由于汽车撞击标准混凝土护栏时，汽车与混凝土护栏之间并没有真正意义上的撞击，而是通过汽车的前轮爬上混凝土护栏的坡面来消耗汽车的冲击动能，汽车结构没有与混凝土护栏发生接触，汽车结构与混凝土护栏之间没有能量交换。而汽车撞击半刚性护栏则是真正意义上的撞击，汽车结构与半刚性护栏之间要接触并进行能量交换。一般而言，半刚性护栏吸收的冲击动能比汽车前轮爬上混凝土护栏坡面吸收的能量大，所以，无论是乘员头部的HIC位，还是假人胸部的合成减速度峰值，半刚性护栏都比标准混凝土护栏具有更低的值，即半刚性护栏比标准混凝土护栏具有更优的耐撞性。

When the car hits the standard concrete guardrail, there is no real impact between the car and the concrete guardrail, but the impact kinetic energy of the car is consumed by climbing the front wheel of the car onto the slope of the concrete guardrail. The automobile structure does not contact the concrete guardrail, and there is no energy exchange between the automobile structure and the concrete guardrail. The semi-rigid guardrail is a real impact, and the vehicle structure and semi-rigid guardrail should contact and exchange energy. Generally speaking, the impact kinetic energy absorbed by semi-rigid guardrail is greater than that of the front wheel of the car climbing on the slope of concrete guardrail. Therefore, whether it is the HIC position of the occupant head or the peak value of the synthetic deceleration of the dummy's chest, the semi-rigid guardrail has lower value than the standard concrete guardrail, that is, the semi-rigid guardrail has better impact resistance than the standard concrete guardrail.

此外，大型车辆撞击标准混凝土护栏时还存在更容易翻车的问题，具体表现在车辆位置的升高上。算例表明，到t=5OOms左右时，车辆班心开始急剧升高，到t=903ms左右时，车辆位且达到极限位置346.6m（车辆侧倾角达240），然后开始下降（即开始出现翻车事故），翻车事故在所难免。由于汽车在撞击标准混凝土护栏的过程中，汽车与护栏之间的接触仅表现在汽车前轮在混凝土护栏坡面的爬行，汽车车体与混凝土护栏之间并不存在接触，即混凝土护栏的高度对预防汽车的侧翻基本不起作用，只有当侧翻已经发生后，汽车车体撞击到混凝土护栏上时，混凝土护栏的高度才对已经发生翻车的车辆的继续翻滚有抑制作用。可见，混凝土护栏并非防御大型失左车辆的理想护栏，那种在山区公路及危险路段普遍采用混凝土护栏的做法并不科学，即使增加了混凝土护栏的高度也是如此。

In addition, the problem of overturning is more easily existed when large vehicles hit the standard concrete guardrail, which is shown in the elevation of vehicle position. The example shows that when t = 5ooms, the shift center of the vehicle starts to rise sharply. When t = 903ms, the vehicle position reaches the limit position of 346.6m (the vehicle side inclination reaches 240), and then starts to decline (i.e. the rollover accident starts), and the rollover accident is inevitable. Because the contact between the car and the guardrail only shows the front wheel crawling on the slope of the concrete guardrail during the process of the automobile hitting the standard concrete guardrail, and there is no contact between the car body and the concrete guardrail, that is, the height of the concrete guardrail does not work for preventing the car from turning over. Only when the rollover has occurred, the car body hits the concrete guardrail When the height of concrete guardrail is used to inhibit the rolling over of vehicles that have already been overturned. It can be seen that concrete guardrail is not an ideal guardrail to protect large left vehicles. It is not scientific to adopt concrete guardrail in mountainous roads and dangerous sections, even if the height of concrete guardrail is increased.

而汽车撞击半刚性护栏时，算例表明，在t=600ms之前，车辆位置高度变化不大，t=600ms之后，在惯性力的作用下，车辆尾部有将护栏梁板向外推进的趋势，但在护拦梁板的阻挡下，由于车辆偏高，出现了车辆以梁板上边沿为支点向外翻滚的趋势，此时，车厢压在了护栏梁板的上沿上，并给护栏梁板施加了向下的压力，在此压力作用下，护栏梁板开始向下运动，并将梁板、防阻块及立往之间的连接螺栓逐渐剪断，使梁板逐渐脱离支撑，在此过程中甲车辆因向外翻滚的支点位置不断下降而迅速外翻，车辆位置上升很快，当t=905ms时，车辆已上升191.56mm，车辆侧倾角达14°。可见，半刚性护栏防御重型车辆侧翻的能力远优于标准很凝土护栏，但目前的半刚性护栏在重型车辆的量力作用下，将不可避免地被压溃，表现出护栏的完整性不足，因此，要彻底解决失控大型车辆的安全性问题，还必须发展新的护栏设计机理。

When the car hits the semi-rigid guardrail, the calculation example shows that before t = 600ms, the height of the vehicle position does not change much. After t = 600ms, under the action of inertia force, the rear of the vehicle has the tendency to push the guardrail beam plate outward. However, under the block of the guardrail beam plate, because the vehicle is on the high side, the vehicle rolls outward with the upper edge of the beam plate as the supporting point. At this time, the carriage is pressed on the guard The upper edge of the guardrail plate is upward and the downward pressure is applied to the guardrail beam plate. Under the pressure, the guardrail beam plate starts to move downward, and the connecting bolts between the beam plate, the anti blocking block and the vertical are cut off gradually, which makes the beam plate gradually detached from the support. During this process, the vehicle a turns out rapidly due to the falling support point position of the roll out, and the vehicle position rises rapidly. When t = 905ms , the vehicle has risen 191.56mm and the vehicle's inclination angle is 14 °. It can be seen that the semi-rigid guardrail is far better than the standard of the rigid guardrail in preventing the overturning of heavy vehicles. However, the current semi-rigid guardrail will inevitably be crushed under the measure force of heavy vehicles, which shows the lack of integrity of the guardrail. Therefore, to solve the safety problems of the runaway large vehicles, a new guardrail design mechanism must be developed.