Hi All,
i have modelled a wall mounted bracket supporting a 300 x 90 Dc PFC column. members 53 is failing in Compression for load of 46.10 but member 52 is passing in 49.58 Comprexssion. Both member are part of single beam only. Same is happening with 54 & 55.
This doesnt make any sense.
I have atached the STAAD file as well as drawing for this bracket.
Please help me solve this.
Thanks in advance
47073914-SW-CV-CALC-MOD-102-R4.std
It might help to view the Track 2 output for the two members side by side. I've attached them here. What I notice is some differences in the effective length and Mx demand that probably account for the difference in the final utilization ratio.
ALL UNITS ARE - KN METE (UNLESS OTHERWISE Noted) MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/ FX MY MZ LOCATION ======================================================================= 52 ST UA150X150X18 PASS BS-4.8.3.3.1 0.968 9 49.58 C 0.46 17.00 - ======================================================================= MATERIAL DATA Grade of steel = S 275 Modulus of elasticity = 205 kN/mm2 Design Strength (py) = 265 N/mm2 SECTION PROPERTIES (units - cm) Member Length = 37.20 Gross Area = 51.00 Net Area = 51.00 Eff. Area = 51.00 z-z axis y-y axis Moment of inertia : 434.846 1691.576 Plastic modulus : 126.078 287.070 Elastic modulus : 70.044 159.483 Effective modulus : 70.044 159.483 Shear Area : 16.200 16.200 DESIGN DATA (units - kN,m) BS5950-1/2000 Section Class : SEMI-COMPACT Squash Load : 1351.50 Axial force/Squash load : 0.037 z-z axis y-y axis Compression Capacity : 1301.8 1208.5 Tension Capacity : 1351.5 1351.5 Moment Capacity : 18.6 42.3 Reduced Moment Capacity : 18.6 42.3 Shear Capacity : 257.6 257.6 BUCKLING CALCULATIONS (units - kN,m) (axis nomenclature as per design code) v-v axis a-a axis b-b axis Slenderness : 23.918 35.761 35.761 Radius of gyration (cm) : 2.920 4.520 4.520 Effective Length : 0.372 0.372 0.372 STAAD SPACE -- PAGE NO. 46 LTB Moment Capacity (kNm) and LTB Length (m): 42.26, 0.372 LTB Coefficients & Associated Moments (kNm): mLT = 1.00 : mx = 1.00 : my = 1.00 : myx = 0.00 Mlt = 0.46 : Mx = 17.00 : My = 0.46 : 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) 0.191 9 - 49.2 - - - BS-4.2.3-(Z) 0.018 8 - - 4.5 - - BS-4.3.6 0.039 8 - 38.0 - - 1.7 BS-4.7 (C) 0.041 9 49.6 - - - - BS-4.8.2.2 0.017 1 1.1 1.0 0.1 0.3 0.0 BS-4.8.2.3 0.016 1 1.1 - - 0.3 0.0 BS-4.8.3.2 0.961 9 49.6 49.2 2.1 17.0 0.3 BS-4.8.3.3.1 0.968 9 49.6 - - 17.0 0.5 BS-4.9 0.016 1 0.0 - - 0.3 0.0 Torsion and deflections have not been considered in the design.
ALL UNITS ARE - KN METE (UNLESS OTHERWISE Noted) MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/ FX MY MZ LOCATION ======================================================================= * 53 ST UA150X150X18 FAIL BS-4.8.3.3.1 1.215 8 46.10 C 0.09 21.80 - ======================================================================= MATERIAL DATA Grade of steel = S 275 Modulus of elasticity = 205 kN/mm2 Design Strength (py) = 265 N/mm2 SECTION PROPERTIES (units - cm) Member Length = 48.60 Gross Area = 51.00 Net Area = 51.00 Eff. Area = 51.00 z-z axis y-y axis Moment of inertia : 434.846 1691.576 Plastic modulus : 126.078 287.070 Elastic modulus : 70.044 159.483 Effective modulus : 70.044 159.483 Shear Area : 16.200 16.200 DESIGN DATA (units - kN,m) BS5950-1/2000 Section Class : SEMI-COMPACT Squash Load : 1351.50 Axial force/Squash load : 0.034 z-z axis y-y axis Compression Capacity : 1280.6 1194.2 Tension Capacity : 1351.5 1351.5 Moment Capacity : 18.6 42.3 Reduced Moment Capacity : 18.6 42.3 Shear Capacity : 257.6 257.6 BUCKLING CALCULATIONS (units - kN,m) (axis nomenclature as per design code) v-v axis a-a axis b-b axis Slenderness : 26.651 37.527 37.527 Radius of gyration (cm) : 2.920 4.520 4.520 Effective Length : 0.486 0.486 0.486 STAAD SPACE -- PAGE NO. 48 LTB Moment Capacity (kNm) and LTB Length (m): 42.26, 0.486 LTB Coefficients & Associated Moments (kNm): mLT = 1.00 : mx = 1.00 : my = 1.00 : myx = 0.00 Mlt = 0.09 : Mx = 21.80 : My = 0.09 : 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 8 - 46.4 - - - BS-4.2.3-(Z) 0.017 7 - - 4.3 - - BS-4.3.6 0.050 7 - 39.6 - - 2.1 BS-4.7 (C) 0.039 8 46.1 - - - - BS-4.8.2.2 0.083 1 1.1 4.3 0.0 1.5 0.0 BS-4.8.2.3 0.082 1 1.1 - - 1.5 0.0 BS-4.8.3.2 1.211 8 46.1 46.2 0.2 21.8 0.1 BS-4.8.3.3.1 1.215 8 46.1 - - 21.8 0.1 BS-4.9 0.082 1 0.0 - - 1.5 0.0 Torsion and deflections have not been considered in the design.
Answer Verified By: Mahesh Gopal