The guardrail is a longitudinal energy absorption structure, which absorbs collision energy through its own deformation or vehicle climbing, thereby changing the direction of the vehicle, stopping the vehicle at the exit or entering the lane, and minimizing the damage of the crew. According to the degree of deformation after collision, the guardrail can be divided into rigid guardrail, semi-rigid guardrail and flexible guardrail. The main representative form is concrete guardrail and wave beam guardrail.
Rigid guardrail (concrete fence)
The rigid guardrail is a basic non-deformation guardrail structure. It absorbs impacting energy by changing the rotation angle, displacement, deformation of the wheel and the friction between the vehicle and the guardrail, the vehicle and the ground. In the collision, the degree of deformation of the vehicle depends on its own stiffness, collision energy and collision time. When the collision angle of the vehicle is large, serious consequences often occur. The rigid guardrail is mainly set on the road that cars needs to stop, so as to avoid secondary accidents. It has a slightly lower security requirement. Rigid guardrails can be divided into concrete wall guardrails, concrete columns and cross-section guardrails according to different structures, and concrete wall fence is the main representative form.
Semi-rigid guardrail (wave beam guardrail)
The semi-rigid guardrail is a continuous beam-column structure. It absorbs collision energy through friction and obstacles between vehicles, friction and obstacles between the vehicle and the ground, and certain elastic and plastic deformations (mainly deformed guardrail systems) generated by the obstacle itself. Thus prolonging the action time of the collision process to reduce the speed of the vehicle and force the direction of the vehicle to change and return to the normal direction, so as to ensure the occupant safety of the vehicle and reduce the loss. The semi-rigid guardrail is mainly set in the part that the occupants need to be protected. Beam column semi-rigid guard column can be divided into W-type corrugated beam guardrail, three-wave beam guardrail, pipe beam guardrail and box girder guardrail.They all have a certain degree of rigidity and toughness and can absorb collision energy through the analysis of beams and columns and the deformation of the foundation. The damaged parts are easy to replace. It equipped with a certain line of sight entrainment, elegant and natural. Corrugated beam guardrails are the most widely used.
The flexible fence is an elastic fence with good buffering capacity and is another extreme form corresponding to the rigid fence. The main obstacle is the flexible obstacles of the cable guardrail. It is the guardrail of the fixed post at the beginning of a few cable ports. It mainly relies on the tensile stress of the cable to resist car collision and impact energy absorption. The cable works within the elastic range and does not need to be replaced. The appearance of this guardrail is attractive, and there is no sense of pressure when the car is running, but the line-of-sight induction effect is poor, and the column will be broken after a maintenance work. It mostly used in places with high environmental quality requirements. In northern China, flexible guardrails are used for the sand dust in spring and the blizzard in winter to reduce workload and increase the road capacity, which has certain social and economic benefits.