Guardrail in Posttensioned Timber‐Bridge Specimen

Abstract

A semiempirical, mathematical model for assessing the load behavior of bridge guardrail systems is described. A full‐scale laboratory specimen was represented by a beam supported by coupled, elastic springs. Empirical flexibility coefficients were used to establish the spring constants for the post and deck subassembly of the specimen. This model was applied to a panelized, longitudinal‐deck bridge specimen. Laboratory load tests were conducted both without and with posttensioning features incorporated into the specimen. Longitudinal, transverse and angular loads were separately applied to the specimen. The model was successful at predicting transverse load‐displacement behavior. A stiffening due to posttensioning was evident. Due to erratic load‐slip behavior of the connection details, the modeling of longitudinal load‐displacement behavior was unsuccessful. The danger of a possible failure of the guardrail post at a low load level was observed under longitudinal loading. Loosening of the post to deck connection during the posttensioning was a factor in the occurrence of load‐slip behavior.