【作者】 王琦；

【导师】 郑达； 赵华；

【作者基本信息】 成都理工大学 ， 土木工程， 2020， 硕士

【摘要】 近几十年来,超越规范设计的大震和特大地震的频繁发生以及地震呈现出连续强震的特点,给结构工程带来了新的挑战。我国现行规范采用延性结构设计,而延性混凝土结构在遭遇超过规范设防水准的强震时,仅能保证结构不倒塌,建筑物已经发生严重的破坏和过大的残余变形,难以修复甚至只能拆除重建。同时,现行规范设计中对大震和长周期地震运动下的结构抗震性能没有充分的研究。为保证新建结构在大震下具有足够的抗震性能且损伤可修复,可恢复结构的概念被提出,可恢复结构至少应该具备以下两个特点:1)稳定的大震响应,即使在高轴压情况下,直到大变形阶段,结构承载能力也不会降低,即结构在大变形下也应该具有正刚性;2)在经历超越现行抗震设计规范规定的设防水准的地震时,控制结构残余变形在2%以内,确保损伤可修复,能快速恢复使用功能。本研究提出采用低粘高强的高强钢棒(HB)作为圆柱主筋,以实现钢筋混凝土柱在大震下的可修复性。进行了6根钢筋混凝土圆柱的低周反复水平荷载试验,分析了纵筋类型、剪跨比、约束方式等因素对试件滞回曲线、承载能力、变形能力和耗能能力的影响;并通过机理分析和数值拟合的方式,建立了自复位混凝土圆柱骨架曲线模型;研究还通过定量评估最大裂缝宽度和残余裂缝宽度来预测地震后受损自复位钢筋混凝土柱修复的可行性。由试验可见,和普通钢筋混凝土圆柱相比,采用HB的钢筋混凝土圆柱表现出明显的二次正刚性,在位移角2%之前最大裂缝宽度仅有1.2mm,残余裂缝宽度仅有0.4mm,在位移角6%之前残余位移角均在2%以内;且抗侧向力提高50%以上,在位移角达到6%时仍表现出良好的自复位能力和抗震性能;而采取了外加钢板约束和HB的组合试件,承载力进一步提高17%,表现出更高的承载力和更好的自复位性能。通过对采用HB的钢筋混凝土圆柱的抗震性能进行研究可见,通过低粘结高强度钢筋的使用,能够有效控制大变形下构件的残余变形,改善结构损伤,实现柱的自复位性,因此HB的使用可以为自复位混凝土圆柱在地震区高层建筑中的发展和应用开辟一条有效且简洁的途径。更多还原

【Abstract】 The frequent occurrence of large earthquakes and mega earthquakes beyond the normal design and continuous strong earthquakes have brought new challenges to structural engineering over the past decades.In China,the ductility structure design is adopted in the current codes.However,encountering strong earthquakes exceeding the standard fortification level,the ductile concrete frames can only ensure that the structure does not collapse,with the buildings already suffering from serious damage and excessive residual deformation.It is so difficult to restore the damaged buildings that they have to be demolished and rebuilt.Meanwhile,the seismic performance of the structures under large earthquake and long-period earthquake motion has not been fully studied in the current code design.In order to ensure that new structure has enough seismic performance and the damage can be repaired,the concept of resilient concrete structure is put forward.The resilient concrete structure should have at least two characteristics: 1)a stable large earthquake response----even under high axial compression,the bearing capacity of the structure will not be reduced until the large deformation stage.In other words,the structure should have a positive rigidity under large deformation;2)the residual deformation of the structure should be controlled within 2% over the seismic level specified in the current seismic design specification,so as to ensure that the structure can be repaired and quickly resume function.In this study,an ultra-high strength steel bar(HB)with low bond-strength is used as the longitudinal reinforcement to realize resilience of RC columns under large earthquake.6 RC columns are tested under the reversed cyclic lateral loading.The effects of longitudinal reinforcement type,shear span ratio and confinement on hysteretic curves,bearing capacity,deformation capacity and energy dissipation capacity of the columns are analyzed.Through the mechanism analysis and numerical fitting,a self-centering RC skeleton curve model is established.The feasibility of restoring damaged concrete columns after earthquake is quantitatively evaluated by the maximum crack width and the residual crack width.Compared with conventional RC columns,the RC columns with HB show obvious post-yield stiffness.The maximum crack width is only 1.2mm before the 2%,the minimum residual crack width is only 0.4mm,and the residual drift ratio before 6% is less than 2%.The lateral force increasing by more than 50% and when reaching 6%,it still shows good self-centering ability and seismic performance.For the combined specimen with steel plate constraint and HB,it has higher bearing capacity and better self-centering performance.By studying the seismic behavior of reinforced concrete columns with HB,it can be seen that the use of low bonding HB can effectively control the residual deformation of components under large deformation,improve structural damage,and achieve self-centering of columns.Therefore,the use of HB can provide an effective and concise way for the development and application of self-centering RC columns in high-rise buildings in earthquake areas.更多还原