| Because of Freeway Rebuilding, old Guardrail is difficult to achieve the strength requirements for guardrail by《Guidelines for Design of Highway safety Facilities》(JTG/T D81-2006,new specification),but they have fine appearance and certain capability of collision warning. If the old guardrail abandoned, it will cause serious waste of resources. To avoid wasting resources, this article proposes an old W-beam guardrail upgrading program to increase the strength of old guardrail and design a new type of concrete activities guardrail, which solves the shortage of ordinary concrete guardrail.At the request of Collision condition of the new specification, this article calculates the collision force by two-Degree-of-Freedom. Considering the guardrail column bended, old guardrail reinforcement scheme is proposed based on the geometric differences of new、old specification.(1) Designing crossbeam on the old column to compensate for the deficiency of W-beam thickness.(2) The depth of the column is increased. It can solve the problem of the deficiency of the anti-pulling force.(3) Pouring self-compacting concrete and configuring rebar in the old column makes up for the shortage of old column and corrosion.Secondly, this article designs a new concrete activities barrier for the median opening. This article designs the rolling wheel and hoisting device installed in concrete barrier. Under normal circumstances, it has isolation and crash performance. When the temporary opening, it can be quickly and flexibly moved. Referring to codes, this article designs the section types、reinforcement and hoisting device.Finally, this article stimulates vehicle crash guardrail with W-beam guardrail and new concrete activities guardrail. In the same collision conditions, new guardrail can arrest the out of control vehicle effectively. The vehicle acceleration and the maximum displacement meet standard requirements. The new concrete activities guardrail is also in compliance with regulatory requirements. |
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