Shear Lugs

With the shear-type coupling, the elastomeric element may be clamped or bonded in place, or fitted securely to the hubs. The compression-type couplings may be fitted with projecting pins, bolts, or lugs to connect the components. Polyurethane, rubber, neoprene, or cloth and fiber materials are used in the manufacture of these elements. 

The code requires that the safe load for threaded hanger rods be based on the root area of the threads. This, however, assumes concentric loading. When hanger rods move to a nonvertical position so that the load is transferred from the rod to the supporting structure via the edge of one flat of the nut on the rod, it is necessary to consider the root area to be reduced by one-third. If a clamp is connected to a vertical line to support its weight, it is recommended that shear lugs be... 

Since lugs are eccentric supports they induce compressive, tensile, imd shear forces in the shell wall. The forces from the eccentric moments may cause high localized stresses that are c ombined unth stresses from internal or e.xternal pressure. In thin-walled vessels, these high local loads have been kn(rwn to physically deform the vessel wall considerably. Such deformations can cause angular rotation of the lugs, which in turn can caii.se angular rotations of the supporting steel. 

C) = horizontal seismic factor (]. = vertical seismic factor F, = horizontal seismic force, lb Fv = vertical seismic force, lb V h = horizontal shear per lug, lb V. = vertical shear per lug, lb P = internal pressure, psi R, = mean radius of shell, in. 

Vn = Horiz shear per lug Worst case from Table dependent on number of legs and direction of seismic force (between legs or through legs). NA V =V/N... 

Shear connector means headed steel studs, steel bars, steel lugs, and similar devices which are attached to a structural member for the purpose of achieving composite action with concrete. 

Dk.si(5n of Welded Lugs. If the two vertical gussets sh w U in Fig. 10.10 are welded to the shell by four vertical welds, the welds will be subjected to both a vertical shear and tensile and compressive stresses produced by the liend-... 

The region beyond the hole is that of shear on two planes which are parallel to each other and the vector of the acting force on the lug, shown in Figure 7.6. The locations of the shear planes are defined by the angle, (t>, shown in Figure 7.7. The shear plane consists of two vertical lines from the point defined by . The ultimate strength of the material decreases as the clearance between the pin and lug hole increases, provided all other dimensions remain constant Duerr [1] records lab tests where a relationship for 4> was developed to account for this clearance. 

Now, continuing with the circular edge lug plate, the area of shear is... 

The stiffness coefficient, K),r, attributable to shear deformation beyond the lug hole, is as follows ... 

P 54.2903226 Angle from lug centerline to shear plane, radians... 

Z1 17.8749705 mm Vertical distance of shear plane in lug with radius of curvature... 

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