Returning to my Car Frame Reinforcements/Calculations/Torque Settings/Abutment Ratios

Referring to the Car Frame for the Elephant & Castle Underground Lifts of 3750 Kg  
(Contract/Pay Load) and Rated Speed of 1.75 M/s
A full strength of material Audit Type Analysis of the Lift Car Frame, for which I suggested when at OTIS-LRT, where the Abutment Ratio (Squeeze) on the corner Plates/Gussets of the Car Frame, I suggested based on past experience (As an Undergraduate at the University of Surrey)--Shanked/Waisted Studs could have been used instead of the existing Grade 8 -- Fasteners, by Grade 10 ones of higher specification--together with larger Cleats/Corner Plates) it would have increased the Flexural/Axial/Buckling Resistance of the Lift Car Frame.

The ductility of the Shank or Studs whether cylindrical or waisted as I used / monitored / tested during my Industrial Year on Petters BA 2 engines, my comments on the subject were made to both Josephine Patel and mentioned to Ron Cooke. Plastic Strain in the Fastenings which with HSFG bolts should have been used/specified. Another way of improving the Fastenings Abutment Ratio is by Pre-Stressing of the Bolts.

For the Cleats/Gussets/Corner Angled Plates; one can increase the plate thickness in order to improve the Corner Plate Flexure, amongst the parameters that are considered critical are;

Distance from Centre-Line to Bolt where the Prying Force Acts.            Thickness of Flange --Tee                                                       Applied Force per bolt                                                        Minimum Proof Stress of bolts                                             "Beta" = 1.0for pre-loaded bolts;    "Beta" = 2.0 for non-preloaded bolts;  "Gamma" 1.0 for working load design; "Gamma"= 1.5. for limit state design (with factored loads)

Refer to Table 32 of BS 5400: Part 3 , taking "Gamma" _m. "Gamma "_f3 equal to 1.1 instead of 1.32 brings it into line with BS 5950

As an example in Grade 8.8 bolts the tension capacity is obtained by taking p= 0.64 U_f is only 2% less than the tension capacity of 0.9 P_o. which would apply if it were to be designed as a pre-loaded grip fastener in accordance with clause 6.4.4.2 of BS 5950: Part 1.

John Irwin C. Eng. M. I. Mech. E. of 22 Princess Court, Queensway, London W2 4RB