list view
in JOB PREFERENCES dialog box.
For example to choose code, first click Design codes tab from left list view, then select code from
Steel/Aluminum structures combo-box or press More codes button which opens Configuration of Code
List:
Put India code into the right list of the box, and then set it as the current code. Press OK.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
To choose code combination first click Loads tab from left list view in JOB PREFERENCES dialog
box,
Then select code from Code combinations combo-box or press More codes to open the Configuration
of Code List.
Pick Load combinations from combo box. The new list view appears:
Put IS: 875 (Part5) code into the right list of the box, then set it as the current code. Press OK.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
After the job preferences decisions are set, press Save Job Preferences icon in JOB PREFERENCES
dialog box. It opens SAVE JOB PREFERENCES dialog box.
Type a new name e.g. “ India Limit State” and save it. The new name appears in the combo-box.
Press OK button.
You can check load combination regulations by pressing right button next to Code combinations
combo-box in Loads tab JOB PREFERENCES dialog box. It opens proper Editor of code combination
regulations dialog box.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
B.
Calculation method
Indian code IS 800: 2007 gives two verification options: Limit State Design and Working Stress
Design. In RSA program you must always manually specify:
1. calculation method
2. load code combination -> appropriate for calculation method
ad.1 calculation method
Calculation method (Limit State or Working Stress) can be chosen on Steel /Aluminum Design layout.
Press the Configuration button in CALCULATIONS dialog box.
Here you can choose calculation method
(not regulation of load combination).
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
ad.2a load code combination – basic approach
To specify load code combination (Limit State or Working Stress) appropriate for calculation method,
click Menu/ Tools/ Job Preferences. JOB PREFERENCES dialog box opens.
Select earlier prepared job preferences (as defined in Section A.) by clicking its name from combobox. In following dialog box India Limit State job preferences should be selected.
By pressing OK button, you accept chosen job preferences for a current task.
ad.2b load code combination - alternative (tricky-easy) approach
Start in Loads layout. Here, you can prepare load combination for both calculation methods for further
using (for member verification). Create manually Limit State Design “LS” load combination and
Working Stress Design “WSD” load combination in Load Types dialog box.
In this case, you can use in verification
appropriate load combination corresponding to
the calculation method.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
VERIFICATION EXAMPLE 1 Design of members for compression
Example taken from: DESIGNERS’ GUIDE to EN 1993-1-1 Eurocode 3:
Design of steel structures, general rules and rules for buildings
written by L. Gardner, D. A. Nethercot, 2005
TITLE:
Example 6.7 – Buckling resistance of a compression member
SPECIFICATION:
A circular hollow section CHS member used as an internal column in a building. The column has
pinned boundary conditions at each end and the inter-storey height is 4 m. The critical combination of
actions results in a design axial force of 1630 kN. Assess the suitability of hot-rolled 244,5x10 CHS in
grade S275 steel (fy = 275 MPa) for this application, using Limit State Design.
SOLUTION:
Specify appropriate parameters in JOB PREFERENCES dialog box (click Menu/Tools/Job
Preferences). Then, choose calculation method Limit State Design in CONFIGURATION dialog box
(press Configuration button in CALCULATIONS dialog box).
In DEFINITIONS dialog box you can define a new type of member in agreement with structure data
It can be set in Member type combo-box. Pre-defined type of member “Column” may be initially
opened.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
For chosen member type, press the Parameters button on Members tab, which opens
MEMBER DEFINITION – PARAMETERS dialog box.
Type a new name in the Member type editable field, e.g. “column 1”. Change parameters to meet
initial data requirements of the structure. In the particular compression case press More button which
opens MEMBER DEFINITION – ADDITIONAL PARAMETERS dialog box:
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
Switch on Hot-rolled pipes. Click OK.
In DEFINITIONS dialog box save the newly-created member type, here “column 1”:
Number of the member must be
assigned to appropriate name
of Member type.
(It is very important when you verify
different member types.)
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
In the CALCULATIONS dialog box set:
-> Verification option; here Member Verification,
-> Loads cases ;
here for no 1 for Limit State Design
-> Limit state ; here only Ultimate Limit state will be analyzed, so switch off Limit stat –Serviceability.
Now, start calculations by pressing Calculations button.
MEMBER VERIFICATION dialog box with most significant results data will appear on screen.
Pressing the line with results for the member 1 opens the RESULTS dialog box with detailed results
for the analyzed member. The view of the RESULTS windows are presented below.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
Simplified results tab
Detailed results tab
Pressing the Calc.Note button in “RESULTS –Code” dialog box opens the printout note for
the analyzed member. You can obtain Simplified results printout or Detailed results printout.
It depends on which tab is active.
The printout note view of Simplified results is presented below.
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RESULTS for Limit State Design method:
a) In the first step CHS 244,5x10 section was considered. The results are presented below.
STEEL DESIGN
---------------------------------------------------------------------------------------------------------------------------------------CODE: IS800: 2007 Indian Standard - General Construction in Steel - Code of Practice (Third Revision)
ANALYSIS TYPE: Member Verification
---------------------------------------------------------------------------------------------------------------------------------------CODE GROUP:
MEMBER: 1 POINT: 1
COORDINATE: x = 0.00 L = 0.00 m
---------------------------------------------------------------------------------------------------------------------------------------LOADS:
Governing Load Case: 1 STA1
---------------------------------------------------------------------------------------------------------------------------------------MATERIAL:
S275 fy = 275.0 MPa fu = 430.0 MPa
E = 210000.0 MPa
gM0=1.100
gM1=1.250
---------------------------------------------------------------------------------------------------------------------------------------SECTION PARAMETERS: CHS 244.5x10
D=24.4 cm
Avy=46.919 cm2
Avz=46.919 cm2
Ag=73.700 cm2
B=24.4 cm
Iy=5073.000 cm4
Iz=5073.000 cm4
It=10150.000 cm4
tw=1.0 cm
Zey=414.969 cm3
Zez=414.969 cm3
tf=1.0 cm
Zpy=550.236 cm3
Zpz=550.236 cm3
---------------------------------------------------------------------------------------------------------------------------------------INTERNAL FORCES AND CAPACITIES:
N = 1630.0 kN
Nd = 1842.5 kN
Pd = 1669.6 kN
Class of section = 1
---------------------------------------------------------------------------------------------------------------------------------------LATERAL BUCKLING PARAMETERS:
---------------------------------------------------------------------------------------------------------------------------------------BUCKLING PARAMETERS:
About Y axis:
About Z axis:
Ly = 4.00 m
Xy = 0.906
Lz = 4.00 m
Xz = 0.906
ky*Ly = 4.00 m Pdy = 1669.6 kN kz*Lz = 4.00 m Pdz = 1669.6 kN
ky*Ly/ry = 48.213
kz*Lz/rz = 48.213
Lamy = 0.555
Lamz = 0.555
---------------------------------------------------------------------------------------------------------------------------------------VERIFICATION FORMULAS:
Section strength check:
N/Nd = 0.885 < 1.000 (9.3.1.1) OK!
Global stability check of member:
ky*Ly/ry = 48.213 < (k*L/r),max = 200.000
kz*Lz/rz = 48.213 < (k*L/r),max = 200.000 STABLE
P/min(Pdy,Pdz) = 0.976 < 1.000 (7.1.2) OK!
---------------------------------------------------------------------------------------------------------------------------------------Section OK !!!
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
b) From economical reason try to check the lighter CHS section.
Being still in RESULTS- CODE dialog box, type CHS 273x8 in the editable field below drawing
of section and press ENTER. Calculations (and results) are refreshed instantly.
The results for new selected section are presented below.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
COMPARISON:
Resistance, interaction expression
For CHS 244,5x10:
RSA
IS 800: 2007
Limit State Design
ϪM0 = 1,1
Handbook
EC3: 2005
ϪM0 = 1,0
1. Cross-section compression resistance
N/ Nd = 1630/ 1842,5
= 0,885
NEd/ Nc,Rd = 1630/2026,8
= 0,804
2. Member buckling resistance
in compression
N/ Pd = 1630/ 1669,6
= 0,976
NEd/ Nb,Rd = 1630/1836,5
= 0,888
CONCLUSIONS:
Underlined values results from handbook (EC3 example) are different then values calculated by RSA
program for Indian code IS 800 because partial safety factors M0 are different in both codes.
If the design resistances from handbook are divided by partial safety factor from IS 800 code
( M0 = 1,1 ):
1. NEd/ (Nc,Rd :1,1) = 1630 / (2026,8 : 1,1 ) = 1630 / 1842,5 = 0,8846 = 0,885
2. NEd/ (Nb,Rd :1,1) = 1630 / (1836,5 : 1,1 ) = 1630 / 1669,5 = 0,9763 = 0,976
.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
VERIFICATION EXAMPLE 2
- combined compression and bending about both axes
(lateral-torsional buckling)
Example taken from: DESIGNERS’ GUIDE to EN 1993-1-1 Eurocode 3:
Design of steel structures, general rules and rules for buildings
written by L. Gardner, D. A. Nethercot, 2005
TITLE:
Example 6.10 -- Member resistance under combined bi-axial bending and axial compression
SPECIFICATION:
Verify if H 305x305x240 section in grade S275 has sufficient available strength to support the axial
forces and moments listed below for Limit State Design:
section A-A, x=0
NEd = 3440 kN
My,Ed = 420 kNm
Mz,Ed = 0
section B-B, x=L
NEd = 3440 kN
My,Ed = 420 kNm
Mz,Ed = 110 kNm
Material Properties:
S275 fy = 275 MPa , E= 210GPa
The member is to be designed as a ground floor column in a multi-storey building.
The column of length 4,2 m is fixed in-plane (for buckling about major axis bending) and pinned out-ofplane, with diagonal bracing provided in both directions ( ky =0,8 ; kz=1,0).
The column is laterally and torsionally unrestrained.
SOLUTION:
Specify appropriate parameters in JOB PREFERENCES dialog box (click Menu/Tools/Job
Preferences). Then, choose calculation method Limit State Design in CONFIGURATION dialog box (
press Configuration button in CALCULATIONS dialog box ).
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
In DEFINITIONS dialog box you can define a new type of member in agreement with structure data
It can be set in Member type combo-box. Pre-defined member type “Column” may be initially opened.
For chosen member type, press the Parameters button on Members tab, which opens
MEMBER DEFINITION – PARAMETERS dialog box.
Type a new name in the Member type editable field, e.g. “My Mz Nc”. Change parameters to meet
initial data requirements of the structure. In this particular combined compression and bending about
both axes case set the following parameters:
1. for Y buckling define appropriate value of ky by manually entering 0,8 value in editable field
or by pressing ky icon which opens BUCKLING DIAGRAM dialog box:
press third icon “0.8” and
switch on Non-sway structure radio button.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
2. for lateral-buckling define:
 lateral buckling type  by pressing Lat. buckling type icon which opens LATERAL BUCKLING
TYPE dialog box
select first icon and press OK.
 lateral buckling length coefficient  by pressing Upper flange or Lower flange button. It opens
EFFECTIVE LENGTH FOR BEAMS, BETWEEN SUPPORTS dialog box:
Change conditions at supports.
Click the first option for unrestrained and free to rotate on plane, press OK.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
3. for additional code parameters  press More… button which opens
MEMBER DEFINITION – ADDITIONAL PARAMETERS dialog box:
3.1. Click Load type My icon. It opens LOAD TYPE dialog box;
Select first option, press OK. Do the same
for Load type Mz icon.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
3.2. Switch on Not weakened in Parameters of a weakened section. Click OK.
3.3. Type for gM0= 1,0 and for gM1= 1,0 ; in this particular case it will be helped in results
comparison to EC3 ;
After changes dialog box
looks like:
Now, you can SAVE changes of
the newly-created member type
named e.g. “ My Mz Nc “ in
MEMBER DEFINITIONPARAMETERS dialog box.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
In DEFINITIONS dialog box
number of the member must be
assigned to appropriate name
of Member type.
(very important when you verify
different member types.)
You must press SAVE button to attribute the member type to number of member, here
“My Mz Nc” to no 1.
In the CALCULATIONS dialog box set:
-> Verification option; here Member Verification,
-> Loads cases ;
here for no 1 for Limit State Design
-> Limit state ; here only Ultimate Limit state will be analyzed, so switch off Limit stat –Serviceability.
Check CONFIGURATION dialog box.
Now, start verificiations by pressing Calculations button.
MEMBER VERIFICATION dialog box with most significant results data will appear on screen.
Pressing the line with results for the member 1 opens the RESULTS dialog box with detailed results
for the analyzed member. The view of the RESULTS windows are presented below.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
Simplified results tab
Detailed results tab
Pressing the Calc.Note button in “RESULTS –Code” dialog box opens the printout note for
the analyzed member. You can obtain Simplified results printout or Detailed results printout.
It depends on which tab is active.
The printout note view of Simplified results is presented below.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
RESULTS for Limit State Design method:
STEEL DESIGN
---------------------------------------------------------------------------------------------------------------------------------------CODE: IS800: 2007 Indian Standard-General Construction in Steel-Code of Practice (Third Revision)
ANALYSIS TYPE: Member Verification
---------------------------------------------------------------------------------------------------------------------------------------CODE GROUP:
MEMBER: 1 column
POINT:
COORDINATE: x = 1.00 L = 4.20 m
---------------------------------------------------------------------------------------------------------------------------------------LOADS:
Governing Load Case:
1 Limit State Design
---------------------------------------------------------------------------------------------------------------------------------------MATERIAL:
S 275
fy = 275.00 MPa
fu = 430.00 MPa
E = 210000.00 MPa
gM0=1.000
gM1=1.000
---------------------------------------------------------------------------------------------------------------------------------------SECTION PARAMETERS: UC 305x305x240
D=35.26 cm
Avy=239.70 cm2
Avz=81.10 cm2
Ag=306.00 cm2
B=31.79 cm
Iy=64200.00 cm4
Iz=20310.00 cm4
It=1271.00 cm4
tw=2.30 cm
Zey=3641.52 cm3
Zez=1277.76 cm3
tf=3.77 cm
Zpy=4243.00 cm3
Zpz=1945.00 cm3
---------------------------------------------------------------------------------------------------------------------------------------INTERNAL FORCES AND CAPACITIES:
N = 3440.0 kN
My = -420.0 kN*m
Mz = 110.0 kN*m
Vy = -26.2 kN
Nd = 8415.0 kN
Mdy = 1166.8 kN*m
Mdz = 534.9 kN*m
Vdy = 3805.7 kN
Pd = 6639.7 kN
Mndy = 773.7 kN*m
Mndz = 502.7 kN*m
Vz = -200.0 kN
Vdz = 1287.6 kN
Class of section = 1
Mymax = 420.0 kN*m
Mzmax = 110.0 kN*m
---------------------------------------------------------------------------------------------------------------------------------------LATERAL BUCKLING PARAMETERS:
L,LT,low=5.04 m
Mcr = 11963.5 kN*m
fbd = 268.02 MPa
X,LT = 0.975
fcr,b = 2819.59 MPa
Lam,LT = 0.312
Mbdy = 1137.2 kN*m
KLT = 0.892
---------------------------------------------------------------------------------------------------------------------------------------BUCKLING PARAMETERS:
About Y axis:
About Z axis:
Ly = 4.20 m
Xy = 0.976
Lz = 4.20 m
Xz = 0.789
ky*Ly = 3.36 m
Pdy = 8213.3 kN
kz*Lz = 4.20 m
Pdz = 6639.7 kN
ky*Ly/ry = 23.197
Ky = 1.028
kz*Lz/rz = 51.553
Kz = 1.204
Lamy = 0.267
Cmy = 0.400
Lamz = 0.594
Cmz = 0.600
---------------------------------------------------------------------------------------------------------------------------------------VERIFICATION FORMULAS:
Section strength check:
N/Nd = 0.409 < 1.000 (9.3.1.1) OK!
My/Mdy = 0.360 < 1.000 (9.3.1.1) OK!
Mz/Mdz = 0.206 < 1.000 (9.3.1.1) OK!
(My/Mndy)^ 2.000 + (Mz/Mndz)^2.044 = 0.340 < 1.000 (9.3.1.1) OK!
Vy/Vdy = 0.007 < 1.000 (8.4) OK!
Vz/Vdz = 0.155 < 1.000 (8.4) OK!
Global stability check of member:
ky*Ly/ry = 23.197 < (k*L/r),max = 200.000
kz*Lz/rz = 51.553 < (k*L/r),max = 200.000 STABLE
P/Pdy + Ky*Cmy*Mymax/Mbdy + 0.6*Kz*Cmz*Mzmax/Mdz = 0.656 < 1.000 (9.3.2.2) OK!
P/Pdz + KLT*Mymax/Mbdy + Kz*Cmz*Mzmax/Mdz = 0.988 < 1.000 (9.3.2.2) OK!
----------------------------------------------------------------------------------------------------------------------------------------
Section OK !!!
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
COMPARISON:
RSA
IS 800: 2007
Limit State Design
Handbook
EC3: 2005
(Annex B, method 2)
ϪM0 = 1,0
ϪM0 = 1,0
1. Cross-section compression resistance
N/ Nd = 3440/ 8415 =
0,409
NEd/ Nc,Rd = 3440/ 8415
= 0,409
2. Cross-section bending resistance
My/Mdy =420/ 1166,8
= 0,360
My,Ed/My,c,Rd = 420/1168
= 0,360
Mz/Mdz =110/ 534,9
= 0,206
Mz,Ed/Mz,c,Rd= 110/536,5
= 0,205
(9.3.1.1) = 0,340
(6.2.9.1.(6)) = 0,340
Resistance, interaction expression
For UB 305x305x240:
4. Cross-section resistance under
My+Mz+V+N
5. Member buckling resistance
N/ Pdy= 3440/8213,3 = NEd/ Ny,b,Rd =3440/8314,0
in compression
= 0,414 ; (ky=0,7)
0,419 ;(ky=0,8)
ky - buckling length coefficient Y
N/ Pdz= 3440/6639,7 = NEd/ Ny,b,Rd =3440/6640
= 0,518
0,518
6. Member buckling resistance in bending
-lateral buckling length
-critical M for lateral-torsional buckling
7. Member buckling resistance in combined
bending and axial compression
My/Mdy =420/1137,2 =
0,369
My,Ed/Mb,Rd =420/1152
= 0,36
LLT = 5,04 m
Mcr = 11 963,5 kNm
Lcr = 4,2 m
Mcr = 17 114 kNm
0,656
0,988
(9.3.2.2)
(9.3.2.2)
0,66
0,97
(6.61)
(6.62)
CONCLUSIONS:
The calculation example was made according to:
- IS:800 code  using RSA program and
- EC3:2005 code  taken from handbook.
To make comparison more adequate, the same value of the partial safety factors M0=1,0 were
assumed in both methods.
The small differences in results are caused generally by:
 small differences in values for elastic and plastic section modulus about Y & Z axis;
 different values for buckling length coefficients in both codes;
 different way of lateral buckling length coefficient description in both codes (effective length for
beams between supports are different); in Indian code there is very precision method to define
conditions at support;
 different accuracy of parameters (e.g. the cross-sectional properties) in calculations.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
CONCRETE
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
1. IS 456:2000 – RC beams
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
VERIFICATION EXAMPLE 1
- Dimensioning of simply supported beam
Example based on:
[1] S. N. Sinha, “Reinforced Concrete Design”, Second Edition, 2002, Example 6.1, pp. 239
DESCRIPTION OF THE EXAMPLE:
Design a simply supported beam. In this example, the results of the program are compared against
[1]. The comparison concerns the amount of longitudinal reinforcement and shear reinforcement.
LOADS:
uniformly distributed: p=50
GEOMETRY:
clear span: l0=6
support width: a=30
cross section: 30x60
MATERIAL:
Concrete:
Steel:
[kN/m]
[m]
[cm]
[cm]
M20
Fe 415
IMPORTANT STEPS:
Define the geometry of the beam (Fig.1.1) and the loads (Fig.1.2). Select support type in dialog box
Dimension definition/Span geometry as Masonry (shear will be calculated from the axis of the
support). Set proper materials (Calculation Options).
Fig. 1.1 Beam geometry
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
Fig. 1.2 Loads and the calculation model
RESULTS OF LONGITUDINAL
CALCULATION:
REINFORCEMENT
(REINFORCEMENT
FOR
BENDING)
The theoretical areas of reinforcement determined by the program are presented on the graph in
Fig.1.3. The values in the midspan, compared with [1], are presented in the table below.
Theoretical areas
tension reinf. Ast
tension reinf. Asc
[1]
23.65 cm2
7.87 cm2
ROBOT
23.77 cm2
7.97 cm2
Fig. 1.3. Theoretical (required) areas of reinforcement in beam.
The real reinforcement generated by ROBOT is different than in [1], but it fulfills the capacity
requirements as well. The real reinforcement in the midspan is compared in the table below.
Real reinforcement
[1]
ROBOT
tension reinf. Ast
3  28 + 2  20
(24.75 cm2)
3  32
(24.13 cm2)
tension reinf. Asc
3  20
(9.42 cm2)
4  16
(8.04 cm2)
RESULTS OF TRANSVERSAL REINFORCEMENT (SHEAR REINFORCEMENT) CALCULATION:
In [1] the beam is divided into three segments with idealised diagrams of shear force assumed. In the
first and last segment (close to supports) the redistribution of sheaf force is assumed. To enable the
distribution in ROBOT select Calculation Options/Advanced/Redistribution of a shear force near
supports.
The shear force on the distance equal to effective height d from the support is assumed as at the end
of this distance. This way, the reduced shear force is equal to 211.57 kN, while the maximum shear
force is 257.51 kN, Fig.1.4.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
Fig. 1.4. Diagram of shear force in beam (blue) and reduced shear force (green).
The shear reinforcement generated automatically by the program is bigger than this determined in [1].
The reason is following: the authors of [1] assume the full area of longitudinal bars influencing the
shear strength of concrete c. This is not a case in ROBOT, where the area of steel is assumed taking
into account the development length. The area of bars develops from zero in point where the bar
starts and reaches the maximum (full) area at the distance equal to development length (see Fig.1.5).
Fig. 1.5. Diagram of theoretical (blue) and real (red) area of reinforcement.
Taking this effect into account, the c near support is equal to 0.288 MPa and not 0.639 MPa as in [1].
This leads to the spacing of stirrups equal to 12cm within the end segment.
In order to verify the calculations of shear in ROBOT based on [1], the spacings will be manually
defined and the anchorage of main bars will be increased (in order to increase the area of still taken
for determination of c ). This allows us to check the calculations of shear capacity carried out in
ROBOT.
First, define the spacing of stirrups as in [1]. Then, increase the length of hooks of main bottom bars.
Next, select Results/Freeze reinforcement. In Reinforcement Pattern/General dialog box enable
Consider hook length in anchorage length.
The capacity for shear is presnted in Fig.1.6. This proves, that taking into consideration the need of
proper anchorage of longitudinal bars, the calculation of shear leads to a similar results as in [1].
Fig. 1.6. Diagram of distribution of shear force (green) and shear capacity (red) for the spacing of
stirrups as in [1]
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
VERIFICATION EXAMPLE 2
- Determination of capacity of a beam
Example based on:
[1] S. N. Sinha, “Reinforced Concrete Design”, Second Edition, 2002, Example 3.14, pp. 107
DESCRIPTION OF THE EXAMPLE:
Determine the bending moment capacity of the beam with the assumed reinforcement. Two cases of
reinforcement given in [1] are analysed here. The reinforcement is defined and the results concerning
capacity are compared.
REINFORCEMENT:
Case
I
Tension steel
Compression steel
4  22
4  16
II
4  25
4  16
GEOMETRY:
Cross-section:
case I: 30x53.6
[cm]
case II: 30x53.8
[cm]*
* In example, there is no height of the section given, instead the effective depth is assumed and the
clear cover of bars. This means, that for two cases of reinforcement, where different diameters of bars
are used, different height of the beam must be defined.
The length of the beam and other geometrical parameters are variables that have no influence on the
analysed results since we analyze the capacity of the section.
MATERIAL:
Concrete:
Steel:
M20
Fe 415
RESULTS OF THE CALCULATION:
The capacity determined by ROBOT (Fig. 2.1) for the reinforcement assumed in [1] is found to be in
agreement with the results in [1].
Case
I
II
March 2014
[1]
250.69 kNm
309.32 kNm
ROBOT
250.78 kNm
309.32 kNm
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
Fig. 2.1. Diagrams of the moment capacities (red) for the two cases of reinforcement.
LITERATURE
[1] S. N. Sinha, “Reinforced Concrete Design”, Second Edition, 2002
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
2. IS 456:2000 – RC columns
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
VERIFICATION EXAMPLE 1
- Uniaxially eccentrically loaded braced rectangular column
Example based on:
[1] S. N. Sinha, “Reinforced Concrete Design”, Second Edition, 2002, Example 9.20, pp. 497
DESCRIPTION OF THE EXAMPLE:
Design the rectangular column in a braced (non-sway) frame. Column is subjected to uniaxial
eccentrical load.
In the following example, the results of the program, concerning the calculations of longitudinal
reinforcement and capacity are compared to the results of [1].
LOADS:
Ultimate axial load:
P = 2000 [kN]
Ultimate axial moment: Mx = 400 [kNm]
GEOMETRY:
Unsupported length
Effective lengths:
Cross section:
lu=3.5 [m]
lx = 3 [m]
ly = 2.75 [m]
40x60 [cm]
MATERIAL:
Concrete
: M 25
Longitudinal reinforcement : Fe 415
IMPORTANT STEPS:
In the dialog box Buckling length set buckling parameters (Fig.1.1.).
Fig. 1.1. Buckling parameters of the column.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
In the Calculation Option/ General dialog box select the proper method of calculation (Fig. 1.2.).
Fig. 1.2. Selection of calculation method.
In order to compare the results of calculation with the final solution assumed in [1], select the same
diameter of main bars as in [1]. The diameter of bars may be set in Reinforcement pattern/Longitudinal
bars dialog box (Fig. 1.3.).
Fig. 1.3. Parameters of main bars.
RESULTS OF CAPACITY CALCULATION:
March 2014
Quantity
[1]
Robot
(results presented
in calculation note)

1.4765
1.4645*
Muy,l
Muz,l
Capacity coefficient
421.2
247.2
1/0.996=1.004
436.6 **
264.5 **
1.026
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
NOTES:
* - In [1] the equation Puz  0.446 f ck  0.75 fyAsc is used, while Robot uses the equation
given in code [2], which is Puz  0.45 f ck  0.75 fyAsc
** - In [1] the simplification takes place due to the use of approximated interaction curves.
Robot calculates the capacity based on the equilibrium of forces in section.
RESULTS OF LONGITUDINAL REINFORCEMENT CALCULATION:
Reinforcement generated by the program (Fig.1.4), after assuming that the diameter 28mm should be
used, is the same as determined in [1].
Fig. 1.4. Reinforcement generated by the program (8 28).
March 2014
Quantity
[1]
Robot
Reinforcement
8 28
8 28
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
VERIFICATION EXAMPLE 2
- Column subjected to axial load and biaxial bending
Example based on:
[1] S. N. Sinha, “Reinforced Concrete Design”, Second Edition, 2002, Example 9.24, pp. 509
DESCRIPTION OF THE EXAMPLE:
Design the rectangular column in a braced (non-sway) frame. Column is subjected to biaxial
eccentrical load. In the following example, the results of the program, concerning the calculations of
longitudinal reinforcement and buckling analysis are compared to the results of [1].
LOADS:
Ultimate axial load:
Ultimate axial moments:
GEOMETRY:
Unsupported length
Effective lengths:
Cross section:
P = 2000 [kN]
Mx1 = 225 [kNm]
Mx2 = 175 [kNm]
My1 = 125 [kNm]
My2 = 75 [kNm]
lu=9.0 [m]
lx = 8 [m]
ly = 6 [m]
40x60 [cm]
MATERIAL:
Concrete
: M 25
Longitudinal reinforcement : Fe 415
IMPORTANT STEPS:
In the dialog box Buckling length set buckling parameters (Fig.2.1.).
Fig. 2.1. Buckling parameters of the column.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
In the Calculation Option/ General dialog box select the proper method of calculation (Fig. 2.2.).
Fig. 2.2. Selection of calculation method.
In the Calculation Option/ General dialog box enable the use of k coefficient for calculation of the
additional moments (Fig. 2.3.).
Fig. 2.3. Parameter k for calculation of additional moments.
In order to compare the results of calculation with the final solution assumed in [1], select the same
diameter of corner and intermediate bars as in [1]. The diameter of bars may be set in Reinforcement
pattern/Longitudinal bars dialog box (Fig. 2.4.).
Fig. 2.4. Parameters of main bars.
Define loads (Fig. 2.5.).
Fig. 2.5. Loads definition.
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
RESULTS OF LONGITUDINAL REINFORCEMENT CALCULATION:
Reinforcement generated by the program (Fig.2.6.) is the same as determined in [1] (after the same
diamteres were assumed).
Fig. 2.6. Reinforcement generated by the program (4 28 + 8 25).
Quantity
[1]
Robot
Reinforcement
4 28 + 8 25
4 28 + 8 25
RESULTS OF BUCKLING ANALYSIS:
Quantity
[1]
ky
kz
Muy
Muz
0.8223
0.7896
292.71
176.06
Robot
(results presented
in calculation note)
0.8590*
0.7899
296.63
176.10
NOTES:
* - This difference is caused by different Pub and Puz values. In [1] Pub are calculated based on
approximated tables, while in Robot the exact calculations are carried out. Moreover, in [1] the
equation Puz  0.446 f ck  0.75 fyAsc is used, while Robot uses the euqtion given in code [2], which
is Puz  0.45 f ck  0.75 fyAsc .
RESULTS OF CAPACITY CALCULATION:
March 2014
Quantity
[1]
Robot
(results presented
in calculation note)

1.4118
1.3886*
Muy,l
Muz,l
Capacity coefficient
493.2
292.8
1/0.964=1.037
527.7**
316.5**
1.085
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Autodesk Robot Structural Analysis Professional - Verification Manual for Indian Codes
NOTES:
* In [1] the equation Puz  0.446 f ck  0.75 fyAsc is used, while Robot uses the euqtion given
in code [2], which is Puz  0.45 f ck  0.75 fyAsc .
** - In [1] the simplification takes place due to the use of approximated interaction curves.
Robot calculates the capacity based on the equilibrium of forces in section. Moreover the capacity is in
[1] found for the assumed percentage of reinforcement. At the end however, the greater reinforcement
is assumed, thus capacities are in [1] underestimated. In Robot, capacities are calculated for the real
reinforcement.
LITERATURE
[1] S. N. Sinha, “Reinforced Concrete Design”, Second Edition, 2002
[2] Indian Standard IS 456:2000 Plain and Reinforced Concrete – Code of Practice (Fourth Revision),
2003
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