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23 CHAPTER 4 Evaluation of Vertical Tear Damage The objective of this evaluation was to determine the effect time sequence snapshots of Test 03-2 obtained from the high of a vertical tear on barrier crash performance (Figure 14). speed camera positioned overhead. The approach was to subject a barrier test section with an In general, the remaining two undamaged barrier tests (not artificially introduced vertical tear to a pendulum test. The shown) had similar results to Test 03-2. Tests 01-2 and 07-1 performance of the barrier section with the flaw was com- both had successful containment of the pendulum mass. In pared to the performance of a similar barrier section with no both tests, the post-rail connection at the splice remained flaw. This chapter presents the pendulum test results of both intact and post-rail bolt pullout was evident at the non-splice the baseline undamaged section and the section with the ver- location. The separation at the splice was also approximately tical tear. The pendulum test setup was described in an ear- 19 mm (0.75 inches) in both tests. For Test 01-2, both the lier chapter on the research approach. impact speed and maximum deflection were slightly higher compared to the analogous 2-cable test (Test 03-2, Table 15). In all three baseline tests, the undamaged barrier section 4.1 Baseline Tests demonstrated satisfactory impact performance by containing the pendulum mass. The cable end fixture designs provided Pendulum tests were conducted at two impact speeds: adequate connection of the w-beam section to the existing 32.2 km/hr (20 mph) and 28.2 km/hr (17.5 mph). In Test 03-2, rigid posts on either side of the pendulum. With the excep- the undamaged barrier contained the pendulum mass impact- tion of the shorter swaged cables, the end fixtures were con- ing at 30.9 km/hr (19.2 mph). The impact speed was calculated structed with standard barrier hardware. The cable end fixtures using the data from the pendulum-mounted accelerometers. provide a very rigid connection of the w-beam to the essen- The maximum dynamic deflection of the test section was tially rigid posts on either side of the pendulum. Based on an 739 mm (29.1 inches) at 140 ms after the initial impact, com- analysis of data from the rigid post mounted accelerometers, puted from the pendulum acceleration data. The maxi- the maximum motion of each rigid post was approximately mum static crush at the center of the w-beam was 356 mm 1 inch (data not shown) toward the pendulum mass, which (14 inches). The overall damage and individual post damage would have a tendency to slightly reduce the tension in the is shown in Figures 15 and 16. The post at the splice location w-beam rail. This rigid connection coupled with the 32.2 km/hr (center in Figure 15) experienced more torsion than the non- (20 mph) pendulum impact speed, though, provides a very splice post and had some minor cracking at the flange. The severe impact to the barrier section, which approaches the post at the splice location also remained connected to the rail limit of the strong post barrier section. The ability of the while the post bolt at the non-splice location pulled through w-beam barrier to withstand an impact of this severity is a tes- the slot in the rail. There were no failures in the anchor tament to its structural robustness. cables in this test, and there was no visible separation of the The pendulum tests appear to be an appropriate surrogate cable from the swaged portion of the anchor cable assembly. for determining the structural adequacy of w-beam barriers. At the splice location, there was approximately 19 mm A limitation of this test methodology is an inability to evalu- (0.75 inches) of relative movement between the two w-beam ate vehicle trajectory/stability as well as occupant risk. Most rail sections. No tears were evident in the guardrail and no importantly, these tests provide insight into the crash per- bolt failure was observed. The left portion of Figure 17 shows formance of modified G4 (1S) strong-post w-beam barriers