Criteria for Restoration of Longitudinal Barriers, Phase II (2021) / Chapter Skim
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272 Simulation of Test C08C3-027-1 Test C08C3-027-1 Summary Test C08C3-027-1 was conducted by MGA Research Corporation on August 6, 2008. The test article consisted of 12.5 feet long 12-gauge w-beam rail; the rail was supported with W6x9 structural steel posts that were 72 inches long, embedded 44 inches in the soil and spaced at 75 inches on center; the rail was blocked out from the post using 6x8x12 inch routed wood blockouts; the blockout and rail were attached to the post using 5/8-inch diameter carriage bolts.
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273 Figure 218. Damage to guardrail in low-speed test C08C3-027-1 (overhead view)
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274 Figure 219. Finite element model of G4(1S)
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275 FEA Simulation Finite element analysis was then used to simulate the impact conditions of Test C08C3027-1. At the beginning of the analysis the post-bolts that fasten the w-beam and blockouts to the post were tightened to approximately 2,000 lb axial force by imposing an initial strain-time history to the bolt elements via the LOAD_THERMAL card in LS-DYNA.
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276 Figure 220. Sequential views of FEA results compared with Test C08C3-027-1.
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277 Figure 221. Impact response at 0.18 seconds for (a)
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278 Figure 222. Comparison of guardrail damage for (a)
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279 Simulation of Test C08C3-027-2 Test C08C3-027-2 Summary The damaged guardrail from Test C08C3-027-1 was then subjected to a second impact at high-speed to evaluate the performance of the crash-damaged system. Test C08C3-027-2 was performed by MGA Research Corporation on August 7, 2008 under Report 350 Test 3-11 conditions.
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280 Figure 224. Contours of effective plastic strain for the initial state of the guardrail model for simulation of Test C08C3-027-2.
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281 26.4 degrees, respectively (i.e., the same impact conditions as the full-scale test)
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282 Figure 225. Sequential Views of Test C08C3-027-2 and FE analysis Case 1 from downstream-backside view perspective.
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283 Figure 220.
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284 Figure 226. Sequential Views of Test C08C3-027-2 and FE analysis Case 1 from an upstream view perspective.
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285 Figure 226.
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286 The acceleration time-histories of the vehicle during the event are shown in Figure 228 through Figure 230 and the angular displacement-time histories are shown in Figure 231. Data from the accelerometer located at the center of gravity of the vehicle were collected and input into the Test Risk Assessment Program (TRAP)
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287 Figure 229. Lateral acceleration-time history at C.G.
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288 Figure 232. Summary report of occupant risk measures for the analysis Case 1.
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289 Comparing the results of Analysis Case 1 to the full-scale test (C08C3-027-1) revealed that the groundline deflections of Posts 11 and 12 were notably higher in the analysis.
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290 Figure 234. Snapshots from low-speed test C08C3-027-1 illustrating the position of the guardrail posts relative to the backside of the soil pit at the beginning of the test and at 0.16 seconds.
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291 overhead view of the test article just before impact, as shown in Figure 235. The resulting model is shown in Figures 236 and 237 from an overhead and a downstream viewpoint, respectively.
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292 failed releasing both the rail and the blockout. Also at this time Post 12 was twisted almost 90 degrees.
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293 Figure 238. Sequential Views of Test C08C3-027-2 and FE analysis from downstreambackside view perspective.
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294 Figure 238.
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295 Figure 239. Sequential views of Test C08C3-027-2 and FE analysis from an upstream view perspective.
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296 Figure 239.
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297 Table 66. Summary of phenomenological events of full-scale test C08C3-027-2 and FEA simulation.
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298 Figure 240. Permanent displacement of the upstream anchor in Test C08C3-027-2.
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299 Figure 242. Maximum rotation displacement of Post 10 in (a)
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300 sensitivity to anchor strength. This was further evidenced from the results of Test MGA C08C3027-2 on that system which resulted in significant anchor deflection and vehicle override.
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301 Figure 243. Anchor stiffness used in FEA model compared to anchor stiffness measured in physical tests.
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302 the vehicle overriding the rail – particularly for cases when the movement of the posts in the soil is restricted (e.g., frozen soil, posts driven through asphalt, etc.)
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