Figure 117. The post breaks earlier in time when modeled with post-peak hardening (default saturated Grade 1 pine properties with Ghard equals 0.5). Diagrams.

The entry point in the following diagrams has been accentuated with a straight line being drawn over the top of the opening in which the post is embedded into the concrete brace.

5 milliseconds.

This figure shows a computer-generated illustration of a post embedded in a concrete brace using the double flap method. The sleeves can be seen on either side of the post, folded over at the entry point. The majority of the post is colored yellow with only a small section near the top colored red and representing the impact point and another small section colored red representing the breaking area. This latter area is the area in which the post is embedded into the concrete brace. The post has begun to split in the red “breaking area” as the post leans a slight degree to the right. The gap forming runs three-quarters the width of the post.

10 milliseconds.

This figure shows the post leaning further to the right. The gap forming has increased, the top half of the post now severed from the lower half in what appears to be a clean break.

25 milliseconds.

This figure shows the post now leaning at a rough twenty-five degree angle from its original position. The left-hand side corner of the break now rests just below the entry point of the concrete brace even with the accentuating straight line.

50 milliseconds.

This figure shows the post now leaning at a rough forty-five degree angle.  The top half of the post is shown to now be leaning completely out of the concrete brace and the sleeves, the break resting above the accentuating straight line.

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FHWA-HRT-05-096