Study On Dynamic Mechanical Properties Of The Special Guardrail For The Middle Pier Of Highway Bridge

There are many high mountains and deep valleys in western region, and the pedestrian bridges and motors bridges as well cross the highway. In Chongqing, there are 247 pedestrian bridges cross the highways. The middle pier of pedestrian bridge is weak under collision, and there have been 8 pedestrian bridges crashed by the vehicle. So the highway traffic safety has become a hot topic and everyone pay close attention to it. In this paper, the special guardrail and its dynamic performance were studied for the middle pier of the highway bridge. This study was supported by the Chongqing Transportation Committee's Science Program of"Study on the Comprehensive Collision Structures for the Middle Pier of the Pedestrian Bridge cross the Highway based on its Safety Operation". The main research works are as follows.①Based on the summary of the current application of highway guardrail, several comprehensive collision measures were proposed for the highway bridge pier's safety protection, which including the double-wave guardrail, encrypt column, additional horizontal K-shaped support and Tic-tac-steel frame structure.②ANSYS / LS-DYNA finite element numerical simulation was carried out by the dynamic collision model, and the special guardrail and its dynamic performance were studied for the middle pier of the highway bridge. Then their collision and guiding functions were analyzed. The results showed that:1) The decrease of kinetic energy of double-wave guardrail with encrypted column is the biggest and the system's internal energy increment as well. It indicated that the guardrail plate's plastic deformation is larger and more energy was absorbed in the course of collision.2) The lateral deformation of double-wave guardrail with encrypted column plus additional horizontal K-shaped support is the least and the decrease of kinetic energy as well. But the guiding effect is the best and the vehicle can be back to the normal lanes.3) The collision deformation and energy conversion rate were compared of the double-wave guardrail, encryption column, additional horizontal K-shaped support and the tic-tac-steel frame. And then the special guardrail optimization was proposed for the bridge pier across the highway.③At last, the design method and construction technology were summarized according to the special guardrail applied in the safety protection for the middle piers of the pedestrian bridges cross the Chongqing highways.