Study On Mechanical Properties Of New Prefabricated Concrete Anti-collision Wall

The anti-collision wall is an indispensable part of bridge construction,and it plays an important role in preventing cars from leaving the road,ensuring the safety of vehicles and passengers,and reducing the degree of damage caused by accidents.The cast-in-place integral anti-collision wall has a long construction period and is inconvenient to construct.Therefore,the construction period is short,and the prefabricated anti-collision wall that conforms to the development trend of the industry has gradually attracted people’s attention.This paper analyzes the mechanical properties of the fabricated anti-collision wall with three different connection methods from both dynamic and static forces,verifies the reasonable reliability of the mechanical performance of the fabricated anti-collision wall,and affects the mechanics of the fabricated anti-collision wall.The performance factors are analyzed,which provides a basis for the application and promotion of prefabricated anti-collision walls.The main research contents are as follows:(1)By comparing and analyzing the mechanical properties of fabricated concrete anti-collision walls with three different connection methods,and comparing them with integral anti-collision walls,the research results show that the ultimate bearing capacity of cast-in-place monolithic anti-collision walls is 195.4kN/m,The ultimate bearing capacity of the fabricated anti-collision wall is slightly lower than that of the cast-in-place monolithic.The ultimate bearing capacity of the edge vertical steel anchor connection is 162.7kN/m;the ultimate bearing capacity of the top vertical steel anchor connection is 167.5kN/m;the sleeve method The ultimate bearing capacity of the anchoring connection is 178.5kN/m.Although it is about 16.73%lower than the ultimate bearing capacity of the cast-in-place anti-collision wall,the ultimate bearing capacity of the anti-collision wall of the three different connection methods meets the standard "Highway Guardrail Safety Performance Evaluation Standard" JTG B05-01-2013)regulations and design requirements.(2)The stress characteristics and failure modes of two kinds of prefabricated concrete anti-collision walls with transverse joints are compared and analyzed.Both tenon-and-mortise anti-collision walls and corbel anti-collision walls are under the same load.There is a big difference in lower deformation,the displacement and deformation of the corbel type transverse connection anti-collision wall are relatively large,and the tenon-and-mortise type transverse connection method is more reliable than the corbel type transverse connection.(3)According to the influence of different influencing factors on the bearing capacity of the new type of prefabricated anti-collision wall,the research shows that when the vertical steel bars reach 8,the ultimate bearing capacity of the prefabricated protective wall is 178.54 kN/m,which is about 8.6% different from that of the whole type.By changing the number and position of vertical steel bars,the bearing capacity and overall stiffness of the protective wall are increased in different degrees.When the vertical bar reaches 35 mm in diameter,against the wall,ultimate bearing capacity of 172 kn/m differ with integral by about 11.9%,by increasing the vertical bar diameter also improve the whole rigidity of fabricated protective wall structure,in practical engineering,can combine economic factors such as cost,complexity of construction technology,from the two methods to select the optimal solution,to meet the requirements of design and engineering standards.It is not obvious to reduce the bearing capacity difference between the two protective wall structures by simply increasing reinforcement ratio or concrete strength grade.The research results provide scientific basis for the popularization and application of prefabricated anti-collision wall.(4)Through the dynamic analysis of the collision process between the car and the anti-collision wall,when the car is at a speed of 80km/h and a collision angle of 20 degrees,it meets the standard "Highway Guardrail Safety Performance Evaluation Standard"(JTG B05-01-2013)stipulates that the maximum deformation of the vehicle collision anti-collision wall shall not exceed the requirement of 100 mm.The new prefabricated concrete anti-collision wall plays the role of blocking,decelerating and guiding,which shows that this kind of anti-collision wall has good protection ability.The anti-collision wall plays an important role in absorbing energy and conforms to the law of conservation of energy during the collision.