Connections - Tensile Fabric Structures: Design, Analysis, and Construction - page 114

7.3.2 Cable Termination Design
All of the terminations described above typically attach to steel plates which are in
turn attached to steel supporting members. These “ear plates” to which jaw, eye, or
clevis terminations are attached must be sized with thickness and edge radius
adequate to prevent both bearing failure at the pin and shear or tension failure on the
net section of the plates adjoining the pinhole. Where the width of opening in a jaw-
type fitting is substantially larger than the thickness of the ear plate, washer-shaped
“boss” plates are welded to each side of the ear to match its thickness to the width of
the jaw and prevent bending of the attachment pin (Figure 7-14).
At mast tops or other critical locations, multiple cables often connect at a single
workpoint. Where this occurs, care must be taken to assure that the connection
geometry provides necessary clearances between adjoining cable terminations and
plates to facilitate installation and to allow for all displacements and rotations
anticipated under load. Where possible, ear plates are configured so that the
worklines of the supporting member and attached cables all coincide, and bending
moments are not introduced to the member. However, it is sometimes necessary or
appropriate to offset cable workpoints at a connection to satisfy geometric
constraints, and both member and connection design must consider bending effects
resulting from such workpoint offsets.
The attachment of ear plates to supporting members will induce local bending,
particularly in thin walled pipes or tubes. The connection design must consider these
moments, and adjust connection geometry or add reinforcing plates as required.
Several approaches are possible:
1. At lightly loaded ear plates, or where supporting member walls are stout, ears
may be welded directly to the outside face of the member.
2. Ears with intermediate force levels may be knifed through the supporting
member to allow welding at both faces of the member.
3. Where force levels are high or where multiple ears make knife plates
impractical, ring plates at the top and bottom of the ear may be utilized to
reduce local bending and punching shear stresses in the supporting member.
4. Where forces are high but ring plates are unacceptable for visual or other
reasons, ear plate connections may be devised in which the supporting
member is cut into sections to allow the insertion of internal stiffening plates,
then welded back together to leave only the ear plates visible.
The design of successful ear plate connections requires attention to resolution of
forces, geometric conflicts, cable rotation under load, and aesthetics. Complex
connections may also require ingenuity to resolve conflicting issues. A typical ear
plate connection utilizing ring plates is shown in Figure 7-14.