PURPOSES : Unlike European standards, domestic performance assessment standards for truck mounted attenuators (TMAs) was first stipulated in 2014 using the NCHRP Report 350 of 1993 as the standard instead of the 2009 MASH of the United States. The purpose of this study is to present an improvement in the domestic performance evaluation criteria for TMAs.. METHODS : Considering the latest TMA performance evaluation standards in the U.S. and Europe, domestic performance evaluation criteria must improve stipulations related to impact speeds, impact conditions, impact cars, and support trucks. The performance change in the TMAs according to the variation in the impact speed, impact condition, impact vehicle, and support vehicle was investigated using finite element analysis (FEA). RESULTS : The TMA for an impact speed of 100 km/h showed a limit to the safety of the occupants of the collision vehicle and workers on the road for a collision speed of 120 km/h. The safety of the workers on the road was also not guaranteed for the collision of the remaining 73.8% of vehicles that exceeds the maximum impact car weight of 1,300 kg, the lower 26.2% of the total mass composition of domestic passenger cars. In addition, a TMA that satisfied only the conditions under which the vehicle was hit head-on to the center of the TMA did not reduce the risk of a secondary collision of the impact vehicle. Furthermore, the safety of workers on the road was not guaranteed when a travel distance of a support truck of 10 tons or more was applied to a work vehicle of less than 10 tons. CONCLUSIONS : To improve the safety of road traffic, a performance level corresponding to an impact speed of 120 km/h was added to the domestic TMA performance evaluation standard, and the eccentricity and oblique collision conditions were mandatory. Furthermore, the maximum impact vehicle weight of 1300 kg was raised to 2000 kg, and the test requester had to present support trucks of lower and upper weights such that TMA mounting trucks of various weights could be used.

Prestressing steel is an effective means of increasing the load carrying capacity and control the deflection of structural steel members. Although the method of prestressing is not new, the application and development of the technique for steel members has been limited and not as advanced as prestressed concrete structures. Prestressing force is commonly introduced using hydraulic jacks and utilizes high strength tendons as the prestressing material. In this paper, a new method of applying prestressing force is introduced. The method involves a segmental beam consisting of three segments and a normal strength bottom plate (BP) as the pretressing material attached to the two initially inclined outer segments of the steel H-beam. Pretressing force is introduced by taking advantage of the geometry of the segmental assembly of the beam. Experiment, analytical studies, and finite element (FE) analysis using ABAQUS is performed to verify the feasibility and applicability of the method and to understand the behavior of a mechanically prestressed segmental steel beam. Results showed that the prestressing method significantly increases the load carrying capacity and at the same time reduces the deflection of the beam. The difficulties encountered in the method are the rigorous assembly and the introduction of the exact required amount of prestressing force. Overall, the method of prestressing performed in the study can be used to introduce pretressing force which improves the performance of steel beams, provided that proper detailing is implemented.