Development and Testing of the Steel U-Channel Slip Splice Sign Support (220500)

Researchers at Texas Transportation Institute designed a new steel U-channel slip splice connection for use with support structures within the highway right-of-way. The slip splice connection has two design configurations. A small slip splice was designed for connection to a single steel U-channel sign support weighing up to 5.9 kg/m for use in any type of soil with up to three supports per installation. Additionally, a larger slip splice was designed for connection to back-to-back steel U-channel sign supports weighing up to 5.9 kg/m for use in any type of soil with up to three supports per installation. The advantages to the new design are that 1) it eliminates much of the dependency on consistent material properties that past steel U-channel connections or splices have depended upon so highly and 2) it is omnidirectional. The performance of lap-splice connections and the Minute-Man splice connection depends on the repeatability of strength of material properties. Unlike other types of engineering design where minimum yield strengths are critical, the design of highway safety appurtenances where performance is dependent on the failure of a bolt(s), consistent ultimate strength of the material being failed is crucial. The slip splice design eliminates material property dependency and thus helps to ensure consistent safe performance every time the installation is impacted.|This report presents the results of full-scale crash tests performed on the back-to-back 5.9 kg/m steel U-channel slip splice sign support installation in standard and weak soil and the evaluation of its impact performance. Testing and evaluation was performed in accordance with guidelines outlined in NCHRP Report 350 and the 1994 AASHTO standards. The steel U-channel sign support slip splice connection performed acceptably. Additionally, performance of the single support slip splice connection during pendulum testing is presented.