PORTABLE CONCRETE MEDIAN BARRIERS: STRUCTURAL DESIGN AND DYNAMIC PERFORMANCE

Types of portable concrete median barriers (CMBs) in use in the United States are described primarily in terms of structural details and the load-bearing characteristics of their end connections. Twelve end-connection designs are analyzed to produce estimates of their resistance to loads in four test conditions: simple tension, shear, yaw moment, and torsion. Rotational connection slack is estimated from the geometric properties of the different end connections. Nine crash tests conducted by four research agencies are examined. These tests cover a range of barrier lengths from 3.81 to 9.14 m (12.5-30 ft) and a range of connection details that vary from low to significant load capacity. The crash tests vary in intensity from a 7 deg test at 104.6 km/h (65 miles/h) to a 25 deg test at 99.8 km/h (62 miles/h). Analysis of these tests yields specific conclusions on the performance of CMBs. An energy analysis of portable CMBs during vehicle impacts is presented. Estimates of barrier deflection derived from this analysis check closely with deflections observed during crash tests. A parametric study of the influence of various barrier characteristics, including barrier length and mass, connection slack and strength, and support media static and sliding friction, is also presented. Based on this analysis, portable CMBs can now be designed to provide specific performance characteristics. (Authors)