【作者】 李伟；

【导师】 田力； 张利民；

【作者基本信息】 天津大学 ， 建筑与土木工程， 2020， 硕士

【摘要】 伴随经济水平的提高,我国建筑行业迎来大发展,钢筋混凝土结构理论体系也日趋完善。然而,由于极端主义、恐怖主义以及生活中的意外等问题的存在,爆炸意外事件也时有发生。本文主要是利用ANSYS/LS-DYNA有限元分析软件,模拟现浇钢筋混凝土框架结构、预应力装配式钢筋混凝土框架结构在爆炸冲击波和预制破片复合作用下的损伤特征及规律。基于本文有限元模型,主要成果如下:(1)建立了现浇钢筋混凝土框架结构、预应力装配式钢筋混凝土框架结构、炸药、空气、破片及刚性地面组成的有限元模型。通过对爆炸荷载下框架结构的动态响应、炸药驱动破片速度及破片侵彻混凝土深度等相关试验进行数值模拟计算,经对比分析,验证本文所选择材料本构模型、研究方法、接触类型及控制参数的合理性和有效性。(2)对比分析了在冲击波单独作用、冲击波和破片复合作用下,框架结构的损伤破坏及连续倒塌情况。研究表明:破片的侵彻穿孔效应能够削弱钢筋混凝土的抗爆能力,从破坏模式看,冲击波单独作用时,背爆面最先破坏,并随着侧向位移的增加逐渐失效破坏;冲击波-破片复合作用下,迎爆面最先破坏,表现为破片侵彻破坏特征。在抗爆设计时,应考虑破片侵彻作用对结构的毁伤破坏。(3)破片层数的增加,结构的损伤破坏增大,倒塌速率加快,抗连续倒塌能力减弱。外部爆炸工况下,破片层数增加,结构的损伤影响较大,倒塌速率明显加快;而内部爆炸工况下,破片层数的增加对结构损伤破坏程度的增大有限,倒塌速率加快较少。(4)柱体外部单独喷涂聚脲弹性体的防护措施具有一定的抗爆效果;采取高强钢丝网加聚脲弹性体联合防护的措施会明显提高结构的抗复合作用性能。改造加固现有框架结构时,可采用梁柱节点处外贴钢板的方法,提高结构的抗倒塌能力;在抗倒塌设计时,可在梁柱节点处一定范围内增加梁纵筋配筋,以加强梁柱连接,提高抗倒塌能力。(5)装配式框架结构的抗倒塌能力弱于现浇结构;预应力钢绞线的存在提高装配式框架结构的抗倒塌能力;同时提高预制构件及现浇部分的混凝土强度,能有效延缓结构的倒塌速率;预制梁伸入核心区长度适当加长,结构的倒塌速率变慢。保持破片总质量不变时,破片尺寸增大,结构的损伤破坏程度降低。保持炸药比例距离不变,在冲击波单独作用以及冲击波-破片复合作用两种荷载类型下,结构损伤呈现相同的规律:随着炸药量及距离增大,结构的损伤破坏程度增大。更多还原

【Abstract】 With the improvement of economic level,China’s building industry ushers in a great development,and the theoretical system of reinforced concrete structure is becoming more and more perfect.In this paper,the finite element analysis software ANSYS / LS-DYNA is used to simulate the damage characteristics and rules of cast-in-place reinforced concrete frame structure and prestressed prefabricated reinforced concrete frame structure under the action of the blast wave and prefabricated fragments.Based on the finite element model,the main achievements are as follows:(1)A finite element model consisting of cast-in-situ reinforced concrete frame structure and prestressed prefabricated reinforced concrete frame structure,explosives,air,fragments and rigid ground was established.Through the numerical simulation of dynamic response of frame structure,fragment velocity driven by explosives and penetration depth of fragments into concrete under explosive load,the material constitutive model,research method,contact type and control parameters selected in this paper are verified rationality.(2)The damage and continuous collapse of frame structure under the action of shock wave alone,shock wave and fragment are analyzed.The results show that penetration and perforation effect of fragments can weaken the ant-explosion ability of reinforced concrete.In terms of failure mode,when blast acting alone,the back blasting surface is the first to be damaged,and gradually fails with the increase of lateral displacement.The front blasting surface is the first to be damaged under the synergistic effects of blast and fragments,showing the characteristics of fragment penetration damage.(3)With the increase of fragments layers,the damage of the structure increases,the collapse rate increases,and the resistance to continuous collapse weakens.Under the external explosion condition,the number of fragments increases,the damage of the structure is greatly affected,and the collapse rate is obviously accelerated;while under the internal explosion condition,the increase of the number of fragments has limited effect on the damage degree of the structure,and the collapse rate is less accelerated.(4)The protective measure of spraying polyurea elastomer outside the column have certain anti-explosion effect.The anti-composite performance of the structure will be improved by adopting the union measures of high-strength steel wire mesh and polyurea elastomer.When strengthening the existing frame structure,the method of attaching steel plates along the beam can be used to improve the anti-collapse ability of the structure.The longitudinal reinforcement ratio can be added in a certain range of beam-column joints to strengthen the connection capacity of beam-column joints and improve the anti-collapse ability in the anti-collapse design.(5)The anti-collapse ability of the prefabricated structure is weaker than that of the cast-in-place structure.The prestressing tendon improves the anti-collapse ability of the prefabricated structure.The collapse rate of the structure can be effectively delayed when improves the concrete strength of prefabricated components and cast-in-place parts at the same time.The length of precast beam extending into the core area is longer,and the collapse rate of the structure is slower.When the total mass of fragments remains unchanged,the size of fragments increases and the damage degree of the structure decreases.When the proportion distance of explosives remains unchanged,the damage degree of structure increases with the increase of explosive amount and distance under the action of shock wave alone.更多还原