When Wyoming's TL-3 and TL-4 Bridge Rail was approved to NCHRP 350, FHWA expressed concerns about addressing brittle failure for ASTM A 500 tubes, something they had seen in other bridge railings. To address this concern, Wyoming adopted a requirement for testing in accordance with ASTM E 436 using criteria similar to the State of New York. The specification calls for a Drop-Weight Tear Tests and reads, "the percentage shear area shall be determined by testing six specimens from the 6-inch side or sides of the structural tube not containing a weld. If the average percent shear area falls below 50, the material represented by these tests shall be rejected."
Trinity is in the process of providing railing for a project and they observed the following results:
Of the six tests, three showed 100% shear and three tests showed 10 % shear. The average of all six tests is 55% which according to the specification would pass. We are concerned however about the spread of the results. Should this be considered a pass, or should additional criteria be applied? Any light you can shead on this mater would be helpful. We are in the process of approving the material, so time is of the essence.
Thanks!
Some parts of this site work best with JavaScript enabled.