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28 CHAPTER 5 Evaluation of Horizontal Tear Damage The objective of this evaluation was to determine the effect 5.2 Results of a horizontal tear on barrier crash performance (Figure 19). The approach was to subject a barrier test section with an arti- The horizontal tear damaged barrier in Test 07-3 contained ficially introduced horizontal tear to a pendulum test. The per- the pendulum mass impacting at 29.3 km/hr (18.2 mph), formance of the barrier section with the flaw was compared to which was calculated using the data from the high speed the performance of a similar barrier section with no flaw. The video footage. The maximum dynamic deflection of the test pendulum test setup is described in an earlier chapter on the section was 579 mm (22.8 inches) at 130 ms after the initial research approach. impact, computed from the pendulum acceleration data. The maximum static crush at the center of the w-beam was 406 mm (16.0 inches). The damage at the impact location 5.1 Method of Introducing and individual post damages are shown in Figure 20. Both the Damage post-rail connections remained intact and there was 16 mm A horizontal tear was simulated by cutting a longitudinal (0.63 inches) of relative movement between the two w-beams notch in the center of the upper protrusion of the w-beam using at the splice location. Figure 21 shows time sequential snapshots a reciprocating saw. Each end of the notch was cut into a "V" of Test 07-3 obtained from the high speed camera positioned shape to provide a stress concentrator similar to those observed overhead. in the field in a crash-induced horizontal tear. The location In Test 02-1, the horizontal tear damaged barrier (overhead of the tear corresponded to the pendulum mass impact loca- sequence not shown) was unable to contain the pendulum tion, as this was believed to have the largest risk for rail rupture. mass impacting at 31.2 km/hr (19.4 mph), which was calcu- The horizontal tear was a total of 306 mm (12 inches) long. lated using the data from the high speed overhead video. The The middle 204 mm (8 inches) of the tear was 13 mm wide deflection of the rail was 699 mm (27.5 inches) at 128 ms after (0.5 inches) with a 51 mm (2 inches) "V" shaped taper on the initial impact, which was just prior to penetration of the either end. w-beam section. The barrier section failed at the splice due to Field Example Pendulum Test Setup Figure 19. Horizontal tear evaluated in pendulum tests.