V. EC3 Malaysian NA - I Section with UDL

Calculate the bending capacity of a beam using an I section subject to a uniformly distributed load per the Malaysian NA to EC3.

Details

The section is a HD320X127, Grade S275 steel. The member is a 5 m, fixed-fixed span subject to a 10 kN/m uniform load.

Calculations

Validation

Moment capacity:

The critical moment is given by:

where

C1
=
0.712
C2
=
0.652
k
=
0.5
=
29,909,000
=
5,599
=
5,934
C2Zg
=
0.652×160 = 104.3

Therefore, Mcr = 966.7 kN·m

From the Malaysian NA, λLT, 0 = 0.4, β = 0.75

So,

H/b = 320/300 = 1.067 < 2. So, from Table 6.5 of Eurocode 3, αLT = 0.34.

From Cl. 6.3.2.3 of Eurocode3:

ФLT = 0.5[1+αLT (λLT- λLT, 0) + β× λLT 2] = 0.5[1 + 0.34×(0.782 - 0.2) +1 × 0.7822] = 0.794

So, Ф Ф

So, but this value cannot be used, so from Table 6.6 of the Eurocode 3, kc = 0.9

Modification factor:

, OK

Results

Result Type Reference STAAD.Pro Difference Comments
Moment capacity, Mckd (kN·m) 591.0 591.0 none
Critical moment, Mcr (kN·m) 966.7 967.3 negligible
Bending capacity, MB (kN·m) 514.4 514.5 negligible

Input

The file C:\Users\Public\Public Documents\STAAD.Pro 2026\Samples \Verification Models\09 Steel Design\Europe\EC3 Malaysian NA - I Section with UDL.std is typically installed with the program.

The following design parametersdesign parameters are used:

  • The Malaysian NA is specified using NA 9
  • Fully fixed span: CMN 0.5
  • Uniformly distributed load w/ fixed-fixed supports: CMM 2
  • The parameter KC 0 instructs the program to calculate the value of kc

STAAD

STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 23-Mar-21
END JOB INFORMATION
INPUT WIDTH 79
UNIT METER KN
JOINT COORDINATES
1 0 0 0; 2 5 0 0;
MEMBER INCIDENCES
1 1 2;
DEFINE MATERIAL START
ISOTROPIC STEEL
E 2.05e+008
POISSON 0.3
DENSITY 76.8195
ALPHA 1.2e-005
DAMP 0.03
END DEFINE MATERIAL
MEMBER PROPERTY EUROPEAN
1 TABLE ST HD320X127
CONSTANTS
MATERIAL STEEL ALL
SUPPORTS
1 2 FIXED
LOAD 1 LOADTYPE None  TITLE LOAD CASE 1
MEMBER LOAD
1 UNI GY -10
PERFORM ANALYSIS
PRINT MEMBER PROPERTIES ALL
PARAMETER 1
CODE EN 1993-1-1:2005
NA 9
CMM 2 ALL
CMN 0.5 ALL
KC 0 ALL
PY 275000 ALL
TRACK 2 ALL
CHECK CODE ALL
FINISH

Output

                         STAAD.PRO CODE CHECKING - MS EN 1993-1-1:2010
                         ********************************************
                         NATIONAL ANNEX - NA to MS EN 1993-1-1:2010
 PROGRAM CODE REVISION V1.14 BS_EC3_2005/1
      STAAD SPACE                                              -- PAGE NO.    4 
 ALL UNITS ARE - KN   METE (UNLESS OTHERWISE Noted)
 MEMBER     TABLE       RESULT/   CRITICAL COND/     RATIO/     LOADING/
                          FX            MY             MZ       LOCATION
 =======================================================================
 *** WARNING:CMN PARAM INVALID FOR NATIONAL ANNEX
 NATIONAL ANNEX ONLY DEALS WITH END RESTRAINT FACTORS OF K = KW = 1.
 HENCE WILL USE ANNEX F FROM DD ENV 1993-1-1:1992
       1 ST   HD320X127   (EUROPEAN SECTIONS)
                           PASS     EC-6.3.2 LTB       0.040         1
                        0.00            0.00          20.83        0.00
 =======================================================================
   MATERIAL DATA                
      Grade of steel           =  USER          
      Modulus of elasticity    =  205 kN/mm2  
      Design Strength  (py)    =  275  N/mm2                         
   SECTION PROPERTIES (units - cm)
      Member Length =    500.00
      Gross Area =  161.30          Net Area =  161.30
                                      z-axis          y-axis
      Moment of inertia        :    30820.004        9239.001
      Plastic modulus          :     2149.000         939.100
      Elastic modulus          :     1926.250         615.933
      Shear Area               :      109.573          51.728
      Radius of gyration       :       13.823           7.568
      Effective Length         :      500.000         500.000
   DESIGN DATA (units - kN,m)   EUROCODE NO.3 /2005
      Section Class            :   CLASS 1     
      Squash Load              :   4435.75
      Axial force/Squash load  :     0.000
      GM0 :  1.00          GM1 :  1.00          GM2 :  1.20
                                      z-axis          y-axis
      Slenderness ratio (KL/r) :         36.2           66.1
      Compression Capacity     :       4078.2         3045.5
      Tension Capacity         :       4355.1         4355.1
      Moment Capacity          :        591.0          258.3 
      Reduced Moment Capacity  :        591.0          258.3
      Shear Capacity           :       1739.7          821.3
   BUCKLING CALCULATIONS (units - kN,m)
      Lateral Torsional Buckling Moment       MB =  514.5 
      co-efficients C1 &amp; K : C1 =0.712 K =0.5, Effective Length= 5.000
      Lateral Torsional Buckling Curve : Curve b
      Elastic Critical Moment for LTB,               Mcr   =   967.3 
      Compression buckling curves:     z-z:  Curve b   y-y:  Curve c
      Critical Load For Torsional Buckling,          NcrT  = 13898.0
      Critical Load For Torsional-Flexural Buckling, NcrTF = 13898.0
      STAAD SPACE                                              -- PAGE NO.    5 
   CRITICAL LOADS FOR EACH CLAUSE CHECK (units- kN,m):
    CLAUSE        RATIO  LOAD     FX       VY      VZ      MZ      MY   
   EC-6.2.5       0.035     1     0.0     25.0     0.0    20.8     0.0
   EC-6.2.6-(Y)   0.030     1     0.0     25.0     0.0    20.8     0.0
   EC-6.3.2 LTB   0.040     1     0.0     25.0     0.0    20.8     0.0
    Torsion has not been considered in the design.
                        _________________________
   ************** END OF TABULATED RESULT OF DESIGN **************