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31 CHAPTER 6 Evaluation of Splice Damage The objective of this evaluation was to determine the effect view of the splice damage and the individual post damage is of splice damage on barrier crash performance by pendulum shown in Figure 24. Figure 25 shows time sequence snapshots testing (Figure 23). The performance of the barrier section of the test obtained from the overhead camera. with splice damage was compared to the performance of a similar barrier section with no flaw. The pendulum test setup 6.2 Recommendation is described in an earlier chapter on the research approach. Splice damage was simulated by removing a rectangular A pendulum test of a strong-post w-beam barrier with splice block of material directly in line with a single splice bolt and damage resulted in successful containment of the pendulum having width equal to the diameter of the splice bolt. The mass. The splice damage consisted of extending the hole for intent was to simulate complete loss of bearing capacity for a single splice bolt to the end of the rail (e.g., no bearing capac- a single bolt (of 8 bolts total) in the splice connection. ity for that particular bolt). Under a pendulum impact at 29.3 km/hr (18.2 mph), this barrier was able to contain the impacting pendulum mass with performance indistinguish- 6.1 Results able from the undamaged barrier section. It is known how- In Test 07-4, the splice damaged barrier contained the pen- ever from full-scale crash testing as well as the splice failures dulum mass impacting at 29.3 km/hr (18.2 mph), which was observed in the pendulum tests that the splice is a weak point calculated using the overhead high-speed video footage. The in the guardrail system. Balancing these two observations, the maximum dynamic deflection of the test section was 574 mm research team recommends a repair threshold of 2 or more (22.6 inches) at 130 ms after the initial impact. Both post-rail splice bolts with any guardrail material missing around the bolts connections remained intact and no serious splice separation with high priority. In the case of damage to a single splice bolt, was observed in the splice damage created prior to the impact. the research team assigned the repair a medium priority There was approximately 13 mm (0.5 inches) of relative move- (rather than a low priority) based on the fact that the splice ment between the two w-beams at the splice location. A detailed is the weak point in the rail element (Exhibit 3.0). Figure 23. Splice damage evaluated in pendulum tests.
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32 Figure 24. Test 07-4: Detail view of splice bolt damage after test (left) and post damage at splice (center) and non-splice location (right). 0.02 s 0.06 s Exhibit 3.0. Recommendations for splice damage repair. Damage Mode Repair Threshold Relative Priority Damage at a rail More than 1 splice bolt: High 0.10 s 0.14 s splice Missing, Damaged, Visibly missing any underlying rail, and Torn through rail. 1 splice bolt: Medium Missing, Damaged, 0.18 s 0.22 s Visibly missing any underlying rail, and Torn through rail. 0.26 s 0.30 s Figure 25. Sequential overhead photographs for splice damage, Test 07-4 (29.3 km/hr).