【作者】 李慧；

【导师】 汪梦甫； 张明；

【作者基本信息】 湖南大学 ， 土木工程， 2023， 硕士

【摘要】 在地震作用下普通的钢筋混凝土连梁容易发生脆性剪切破坏,震后难以修复。随着各国学者对可恢复功能结构的研究,提出了可更换连梁的概念,将损伤和变形都集中在更换段部分,保持非更换段基本处于弹性状态,只需要在地震作用后更换更换段部分,就能达到快速恢复使用的目的。本文主要针对可更换混凝土连梁进行研究,主要的研究内容和成果如下:(1)对可更换混凝土连梁的抗震设计进行了总结,包括更换段设计、非更换段设计及连接部分设计,对基于以上设计方法设计的可更换混凝土连梁试件的试验概况进行了描述。(2)基于ABAQUS有限元软件建立精细化的实体单元模型,并进行单调加载,将模拟得到的骨架曲线和应力应变云图与试验结果及试验现象进行对比,验证该建模方法的有效性。基于Open Sees建立简化数值模型,进行循环加载,将模拟得到的滞回曲线、骨架曲线及耗能等与试验数据进行比较,二者吻合较好。(3)基于验证过的模型,研究刚度比对带楼板可更换混凝土连梁力学性能及耗能能力的影响,并给出参数取值范围。随着刚度比增大,带楼板可更换混凝土连梁的极限荷载逐渐增大,延性和耗能能力逐渐减小。刚度比在0.42～0.50之间时,更换段腹板达到了极限抗拉强度,非更换段混凝土连梁的钢筋和预埋板都没有屈服,混凝土状态良好,损伤集中在更换段上;在此区间,试件的极限承载力有很大提高,延性和耗能能力都相对较好。(4)基于验证过的模型,研究长度比对带楼板可更换混凝土连梁力学性能及耗能能力的影响,并给出参数取值范围。随着长度比增大,带楼板可更换混凝土连梁的极限荷载逐渐降低,其延性系数先增大后减小。长度比在0.70～0.98之间时,更换段腹板达到了极限抗拉强度,非更换段混凝土梁的钢筋和预埋板都没有屈服,混凝土状态良好,损伤集中在更换段上;在此区间,楼板的损伤相对较小,试件的极限承载力相对较高,且随着长度比增大,对试件承载力的削弱也较小,延性和耗能能力都比较好。(5)对可更换连梁进行性能水准划分,分为基本完好、轻度损伤、中度损伤和严重损伤四个水平。收集相关文献的试验数据,通过数理统计的方法计算出各性能状态下的梁端转角限值分别为0.004、0.01、0.023、0.04。采用Kratzig损伤模型对试件进行损伤分析,得到各性能状态下的损伤指标限值分别为0.1、0.4、0.85、1。更多还原

【Abstract】 Ordinary reinforced concrete coupling beams are prone to brittle shear failure under earthquake action and are difficult to repair after an earthquake.With the research on recoverable functional structures by scholars from various countries,the concept of replaceable coupling beams has been proposed.Damage and deformation are concentrated in the replacement section,keeping the non-replacement section basically in an elastic state.After an earthquake,it is only necessary to replace the replacement section to achieve the goal of rapid recovery.This article mainly focuses on the research of replaceable concrete coupling beams.The following are the main research contents and achievements of this article:(1)The seismic design of replaceable concrete coupling beams is summarized,including the design of replacement section,the design of non-replacement section,and the design of connecting section.The experimental overview of replaceable concrete connecting beam specimens designed based on the above design methods was described.(2)A refined solid element model was established based on ABAQUS and subjected to monotonic loading.The simulated skeleton curves and stress-strain nephogram were compared with experimental results and phenomena to verify the effectiveness of the modeling method.A simplified numerical model was established based on Open Sees,and cyclic loading was performed.The simulated hysteretic curve,skeleton curve,and energy consumption were compared with the experimental data,and the results were close.(3)Based on the validated model,study the effects of stiffness ratio on the mechanical properties and energy dissipation capacity of replaceable concrete coupling beams with floor slabs,and provide parameter ranges.As the stiffness ratio increases,the ultimate load of replaceable concrete connecting beams with floor slabs gradually increases,while ductility and energy dissipation capacity gradually decrease.When the stiffness ratio is between 0.42 and 0.50,the web of the replacement section reaches the ultimate tensile strength,and the reinforcement and embedded plate of the nonreplacement section concrete coupling beam do not yield.The concrete is in good condition,with damage concentrated on the replacement section;In this interval,the ultimate bearing capacity of the specimen has been greatly improved,with relatively good ductility and energy consumption capacity.(4)Based on the validated model,study the effects of length ratio on the mechanical properties and energy dissipation capacity of replaceable concrete coupling beams with floor slabs,and provide parameter ranges.As the length ratio increases,the ultimate load of replaceable concrete connecting beams with floor slabs gradually decreases,and their ductility coefficient first increases and then decreases.When the length ratio is between 0.70 and 0.98,the web of the replacement section reaches the ultimate tensile strength,and the reinforcement and embedded plate of the nonreplacement section concrete beam do not yield.The concrete is in good condition,with damage concentrated on the replacement section;In this interval,the damage to the floor is relatively small,and the ultimate bearing capacity of the specimen is relatively high.As the length ratio increases,the weakening of the bearing capacity is also small,and the ductility and energy dissipation capacity are relatively good.(5)The performance level of replaceable coupling beams is divided into four levels: basically intact,mildly damaged,moderately damaged,and seriously damaged.Collect experimental data from relevant literature,and calculate the displacement angle limit values of 0.004,0.01,0.023,and 0.04 for each performance state through mathematical statistics.The Kratzig damage model was used to analyze the damage of the specimen,and the damage index limits for each performance state were obtained to be 0.1,0.4,0.85,and 1,respectively.更多还原