With the continuous increase of highway mileage in China, the absolute number of traffic accidents is also on the rise, resulting in huge loss of life and property. According to statistics, there were 567,753 road traffic accidents in 2004, causing 99,217 deaths and 451,810 injuries. Direct property losses of 2.77 billion yuan One-third of the fatal accidents occurred in bicycle accidents involving car and roadside collisions. As the most important warning device on the road to ensure the normal running of the vehicle, the design of the structure and the location setting have been widely recognized by many road design departments. Studies have shown that some road traffic accidents are caused by unsafe or unreasonable road safety and warning facilities. For example, there are problems with the setting of the signboard position on both sides of the road and the central isolation belt in China, which is likely to cause high-speed collision stiffness of the car. Huge signposts that cause serious loss of life and property. Therefore, research on safety and warning facilities where vehicles and roadsides are likely to collide, such as high-speed collision signage pillars, streetlight pillars, traffic light pillar emergency call booths, etc., to reduce the damage of vehicles and occupants in traffic accidents, China's road driving environment is more humanized, and it has become an urgent problem to be solved. 1 The problem of the indicator column is that the design of the road traffic warning facilities used in China is mostly to introduce advanced foreign mature technologies and products, basically in accordance with relevant The technical specification design and construction did not fully take into account the serious damage caused by the high-speed collision rigidity of the indicator column. As shown, a high-speed collision signage column of a convertible car, due to the rigidity of the column and the narrow contact surface, causes the vehicle to be scrapped and the occupant is seriously injured. However, the column is only slightly deformed during the entire collision process, so the difference between the column and the vehicle stiffness is too great. , does not meet the requirements of collision compatibility. Car collision signposts China's highway signs are roughly divided into single-column double-column type and gantry type. The main column materials are steel and concrete. With the development of the times, the concrete columns have been basically The indicator pillars that have been installed and used are mostly made of steel pipe and I-beam. The single-column and double-column (as shown) columns are made of steel pipes and are placed on the roadbed. The gantry type The column is made of I-beam, placed on the roadbed on both sides, or one of the diameters of the steel pipe column placed on the one side of the central separation zone (: 200~ thickness is 4~8mm; The section of the word steel column is (150~250)mmX(280~350)mm, and the thickness is 4~8mm. The specific size parameters of the column are determined according to the actual conditions of the highway. The signboard mainly bears the wind load. The specification requires that the signs designed and installed are resistant to the 12th grade wind because the rigidity of the sign post is huge, and the contact faces of the car when the car collides with the column are narrow, so that the damage degree of the car and the occupant is greater than that of the collided guardrail under the same collision condition. The degree of damage is as shown in the figure. A foreign company conducted a test of a car crashing concrete column. The collision speed of the car is only 30km/h. According to the average acceleration formula: /s; vi is the pre-collision speed, m/s; g is the gravitational acceleration. 9.8m/s2; S is the collision deceleration distance, the car movement diagram when the m car collides with the column. In order to reduce the damage degree of the collision to the vehicle and the occupant, some foreign research institutions have designed the aluminum sign post (as shown). The truss structure is used to make the column have sufficient rigidity to withstand the wind load; in the collision process, since the tensile strength e of the aluminum is only 30% of the steel, the root of the column is broken, which can greatly reduce the damage degree of the vehicle and the occupant. The change makes the collision process change from the original "column strong car weak" to "car strong column weak", in line with the requirements of collision compatibility. The accidental P-Camel ublisher has designed and installed and used the experience! The collision distance of the collision column of the car is only 0.1m. Substituting the formula (1) can reduce the occupant by up to 35g. Exceeding the maximum allowable deceleration value recommended by the US standard in Table 1, the collision will cause serious injury to the occupant.
Table 1 The maximum allowable deceleration value recommended by the US standard. Occupant restraint condition Maximum deceleration / g Horizontal longitudinal composite value Unconstrained situation Belt belt type three-point seat belt collision barrier Re-collision column accident identification work, found accident secondary The reason is that the position of the indicator column is unreasonable and the rigidity of the column is too large. The collision causes the vehicle to appear appendix, and the vehicle and the occupant are seriously injured. As shown in the foreign new aluminum sign post, although the aluminum sign column has good collision performance. However, the high price of aluminum material will inevitably increase the cost of road construction. Therefore, the aluminum column can not be used as the research and development direction of China's indicator column. According to the research on a large number of such traffic accidents in China, the author believes that the new type of column that can be quickly separated during the collision process is the research and development direction of China's indicator column and other similar columns. It should have the advantages of reasonable structure, convenient installation and use. It is conducive to reducing the damage degree of vehicles and occupants in collisions. 2 New signage column research According to the above analysis, measures to reduce the damage degree of vehicles and occupants during collision can be roughly divided into three types: (1) reduction indication The thickness of the column; (2) increase the collision contact area; (3) the column and the foundation quickly detach from the collision process. According to the above guiding ideology, the new type of signpost column with rapid separation after collision and collision is 2mm thick. The elastoplastic deformation of the column absorbs the kinetic energy of the vehicle during the collision process, so that it can absorb in both directions and meet the requirements of collision compatibility. The shape of the column is square, the section size is 300mmK300mm, which can increase the collision contact area and prevent the car from being seriously deformed locally; the base is installed at the lower end of the column, and the base is installed on the concrete foundation. The base and the column are connected by 8 rivets. By cutting the rivet method to achieve rapid separation of the two according to the actual requirements of different regional roads, the size parameters of the column can be adjusted slightly. The above designed column has sufficient rigidity to resist the 12-level typhoon in order to test the rapid detachment after collision. The collision performance of the new indicator column, using the finite element simulation software to carry out two car collision sign column test collision vehicles selected the current mainstream models on the road: intermediate cars and heavy goods vehicles; the collision angle refers to the design requirements of the collision barrier; collision Speed ​​is the highest for highways
Table 2 Test Collision Parameters Collision Model Quality Collision Speed ​​Collision Angle Medium-size car heavy-duty truck signage column, base and rivet material selection 1018 steel, select plastickinematicalmodel (plastic follow-up elastic plastic material) model, the specific parameters are shown in Table 3 project unit numerical elasticity Modulus E density Poisson's ratio No unit yield stress e Tangential modulus Et The equivalent plastic strain at failure No unit, no unit, sm:c ternary model of the intermediate car collision signage column as shown, the entire finite element model It is divided into 36294 nodes and 35243 shell units. It takes 2h12min on the Pentium4 computer. The simulation results are shown as ~0. The finite element model of the heavy truck collision sign column is shown as 1 and the whole finite element model is divided into 116245. According to the above finite element simulation test, the node and 129586 shells are used to calculate the rapid detachment function of the column when the vehicle collides with the column. The column is under the action of the collision force within 50ms. The shear rivet is separated from the base; according to the velocity and acceleration diagram analysis, the maximum acceleration of the two collisions Do not be 8g, refer to Table 1, it can be proved that the occupant under the protection of the seat belt, the collision will not cause serious damage to the occupant. According to the above test, the design has good protection for vehicles and occupants, and it is worthy of further research and promotion.
3 Conclusion With the rapid development of China's high-grade highways and ordinary highways, the highway design puts forward a new concept of humanization, embodying the people-oriented thinking, and therefore vigorously carry out research on safety and warning facilities where vehicles and roadsides may collide. The new trend of highway design and research According to the test, the new indicator column can realize the separation of the column and the base by cutting the rivet during the collision process, which is beneficial to reduce the damage degree of the vehicle and the occupant in the collision. Value and marketing value The new indicator column also needs to be improved by the following studies: statistics and analysis of accidents in the roadside safety and warning facilities of the car collision in the past five years, and determining the distance between the indicator column and the curb in different grades of roads; In-depth study of plastics and its use in roadside safety and warning facilities to save costs, engineering plastics is a new direction for roadside safety and warning facilities research; actual vehicle crash test, modification of dimensional parameters, further improve Performance of new signage columns
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