V. BS5950 2000 - Unrestrained Simply Supported Beam
Design of a 9 m, unrestrained beam with end moments.
Reference
Steelwork Design Guide to BS 5950-1:2000, Volume 2, Worked Examples, SCI publication P326, Example 3, The Steel Construction Institute.
Problem
Intermediate point loads are applied to the bottom flange. These do not provide restraint against lateral-torsional buckling. The beam is designed in S275 steel.
Dead Loads, γfd = 1.4:
- Selfweight ws = 3 kN/m
- Point Load W1d = 40 kN
- Point Load W2d = 20 kN
Imposed Loads, γfi = 1.6:
- Point Load W1i = 60 kN
- Point Load W2i = 30 kN
Comparison
| Result Type | Theory | STAAD.Pro | Difference |
|---|---|---|---|
| Shear capacity, Pv (kN) | 636 | 635.9 | none |
| Moment capacity, Mcx (kN-m) | 404 | 404.5 | none |
| Lateral-torsional buckling capacity, Mb (kN-m) | 150 | 150.26 | none |
STAAD Input
- TRACK 2 ALL
- Maximum detail output
- MLT 0.46ALL
- Specifies the mLT value to use in the lateral-torsional buckling calculations
- UNI 6.3 ALL
- Specifies the lateral-torsional buckling length to be used
The file C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\ Verification Models\09 Steel Design\UK\BS5950 2000 - Unrestrained Simply Supported Beam.STD is typically installed with the program.
STAAD SPACE
START JOB INFORMATION
JOB NAME Example no. 3
JOB CLIENT The Steel Construction Institute
JOB COMMENT Unrestrained beam with end moments
ENGINEER DATE Jun-2003
END JOB INFORMATION
INPUT WIDTH 79
UNIT METER KN
JOINT COORDINATES
1 0 0 0; 2 3 0 0; 3 6 0 0; 4 9 0 0;
MEMBER INCIDENCES
1 1 2; 2 2 3; 3 3 4;
*************************************
DEFINE MATERIAL START
ISOTROPIC STEEL
E 2.05e+08
POISSON 0.3
DENSITY 76.8195
ALPHA 1.2e-05
DAMP 0.03
END DEFINE MATERIAL
MEMBER PROPERTY BRITISH
1 TO 3 TABLE ST UB457X191X67
CONSTANTS
MATERIAL STEEL ALL
SUPPORTS
1 4 FIXED
*************************************
LOAD 1 DEAD
JOINT LOAD
2 FY -40
MEMBER LOAD
1 TO 3 UNI GY -3
UNIT MMS KN
JOINT LOAD
3 FY -20
UNIT METER KN
LOAD 2 LIVE
JOINT LOAD
2 FY -60
UNIT MMS KN
JOINT LOAD
3 FY -30
UNIT METER KN
LOAD COMB 100 COMBINATION LOAD CASE 3
1 1.4 2 1.6
PERFORM ANALYSIS PRINT STATICS CHECK
***************************************
PARAMETER 1
CODE BS5950
TRACK 2 ALL
MLT 0.46 ALL
UNL 6.3 ALL
CHECK CODE ALL
FINISH
***************************************
STAAD Output
STAAD.Pro CODE CHECKING - (BSI ) *********************** PROGRAM CODE REVISION V2.13_5950-1_2000 STAAD SPACE -- PAGE NO. 5 ALL UNITS ARE - KN METE (UNLESS OTHERWISE Noted) MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/ FX MY MZ LOCATION ======================================================================= 1 ST UB457X191X67 PASS BS-4.3.6 0.861 100 0.00 0.00 280.96 0.00 ======================================================================= MATERIAL DATA Grade of steel = S 275 Modulus of elasticity = 205 kN/mm2 Design Strength (py) = 275 N/mm2 SECTION PROPERTIES (units - cm) Member Length = 300.00 Gross Area = 85.50 Net Area = 85.50 Eff. Area = 85.50 z-z axis y-y axis Moment of inertia : 29400.002 1450.000 Plastic modulus : 1470.000 237.000 Elastic modulus : 1296.868 152.712 Effective modulus : 1470.000 237.000 Shear Area : 43.411 38.539 DESIGN DATA (units - kN,m) BS5950-1/2000 Section Class : PLASTIC z-z axis y-y axis Moment Capacity : 404.3 63.0 Reduced Moment Capacity : 404.3 63.0 Shear Capacity : 716.3 635.9 BUCKLING CALCULATIONS (units - kN,m) (axis nomenclature as per design code) LTB Moment Capacity (kNm) and LTB Length (m): 150.11, 6.300 LTB Coefficients & Associated Moments (kNm): mLT = 0.46 : mx = 0.00 : my = 0.00 : myx = 0.00 Mlt = 280.96 : Mx = 0.00 : My = 0.00 : My = 0.00 CRITICAL LOADS FOR EACH CLAUSE CHECK (units- kN,m): CLAUSE RATIO LOAD FX VY VZ MZ MY BS-4.2.3-(Y) 0.238 100 - 151.0 - - - BS-4.3.6 0.861 100 - 151.0 - 281.0 - Torsion and deflections have not been considered in the design. _________________________ STAAD SPACE -- PAGE NO. 6 ALL UNITS ARE - KN METE (UNLESS OTHERWISE Noted) MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/ FX MY MZ LOCATION ======================================================================= 2 ST UB457X191X67 PASS BS-4.3.6 0.470 100 0.00 0.00 153.25 0.00 ======================================================================= MATERIAL DATA Grade of steel = S 275 Modulus of elasticity = 205 kN/mm2 Design Strength (py) = 275 N/mm2 SECTION PROPERTIES (units - cm) Member Length = 300.00 Gross Area = 85.50 Net Area = 85.50 Eff. Area = 85.50 z-z axis y-y axis Moment of inertia : 29400.002 1450.000 Plastic modulus : 1470.000 237.000 Elastic modulus : 1296.868 152.712 Effective modulus : 1470.000 237.000 Shear Area : 43.411 38.539 DESIGN DATA (units - kN,m) BS5950-1/2000 Section Class : PLASTIC z-z axis y-y axis Moment Capacity : 404.3 63.0 Reduced Moment Capacity : 404.3 63.0 Shear Capacity : 716.3 635.9 BUCKLING CALCULATIONS (units - kN,m) (axis nomenclature as per design code) LTB Moment Capacity (kNm) and LTB Length (m): 150.11, 6.300 LTB Coefficients & Associated Moments (kNm): mLT = 0.46 : mx = 0.00 : my = 0.00 : myx = 0.00 Mlt = 153.25 : Mx = 0.00 : My = 0.00 : My = 0.00 CRITICAL LOADS FOR EACH CLAUSE CHECK (units- kN,m): CLAUSE RATIO LOAD FX VY VZ MZ MY BS-4.2.3-(Y) 0.041 100 - 26.2 - - - BS-4.3.6 0.470 100 - 13.6 - 153.2 - Torsion and deflections have not been considered in the design. _________________________ STAAD SPACE -- PAGE NO. 7 ALL UNITS ARE - KN METE (UNLESS OTHERWISE Noted) MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/ FX MY MZ LOCATION ======================================================================= 3 ST UB457X191X67 PASS BS-4.3.6 0.710 100 0.00 0.00 231.74 0.00 ======================================================================= MATERIAL DATA Grade of steel = S 275 Modulus of elasticity = 205 kN/mm2 Design Strength (py) = 275 N/mm2 SECTION PROPERTIES (units - cm) Member Length = 300.00 Gross Area = 85.50 Net Area = 85.50 Eff. Area = 85.50 z-z axis y-y axis Moment of inertia : 29400.002 1450.000 Plastic modulus : 1470.000 237.000 Elastic modulus : 1296.868 152.712 Effective modulus : 1470.000 237.000 Shear Area : 43.411 38.539 DESIGN DATA (units - kN,m) BS5950-1/2000 Section Class : PLASTIC z-z axis y-y axis Moment Capacity : 404.3 63.0 Reduced Moment Capacity : 404.3 63.0 Shear Capacity : 716.3 635.9 BUCKLING CALCULATIONS (units - kN,m) (axis nomenclature as per design code) LTB Moment Capacity (kNm) and LTB Length (m): 150.11, 6.300 LTB Coefficients & Associated Moments (kNm): mLT = 0.46 : mx = 0.00 : my = 0.00 : myx = 0.00 Mlt = 231.74 : Mx = 0.00 : My = 0.00 : My = 0.00 CRITICAL LOADS FOR EACH CLAUSE CHECK (units- kN,m): CLAUSE RATIO LOAD FX VY VZ MZ MY BS-4.2.3-(Y) 0.180 100 - 114.8 - - - BS-4.3.6 0.710 100 - 102.2 - 231.7 - Torsion and deflections have not been considered in the design. _________________________