摘要
长周期地震动因含有丰富的低频成分易使(超)高层建筑等长周期结构发生严重震害。SRC(steel reinforced concrete)框架-RC(reinforced concrete)核心筒混合结构作为广泛应用于高烈度区的双重抗侧力结构体系,确保其强震下的协同工作是实现多道抗震防线,形成合理破坏模式的关键。该文通过与普通地震动对比,阐明了远场长周期地震动对SRC框架-RC核心筒混合结构协同工作的影响规律,并基于谐振激励下的结构动力分析模型及经验模态分解初步揭示了其内在机理。算例分析结果表明:受低频特性影响,远场长周期地震动作用下结构框架剪力分担率与底层倾覆力矩占比明显大于普通地震动,最大框架剪力分担率所在楼层与普通地震动相比出现下移,且当峰值加速度增至400 gal时,SRC框架中下部楼层剪力分担率超过40%,底部倾覆力矩占比超过70%,按照现行规范设计的SRC框架将难以保证远场长周期地震动作用下结构的抗震安全;激励频率对于SRC框架-RC核心筒混合结构协同工作的影响与振型参与方式有关,低频激励(周期为0.5倍~2.0倍结构基本周期)下结构响应主要受低阶振型主导;远场长周期地震动的卓越分量是导致框架剪力分担率增大的原因。
Due to the abundance of low-frequency components in FLPGMs(far-field long-period ground motions),long-period structures,such as high-rise buildings,are susceptible to severe damage.The SRC(steel reinforced concrete) RC(frame-reinforced concrete) core wall hybrid structure is a kind of dual structural system widely used in regions with high seismic intensity.Ensuring its cooperative work is the key to realizing multiple seismic fortification lines and reasonable structural failure modes under severe earthquakes.In this paper,the influence of FLPGMs on the cooperative work of SRC frame-RC core wall hybrid structures was clarified by comparing it with that under CGMs(conventional ground motions).Its internal mechanism was preliminarily revealed based on the structural dynamic analysis model under harmonic excitation and empirical mode decomposition.The calculated examples show that the frame shear and overturning moment sharing ratios under FLPGMs are significantly greater than those under CGMs.The floor with the maximum frame shear sharing ratio is lower than that under CGMs.When the PGA(peak ground acceleration) of FLPGMs increases to 400 gal,the frame shear and overturning moment sharing ratios of the SRC frames exceed 40% and 70%,respectively.It will be difficult to ensure the seismic safety of SRC frame-RC core wall hybrid structures designed by the current code under FLPGMs.The influence of excitation frequency on the cooperative work of structures is related to the participation of vibration modes.Structural responses under low-frequency excitation(with a period of 0.5-2.0 times the structural period) are dominated by the lower mode.The predominant IMF component of FLPGMs is the cause of the increased frame shear shearing ratio.
作者
杨柯
王博
祝超
刘伯权
李红
YANG Ke;WANG Bo;ZHU Chao;LIU Boquan;LI Hong(School of Civil Engineering,Chang’an University,Xi’an 710061,China)
出处
《振动与冲击》
EI
CSCD
北大核心
2024年第12期36-45,共10页
Journal of Vibration and Shock
基金
国家自然科学基金(51978076)。
