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.     

Seismic behavior of T‐shaped steel reinforced concrete shear walls in tall buildings under cyclic loading

Shear walls are often used as the primary lateral load resisting elements in high‐rise buildings because of their large in‐plane stiffness and strength. It is a common practice to combine rectangular walls to form T‐shaped, I‐shaped and L‐shaped walls for functionality and esthetic reasons. Three relatively slender steel reinforced concrete (SRC) shear walls with T‐shaped cross‐sections were constructed and tested to failure under cyclic lateral loading. This research was conducted to assess the failure mechanism, hysteretic behavior, ductility and energy dissipating capacity of SRC T‐shaped walls under various axial load ratios. All the specimens exhibited a flexural mode characterized by crushing of the concrete and buckling of the steel at the free web boundary. The experimental results showed good hysteretic characteristics without pinching phenomena. The ductility coefficient varied from 2.3 to 4.1, and the deformation capability decreased with the increasing of axial load ratios. The stiffness, strength and ductility of T‐shaped walls are dependent upon the direction of the applied lateral loads. Higher stiffness and strength and lower ductility are achieved when the flange is in tension. The failure mechanism suggested that special attention should be paid to the design of the free web boundary to prevent premature failure under compression. Copyright © 2014 John Wiley & Sons, Ltd.     

Experimental study on seismic performance of L‐shaped partly precast reinforced concrete shear wall with cast‐in‐situ boundary elements

In order to promote industrial production of reinforced concrete shear wall, a typical partly precast reinforced concrete shear wall with both end boundary elements cast‐in‐situ and the other part precast is experimentally studied. In this paper, three L‐shaped specimens of this kind and one completely cast‐in‐situ specimen as a control group are tested under low‐frequency cyclic loading to investigate their safety, applicability, and different characteristics. For the partly precast specimen, the vertical distributed reinforcements of precast part are equivalently spliced by grouting sleeves arranged along the center line of the wall whereas the horizontal reinforcements are directly anchored into the cast‐in‐situ boundary elements. During the test, the axial compression ratio of these specimens is fixed at 0.2, 0.3, and 0.5, respectively. Such test phenomena and test data including failure modes, yielding load and displacement, the skeleton curve, energy dissipation, stiffness degradation, ductility, and so on are observed, analyzed, and compared. Chinese code and American Concrete Institute code are adopted to estimate the bearing capacity. Results show that the partly precast specimens have good integrity. With the increase of axial compression ratio, the bearing capacity of these partly precast specimens increases whereas the ductility decreases. It is also found that the partly precast specimens have slightly lower bearing capacity compared with the cast‐in‐situ specimen as well as excellent deformation capacity and ductility, which indicates the tested partly precast shear wall has good and reliable seismic performance and can be used as a structural element in building construction.     

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 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.     

高轴压比钢管混凝土剪力墙抗震性能试验研究

为研究约束边缘构件内配置圆钢管的钢管混凝土剪力墙的抗震性能、探讨钢管混凝土剪力墙的轴压比限值及其约束边缘构件的配箍要求,完成了6个剪跨比大于2.0的高轴压比钢管混凝土剪力墙试件和1个钢筋混凝土剪力墙试件的拟静力试验。试验结果表明：剪力墙的破坏形态为压弯破坏及底部混凝土压溃而丧失竖向承载能力;钢管混凝土剪力墙的开裂水平力、名义屈服水平力、正截面受弯承载力和变形能力均比相同参数的钢筋混凝土剪力墙大;配置双钢管剪力墙的变形能力大于配置单钢管的剪力墙,约束边缘构件为端柱的剪力墙的变形能力大于约束边缘构件为暗柱的剪力墙;正截面受弯承载力试验值大于计算值。根据试验结果,提出了钢管混凝土剪力墙的设计建议。图9表7参13     

Seismic performance of l‐shaped rc shear wall subjected to cyclic loading

Shear wall systems are one of the most commonly used lateral‐load resisting systems in high‐rise buildings. The height–thickness ratio of traditional RC shear wall is more than 8. In order to study the seismic performance of a new type of shear wall structure (short‐limb shear wall structure) with height–thickness ratio of 5–8, L‐shaped cross‐section. A total of six shear wall specimens with 1/2‐scaled model were tested under the cyclic loading. The test parameters included: six specimens were loaded in the web plane; axial–load ratio and height‐thickness ratio were in the range of 0.1–0.4 and 5–8, respectively. The failure process, failure mode and deformation properties were studied. The test results are shown that: L‐shaped RC shear wall with a better deformation than the traditional shear wall, when the axial‐load ratio and height‐thickness ratio are within a certain range, the seismic performance will be able to play to the best. Specimens of the axial‐load ratio of 0.1, height‐thickness ratio of 6.5, they have the most excellent ductility and energy dissipation capacity. Copyright © 2010 John Wiley & Sons, Ltd.     

Steel–concrete composite shear walls using precast high performance fiber reinforced concrete panels

In this research, seismic performance of composite steel plate shear walls (CSPSWs) using high performance fiber reinforced concrete (HPFRC) panels is experimentally and numerically investigated. Three one‐story one‐bay CSPSW specimens using precast HPFRC panels were designed and fabricated for cyclic quasi‐static experiments. The HPFRC panels of composite shear wall specimens did not have any steel rebars. The main purpose of the study was to understand the effects of rigid and semirigid HPFRC panels on the seismic behavior of the system. Shear capacity, ultimate shear strength, lateral stiffness, energy dissipation, and ductility ratios of the specimens are evaluated. The experimental results demonstrate that specimens were able to resist lateral load up to at least interstory drift of 6%. Using HPFRC panels, CSPSW specimens becomes stiffer in the elastic region, and the yield displacement of the shear wall is decreased; therefore, the ductility ratio of the system is increased. It should be noted that ultimate shear strength, initial elastic stiffness, and energy absorption of specimens with an HPFRC panel on one side or both sides of the infill steel plate were approximately the same. However, using two HPFRC panels is not economical in comparison with CSPSW with an HPFRC panel on one side. Additionally, the second panel increases the seismic mass of the structure.     

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.     

型钢混凝土T形截面剪力墙抗震性能试验研究

为研究型钢混凝土T形截面剪力墙的抗震性能,对3个剪跨比为2.2的T形截面剪力墙进行了拟静力试验。通过改变试件的轴压比,研究其在水平往复荷载作用下的破坏机理、滞回性能、延性以及耗能能力等。试验结果表明：T形截面剪力墙的破坏形态为无翼墙腹板端约束边缘构件底部混凝土被压碎的受弯破坏;剪力墙的滞回曲线饱满,没有明显的捏缩现象,具有良好的耗能能力;位移延性系数在2.3~4.1之间,且随轴压比的增加,剪力墙变形能力降低;在水平正负向加载时T形剪力墙刚度、承载力及延性呈非对称,翼缘受拉相对翼缘受压时承载力高,刚度大,延性小,需合理设计腹板无翼缘侧约束边缘构件,防止其受压时提早破坏。     

内置钢板与内置钢桁架混凝土组合剪力墙抗震性能对比研究

通过对2组内置钢板混凝土组合剪力墙和内置钢桁架混凝土组合剪力墙拟静力试验的模拟,确定计算模型的建立方法,并选取2片相同含钢率的内置钢板混凝土组合剪力墙和内置钢桁架混凝土组合剪力墙模型进行侧向低周反复荷载作用下的计算分析,对比了2片剪力墙模型的承载力、刚度及其退化过程、延性、耗能及滞回特性,并选取实际工程为算例,对采用两种组合剪力墙的整体结构从抗侧刚度、破坏模式、层间位移角、位移时程及塑性发展等方面进行了抗震性能的对比。研究结果表明：对于构件层次,随着墙体高宽比的增大,内置钢板混凝土组合剪力墙的承载力、耗能能力及延性逐渐优于内置钢桁架混凝土组合剪力墙;对于结构层次,当墙体高宽比较大时,采用内置钢板混凝土组合剪力墙结构的抗震性能要优于采用内置钢桁架混凝土组合剪力墙的结构。     

内置轻钢桁架混凝土组合剪力墙抗震性能试验研究

将冷弯薄壁型钢桁架配置在普通钢筋混凝土剪力墙中代替钢筋而形成轻钢桁架混凝土组合剪力墙。为研究该类墙体的抗震性能,对两组共6个内置轻钢桁架混凝土组合剪力墙进行拟静力试验,研究轴压比和斜撑体积配钢率对其滞回性能、变形性能、刚度退化以及耗能能力的影响。对比了低矮剪力墙和中高剪力墙的位移延性和耗能能力。结果表明：轴压比对该类剪力墙的变形能力和耗能能力均不利,应予以控制;斜撑体积配钢率对提高低矮墙的延性、耗能能力效果明显,但对承载力的提高作用较小;对中高剪力墙,斜撑体积配钢率的增加,对其耗能能力不利。     

Study on seismic performance test and calculation method of recycled steel fiber reinforced concrete shear wall

Recycled steel wire is taken from used tires, and by procedures like mechanical cutting and friction treatment, it can be converted into industrial recycled steel fiber that meets precise criteria. Such green fiber may effectively limit the growth of fractures in concrete and diffuse the fracture energy of concrete when incorporated into concrete. An investigation of the effects of materials and horizontal reinforcement spacing on the seismic performance of shear wall specimens is presented in this research. The test and numerical simulation findings indicate that the RSFRC (recycled steel fiber reinforced concrete) shear wall's fracture is substantially narrower than that of a conventional shear wall and that the shear carrying capacity and deformation ductility of the shear wall have been greatly enhanced. The energy dissipation capacity of the RSFRC shear wall specimen with varying horizontal reinforcement spacing is significantly enhanced when compared to the conventional shear wall, and the ultimate displacements are reduced. RSFRC shear wall specimen has higher stiffness in the early stage, and the overall stiffness decreases slowly. With the decrease of fiber volume fraction of RSFRC shear wall in a certain range, the shear bearing capacity and stiffness of the model will decrease slightly, but the ductility will increase significantly. Compared with the RSFRC shear wall with fiber aspect ratio of 40 and 25, the bearing capacity and ductility of the two are close, but the RSFRC shear wall with low aspect ratio is slightly insufficient. When the axial compression ratio is in the range of 0.2–0.4, the horizontal shear capacity of RSFRC shear wall increases with the increase of vertical load, but the maximum horizontal displacement becomes smaller, and the model is damaged by compression. Using theoretical calculation, this work also creates the simplified calculation method and restoring force model for the bearing capacity of the diagonal section of RSFRC shear wall. The observed findings correspond well with the test hysteresis curve and may serve as a benchmark for future study. This study provides a new research direction for the seismic performance of RSFRC structures, as well as a solid theoretical foundation and promotion for future research.     

纤维增强混凝土剪力墙抗震性能试验研究与理论分析

为根本改善混凝土基体的脆性,提高混凝土剪力墙的抗震性能和损伤容限,设计制作6个局部纤维增强混凝土（FRC）剪力墙试件,在试件变形关键部位采用FRC替代普通混凝土,并考虑高轴压比下剪力墙受压钢筋屈曲和受拉纵筋应力集中的问题,在塑性铰区纵向钢筋上设置钢套管,以改善受力钢筋的稳定性和变形性能。通过对悬臂剪力墙试件的拟静力试验,研究此类剪力墙的破坏现象、受力机理和滞回特性,探讨轴压比、FRC区高度、纵筋强度和钢套管长度等因素对墙体变形能力及耗能能力的影响。研究表明,与普通混凝土剪力墙试件相比,塑性铰区采用FRC的剪力墙试件具有较高的损伤容限和变形能力;提高钢筋强度和延性以及在纵筋上设置钢套管,对其抗震性能和耗能能力均具有明显的改善作用。     

间隔钢管混凝土组合剪力墙抗震性能试验研究

间隔钢管混凝土组合剪力墙是一种新型抗侧力构件,其施工方便、布置灵活,具有良好的经济效益和工程应用价值。为研究轴压比对这种新型抗侧力构件的抗震性能的影响,对3个不同轴压比的足尺四管间隔钢管混凝土组合剪力墙试件进行水平低周反复加载试验,观察组合剪力墙破坏特征和破坏过程,得到组合剪力墙的滞回曲线、骨架曲线、承载力和刚度退化、延性、耗能能力等抗震性能指标。结果表明：组合剪力墙的破坏形式均为受压区钢管内混凝土压溃和钢管壁凸屈,缀板与钢管连接区域撕裂;随着轴压比增大,组合剪力墙的刚度和承载力增大,延性降低,与轴压比为0的组合剪力墙相比,轴压比为0.4的剪力墙承载力提高25%,延性降低19%;组合剪力墙的位移延性系数在2.401~3.479之间,极限位移角在1/40~1/34之间,等效黏滞阻尼系数达到0.15,整体抗震性能良好。     

T形型钢混凝土短肢剪力墙斜截面承载力影响因素研究

为了确保T形型钢混凝土短肢剪力墙发生延性剪切破坏,在对其破坏机理进行试验研究的基础上,采用ANSYS有限元分析软件模拟其破坏形态。在分析过程中考虑水平钢筋的配筋率、混凝土强度、轴压比以及型钢配钢率等影响因素的作用。结果表明：水平钢筋体积配筋率、混凝土强度以及型钢配钢率可以明显改变构件的承载力和延性。     

装配复合模壳体系混凝土剪力墙抗震性能试验研究

装配复合模壳体系剪力墙是一种新型的免拆模现浇混凝土剪力墙。进行了6个装配复合模壳体系剪力墙试件的拟静力试验,其中试件的剪跨比包括1.75和1.0,试验轴压比包括0.11、0.25和0.38。研究了模壳剪力墙试件的破坏形态、滞回曲线、骨架曲线、刚度、耗能与位移延性等抗震性能和极限承载力,并与整浇剪力墙试件进行对比,分析了拼缝连接钢筋构造以及模壳对模壳剪力墙抗震性能的影响。结果表明：模壳试件均为受弯破坏,破坏时试件两端根部模壳剥裂,且轴压比为0.38的试件的墙身下部模壳出现胀裂;模壳试件与整浇试件的滞回曲线相似,均较为饱满;达到峰值荷载前,模壳试件的刚度比整浇试件的略大,但破坏时二者刚度基本相同;模壳试件位移延性系数为2.46~4.71,极限位移角为1/50~1/38,具有较好的延性性能;模壳试件的极限承载力与整浇试件相当,二者之比平均为1.04;对边缘构件竖向纵筋采用逐根搭接、对竖向分布纵筋采用双排或单排钢筋搭接以及对水平分布纵筋采用双排钢筋搭接的构造做法,能保证装配复合模壳体系剪力墙的有效传力。最后,进行装配复合模壳体系剪力墙受力分析,并提出了相关设计建议。     

带约束拉杆双层钢板内填混凝土组合剪力墙抗震性能试验研究

提出一种带约束拉杆双层钢板内填混凝土组合剪力墙,通过对6个剪跨比为2.0、轴压比为0.6的此类剪力墙试件的低周往复加载试验,研究试件的破坏形态、滞回曲线、骨架曲线、承载力退化、刚度退化、位移延性系数和耗能等抗震性能。结果表明：带约束拉杆双层钢板内填混凝土组合剪力墙抗震性能良好,6个试件的屈服位移角平均值为1/147,极限位移角平均值为1/48,位移延性系数平均值为3.57;减小约束拉杆间距和采用梅花式布置约束拉杆的方式,能更好地对钢板和混凝土提供约束,延缓钢板局部屈曲,增大混凝土的极限变形能力,提高剪力墙承载力、延性和耗能能力,减缓承载力退化和刚度退化,改善剪力墙抗震性能。     

Cyclic behavior of shear walls with HPFRCCs in the inelastic deformation critical region

This study presents a structural application of high‐performance fiber‐reinforced cement composites in the inelastic deformation critical region of the shear wall to improve the performance and reduce the disadvantages of conventional reinforced concrete members. Six small‐scale wall specimens with the same aspect ratio and various configurations were tested under reversed cyclic loading, and their cyclic behaviors were evaluated and compared. The fiber cementitious material examined in this study exhibited excellent pseudo strain‐hardening behavior in tension and high tensile ductility. The results of the quasi‐static cyclic tests revealed that the deformation compatibility between the steel reinforcements and high‐performance fiber‐reinforced cement composite (HPFRCC) matrix could maintain composite integrity. Accordingly, the damage tolerance of the wall specimens for high inelastic deformation could be improved. Furthermore, the ultimate deformation and energy dissipation capacities of the wall specimens were dominated by the ductility and stability of the longitudinal reinforcements. Consequently, the combination of highly ductile mixture material and buckling‐restrained measures of steel reinforcement, such as the steel sleeve presented in this paper, was proposed for use in shear walls under moderate or even higher axial loads. Copyright © 2016 John Wiley & Sons, Ltd.     

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.