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1.
This paper assesses the seismic performance of a high‐rise building with steel reinforce concrete column and reinforce concrete core tube in Shanghai, China. This building has 54 floors above the ground and 4 basements, and it has two strengthened layers, which are composed of outrigger truss and belt truss. In order to validate the reliability and the safety of this structure, besides the conventional analysis, shaking table test of scale model was conducted. In the test, the maximum responses of acceleration and deformation were measured and evaluated, as well as the dynamic characteristics, crack pattern, and failure mechanism of the building. Meanwhile, elastic‐plastic time‐history analysis for prototype structure was carried out by the finite element analysis program, and the experimental data were compared with the analytical results to gain a better understanding of the seismic performance of the building. The conclusions are summarized below:

2.
Concrete‐filled‐steel‐tube (CFST) columns have been widely adopted for column construction of tall buildings due to its superior strength and ductility performance contributed by the composite action. However, this beneficial composite action cannot be fully developed at early elastic stage as steel dilates more than concrete and thereby causing imperfect interface bonding. Hence, it reduces the elastic strength and stiffness of the CFST columns. To resolve the problem, external confinement in the form of steel rings is proposed in this study to restrict the lateral dilation of concrete and steel at initial elastic stage. In this paper, CFST columns of various dimensions cast with normal‐strength or high‐strength concrete and installed with external steel rings were tested under uni‐axial compression. From the results, it was evident that (a) the external steel rings could restrict the lateral dilation of CFST columns and improve the interface bonding condition and (b) externally confined CFST columns had uni‐axial strength and stiffness larger than those of unconfined CFST columns. With the experimental results, an analytical model taking into account the confining effects of steel tube and rings has been developed to predict the uni‐axial strength of ring‐confined CFST columns. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

3.
The behavior of reinforced concrete members subjected to seismic loads is mainly based on the ultimate strength of concrete and its ductility. Based on this, an additional configuration of transverse reinforcement using high‐strength multiple‐tied‐spiral was proposed to improve the strength and ductility of concrete. In this paper, an experimental study of a number of axial loading tests on reinforced concrete columns confined with high‐strength multiple‐tied‐spiral transverse reinforcement is described. The effects of spacing of circular spiral and rectangular hoop, the confined area of circular spiral and concrete strength on axial behavior of confined concrete were investigated. The formulas of confined compressive strength and corresponding axial strain, factor to control the slope of descending branch, and stress in high‐strength circular spiral at confined strength are proposed based on the test results. A stress–strain model is also proposed that is found to give reasonably good prediction of the experimental behavior of reinforced concrete (RC) columns confined by high‐strength multiple‐tied‐spiral transverse reinforcement.  相似文献   

4.
This paper innovatively designs polyvinyl chloride tube (PVCT) with high‐strength concrete (HC) and presents the results of cyclic loading tests on new reinforced high‐strength concrete short columns, including three high‐strength concrete‐filled PVCT (HC‐PVCT) short columns, one high‐strength concrete‐filled steel tube short column and one HC short column. The main objective of this research was to evaluate the seismic behaviors of HC short columns based on the quasistatic test of the columns. The design parameters of the columns in the experiments were axial compression ratio, reinforcement measures, concrete strength, stirrups configuration, and the height‐diameter ratio of tubes. The crack distribution, failure modes, hysteresis loops, skeleton curves, energy dissipation capacity, strength degradation, stiffness degradation, and cumulative damage of the columns were presented and analyzed. The results showed that the HC‐PVCT column had a fuller hysteretic loop and a higher peak load than the HC column. Compared with HC column, the strength degradation of HC‐PVCT columns was slower, and the ductility increased significantly. With a larger axial compression ratio, the ductility of HC‐PVCT columns was decreased. Based on the test and analysis results, a modified HC‐PVCT design method was proposed to calculate the nominal shear strength of HC‐PVCT short columns.  相似文献   

5.
The outrigger system has been widely adopted as an efficient structural lateral‐load resisting system for super‐tall buildings in recent years. Although the outrigger system has many structural advantages, it has a significant defect due to differential shortening, which cannot be neglected. Due to the shrinkage and creep of concrete, as well as the differential settlement of foundation, the shortening of the structural member is an important time‐dependent issue, which leads to additional forces in the outriggers after the lock‐in of the outriggers. As a result, it will increase the size of the structural member cross section in the design. In a real project, engineers can delay the lock‐in time of the outrigger system to release the additional forces caused by the differential shortening during the construction phase. The time‐dependent actions, such as the column shortening and the differential settlement of the foundation, were estimated. A mega frame steel structure was employed to illustrate the analysis and design of the outrigger under the time‐dependent actions. Furthermore, a simple optimal method, considering the structural stability and overall stiffness, was proposed to optimize the construction sequence of the outrigger system.  相似文献   

6.
钢管混凝土叠合柱轴压性能研究   总被引:1,自引:0,他引:1  
为研究钢管混凝土叠合柱轴压性能,基于合理的钢材和混凝土本构关系模型,采用纤维模型法和有限元法分析方法计算叠合柱轴压荷载-变形关系曲线。将理论计算结果与试验结果进行对比,验证了理论分析模型的正确性。在此基础上,对叠合柱的破坏模态、轴向荷载分配以及组成钢管混凝土叠合柱的外围钢筋混凝土、钢管和钢管内部混凝土之间相互作用等进行分析,提出了叠合柱的轴压承载力简化计算式,简化计算结果与试验结果吻合较好。为保证外围钢筋混凝土和内部钢管混凝土较好地协同工作,建议外围钢筋混凝土中箍筋的约束指标与内部钢管混凝土的约束效应系数比值不应小于0.188。  相似文献   

7.
This paper deals with a new and simple mathematical model that may be used to determine natural frequencies and mode shapes of a multistory building that consists of a framed tube, a shear core and multi‐outrigger–belt trusses. The effect of outrigger–belt truss and shear core on a framed tube was modeled as a concentrated moment placed at outrigger–belt truss location, which acted in opposite direction of the rotation created by lateral loads. The analysis is based on a continuum approach, in which a tall building structure may be replaced by an idealized cantilevered beam to model the building's structural characteristics. Energy method and Hamilton's principle have been used to develop the governing equations. After applying separation of variables method to time and space variables, the resulting eigensystem was solved to obtain the building's natural modes and frequencies of vibration. A computer program has been developed in MATLAB (Mathworks Inc., CA, USA) environment, and a numerical example has been solved to demonstrate the accuracy of this method. Results obtained from the proposed mathematical model give a good understanding of a structure's dynamic characteristics. The method is simple to use yet reasonably accurate and hence suitable for quick evaluations during preliminary design stages. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

8.
对3根带肋冷弯薄壁方钢管混凝土柱进行滞回试验,主要参数为轴压比。试验结果表明:纵向加劲肋有效延缓了钢管壁局部屈曲的发生;其滞回曲线饱满,具有良好的耗能能力;随着轴压比的增大,柱承载力略有增大,而延性、耗能能力则明显减小;当横向位移大于6倍的屈服位移时,大轴压比的刚度退化速度最快。建立了该类试件的有限元模型,对比可得有限元模拟结果与试验结果吻合较好。基于有限元模型对该类构件开展机理分析和参数分析。结果表明:在带肋冷弯薄壁方钢管的约束下,核心混凝土的强度得到了较大提高;钢管局部屈曲发生在峰值荷载后,局部屈曲只发生在纵向加劲肋和钢管角部间;材料强度、轴压比、钢管宽厚比和长细比等参数对该类构件的承载力有较大影响;混凝土强度、轴压比和长细比对荷载-位移骨架曲线形状有较大影响。基于参数分析建议了该类构件的简化滞回模型,简化计算结果和有限元计算结果吻合较好。  相似文献   

9.
Concrete beams reinforced with fiber reinforced polymer (FRP) bars exhibit large deflections and crack widths as compared to concrete beams reinforced with steel due to the low modulus of elasticity of FRP. Current design methods for predicting deflections at service load and crack widths developed in concrete structures reinforced with steel bars may not be used for concrete structures reinforced with FRP bars. Thus, the ACI 440 Committee has provided design guidelines for concrete beams reinforced with FRP bars. Verification of the ACI 440 methods for predicting deflections and crack widths for glass fiber reinforced polymer reinforced concrete beams are presented in this paper. In addition, improvement to the crack width equation was suggested to account for 2 layers of reinforcement. This study shows that ACI 440.1R-01 can be effectively used to predict deflections in concrete beams reinforced with FRP bars and crack width in beams with one-layer FRP bars. However, when FRP bars are placed in two layers, ACI 440.1R-01 can be used after some parameters are modified. Six full concrete beams reinforced with different GFRP reinforcement ratios were load tested and the measured deflections and crack widths were analyzed and compared with those predicted by the proposed models. The experimental results compared well with those proposed by the model.  相似文献   

10.
GFRP套管钢筋混凝土短柱轴压力学性能试验研究   总被引:2,自引:0,他引:2       下载免费PDF全文
为研究GFRP套管钢筋混凝土短柱的轴压力学性能,进行了22个GFRP套管钢筋混凝土短柱和6个无GFRP套管约束的钢筋混凝土短柱对比试验。研究了影响GFRP套管钢筋混凝土组合短柱轴压力学性能的主要因素,包括GFRP套管不同的受力方式、混凝土强度、纵筋配筋率等。试验结果表明:由于GFRP套管的约束,提高了核心混凝土的强度,增大了核心混凝土的变形能力;GFRP套管在不同的受力方式下,组合短柱的轴压承载力和变形基本相同;GFRP套管内配置纵筋可提高GFRP套管混凝土短柱的轴压承载力,适当提高纵筋配筋率可改善短柱的延性。根据试验结果及现有FRP管约束混凝土轴心抗压强度计算公式,建议了GFRP套管钢筋混凝土短柱承载力计算公式,计算结果与试验结果基本吻合。  相似文献   

11.
Load‐carrying capacity of anchor plates in reinforced concrete. For the load transmission into concrete constructions frequently anchor plates with welded studs are used. At the Institute of Structural Design two test series at reinforced concrete specimens were accomplished, which show that reinforcement decisively influences the load‐carrying capacity and the actually calculated design loads tend to underestimate the real resistance. On the basis of 27test results and supplementary FE analyses a first mechanical model based on the component method is presented, describing the load‐carrying capacity of anchor plates with welded studs in reinforced concrete elements.  相似文献   

12.
In this study, the seismic performance of special and intermediate moment‐resisting reinforced concrete frames are evaluated through nonlinear static and dynamic analysis. According to experimental studies, one of the most important parameters affecting the behavior of special and intermediate ductile reinforced concrete frames is the transverse reinforcement ratio. In this paper, constitutive law of material for concrete under the influence of various transverse reinforcement ratios have been derived using Mander et al. model, and 20 ground‐motion accelerograms have been utilized for dynamic analysis. Additionally, the results of pushover and incremental dynamic analysis were compared in order to evaluate seismic performance of the selected high‐rise structures. Results reveal that both types of reinforced concrete frames with beam‐hinge type failure mechanisms have ductile behavior. Special moment frames have higher ductility because of early entry into nonlinear range resulting in higher plastic rotations, which result in greater lateral displacements. Due to the differences in behavior of intermediate and special ductility frames, confinement has an important role in the ductile behavior of structures. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

13.
Shear wall systems are the most commonly used lateral load resisting systems in high‐rise buildings. Six 1:2 scale mid‐rise T‐shaped reinforced concrete shear wall specimens with aspect ratio of 1.75, 2.15 and 2.80 were respectively tested under reversed cyclic loading. The seismic behavior and displacement ductility were investigated. The effects of aspect ratio, axial load level and transverse steel ratio on the seismic behavior and displacement ductility were also analyzed. Test results were discussed and compared with T‐shaped steel–concrete composite shear wall. Results mainly showed that the T‐shaped shear wall specimens mainly presented bending–shear failure mode and were all destroyed because of the concrete crushing at the web (negative direction) and the longitudinal reinforcement of the web reaching the limited deformation (positive direction), showing that the web was the weakest part of T‐shape shear wall. The ductility of the specimens was decreased, and the ultimate load‐bearing capacity was increased by increasing the axial load. To specimens with smaller aspect ratio and higher axial load ratio, the special transverse steel ratio of the web should be increased to improve the crushing strain of the confined concrete of the web in order to satisfy the ductility of the walls. The seismic performance was obviously improved in the T‐shaped steel–concrete shear wall compared with that of the T‐shaped reinforced concrete shear wall. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

14.
Certain maximum lateral displacement (LAT) and differential axial shortening (DAS) values can lead to the deterioration of the serviceability of a structure. Previous studies indicated that an outrigger system can be used to control both the DAS and the LAT in a tall building. In order to enhance the applicability of the dual‐purpose outrigger system, the amount of stress developed on the outrigger due to the reductions of the LAT and DAS should be determined. Therefore, in this study, the stresses due to the LAT and DAS were analyzed in terms of the reduction ratio of the LAT and DAS, and the absolute sum of stresses, which was the strength demand of the outrigger, was evaluated as well. To identify the parameters affecting the additional stress of the outrigger, analytic equations were proposed to predict the additional shear force acting on the outrigger due to DAS reduction. A finite‐element analysis was performed to quantitatively identify the reduction ratio of the LAT and DAS as well as the resulting stress by changing four parameters: the stiffness, location, number, and connection time of outriggers. The results demonstrated that the stress of the dual‐purpose outrigger can be minimized by adjusting the design parameters.  相似文献   

15.
玻璃纤维混凝土梁挠度和裂缝宽度计算方法研究   总被引:7,自引:0,他引:7  
王增忠  Bin SHI 《工业建筑》2002,32(11):8-10
利用梁的有效惯性矩 ,将玻璃纤维配筋率和弹性模量的影响在Branson公式的m系数中集中得以体现 ,提出了玻璃纤维混凝土梁挠度的计算方法 ,并基于已有的研究成果 ,给出了玻璃纤维混凝土梁裂缝宽度的理论计算公式 ,且与 6根不同配筋率的玻璃纤维混凝土梁的试验结果相比较 ,理论计算与试验结果比较接近  相似文献   

16.
The method of effective stresses for simple calculation of creep deflections of reinforced concrete girders A method for simple calculations of deflections of reinforced concrete beams is taken on and enhanced. It is shown how the results of computer analysis on the basis of linear‐elastic material behaviour can replace the integration of the curvature distribution by hand to evaluate the deflection. For a systematic evaluation of deflections of reinforced concrete beams with regard to creep effects, parameters of major influence are identified and first evaluations are presented.  相似文献   

17.
A new method of analysing the post‐peak flexural behaviour of reinforced concrete beams has been developed and applied to normal‐ and high‐strength concrete beams. It was revealed that at the post‐peak stage the neutral axis depth keeps on increasing, and at a certain point the strain in the tension reinforcement starts to decrease, even though the curvature is increasing monotonically. Such strain reversal in the tension reinforcement occurs in all concrete beams and has significant effects on the post‐peak behaviour and flexural ductility of concrete beams. Therefore, the stress path dependence of the tension reinforcement needs to be taken into account in the analysis. By means of a parametric study, the variation of ultimate concrete strain with tension steel ratio and the effects of various structural parameters on flexural ductility have been studied. Based on the numerical results, design values of ultimate concrete strain that are independent of tension steel ratio have been recommended and a simple formula for predicting the flexural ductility of reinforced normal‐ and high‐strength concrete beams has been developed. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

18.
This paper presents theoretical studies on load‐bearing capacity of reinforced concrete flat‐plate framed structures. The existing methods for determining load‐bearing capacity of simply supported slabs are first reviewed, and their limitations are presented. An energy‐based refined method is then proposed to enhance the accuracy of the existing methods by considering the contributions to internal energy dissipation due to the extension of reinforcing bars along yield lines, the additional resultant bending moment from membrane forces, and the sectional bending moment along yield lines of slabs. The refined method for simply supported slabs is extended for fixed supported slabs, and thus, the load‐bearing capacity of reinforced concrete flat‐plate structures subject to a middle column loss is analytically determined. The performance of the proposed method is validated against test results and also verified against finite element analyses. Parametric studies are conducted to investigate the effect of reinforcement ratio, slab thickness and aspect ratio on the stiffness, and yield‐line resistance of structures. It is found that for the fixed supported slabs, it is reasonable to assume negative yield lines along the slab edges to consider the effect of obvious concrete crushing along the edge. Square slabs have higher ultimate loads than rectangular slabs, due to a longer horizontal yield line in the middle in the rectangular slab, which has detrimental effect on the sectional ultimate bending moment. The numerical results show that the reinforcement ratio has little effect on the initial bending stiffness and yield‐line resistance of slabs for a given slab thickness and aspect ratio. The initial stiffness and yield‐line resistance increase as the slab thickness increases. For the same reinforcement ratio and slab thickness, a larger aspect ratio leads to a lower initial bending stiffness, yield‐line resistance, and stiffness in tensile membrane action stage, due to a longer yield line along which tensile membrane forces have a detrimental effect on the sectional bending moment.  相似文献   

19.
进行了1个14层1/10缩尺的钢筋混凝土筒中筒结构模型静力试验,重点分析了偏心水平荷载和顶部竖向荷载对模型受力性能的影响,得出了几点结论,可供筒中筒结构分析和设计时参考。  相似文献   

20.
This paper discusses modelling, analysis and design issues for a 55‐storey hotel building recently planned for New York City, USA. The lateral force resistance of the investigated building primarily makes use of exterior reinforced concrete shear walls in one direction and exterior reinforced concrete moment frames in the other direction, in which tube action credited to the connection of the walls and frames was designed to play a significant role in the lateral stiffness and strength. In addition, a full‐storey belt wall system, enclosing the entire perimeter of the building at approximately the mid‐height, is expected to provide a considerable contribution to the lateral force resistance. In this paper, the contribution of tube action and the belt wall system to structural behaviour is investigated in terms of quantitative measures such as lateral drift, building dynamic properties and flange frame contribution to overturning moment resistance. In addition, axial force distribution among the various vertical members under lateral forces is discussed for each of the two principal building directions. Finally, the seismic behaviour of the investigated building is qualitatively discussed in order to propose a seismic force‐resisting system classification into which this concrete tube system would fit. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

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