小开洞砌体墙抗震性能研究

为研究小开洞砌体墙的抗震性能,设计了3片小开洞砌体墙试件和1片无洞口砌体墙试件,并进行了低周往复加载试验;介绍了砌体墙试件的主要破坏过程及破坏机理,对比分析了各片砌体墙承载力、抗侧刚度及延性等抗震性能差异;基于试验建立有限元模型,研究了开洞率及洞口位置对砌体墙抗震性能的影响。结果表明：小开洞砌体墙破坏机理较实体墙发生了显著改变,无洞口墙表现为明显的转动破坏特征,小开洞墙主要表现为典型的脆性剪切破坏;开单个小洞口会削弱砌体墙的水平承载力和抗侧刚度,大幅降低墙体的延性;增加洞口数量或高度可适当提高小开洞砌体墙的抗震性能;随着开洞率的增大,墙体承载力和初始刚度逐渐下降,延性性能表现为先降低后提高的趋势;竖直方向上,洞口越往下,墙体抗震性能越差,水平方向上,洞口宜居中布置。     

含嵌固墙体古建筑木结构震害数值模拟研究

以四川广元市某古建筑木结构为例,在考虑墙体嵌固作用的基础上,研究了汶川地震下古建筑的震害症状与地震响应状况。采用ANSYS软件对该古建筑榫卯节点的半刚性特征及砖砌体与木构架的嵌固作用进行了模拟,并建立了结构的有限元模型。通过模态分析,获得了结构的基频和主振型;通过将汶川波进行调幅作用于该结构,获得了结构在不同时刻的内力及变形峰值,并获得了典型节点的地震响应曲线。结果表明:考虑墙体的嵌固作用后,该古建筑的基频为1.59Hz,振动形式以第一振型为主,地震作用下木构架产生的位移很小,内力均在容许范围内,且保持稳定的振动状态;墙体由于强度不足,在某些部位将产生破坏,与震害现状基本吻合。     

碳纤维布抗震加固开门窗洞口砌体墙片的试验研究与受剪承载力分析

通过对6片开门窗洞口砖砌体墙片在低周往复荷载作用下的抗震性能试验研究,探讨碳纤维布用于抗震加固无筋开洞口墙片的破坏形态、受力特性和加固效果,对比不同碳纤维布粘贴方式对无筋开洞口砌体墙片抗震加固效果的影响,据此建议对地震区开窗洞墙体采用沿洞口周围粘贴碳纤维布并在窗洞角部附加锚固碳纤维布条的有效加固方式,对开门洞墙体采用沿洞口周围粘贴碳纤维布并在宽墙肢上对角粘贴碳纤维布的有效加固方式。同时根据试验研究结果,建立以碳纤维布拉杆机制为基础的碳纤维布加固开洞口砌体墙片的受剪承载力计算模型,计算结果与试验结果吻合较好,说明该计算模型能较好地反映碳纤维布与无筋砌体墙体共同工作的受力机理,可供工程设计参考使用。     

陶粒粉煤灰配筋砌体墙抗震性能试验及理论研究

提出一种新型配合比的陶粒粉煤灰发泡混凝土作为砌体墙材料,对该种绿色材料进行基本力学性能试验,得到其砌块和砌体的力学指标和本构方程;设计了两榀陶粒粉煤灰配筋砌体墙,通过拟静力试验检验其抗震性能,并与其他绿色材料配筋砌体墙进行对比.建立与试验相关的数值模型,通过数值模型扩展分析,研究改变关键参数对墙体抗剪承载力的影响,并提...     

性能增强古建筑砌体墙抗震性能试验及有限元分析

为提高古建筑砌体结构抗震性能,设计制作了3组古建筑砌体试块和3片古建筑砌体墙试件,分别利用环氧树脂和甲基丙烯酸甲酯进行性能增强。通过试块的材料力学性能试验研究其力学性能,提出了性能增强古建筑砌体的本构关系;通过墙体的拟静力试验研究了性能增强古建筑砌体墙的破坏形态、滞回性能、延性、耗能能力等。结果表明:高分子材料能够有效约束古建筑砌体结构墙体裂缝的开展,提高墙体的承载力和变形能力,其中采用环氧树脂进行性能增强后,墙体承载力和延性相对于未增强墙体分别提高了30%和31%,采用甲基丙烯酸甲酯进行性能增强后,墙体承载力和延性分别提高了18%和42%;性能增强后墙体的滞回环面积和等效黏滞阻尼系数均大于未增强墙体,耗能能力得到增强;最后根据拟合试验曲线建立性能增强古建筑砌体的本构模型,并进行了有限元分析,有限元计算结果与试验结果吻合较好,可为古建筑砌体结构抗震保护提供参考。     

Robustness of hollow clay masonry units and seismic behaviour of masonry walls

As the recent experimental investigations indicated, the robustness of masonry units is one among the most decisive parameters which define the behaviour of masonry walls when subjected to seismic loads. If local brittle failure of units occurs, the mechanism of behaviour and known relationships between the strength and ductility properties of masonry walls change. In such a case, the design values of load bearing and energy dissipation capacity of masonry walls are overestimated, although the equations and requirements specified in the codes have been taken into consideration. If brittle units are used for the construction of structural walls, the actual structure will be exposed to an increased level of seismic risk although it has been designed for earthquake loads according to codes. This is especially the case of reinforced masonry, where brittle local failure prevents the transfer of predicted forces from reinforcing steel to masonry units. In order to provide limitations for the use of hollow units with large hole volume ratio and thin shells and webs in seismic areas, a measure to define the qualitative term “sufficient robustness”, specified in Eurocode 8, should be found.     

底层框架—抗震墙砖房抗震性能研究

通过对结构进行静力弹塑性分析,研究了底层设置不同数量抗震墙对结构薄弱楼层位置和整体结构抗震能力的影响,提出了应合理设置底层抗震墙的数量,使这类结构的底层与第二层的承载力尽量均匀。     

Out-of-plane behavior of dry-stack brick masonry walls

As a result of the combination of the complex behavior of masonry buildings with insufficient material quality and lack in engineering calculations, a large number of damages has been observed in the earthquakes that occurred in recent years. Therefore, a realistic understanding of the behavior of masonry walls and buildings is necessary to construct seismic-resistant structures. Since masonry walls have many variables, performing experiments in which each variable is present at the same time will make it difficult to understand the behavior. For these reasons, considering the out-of-plane failures that are frequently mentioned in recent earthquakes, in this study, variables in dry-stack brick masonry buildings such as the aspect ratio of the wall (2, 1.33, and 1), the presence of the transverse walls (2, 1, and 0), and the openings in the walls (door and/or window) were taken into account separately. Eighteen different wall configurations were designed, and a total of 48 dry-stack walls having U-shape, L-shape, and I-shape in plan were tested by a specially constructed tilting table setup to determine their out-of-plane behavior. From the test results, it was found that lateral load capacity of the U-shaped walls without openings increased as the aspect ratio (L/H) decreased. No change in capacity was observed in L- and I-shaped walls when the aspect ratio was reduced from 2 to 1. Door and/or window openings were found to affect only the L-shaped walls. In addition, it was determined that failure patterns were affected from the aspect ratio and the presence of the openings.     

Parametrical study of masonry walls subjected to in-plane loading through numerical modeling

This paper deals with the numerical assessment of the influence of parameters such as pre-compression level, aspect ratio, vertical and horizontal reinforcement ratios and boundary conditions on the lateral strength of masonry walls under in-plane loading. The numerical study is performed through the software DIANA^® based on the Finite Element Method. The validation of the numerical model is carried out from a database of available experimental results on masonry walls tested under cyclic lateral loading. Numerical results revealed that boundary conditions play a central role on the lateral behavior of masonry walls under in-plane loading and determine the influence of level of pre-compression as well as the reinforcement ratio on the wall strength. The lateral capacity of walls decreases with the increase of aspect ratio and with the decrease of pre-compression. Vertical steel bars appear to have almost no influence in the shear strength of masonry walls and horizontal reinforcement only increases the lateral strength of masonry walls if the shear response of the walls is determinant for failure, which is directly related to the boundary conditions.     

新型混合装配式混凝土剪力墙抗震性能试验研究及有限元分析

预应力筋面积、预应力筋张拉应力、浆锚钢筋无黏结长度及轴压比是新型混合装配式混凝土剪力墙的重要设计参数。在前期试验基础上,开展考虑不同预应力筋面积的新型混合装配式混凝土剪力墙低周反复荷载试验,并采用Abaqus进行有限元参数分析。试验结果表明：相较现浇对比试件,新型混合装配式剪力墙试件抗裂性能、承载力、刚度均明显提高,位移延性性能及耗能能力接近,在预拉力不变的条件下,预应力筋面积变化对试件性能影响较小;有限元参数分析结果表明,预应力筋张拉应力与轴压比的变化将明显影响新型混合装配式混凝土剪力墙的强度与刚度,且均呈正相关关系,而预应力筋面积、浆锚钢筋无黏结长度影响则不够明显。综合分析认为,对于试验涉及的新型混合装配式混凝土剪力墙,建议预应力筋根数取3根,初始张拉力宜为416.6kN,浆锚钢筋无黏结长度宜为150mm。     

高层混凝土框架核心筒-木盒混合结构抗震性能研究

提出了一种以混凝土框架-核心筒结构为“主结构”,每层主结构间内嵌3层装配式轻型木结构为“子结构”的装配式高层建筑结构体系。该混合结构体系实现了建筑使用功能多样化,结构体系集成化,建筑材料绿色化,建造施工装配化的特点。着重研究了体系中主结构与子结构间的连接,根据连接的特点和强弱,提出了3种不同的结构模型：1）重力模型,其特点是主结构与子结构在侧向不连接或弱连接,不考虑子结构对整体结构抗侧刚度的贡献;2）刚度模型,主子结构间采用螺栓有效连接;3）隔震模型,其子结构底面与主结构采用隔震支座连接。采用有限元软件SAP2000对3种具有不同受力特点的模型结构进行抗震性能分析研究。结果表明：重力模型主结构受力安全合理;刚度模型中子结构对整体结构抗侧刚度的贡献可达6%~35%;隔震模型中隔震子结构可明显降低整体结构的地震反应。与建筑功能相同的混凝土框架核心筒结构相比,混凝土框架核心筒-木盒结构自重可减轻25%,地震作用可减小30%,有利于在地震设防区应用。     

配筋混凝土砌块砌体小高层框支结构抗震研究

论述了与配筋混凝土砌块砌体小高层框支结构相关的剪力墙及房屋抗震设计和性能的研究进展概况，介绍了其需要重点研究的几个方面，促进其在抗震设计中广泛地应用。     

设置透风孔的超高层建筑风荷载特性

采用同步测压技术,进行设置透风孔的超高层建筑刚性模型风洞试验,对该类建筑物的风荷载特征进行研究。结果表明:孔洞附近,顺风向阻力表现出一定涡激力特性,横风向升力功率谱的谱峰下降幅度较大,阻力与升力系数的根方差均减小,但扭转向扭矩系数根方差的减小幅度有限。受孔洞影响的区域,阻力系数与扭矩系数的自相关性减弱,但升力系数的自相关性增强,阻力系数、升力系数的相干函数衰减程度减弱,相干系数的数值减小。设置透风孔后,超高层建筑升力系数、扭矩系数与阻力系数的互相关性不能再忽略不计,但升力系数与扭矩系数之间的互相关性有所减弱。     

平面不规则砌体结构房屋震害情况评估

结合GB50011-2010建筑抗震设计规范相关规定,针对三幢不规则砌体房屋在地震中的破坏情况进行了分析,并评估其震损程度,指出了房屋规则性在建筑和结构设计中的重要性。     

Effect of unreinforced masonry infills on seismic performance of reinforced concrete frame-shear wall buildings

Reinforced concrete (RC) shear wall buildings with unreinforced masonry (URM) infilled moment frames are common in India and neighboring countries. This study assesses the influence of the URM infills on their seismic performance. Fully infilled, open first-storied, and bare frame versions of a 25-story shear wall building are considered. Multiple stripe analysis is conducted at five return periods to estimate their performance. Fragility functions for the collapse prevention limit state, which is based on seven engineering demand parameter exceedance thresholds, are generated and compared. The presence of infills (full or partial) is observed to have an overall positive effect on the performance of the RC frame-shear wall buildings. The performance of the open first-story building was comparable to that of the fully infilled building. The ratio of story shear carried by the moment frames and shear walls is studied at all return periods to understand the variation in frame shear wall interaction with increased damage for each building. In the case of buildings with infills, the frames carry a higher proportion of story shear at lower return periods. For all three buildings, the fraction of story shear carried by moment frames increases along the height of the building.     

多层砌体结构窗下墙破坏模式试验研究

为验证多层砌体结构开洞墙体窗下墙破坏模式震害现象,设计缩尺比例为1:3的三层三跨砌体结构开洞墙体试件,对其进行拟静力低周往复加载试验。分析多层砌体墙体窗下墙破坏模式的破坏特征,研究整体墙及各层墙体的滞回特性、骨架曲线、刚度退化规律、耗能特性、延性与变形特征等抗震性能。试验结果表明：发生窗下墙破坏模式的开洞墙体破坏过程分为裂缝出现、变形发展与强度退化三个阶段;窗下墙作为第一道抗震防线可提前参与整体结构耗能、降低墙体刚度退化速率、增加整体墙的延性和变形能力,其破坏模式相对窗间墙破坏模式更为合理。研究结果揭示了发生窗下墙破坏模式墙体的抗震性能与变形特征,为实现砌体结构合理破坏机制提供依据。     

开洞矩形截面超高层建筑局部风压风洞试验研究

基于一栋立面上有多个开洞的矩形截面超高层建筑的刚性模型表面压力测量风洞试验结果,分析了矩形截面超高层建筑在长边立面上不同开洞工况下建筑各表面平均风压系数和最不利风压系数的变化规律。试验结果表明:当建筑长边迎风时,开洞使得背风面洞口附近的平均风压系数绝对值增大,但迎风面上的平均风压系数变化很小;当建筑短边迎风时,开洞对洞口附近的平均风压系数和最不利正风压系数均只有微弱影响,但对其最不利负风压系数却有很大影响,特别是中部开洞,将使其周围的最不利负风压系数增大一倍以上;开洞对短边立面上的最不利风压系数不产生明显的影响。为有结构开洞的高层建筑洞口附近的围护结构设计提供了参考数据。     

不同影响因子对砌体建筑震害影响程度的分析及研究

通过提出了一种主观、客观相结合的权重确立方法,研究不同影响因子对砌体建筑震害影响程度。采用模糊层次分析结合灰色关联度分析相结合,以确定影响因子对砌体建筑抗震性能的影响程度的综合权重。通过研究发现：层次分析法结合灰色关联度法确立的综合权重,既反映了专家意见及建议,又反映了实际样本数据的信息,使得综合评价结果更合理和客观。     

GFRP复合材料加固带壁柱砖墙抗震性能试验研究

对玻璃纤维复合材料(Glass Fiber Reinforced Polymer,GFRP)加固带壁柱砖墙抗震性能进行试验研究。通过1片未加固带壁柱砖墙和8片GFRP加固带壁柱砖墙在低周往复荷载作用下的抗震性能试验,阐述了各试件的破坏特征;研究GFRP加固前后墙体的滞回特性、刚度及退化特性、变形性能、耗能性能等变化规律,以及加固方式、加固量和“对拉”锚固措施对加固效果的影响。研究结果表明:加固方式对墙体的刚度退化性能和变形性能影响不大,但对墙体的耗能性能影响较明显;按照本文提出的加固方式粘贴GFRP能够有效地提高墙体的极限荷载、减缓墙体的刚度退化、增强其变形能力和耗能能力;同时考虑采用混合加固方式、增大加固量、采用锚固措施三因素时,墙体的抗震性能较好。