Experimental study of L‐shaped precast RC shear walls with middle cast‐in‐situ joint

Precast shear walls, as an environmentally friendly building system, have been vigorously developed in China. There are many vertical and horizontal joints on precast reinforced concrete shear wall system, which certainly have a significant effect on seismic performance of structures. In this paper, 3 L‐shaped precast reinforced concrete shear walls that were assembled by 2 precast parts through a middle cast‐in‐situ joint and a compared 1 completely cast‐in‐situ were tested under low frequency cyclic loading to investigate their seismic behaviors. The vertical distributed reinforcements in the three precast specimens were equivalently spliced by grouting sleeves arranged along the center line of the wall, and the horizontal reinforcements were directly anchored in cast‐in‐situ joints. The experimental results, including failure mode, yielding load and displacement, skeleton curve, energy dissipation, stiffness degradation, ductility, and so forth were presented in the paper. The results show that the precast specimens have similar bearing capacity whereas much better deformation capacity and ductility compared to the cast‐in‐situ specimen. Additionally, the experimental results of ultimate shear capacity of specimens were also compared with that of the calculation results. These results indicate that the tested precast shear walls have good and reliable seismic performance and can be used as a structural member in engineering projects.     

Experimental study on seismic performance of L‐shaped insulated concrete sandwich shear wall with a horizontal seam

A series of new L‐shaped insulated concrete sandwich shear walls integrated with heat preservation function are tested for its seismic performance. Those specimens, partially excavated and filled with insulation materials, are made up of three precast specimens and one cast‐in‐situ specimen as a control group. For the three precast specimens, the vertical distributed reinforcements are equivalently spliced to the bottom beam by grouting sleeves arranged along the centerline of the wall, whereas for the compared specimen, they are directly cast‐in‐situ anchored. These specimens are tested under low frequency cyclic loading. The failure mode, yielding load and displacement, skeleton curve, energy dissipation, stiffness degradation, ductility, and so forth, are recorded and analyzed. The result shows that the precast specimens have similar bearing capacity and much better deformation capacity and ductility than that of the control group in this experiment. This indicates that the seismic performance of the proposed L‐shaped insulated concrete sandwich shear wall is desirable and generally meets the requirements of both function and safety, thus can be used as structural elements in practice. The methods in Chinese design code and American Concrete Institute code are adopted to calculate the ultimate shear capacity of this precast insulation shear wall, and it is found that the tested result is larger than the calculated one, indicating the calculation method is reliable.     

Experimental study on seismic performance of T‐shaped partly precast reinforced concrete shear wall with grouting sleeves

Prefabricated structure has prominent advantages such as easy control of construction quality, saving fabricating time and natural resources, and reducing environmental pollution and construction noise. The mostly used structural system in high‐rise buildings is reinforced concrete shear wall structure, which has high load capacity and lateral stiffness. Focusing on the connection of reinforcements, three T‐shaped partly prefabricated reinforced concrete shear walls and one cast‐in situ specimen in same dimensions as a control group are tested under low‐frequency cyclic loading to analyze their seismic performances in this paper. During the experiment, the axial compression ratio of specimens is fixed at 0.3, 0.4, and 0.5. Through the observation of phenomena and data analysis, hysteretic curve, skeleton curve, stiffness degradation, ductility, and load bearing capacity are compared and analyzed. The results show that partly prefabricated reinforced concrete shear wall has similar load bearing capacity with the cast in situ specimen, and it also has excellent ductility, stiffness, and energy‐dissipating capacity. The experimental results and analysis indicate that partly prefabricated reinforced concrete shear wall has outstanding seismic performances; under effective and reliable design, it can be used in building structures to play the same role as cast in situ components.     

钢筋混凝土水平拼接叠合剪力墙抗震性能试验研究

通过对3片钢筋混凝土水平拼接叠合剪力墙、1片钢筋混凝土整体叠合剪力墙和1片钢筋混凝土全现浇剪力墙进行抗震性能试验研究,对比研究了试件的裂缝发展情况及破坏形态,分析了试件的承载能力、滞回曲线、骨架曲线、刚度退化曲线、延性性能、耗能性能等。研究结果表明：水平拼接叠合剪力墙与整体叠合剪力墙以及全现浇剪力墙的受力过程、破坏模式基本相同,抗震性能指标相近,具有较好的抗震性能;水平拼接节点构造合理,水平拼接叠合剪力墙的承载能力不低于整体叠合剪力墙;剪式支架能使钢筋混凝土叠合剪力墙的预制部分与现浇混凝土形成整体,协同工作承受外部荷载。     

带接缝连接梁的预制混凝土剪力墙抗震性能试验研究

采用钢筋混凝土接缝连接梁来实现预制墙体竖向钢筋的连续性连接。通过6个高宽比为1.7、不同截面高度和位置的接缝连接梁预制混凝土剪力墙的低周反复加载试验,分析了试件的破坏形态、顶点荷载-位移滞回曲线、承载力、变形能力、刚度退化等特性,并与整体现浇墙体进行对比。试验结果表明：预制墙体试件与整体现浇墙体试件的破坏模式、破坏形态基本相同,均为墙体角部混凝土压碎、钢筋拉断或屈曲;预制墙体试件的水平承载力相当,略低于现浇墙体,接缝连接梁的位置及截面高度对承载力有一定程度的影响;预制墙体试件的变形能力略小于现浇墙体试件,但极限位移角均超过1/100;接缝连接梁可以有效传递荷载。     

套筒灌浆缺陷整治预制混凝土剪力墙抗震性能试验研究

为了研究预制混凝土剪力墙的套筒灌浆缺陷整治效果,设计了带灌浆缺陷的预制混凝土剪力墙,采用直接补灌法和破型修复法整治后开展了低周反复加载试验,对比了套筒灌浆缺陷整治前后预制剪力墙的抗震性能,考察了整治前后预制剪力墙的破坏特征和滞回性能的变化规律.试验结果表明:所有预制剪力墙发生了墙底截面破坏与套筒连接区域破坏这两种破坏模...     

Deformation limits of L‐shaped reinforced concrete shear walls: Experiment and evaluation

L‐shaped reinforced concrete (RC) shear walls have been studied over the years due to their importance in tall buildings. However, few investigations focus on the progression of damage with increasing deformation, especially on the deformation limits for different performance levels. Hence, an experiment was conducted on 12 L‐shaped RC shear walls subjected to axial and cyclic lateral loadings. The variables were shear span ratio, axial load ratio, and longitudinal boundary element reinforcement ratio. The seismic performances were analyzed and discussed in terms of crack pattern, failure mode, hysteretic response, backbone envelope, and ductility factor. On the basis of the three key performance state points on the backbone envelope, a method was proposed to assess the seismic performances of L‐shaped RC shear walls using six distinct performance levels. These performance levels were provided with relevant deformation limits and proved to be in good agreement with six significative damage states. Further, comparative analysis showed that the deformation limits derived from experiments were significantly underestimated by current codes and methods available in literature, because these prediction models were mainly developed for rectangular shear walls. Considering the contribution of flange, a modification of Cui's method yields good estimations of deformation limits for L‐shaped RC shear walls.     

钢筋混凝土开洞叠合剪力墙抗震性能试验研究

通过对4片钢筋混凝土开洞叠合剪力墙和2片普通钢筋混凝土开洞剪力墙进行抗震性能试验研究,对比研究了试件的受力全过程、开裂部位、裂缝发展情况以及破坏形态,分析了试件的承载能力、滞回曲线、骨架曲线、刚度退化曲线、延性性能、耗能能力等。研究结果表明：钢筋混凝土开洞叠合剪力墙的受力性能基本和普通钢筋混凝土开洞剪力墙相同,具有较好的抗震性能;保温层外侧的预制钢筋混凝土板能够协同参与受力,与普通钢筋混凝土开洞剪力墙相比,其承载力可提高约7%,并可有效降低其刚度退化;剪式支架能使钢筋混凝土开洞叠合剪力墙的预制部分与现浇混凝土形成整体,共同参与工作。     

预制空心板剪力墙抗震性能试验研究

装配整体式空心板剪力墙结构(EVE)采用钢筋间接搭接实现上下层预制墙、同层相邻预制墙的连接。通过3个空心板剪力墙的拟静力试验,研究钢筋间接搭接、接缝构造、灌孔构造边缘构件的可行性。结果表明:竖向孔、水平孔内连接钢筋与对应的空心板内竖向、水平钢筋同一位置应变随水平力的变化规律相同,空心板剪力墙边缘构件竖向钢筋、竖向接缝水平钢筋间接搭接可依靠桁架机制有效传递钢筋拉压力;试件均实现了预期的破坏模式,竖向孔、水平孔内后浇混凝土可与空心板共同工作;压剪破坏的空心板剪力墙受剪承载力试验值为JGJ 3—2010《高层建筑混凝土结构技术规程》(简称《高规》)现浇剪力墙公式计算值的1. 77倍,压弯破坏的空心板剪力墙受弯承载力试验值为《高规》现浇剪力墙公式计算值的1. 15～1. 23倍,可按《高规》现浇剪力墙斜截面受剪承载力、正截面受压承载力计算方法计算EVE空心板剪力墙的承载力;空心板剪力墙极限位移角为1/66～1/54,满足罕遇地震作用下剪力墙结构弹塑性变形能力的要求;灌孔边缘构件可采用全预制构造(竖向钢筋间接搭接,箍筋布置于空心板内)代替半预制构造(竖向孔内竖向钢筋贯通,箍筋布置于竖向孔内);空...     

预制钢筋混凝土剪力墙结构拟动力子结构试验研究

在预制钢筋混凝土剪力墙结构拟静力试验研究的基础上,采用等效力控制方法对足尺试验模型进行了拟动力子结构试验,研究该结构在地震作用下的破坏过程和变形能力,获得了模型下降段试验数据,给出了结构各层的位移时程曲线、层间滞回曲线、骨架曲线、刚度退化曲线以及延性等,为该类结构在地震作用下的弹塑性分析提供了试验数据。试验结果表明：采用的水平连接技术是可靠的,能够很好地保证其在地震作用下连接性能;该结构模型属于延性结构,可以满足我国现行抗震设计规范7度设防区多道抗震设防的要求,符合“三水准”抗震设防目标,具有较好的整体抗震性能,经过合理设计可以在地震设防区使用。图15表5参15     

Experimental study on seismic performance of steel‐reinforced recycled concrete frame with infill wall

In order to investigate the seismic performance of steel‐reinforced recycled concrete (SRRC) frame with infill wall, low cyclic loading tests on four frames with infill wall and one frame without infill wall were conducted. The failure modes, hysteresis loops, skeleton curves, bearing capacity, ductility, stiffness degradation, and energy dissipation capacity of specimens were analyzed. The seismic performance of SRRC frames with and without infill wall was compared. The influence of the aspect ratio of infill wall, the axial compression ratio of column, and the distance of horizontal reinforcements of infill wall were investigated. Test results show that compared to the SRRC frame without infill wall, the SRRC frame with infill wall had higher bearing capacity and initial stiffness, but faster stiffness degradation and worse energy dissipation capacity. With the increase of aspect ratio of infill wall and axial compression ratio of column, the bearing capacity and initial stiffness of SRRC frame with infill wall increased, whereas the ductility decreased. With the decrease of distance of horizontal reinforcements of infill wall, the initial stiffness and energy dissipation capacity of SRRC frame with infill wall increased. After the infill wall fails under earthquake, the remaining SRRC frame has good seismic performance.     

高配筋率边缘约束构件高强混凝土剪力墙抗震性能试验研究

为改善高强混凝土剪力墙的延性,设计了7个不同形式的高配筋率边缘约束构件高强混凝土剪力墙试件（边缘约束构件内的纵筋配筋率约为5%~8%）和1个普通配筋率的高强混凝土剪力墙试件,对其进行低周反复水平荷载作用下的拟静力试验,研究了剪力墙试件的破坏形态、滞回特性、变形能力、截面应变、刚度退化、耗能能力等。试验结果表明：对于剪跨比λ≥2的剪力墙,在高强混凝土剪力墙中设置高配筋率暗柱或端柱,并适当提高水平和竖向分布钢筋的配筋率,可以显著提高高强混凝土剪力墙的抗震性能。     

钢板带加强型型钢混凝土低矮剪力墙抗震性能试验研究

为进一步改善一字型内置竖向型钢混凝土低矮剪力墙的抗震性能,设计和完成了2个剪跨比为1.0的钢板带加强型内置竖向型钢混凝土低矮剪力墙低周往复水平加载试验,并与1个未设置钢板带的内置竖向型钢混凝土低矮剪力墙进行对比分析。试验结果表明:钢板带的设置使剪力墙的水平承载力有显著提升,极限位移角提高20%左右,满足了相关规范极限位移角大于1/100的要求;钢板带的设置使试件破坏模式发生变化,总耗能有大幅度提升;钢板带的设置要适度,不能过强,以免形成新的薄弱区。     

既有钢筋混凝土梁抗震性能试验研究

既有钢筋混凝土构件的特性不同于拟建构件,除了可能存在设计构造方面的不足之外,还受到所经受的荷载历程和环境腐蚀的影响。根据5根既有钢筋混凝土梁的低周往复加载试验,得到了既有钢筋混凝土梁的破坏特征。根据试验中得到的滞回曲线计算既有钢筋混凝土梁的耗能能力和延性,分析了不同的加载制度对其耗能能力的影响。结论表明,既有构件所经历的最大荷载及最大荷载出现的相对时序均会影响到既有构件的抗震性能。     

预制墙板内现浇自密实混凝土叠合剪力墙抗震性能试验研究

通过5片预制普通混凝土(NC)墙板内现浇自密实混凝土(SCC) 叠合剪力墙试件,2片预制普通混凝土墙板内现浇普通混凝土叠合剪力墙试件的低周反复荷载试验,研究在不同墙体边缘构件约束形式、轴压比以及保温层设置与否等条件下,预制墙板内现浇SCC叠合剪力墙的抗震性能,分析现浇SCC与预制墙板叠合剪力墙受力全过程,以及承载能力、破坏形态、滞回曲线、骨架曲线、刚度退化曲线、延性性能、耗能能力等,并将现浇SCC与现浇NC两种叠合剪力墙进行对比。分析结果表明：现浇SCC与预制墙板叠合剪力墙具有较好的抗震性能;两侧预制墙板之间的桁架钢筋起着良好连接作用,使预制加现浇的叠合墙体能整体协同受力;预制墙板内现浇SCC叠合剪力墙承载力不低于预制墙板内现浇NC叠合剪力墙;两者的受力性能、破坏形态及裂缝分布基本相同,滞回曲线、耗能能力、刚度退化等指标接近;预制墙板内现浇SCC叠合剪力墙的延性好于预制墙板内现浇NC叠合剪力墙;轴压比从0.1增加到0.2,有利于改善叠合墙体承载力;与不设置边缘构件叠合剪力墙相比,边缘构件采用暗柱形式的叠合剪力墙整体工作性能增强。     

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。     

底部预留后浇区钢筋搭接的装配整体式剪力墙抗震性能试验研究

通过在预制剪力墙底部预留混凝土后浇区,上、下层墙体竖向分布钢筋在此区域内搭接连接,在此区域外支腿范围内的纵向钢筋采用套筒灌浆连接,形成装配整体式剪力墙结构。为研究该类剪力墙的抗震性能,设计了5组共15片装配整体式足尺剪力墙,对其进行拟静力试验。研究表明：装配整体式剪力墙为典型的弯剪破坏模式;底部预留混凝土后浇区上方的水平接缝和墙底水平接缝开裂并贯通,在试验过程中竖向接缝未开裂,当轴压比较大或剪跨比较小时,底部后浇区角部混凝土会产生压溃或剥落现象;装配整体式剪力墙的破坏模式以及滞回特征、承载力、延性、刚度退化情况等指标与对应的现浇试件基本一致,水平承载力相差不超过5.7%,位移延性系数不低于4.1,极限层间位移角均在1/87以上,呈现良好的整体性能和抗震性能。     

劲性钢筋混凝土开洞低剪力墙拟静力试验研究

本文进行了10榀劲性钢筋混凝土开洞低剪力墙在低周反复荷载作用下的试验研究。结果表明,劲性钢筋混凝土低剪力墙延性相对较好,滞回曲线丰满,并有较强的塑性变形能力和耗能能力,承载力也有较大的提高。门窗洞口的存在对试件承载力有一定的削弱,但对延性和耗能能力则有一定的提高。采用劲性钢筋混凝土结构可有效地提高低剪力墙的抗震性能。     

大剪跨比预制空心板剪力墙抗震性能试验研究#br#

预制空心板剪力墙结构是一种新型装配式剪力墙结构。为研究预制空心板剪力墙的抗震性能、同层相邻预制空心板的整体性、采用水平插筋间接搭接连接的水平钢筋的抗剪作用、灌孔边缘构件的有效性,完成了6个轴压比设计值为0.3、剪跨比为1.61~2.42、压弯破坏为主的空心板剪力墙试件的拟静力试验。试验结果表明：试件的破坏形态均为压弯破坏,实现了预期的强剪弱弯设计目标,水平钢筋能有效抵抗水平剪力;试件的水平力-位移滞回曲线比较饱满,极限位移角为1/72~1/38,可按现浇剪力墙计算偏心受压空心板剪力墙的受压承载力;同层相邻空心板之间竖向接缝的开裂宽度小,接缝两侧构件竖向错动小,斜裂缝在竖向接缝处连续,直接拼接连接、后浇竖向拼缝连接都能使空心板成为整体;采用灌孔边缘构件的空心板剪力墙,其抗震性能满足现行规范要求。     

Experimental study of lateral load behavior of H‐shaped precast reinforced concrete shear walls with bolted steel connections

This paper presents an experimental study of H‐shaped precast reinforced concrete shear walls involving vertical connections under combined vertical and lateral loading. The H‐wall is composed of two prefabricated flange wall panels: one prefabricated web wall panel and vertical bolted steel connections between the flange and web panels. The assembling of the H‐wall is completely dry without any in situ casting. Three H‐wall specimens were constructed and tested to investigate the mechanical behavior and seismic performance of them. The lateral load‐bearing capacity, ductility, energy dissipation, lateral stiffness, strain in the connecting steel frame, and sliding within the bolted steel connections are presented and discussed to evaluate the effectiveness of the vertical connections. The ultimate shear‐resistance mechanism of the precast H‐wall assembly is also analyzed. The H‐wall assemblies generally possess high load‐bearing capacity, favorable ductility, and good energy‐dissipating capacity. The thickness of the steel plates in the connecting steel frame affects the lateral stiffness and the ultimate load‐bearing capacity of the H‐walls. Furthermore, the encasing steel plates for the web wall panel not only helps transfer the stress in the wall steel bars but also confines the concrete resulting in improved ductility.