Author(s):
D.W. Eggers, T.J. Hirsch
Publication Date
August 1986
Abstract
The Texas State Department of Highways and Public Transportation (TSDHPT) currently uses two types of guardrail posts: (1) a circular wood post and (2) a steel W6 x 8.5 post. The current specifications require that the post must have a minimum soil embedment depth of 38 in. When a guardrail system is required at a culvert, SDHPT currently requires a rigid bridge rail when the full embedment depth of 38 in. cannot be achieved. The objective of this research study was to determine if the current guardrail design could be modified to achieve the necessary strength when full post embedment could not be achieved. The purpose of this report was to assess the effects of post type, soil conditions, and embedment depth on the load-deformation characteristics of the guardrail post. With this information, it is believed that a successful guardrail can be designed using more post with less than the full 38 in. embedment. Posts with only 18 in. or 24 in. embedment could be used at 3 ft-1/12 in. spacing and still produce the required strength for example. A series of static load tests were conducted on timber and steel posts embedded 18 in., 24 in., 30 in., and 38 in. in two different soils to determine the effects of post type, soil conditions, and embedment depth on the amount of energy dissipated by the soil. The results of these field tests were used to verify a mathematical model which could be used to predict guardrail post load capacity.
Report Number:
405-1
Keywords:
Embedment Depth, Post Types, Soil Properties, Static Load Tests
Link(s):
Document/Product
http://tti.tamu.edu/documents/405-1.pdf
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