预应力混凝土连续梁桥桥面爆炸损伤试验研究

Experimental Study on Damage of Prestressed Concrete Continuous Girder Bridge Subjected to Explosions Above the Deck

为了研究桥面爆炸荷载作用下预应力混凝土连续T梁桥的抗爆性能,进行了2×8 m两跨预应力混凝土连续T梁桥模型的野外爆炸试验,并结合数值模拟的方法,研究了不同爆心位置和桥面爆炸荷载作用下预应力混凝土连续T梁桥的动力响应、破坏模式及损伤程度。研究结果表明:跨中桥面上方发生爆炸时,预应力混凝土连续T梁桥桥面破坏形态均表现为桥面板混凝土破碎开洞、T梁腹板和梁底混凝土崩落,属局部冲切破坏;中墩墩顶上方发生爆炸时,预应力混凝土连续T梁桥桥面未发生严重毁伤,邻近中支点的横隔板出现由顶部爆心轴线处向横隔板底放射形扩散的裂缝。相同药量和爆心高度下,桥面中梁跨中爆炸时中梁底加速度峰值最大,桥面边梁跨中爆炸时中梁底加速度峰值最小;提升混凝土强度、箍筋加密布置、施加预应力和增大宽跨比等能一定程度地提高主梁的抗爆性能;研究成果可供梁桥的抗爆防护设计参考。

In order to study the blast-resistant capability of prestressed concrete continuous T-girder bridges under explosions above the deck, the field explosion test of the 2×8 m two-span prestressed concrete continuous T-girder bridge model was carried out, and the dynamic response, failure mode and damage degree of the prestressed concrete continuous T-girder bridge under the explosion above the deck with different explosive center position were studied in combination with the numerical simulation method. The results show that when explosions above the deck occur at mid-span, the damage patterns of the prestressed concrete continuous T-girder bridge are characterized by the broken of the concrete deck, the spalling of the web and the bottom of the girder. They are local punching failures. When explosions above the deck occur at the top of the middle pier, the deck of the prestressed concrete continuous T-beam bridge is not seriously damaged, and the diaphragm adjacent to the middle bearing has cracks radially spreading from the top explosive center axis to the bottom of the diaphragm. At the same charge weight and height, the peak acceleration at the bottom of the central girder is the largest when the explosion occurs at the mid-span of the central girder, and the peak acceleration at the bottom of the central girder is the smallest when the explosion occurs at the mid-span of the side girder. Improving the strength of concrete, infilling arrangement of stirrups, applying prestress and increasing the ratio of width to span can improve the blast-resistant performance of girders to some extent. The research results can be used as references for the blast-resistant protection design of girder bridges.