Reinforced concrete(RC) load bearing wall is widely used in high-rise and mid-rise buildings. Due to the number of walls in plan and reduction in lateral force portion, this system is not only stronger against earthqu...Reinforced concrete(RC) load bearing wall is widely used in high-rise and mid-rise buildings. Due to the number of walls in plan and reduction in lateral force portion, this system is not only stronger against earthquakes, but also more economical. The effect of progressive collapse caused by removal of load bearing elements, in various positions in plan and stories of the RC load bearing wall system was evaluated by nonlinear dynamic and static analyses. For this purpose, three-dimensional model of 10-story structure was selected. The analysis results indicated stability, strength and stiffness of the RC load-bearing wall system against progressive collapse. It was observed that the most critical condition for removal of load bearing walls was the instantaneous removal of the surrounding walls located at the corners of the building where the sections of the load bearing elements were changed. In this case, the maximum vertical displacement was limited to 6.3 mm and the structure failed after applying the load of 10 times the axial load bored by removed elements. Comparison between the results of the nonlinear dynamic and static analyses demonstrated that the "load factor" parameter was a reasonable criterion to evaluate the progressive collapse potential of the structure.展开更多
砌体填充墙作为非结构构件在建筑结构抗爆分析中常被忽略,而实际爆炸事故中填充墙多发生严重破坏,从而影响爆炸波的传播及其与结构的相互作用以及结构的损伤破坏等级。基于精细化数值仿真方法评估外部爆炸作用下砌体填充墙对钢筋混凝土(...砌体填充墙作为非结构构件在建筑结构抗爆分析中常被忽略,而实际爆炸事故中填充墙多发生严重破坏,从而影响爆炸波的传播及其与结构的相互作用以及结构的损伤破坏等级。基于精细化数值仿真方法评估外部爆炸作用下砌体填充墙对钢筋混凝土(reinforced concrete,RC)框架结构损伤破坏的影响。首先,采用LS-DYNA有限元分析软件分别对典型砌体填充墙和含填充墙RC框架的近区爆炸试验进行复现,验证所采用的填充墙简化微观建模方法、材料本构模型和参数,以及任意拉格朗日欧拉爆炸荷载施加方法和爆炸波-结构流固耦合算法的适用性。进一步结合结构混合单元建模方法,开展了美国联邦应急管理署规定的普通轿车炸弹(454 kg TNT当量)在底层边柱位置爆炸下,6度、7度和8度抗震设防烈度的典型6层纯框架和含填充墙框架结构动力行为的数值仿真分析,考察了爆炸波传播路径,以及结构的动态响应、损伤破坏和抗倒塌机制。结果表明:该工况中填充墙能够有效阻挡爆炸波的传播,作用于目标柱相邻内柱上的超压峰值降低95%,减轻了内部构件的损伤程度;但同时加剧了结构迎爆面的损伤破坏,如3种抗震设防烈度的含填充墙框架目标柱柱中侧向位移较纯框架分别增加21.4%、31.1%和14.8%;不同抗震设防烈度的纯框架和含填充墙框架的顶层目标柱竖向位移基本相同,即抗震设防烈度及砌体填充墙对框架结构整体倒塌行为的影响可以忽略。展开更多
文摘为探究钢筋混凝土(reinforced concrete,RC)梁在侧向近爆荷载下的动力响应和破坏形态,基于通用显式有限元分析软件LS-DYNA建立RC梁数值模型展开数值分析,并与竖向近爆荷载作用时RC梁进行对比,分析比例距离、惯性矩、荷载作用面积及不对称配筋对RC梁动力响应和破坏形态的影响。通过改进等效单自由度法进一步分析RC梁承受侧向近爆荷载时的动力响应发现:随着比例距离的减小,RC梁的动力响应逐渐增大;由于惯性矩和荷载作用面积的影响,侧向起爆时的峰值位移是竖向起爆时的4~5倍;侧向起爆时RC梁不对称配筋对位移影响较小;改进的等效单自由度(single degree of freedom,SDOF)法可用于侧向近爆荷载作用下RC梁的动力响应计算,结果可靠且计算效率高;竖向起爆时,随着比例距离的减小,RC梁的破坏形态由弯曲破坏逐渐转变为弯剪破坏,随着比例距离的减小剪力影响越来越大;侧向起爆时,随着比例距离的减小,RC梁的破坏形态由弯曲破坏逐渐转变为局部破坏,配筋率高的侧面可以更好地抑制混凝土裂缝的产生和发展;竖向起爆时RC梁具有更强的抗爆性能,RC梁承受侧向爆炸荷载时会发生更严重的破坏,对结构的影响更大,因此需重视侧向爆炸荷载下RC梁的工程防护研究。
文摘Reinforced concrete(RC) load bearing wall is widely used in high-rise and mid-rise buildings. Due to the number of walls in plan and reduction in lateral force portion, this system is not only stronger against earthquakes, but also more economical. The effect of progressive collapse caused by removal of load bearing elements, in various positions in plan and stories of the RC load bearing wall system was evaluated by nonlinear dynamic and static analyses. For this purpose, three-dimensional model of 10-story structure was selected. The analysis results indicated stability, strength and stiffness of the RC load-bearing wall system against progressive collapse. It was observed that the most critical condition for removal of load bearing walls was the instantaneous removal of the surrounding walls located at the corners of the building where the sections of the load bearing elements were changed. In this case, the maximum vertical displacement was limited to 6.3 mm and the structure failed after applying the load of 10 times the axial load bored by removed elements. Comparison between the results of the nonlinear dynamic and static analyses demonstrated that the "load factor" parameter was a reasonable criterion to evaluate the progressive collapse potential of the structure.
文摘砌体填充墙作为非结构构件在建筑结构抗爆分析中常被忽略,而实际爆炸事故中填充墙多发生严重破坏,从而影响爆炸波的传播及其与结构的相互作用以及结构的损伤破坏等级。基于精细化数值仿真方法评估外部爆炸作用下砌体填充墙对钢筋混凝土(reinforced concrete,RC)框架结构损伤破坏的影响。首先,采用LS-DYNA有限元分析软件分别对典型砌体填充墙和含填充墙RC框架的近区爆炸试验进行复现,验证所采用的填充墙简化微观建模方法、材料本构模型和参数,以及任意拉格朗日欧拉爆炸荷载施加方法和爆炸波-结构流固耦合算法的适用性。进一步结合结构混合单元建模方法,开展了美国联邦应急管理署规定的普通轿车炸弹(454 kg TNT当量)在底层边柱位置爆炸下,6度、7度和8度抗震设防烈度的典型6层纯框架和含填充墙框架结构动力行为的数值仿真分析,考察了爆炸波传播路径,以及结构的动态响应、损伤破坏和抗倒塌机制。结果表明:该工况中填充墙能够有效阻挡爆炸波的传播,作用于目标柱相邻内柱上的超压峰值降低95%,减轻了内部构件的损伤程度;但同时加剧了结构迎爆面的损伤破坏,如3种抗震设防烈度的含填充墙框架目标柱柱中侧向位移较纯框架分别增加21.4%、31.1%和14.8%;不同抗震设防烈度的纯框架和含填充墙框架的顶层目标柱竖向位移基本相同,即抗震设防烈度及砌体填充墙对框架结构整体倒塌行为的影响可以忽略。
