The Effect of Core Eccentricity on the Structural Behavior of Concrete Tall Buildings

The main purpose of this paper is to investigate the effect of core eccentricity on the structural behavior of concrete tall buildings.Concrete buildings of 55 floors with plan dimensions 48.0×48.0 m2 were investigated.Three cases of main core locations are studied:centric(A),eccentric by one sixth(B)and one third(C)of building width.The three-dimensional finite element method has been used in conducting structural analysis through ETABS software.Gravity and lateral(wind and seismic)loadings are applied to all building cases.It has been concluded that the core location is the prime parameter governing the structural behavior of tall buildings.Although the first two cases(A,B)have acceptable and similar structural behaviors conforming to code limits,in the third case(C),the building behavior came beyond code limits.The author introduced remedial action by adding two secondary cores in the opposite direction of the main core(C-R)to restore the building behavior to the code limits.The results of this action were satisfactory.

Seismic response of tall building considering soil-pile-structure interaction

The seismic behavior of tall buildings can he greatly affected by non-linear soil-pile interaction during strong earthquakes.In this study a 20-storey building is examined as a typical structure supported on a pile foundation for different conditions:(1) rigid base,i.e.no deformation in the foundation:(2) linear soil-pile system;and (3) nonlinear soil-pile system. The effects of pile foundation displacements on the behavior of tall building are investigated,and compared with the behavior of buildings supported on shallow foundation.With a model of non-reflective boundary between the near field and far field, Novak's method of soil-pile interaction is improved.The computation method for vibration of pile foundations and DYNAN computer program are introduced comprehensively.A series of dynamic experiments have been done on full-scale piles, including single pile and group,linear vibration and nonlinear vibration,to verify the validity of boundary zone model.

Push-Over Analysis for Concrete Structures of Tall Building

In this paper, push-over analysis for tall concrete structures was made and a corresponding computer program was given. Several kinds of elements in the program were considered to meet the demand of tall buildings with complex structural type. These elements included beam-column element for beams and columns, single slice wall element and three vertical line element for walls, and tube-wall element for tubes. Computational example for verifying the models indicates that the result obtained by this method is identical with a well-known test result and the program can be used to search for the full process of structural reaction, even the softening stage of the structure. With this push-over analysis method, an actual tall building with complex structural type was analyzed, and the result has been put into practice of the structural design of the building. Key words push-over analysis - tall structure - complex type - nonlinearity - earthquake level - weak storey MSC2000 74S05 - 74L99 Project supported by the National Natural Science Foundation of China (Grant No. 50025821)

Influence of soil——structure interaction on seismic collapse resistance of super-tall buildings

Numerous field tests indicate that the soilestructure interaction （SSI） has a significant impact on thedynamic characteristics of super-tall buildings, which may lead to unexpected structural seismic responsesand/or failure. Taking the Shanghai Tower with a total height of 632 m as the research object, thesubstructure approach is used to simulate the SSI effect on the seismic responses of Shanghai Tower. Therefined finite element （FE） model of the superstructure of Shanghai Tower and the simplified analyticalmodel of the foundation and adjacent soil are established. Subsequently, the collapse process of ShanghaiTower taking into account the SSI is predicted, as well as its final collapse mechanism. The influences ofthe SSI on the collapse resistance capacity and failure sequences are discussed. The results indicate that,when considering the SSI, the fundamental period of Shanghai Tower has been extended significantly,and the collapse margin ratio has been improved, with a corresponding decrease of the seismic demand.In addition, the SSI has some impact on the failure sequences of Shanghai Tower subjected to extremeearthquakes, but a negligible impact on the final failure modes. 2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.

Structural Design of a Tall Building with Underpinning Structure in Guangzhou

This paper introduces the structural design optimization of a tall building with reinforced concrete frame-core shear walls in Guangzhou downtown.To decrease the construction cost,wide flat beam with 400 mm ×650 mm rectangular cross-section are adopted for main beam.Special measures are used to decrease noncoincident centers of mass and stiffness.Because subway tunnels cross the building underground,inclined columns,the second and third floor underground together function as the underpinning structures.Different from traditional transform beam,the proposed underpinning structures show good performance without using large dimensional bending members.Special attentions should be paid to the beams connecting with the inclined column in the underpinning structures,and these beams show large tensile or compressive forces.Settlement observations after completion construction indicate that the building as well as the proposed design measures work well.

Extended consecutive modal pushover procedure for estimating seismic responses of one-way asymmetric plan tall buildings considering soil-structure interaction

Performance based design becomes an effective method for estimating seismic demands of buildings. In asymmetric plan tall building the effects of higher modes and torsion are crucial. The consecutive modal pushover （CMP） procedure is one of the procedures that consider these effects. Also in previous studies the influence of soil-structure interaction （SSI） in pushover analysis is ignored. In this paper the CMP procedure is modified for one-way asymmetric plan mid and high-rise buildings considering $SI. The extended CMP （ECMP） procedure is proposed in order to overcome some limitations of the CMP procedure. In this regard, 10, 15 and 20 story buildings with asymmetric plan are studied considering SSI assuming three different soil conditions. Using nonlinear response history analysis under a set of bidirectional ground motion; the exact responses of these buildings are calculated. Then the ECMP procedure is evaluated by comparing the results of this procedure with nonlinear time history results as an exact solution as well as the modal pushover analysis procedure and FEMA 356 load patterns. The results demonstrate the accuracy of the ECMP procedure.

Flexural behavior of in-plane bending glass structures for design method

Experimental study was carried out on the in-plane bending behavior of glass plates without lateral supports, and the effects of the factors, such as height-to-span ratio, on the stability of glass panels were studied. Results show that the in-plane bending glass plates with both ends simply supported and their upper edge free lose overall stability under loads, which belongs to the limit-point type of instability. It is found that the buckling load increases linearly with the increase of height-to-span ratio of the glass plates. The lateral stress of in-plane bending glass plates without lateral supports increases linearly under loads; while the large-area stress increases nonlinearly and the lateral stress is not the controlling factor of instability. In finite element analysis, the first buckling mode is regarded as the initial imperfection and imposed on the model as 1/1000 of the span of the components. The numerical buckling load according to the theory of large deflection is less than the experiment result, which is more conservative and can provide some reference for design. For the design method, when the in-plane load is imposed on the glass plate, its lateral strength and the deflection should be verified. Considering the stability of the in-plane bending glass plate without reliable lateral support, buckling is another possible failure mode and calls for verification.

Design and Mechanical Characterization of an S-Based TPMS Hollow Isotropic Cellular Structure

Cellular structures are regarded as excellent candidates for lightweight-design,load-bearing,and energy-absorbing applications.In this paper,a novel S-based TPMS hollow isotropic cellular structure is proposed with both superior load-bearing and energy-absorbing performances.The hollow cellular structure is designed with Boolean operation based on the Fischer-Koch(S)implicit triply periodic minimal surfaces(TPMS)with different level parameters.The anisotropy and effective elasticity properties of cellular structures are evaluated with the numerical homogenization method.The finite element method is further conducted to analyze the static mechanical performance of hollow cellular structure considering the size effect.The compression experiments are finally carried out to reveal the compression properties and energy-absorption characteristics.Numerical results of the Zener ratio proved that the S-based hollow cellular structure tends to be isotropic,even better than the sheet-based Gyroid TPMS.Compared with the solid counterpart,the S-based hollow cellular structure has a higher elastic modulus,better load-bearing and energy absorption characteristics.

ODE-Solver-Oriented Computational Method for the Structural Dynamic Analysis of Super Tall Buildings

The paper is to introduce a computational methodology that is based on ordinary differential equations （ODE） solver for the structural systems adopted by a super tall building in its preliminary design stage so as to facilitate the designers to adjust the dynamic properties of the adopted structural system. The construction of the study is composed by following aspects. The first aspect is the modelling of a structural system. As a typical example, a mega frame-core-tube structural system adopted by some famous super tall buildings such as Taipei 101 building, Shanghai World financial center, is employed to demonstrate the modelling of a computational model. The second aspect is the establishment of motion equations constituted by a group of ordinary differential equations for the analyses of free vibration and resonant response. The solutions of the motion equations （that constitutes the third aspect） resorted to ODE-solver technique. Finally, some valuable conclusions are summarized.

Ultra-low Friction and High Load-Bearing Hydrogel with Tubular Structure Based on Controllable Light-Induced Dissociation

With high water content,excellent biocompatibility and lubricating properties,and a microstructure similar to that of the extracellular matrix,hydrogel is becoming one of the most promising materials as a substitute for articular cartilage.However,it is a challenge for hydrogel materials to simultaneously satisfy high loading and low friction.Most hydrogels are brittle,with fracture energies of around 10 J·m^(-2),as compared with∼1000 J·m^(-2) for cartilage.A great deal of effort has been devoted to the synthesis of hydrogels with improved mechanical properties,such as increasing the compactness of the polymer network,introducing dynamic non-covalent bonds,and increasing the hydrophobicity of the polymer,all at the expense of the lubricating properties of the hydrogel.Herein,we develop a hydrogel material with anisotropic tubular structures where the compactness gradually decreases and eventually disappears from the surface to the subsurface,achieving a balance between lubrication and load-bearing.The porous layer with hydrophilic carboxyl groups on the surface exhibits extremely low friction(coefficient of friction(COF)∼0.003,1 N;COF∼0.08,20 N)against the hard steel ball,while the bottom layer acts as an excellent load-bearing function.What is more,the gradual transition of the tubular structures between the surface and the subsurface ensures the uniform distribution of friction stress between a lubricating and bearing layers,which endows the material with long-lasting and smooth friction properties.The extraordinary lubricious performance of the hydrogels with anisotropic tubular structure has potential applications in tissue engineering and medical devices.

设置结构缝的矩形高层建筑风荷载及风致响应研究

大长宽比的矩形高层建筑往往需要设置结构缝,设缝后建筑物的风压分布仍由整体建筑外形决定,但各建筑单元的风荷载及风致响应与单一建筑相比会有很大不同。为探究设缝建筑中各单元的风荷载和风振特性,本文以长宽比为3的单一建筑为参照对象,对长宽比分别为6和9、在长边分别设置1道和2道结构缝的矩形高层建筑进行了同步测压风洞试验;分析正交风向下不同建筑单元的三分力系数、功率谱和整体体型系数特性;对不同建筑单元采用同一结构参数计算其风振响应,探讨不同单元的顶层位移和加速度响应随风向角的变化特点,考察正交风向下这些响应的频谱特性。研究结果表明:不同单元的气动力系数和气动力谱差别明显,且短边迎风时的差异大于长边迎风时的差异;考虑全风向角情况,设置结构缝的建筑两侧单元整体体型系数比同等长宽比的单一建筑的小,中间单元整体体型系数与单一建筑的基本相同;两侧单元的顶层平动风振响应比单一建筑的小,扭转风振响应比单一建筑的略大,中间单元的平动和扭转响应都明显比单一建筑的小。因此,设置结构缝的矩形高层建筑不同单元的抗侧力构件应采取差异化布置。

落地与悬挑组合式支模体系在高位逐层外悬挑结构施工中的应用

高位逐层外悬挑混凝土结构造型奇特、受力复杂,在建造过程中普遍存在技术难度大、安全风险高、措施费用高、施工工期长等突出问题。以光谷人民医院项目塔楼单侧高位逐层外悬挑混凝土结构支模体系实施为例,从安全性、经济性、可实施性等多方面进行方案综合比选,采用落地与悬挑组合式支模体系。分析结构荷载传递路径和多种施工工况,对支模体系进行精细设计和验算。严格按设计方案指导现场支模体系搭设和拆除。实践表明,提出的落地与悬挑组合式支模体系可安全、便捷、高效地完成高位逐层外悬挑混凝土结构施工。

盘扣式支架在高支模中的应用技术

本文对盘扣式支架在高大模板支撑体系中的应用进行了深入研究,详细探讨了其施工工艺、优势及效果。通过其在重庆地铁金鳌寺车辆段运用库高支模中的运用实践,对其运用技术和加固安全措施进行了探索和总结。实践表明,盘扣式支架具有较高的稳定性和安全性,能够显著提升高大模板支撑体系的承载能力。同时,其简单易行的安装和拆卸方式大大缩短了施工周期,提高了施工效率。因此,盘扣式支架在高大模板支撑体系中具有广泛的应用前景。

考虑SSI效应的高耸烟囱风振系数计算和风致响应分析

为研究风荷载作用下考虑土-结构相互作用(Soil-structure Interaction,SSI)对高耸烟囱结构的影响,文章利用ABAQUS分别建立考虑与不考虑SSI效应的烟囱有限元模型,对两种工况下的模型进行结构动力特性分析,根据规范计算两种工况下的烟囱风振系数。通过对结构进行动力时程分析,比较不同刚度的地基土对烟囱结构的具体影响。结果表明:考虑SSI效应后,烟囱自振周期增大。高度越高,考虑SSI效应得到的烟囱风振系数与刚性地基时的风振系数相比偏差越大,在结构设计时考虑SSI效应可以更准确地计算风振系数。地基土刚度越小,烟囱上部结构的位移和加速度响应越大,在软土地基上的结构设计应当考虑SSI效应对高耸烟囱结构的不利影响。

超高层钢构件锈蚀补强加固施工技术研究

某超高层钢构件自停工以来长期处于沿海地区的湿润环境中,经过现场检测,钢板剪力墙翼缘最大腐蚀厚度达到了0.2mm,巨柱的竖向加劲板最大腐蚀厚度为0.1mm。通过分析现场钢构件腐蚀现状及发展趋势,根据钢结构腐蚀评估现状及相关规范针对性地提出钢管柱补强加固和钢板剪力墙补强加固措施,实现锈蚀钢结构的补强利用。

超高层内倾外斜式大直径分叉圆管柱施工技术

在西安曲江文创中心项目中,塔楼外框主体结构3根角部钢柱为内倾外斜式分叉大直径圆管柱,分叉处柱体直径大,分叉相交贯口长、轴向受力大,对钢构件加工和现场安装精度要求高,不宜应用常规贯口切割技术。为解决相交大贯口加工难度大、制作精度与现场安装要求高、分叉节点整体运输难度大、焊接要求高的难题,从节点优化、贯口放样切割、工厂预拼装、现场安装等过程进行控制,顺利实现项目分叉圆管柱安装,且精度控制满足设计要求。

四塔高位连体钢桁架结构施工关键技术

以江门市档案中心高层建筑工程为例,该工程为四塔高位连体结构,在高层塔楼结构顶部采用带悬挑的大跨度钢桁架作为连接体,将4栋塔楼连为一体,其结构形式较复杂、施工难度大。为此,根据结构特点、工期、场地及垂直运输等因素,提出高位连体桁架采用“胎架拼装、低位滑移后整体提升”的一体化施工工艺,局部悬挑桁架采用“高空散装+临时支撑”的常规施工方法。在此基础上,制定了钢结构施工总体流程和具体实施要点。

某混合结构高层建筑的抗震鉴定

混合结构是高层建筑中常见的一种结构类型,但是GB 50023-2009《建筑抗震鉴定标准》对此类建筑的抗震鉴定没有明确的规定。论文以一栋2002年竣工的混合结构高层建筑为例,探讨了此类建筑的抗震鉴定原则及方法,可以为此类建筑的抗震鉴定提供参考。

多高层工程竹结构的研究与应用进展

基于格鲁斑工程竹的力学及加工方法的研究成果,参照现有木结构设计方法,完成了两栋多高层工程竹结构的结构设计与施工建造。其中一栋为3层办公楼,总高度105m,总建筑面积约1500m^(2)。另一栋为6层办公楼,总高度203m,总建筑面积约800m^(2)。两栋建筑均以重型工程竹框架构成结构主体,并设置了抗侧力斜撑及剪力墙。通过计算设计了结构构件的尺寸,并进行了抗震和抗风分析,结果表明竹结构满足现有规范要求。在施工建造过程中,采用北美木结构的“框架式”和“平台式”相结合的方法进行竹结构的搭建,有效保证了施工效率。

复杂梁结构施工中模板支撑体系的设计与实践

为了加强复杂梁结构施工的稳定性和安全性,特提出了研究复杂梁结构施工中模板支撑体系的设计与实践,并结合实际项目展开了对高大模板支撑体系的研究。首先选择施工方案、设计相关参数,包括梁侧模板面板、梁侧模板支撑、穿梁螺栓、梁底模板面板、梁底支撑梁、立杆的稳定性以及立杆的地基承载力;然后探讨模板支撑体系的施工技术,包括梁下及板下的立杆搭设、水平杆搭设、剪刀撑搭设、顶板主次龙骨模板安装、后浇带处支撑架搭设和混凝土浇筑。通过相关内容的研究,以使项目建筑结构更加稳定和安全。