【作者】 吴昊；

【导师】 赵世春；

【作者基本信息】 西南交通大学 ， 结构工程， 2013， 博士

【摘要】 2008年汶川大地震造成砖砌体结构教学楼大量破坏,部分教学楼受到严重破坏甚至倒塌,砌体结构教学楼在强震作用下的抗震性能和抗倒塌安全性引起学者们的广泛关注。砌体结构教学楼一般具有开间和进深较大、墙体数量少、纵墙开洞率高等不利于结构抗震的特点,目前对其抗震性能的认识主要基于震害调查分析,现行抗震设计规范针对大开间砌体结构的地震破坏模式设计缺少特别规定,对砌体结构教学楼的抗震性能、地震破坏机制控制以及窗间墙和进深较大墙体的抗震性能及其影响因素等研究不够。本文选取砌体结构教学楼为研究对象,对大开间砌体结构的抗震性能及地震破坏机制控制进行研究,主要研究工作和结论如下：1)分析了砌体结构教学楼的组成特点和典型震害特征,比较了砌体结构“强柱弱梁”和“强梁弱柱”两种宏观破坏机制下结构抗震能力的差异,对结构震害原因进行了初步分析,针对结构抗震的薄弱环节提出了相关的抗震设计建议。2)进行了5片纵墙试件的拟静力试验,研究了窗间墙的抗震性能及其影响因素。结果表明,按照规范要求设置构造柱的墙体具有较好的抗震能力,适当增大构造柱截面尺寸能够进一步改善墙体的破坏形态、延性和耗能能力,但增大中柱截面配筋率到一定程度时反而降低墙体的延性和耗能能力。3)进行了5片横墙试件的拟静力试验,分析了圈梁与构造柱的布置方式对其破坏模式和抗震性能的影响。结果表明,圈梁与构造柱的设置方式决定了墙体的抗震性能,按照现行抗震设计规范在横墙两端设置构造柱,同时保证墙体与基础梁间不发生剪切滑移,则横墙的抗震性能相对较好；中间增设构造柱或同时加设圈梁墙体的抗震性能并没有得到有效改善,但增设圈梁和构造柱的试件,极限变形后破坏墙块的变形受到中间圈梁的约束,墙体具有较好的后期整体性。4)通过1个两层砖砌体结构缩尺模型的拟静力试验,对窗间墙扶壁柱配筋率为1.67%的砌体模型的破坏特点、抗震性能、窗间墙的破坏模式以及纵墙的破坏机制等进行了研究。结果表明,窗间墙扶壁柱配筋率增大到一定程度时,扶壁柱与两侧砖砌体部分的协调变形能力很差,导致模型发生层间破坏机制,窗间墙剪切破坏,纵墙发生“强梁弱柱”式破坏,部分窗间墙出现垮塌破坏,最终形成倒塌机制,模型的延性和耗能能力均较差。5)进行了2个砖砌体结构缩尺模型(窗间墙扶壁柱配筋率为0.77%)的拟静力试验,分别对普通砖砌体窗间墙模型和窗间墙锚固配筋模型的破坏特征、承载能力、变形能力、延性和耗能能力、窗间墙的破坏模式、纵墙的宏观破坏机制及其控制条件等进行了研究。结果表明,普通窗间墙模型发生层间破坏机制,窗间墙剪切破坏,纵墙发生“强梁弱柱”式破坏,模型最终形成倒塌机制；窗间墙锚固配筋模型发生整体型破坏,窗间墙弯曲破坏,纵墙的宏观破坏具有“强柱弱梁”特征,模型的破坏形态、延性和耗能能力等均得到显著改善,层间变形均匀。因此,窗间墙局部锚固配筋的抗震设计方法能够实现对结构地震破坏机制的有效控制,而保证相邻层两窗间墙的受弯承载力之和高于相邻两窗下墙承载力之和有利于“强柱弱梁”式破坏机制的形成。6)采用钢筋网水泥砂浆面层对砌体结构教学楼的纵向窗间墙进行三面抗震加固并采取锚固措施,通过模型拟静力试验对加固窗间墙砖砌体结构模型的破坏特点、抗震性能、窗间墙的破坏模式、纵墙的破坏机制及其设计控制条件等进行了分析。结果表明,模型发生整体型破坏,窗间墙弯曲破坏,模型的延性和耗能能力比普通砖砌体窗间墙模型得到明显改善,承载能力和变形能力也得到提高,最终形成“强柱弱梁”抗倒塌机制。更多还原

【Abstract】 Considerable brick masonry school buildings suffered severe damage or even totally collapsed due to the formation of weak pier story mechanism during the Wenchun Earthquake. The seismic behavior and anti-collapse performance of masonry school buildings has become a major concern for researchers. Masonry school buildings that characterized by large bay, few walls and high percentage of openings in longitudinal walls are vulnerable to earthquake action. However, no special provisions are provided in the current seismic design code for earthquake collapse prevention design of masonry schoolhouses during a seismic event. A number of recommendations have been proposed based on earthquake damage investigation and analysis. Less attention has been paid on seismic performance of masonry school buildings, structural control of strong pier-weak spandrel damage mechanism and seismic behavior of wall piers and transverse walls within masonry structures. Quasi-static tests on reduced-scale sub-structure model of brick masonry school buildings were carried out in order to study the seismic performance and earthquake damage mechanism control of large bay masonry structures. The major contents and conclusions are summarized as follows:1) The structural characteristics and typical earthquake damage of masonry school buildings are summarized. The two types of earthquake damage mechanism of masonry structures, strong pier-weak spandrel and strong spandrel-weak pier, are analyzed. The reason of typical earthquake damage are studied and some recommendations on seismic design of brick masonry school buildings are presented.2) Five reduced-scale masonry wall specimens were subjected to in-plane quasi-static reversed cyclic lateral loads to study the seismic performance of piers between window and door openings and the influences. The results indicate that the specimen designed in accordance with current code provisions just exhibits good seismic behavior. Increasing the cross section size of structural column can ensure better seismic performance. The failure modes, ductility and energy dissipation capacity of specimen are significantly improved. However, to some extent, increasing the reinforcement ratio of structural column can decrease the ductility and energy dissipation capability. Therefore, increasing the section size of structural column properly and controlling the reinforcement ratio reasonably is of crucial important in seismic design of masonry school buildings.3) Quasi-static tests on five transverse wall specimens are conducted to study the failure modes and seismic performance of transverse walls. The results indicate that the arrangement of structural measures in transverse wall specimens has a significant effect on the seismic performance of transverse wall specimens. The specimen designed in accordance with the current code for seismic design generally exhibits good seismic behavior while ensuring that there is no slip between the wall and the base. The presence of additional structural column or additional structural column and ring beam in composite wall specimens does not improve the seismic performance significantly. However, the specimen with additional structural column and ring beam exhibits better integrity even under ultimate deformation conditions.4) A half-scale two-story sub-structure brick masonry house model was subjected to in-plane reversed cyclic lateral displacements at roof level in order to investigate the earthquake damage mechanism and seismic performance of masonry school buildings with pilastered piers. The reinforcement ratio of pilaster is1.67%. Failure characteristics, seismic performance of the model, as well as failure modes of piers between window and door openings and the failure mechanism of longitudinal walls are studyed. The results indicate that damage of the model mainly concentrates in piers, because increasing reinforcement ratio of pilaster to some extent can decrease the deformation compatibility between pilaster and masonry. A soft story mechanism occurs with piers fail in shear failure and spandrels slightly damaged. And the longitudinal walls exhibit strong spandrel-weak pier failure mechanism. Some piers are severely damaged or even collapsed and a collapse mechanism forms, resulting in the poor ductility and energy dissipation capacityof model.5) Quasi-static tests on two half-scale two-story sub-structure house models were carried out. The reinforcement ratio of structural column within wall piers is0.77%. The failure characteristics, load bearing capacity, deformability, ductility and energy dissipation capacity of two models, as well as failure modes of piers and failure mechanism of longitudinal walls and the control condition were investigated. The results indicate that a weak pier story mechanism occurs in ordinary masonry model with the piers fail in shear failure. And the longitudinal walls exhibit strong spandrel-weak pier failure mechanism, resulting in the collapse failure mode of model. However, partially reinforced piers with anchored reinforcements are characterized by flexural failure with horizontal cracking in the mortar bed joints. Spandrels are severely damaged due to the formation of global failure mechanism. Strong pier-weak spandrel failure mechanism is guaranteed with uniform drift distribution. The level of damage, global ductility and energy dissipation capacity of masonry structure are significantly improved. It is necessary to ensure that the moment bearing capacity of piers is higher than that of spandrels to the development of strong pier-weak spandrel mechanism.6) A strengthening method aimed at enhancing the seismic performance and ensuring the strong pier-weak spandrel failure mechanism of longitudinal walls is present in order to improve the anti-collapse capacity of existing brick masonry school buildings. The wall piers are partially strengthened with steel mesh mortar splint. Quasi-static test on a reduced scale sub-structure brick masonry model is carried out. The failure characteristics and seismic performances of test model, as well as failure modes of piers and failure mechanism of longitudinal walls are investigated. The results indicate that the model exhibits global failure mechanism, and the partially strengthened piers are characterized by flexural failure. The analysis indicates that the proposed seismic retrofitting method can improve the global failure modes and seismic performance significantly due to the formation of strong pier-weak spandrel failure mechanism. Therefore, the desired ductility failure mechanism can be developed.更多还原