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Cable Terminal Anchor Bracket

Question
State NE
Description Text

We are trying to get this fabricated and need some changes discussed at your level.
(See Figure 1.jpg)


Attaching the cable plate to the base plate:

What is the weld symbol at the bottom right of this sketch referring to?

Can I remove the weld symbol? I think it is redundant from the one below on the 1/8" / 3/8" on the bottom right. (See Figure 2.jpg)


Lever Retaining Cable 3/8" is shown in the report: should this be smaller/ more flexible?

I seem to recall this being a fairly limp cable, 3/8" would be stiff.

Smaller would hold the lever to keep it from flying into traffic, and breakaway if snagged on the impacting vehicle.

Unsure of size of cable (See Figure 3.jpg) " found in Pooled Fund Progress 2005 V3.ppt

3/8" was used on the short radius system (See Figure 4.jpg)


The ¾" hole used in the small gusset plates out front is too large to place at the location shown & still allow a weld on the bottom side, the metal gets too thin.

The bolt used to retain the lever we don't see dimensioned: can I change this to a ½" bolt and use a 5/8" hole?

If so I would raise it 1/8" and move 1/8" right- this will allow enouph metal to weld too.


Keywords
  • Approach Guardrail Transitions
Other Keywords none
Date June 30, 2011
Attachment Figure 3.jpg
Attachment Figure 2.jpg
Attachment Figure 1.jpg
Attachment Figure 4.jpg


Response
Response

Responses are shown below in red.

 

Attaching the cable plate to the base plate: What is the weld symbol at the bottom right of this sketch referring to? Can I remove the weld symbol? I think it is redundant from the one below on the 1/8" / 3/8" on the bottom right.


While I agree that the top weld symbol is redundant, the weld symbol on the lower drawing has the top and bottom welds reversed. The 1/8" fillet weld should be on the bottom of the weld specification. The arrow side of the detail is shown on the bottom, while the opposite side is detailed on the top.

 

Lever Retaining Cable 3/8" is shown in the report: should this be smaller/more flexible? I seem to recall this being a fairly limp cable, 3/8" would be stiff. Smaller would hold the lever to keep it from flying into traffic, and breakaway if snagged on the impacting vehicle.


Your first attached photograph corresponds to a low-tension, three-cable end terminal test, test no. CT-3. The lever retaining cable was added to the system between test nos. CT-2 and CT-3 to address the occupant compartment penetration caused by the free-flying cable release lever. While the report states that the cable was 3/8", the initial as-tested cable size was smaller (if I remember correctly, it was likely 5/16") and utilized different clamping methods. However, during test no. CT-3, the lever retaining cable ruptured, thus allowing for the cable release lever to travel downstream with the vehicle. The lever retaining cable was increased to 3/8" for test no. CT-4. During that test, the cable again ruptured allowing the cable release lever to travel downstream but without occupant compartment problems.

The lever retaining cable was also used in test no. SR-5 for the R&D effort pertaining to the short radius guardrail system, where a 3/8" cable was utilized and did not rupture. For test no. SR-5, the cable release lever was retained.

Based on the hardware used in test no. CT-4, we believe that the 3/8" size should be maintained within the actual system. I can attach the FHWA acceptance letter CC-111 which contains additional CAD details regarding the retainer cable hardware.

 

The ¾" hole used in the small gusset plates out front is too large to place at the location shown & still allow a weld on the bottom side, the metal gets too thin. The bolt used to retain the lever we don't see dimensioned: can I change this to a ½" bolt and use a 5/8" hole? If so I would raise it 1/8" and move 1/8" right- this will allow enough metal to weld too.


Response:
On the first page of the cable guardrail plans and near the top-left corner, the retainer bolt is specified as being a 5/8" diameter, Grade 5 hex head bolt, 10" long. Based on the bending strength of the cable, I would not recommend lowering its diameter to a ½" bolt. Technically speaking, the 3/8" wire rope could impart a bending load to the middle of the bolt that exceeds the yield and plastic bending capacities. The shear capacity of 1 or 2 planes would be adequate with 5/8" bolt. A ½" bolt would not have sufficient shear strength if shifted to one side. Bending strength is also much weaker. At this time, I would not recommend using a smaller diameter bolt. We may need to re-examine the bolt strength for a cable loop positioned in the center of the bolt as well. As for the ½" gusset plates, the current bolt placement does interfere with the weld. We have drawn a second line in the shape of the gusset but inwardly offset by 3/8" to show the interference. By adjusting the hole position, one can minimize the interference without having to alter the hole and bolt specifications. For this configuration, the hole was moved down 1/16" and to the left 3/16". The proposed location for the hole is shown in the attached detail.

Date February 9, 2012
Attachment Proposed Gusset Config.jpg
Attachment Current Gusset Config.jpg


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