Lee Jaeha, Jeong Yoseok, Kim Kyeongjin, Lee Ilkeun, Kim WooSeok
Department of Civil Engineering, National Korea Maritime and Ocean University, 727 Taejong-ro, Youngdo-gu, Busan 49112, Korea.
Research Institute for Construction Disaster Prevention, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Korea.
Materials (Basel). 2019 Sep 27;12(19):3176. doi: 10.3390/ma12193176.
In South Korea, the number of vehicles is gradually increasing. The number of heavy vehicles in 2010 increased up to 19% in less than five years. Therefore, the chances of heavy vehicle-concrete median barrier (CMB) collision also became higher than in the past; therefore, a need to study a stricter design level for improving the current CMB (CMB-15) under harsher environments arose. Accordingly, in the present study, a new concrete median barrier was designed under a stricter impact severity, SB6(420 kJ), compared to the current design impact severity, SB5-B (270 kJ). In particular, shock absorbing devices to absorb impact energy were applied to the CMB. An empty space allows the dowel bars to deform and absorb collision energy. Therefore, deformable CMB was designed and tested. The key parameters selected in our study were dowel bar and wire-mesh. A series of numerical analyses were conducted to evaluate the proposed new deformable CMB designs with shock absorbers. Finally, the optimal design, CMB-17S, was proposed after several evaluations of the proposed designs and a full-scale field test. It was found that, although the developed model did not accurately predict the impact sequence due to certain differences between the actual truck and the truck model, the permanent deformation after collision could be well predicted. Based on the observations from a full-scale impact test, it was recommended that the top part of the CMB should be strengthened since major volume loss occurred due to local impact, which appeared to be due to punching shear failure.
在韩国，车辆数量在逐渐增加。2010年重型车辆的数量在不到五年的时间里增长了19%。因此，重型车辆与混凝土中央分隔带（CMB）碰撞的几率也比过去更高；因此，需要研究在更恶劣环境下提高当前CMB（CMB - 15）的更严格设计标准。相应地，在本研究中，与当前设计冲击强度SB5 - B（270 kJ）相比，在更严格的冲击强度SB6（420 kJ）下设计了一种新的混凝土中央分隔带。特别是，在CMB上应用了吸收冲击能量的减震装置。一个空隙允许传力杆变形并吸收碰撞能量。因此，设计并测试了可变形CMB。我们研究中选择的关键参数是传力杆和金属丝网。进行了一系列数值分析，以评估提出的带有减震器的新型可变形CMB设计。最后，在对提出的设计进行多次评估和全尺寸现场测试后，提出了最优设计CMB - 17S。结果发现，尽管由于实际卡车与卡车模型之间存在某些差异，所开发的模型没有准确预测冲击顺序，但碰撞后的永久变形可以得到很好的预测。基于全尺寸冲击试验的观察结果，建议加强CMB的顶部，因为由于局部冲击导致了大量体积损失，这似乎是由于冲剪破坏造成的。
