The multidirectional slip base design operates on the same principle as the inclined slip base design. The multidirectional design consists of a triangular slip base employing
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FIGURE 7.19 Typical inclined, unidirectional slip base. Dimensions shown as mm: 100 mm = 4 in. |
only three slotted bolt holes, as presented in Fig. 7.20. The bolts are positioned at the flattened corners of the triangular plate. An impact from any direction slides the bolts out of the slots and allows the signpost to separate from the anchor piece. The desired lifting action is obtained by a lift cone located on the bottom plate. The sign support is tubular and beveled at the top triangular slip plate to help the lift cone push the support off the anchor plate during impact. The anchor piece is encased in concrete to prevent
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FIGURE 7.20 Details of multidirectional triangular slip base. Dimensions shown as mm: 100 mm = 4 in. |
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FIGURE 7.21 Frangible-coupling sign support. |
movement. The pipe generally used for multidirectional slip bases ranges from 3 to 5 in (75 to 127 mm) in diameter. The design specification for each size must be checked, since the required bolt size, torque requirements, and lift cone design are dependent upon the size of the sign support.
