天津高银117大厦: 细长体型的结构解决方案

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Overturning Moment, Story Shear and Shear-Gravity Ratio

The distribution of shear under frequently occurring earthquakes and wind is shown below. The seismic story drift, scaled according to the minimum base shear, was found to be larger than the wind load. Accordingly, it was determined that seismic loads controlled the design.

倾覆弯矩、层剪力和剪重比

小震和风荷载作用下底部剪力如下所示。结构地震下的位移根据最小底部剪力进行了调整，大于风荷载下的位移。因此结构的侧向刚度主要受地震荷载控制。

Story shear and frequent earthquake shear-gravity ratio distribution
楼层剪力和小震剪重比分布图

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Displacement

The maximum inter-story drift is 1/667 for a 50-year wind event, while inter-story drift under frequently occurring earthquakes, magnified per the allowable shear-gravity ratio and
considering vertical earthquake response, is 1/516 (1/614 beforemagnification) at Level 97, which is within the 1/500 limit of theChinese code.

位移

采用50年一遇的风荷载，最大层间位移角为1/667，小震下层间位移角计算考虑了剪重比和竖向地震放大的影响，最大层间位移角为1/516（放大前为1/614），均处于建筑层97，在中国设计规范限制的1/500以内。

Inter-story drift under earthquake and wind

地震及风作用下层间位移角

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Elastic Time-History Analysis of Level 1 Seismic

Seven sets of earthquake acceleration records have been studied in the frequent seismic dynamic time-history analysis, in which two sets are artificial records and five sets are natural records. All seven sets of records have base shears greater than 65% of that obtained from the response spectrum analysis, with an average value greater than 80%, which satisfies Code requirements. In the structural design,an average value of the story shear has been used to magnify the story shear obtained from the response spectrum analysis.

小震弹性时程分析

小震分析采用了七组强震加速度记录作为动力时程分析，其中两组为人工波，其余五组为天然波。七条时程曲线的基底剪力均大于反应谱法的65％，平均值大于反应谱法的80％，满足规范要求。结构设计取时程波在各层的平均值，在反应谱基础上将内力值进行放大调整，进行构件的补充验算。

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Shear and Overturning Moment distribution between Internal and External Frame

The external tube carries over 70% of the story shear on typical floors, which is considerably greater than that taken by the core (see Figure 11). At the strengthened floors, the sudden increase in stiffness of the external tube results in a sharp increase in shear force taken by the external frame with a horizontal force transfer between the internal and the external tube.

About 80% of the total overturning moment is taken by the perimeter structure.

These distributions of shear and overturning moments between the internal and external tube indicates that the perimeter mega-structure provides the majority of stiffness while the internal core becomes a “secondary” system. The advantage of this arrangement is that the core can be designed for a relatively low demand.


内外框架剪力与倾覆力矩

外框筒承担了标准楼层约70％以上的剪力，明显大于核心筒。在结构加强层，由于外框筒刚度在该楼层的显著增大，导致外框筒吸收的地震剪力出现突变，同时伴随水平力在内外筒间进行传递。

外框筒分担了各层约80％的倾覆力矩。

从层剪力和倾覆力矩内外筒分担比例分析看，带有巨型支撑的巨型框架结构体系提供了大部分刚度，而内部核心筒则成为“次级”体系。这种布置的好处是对内部核心筒的抗震性能要求可以降低。

Distribution of shear and overturning moment between internal and external frame
剪力及倾覆弯矩在内外框架分布示意图

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Wind Comfort Analysis

Wind tunnel tests for the tower were independently completed by BMT Fluid Mechanics and Shantou University Wind Tunnel Laboratory.Results from both laboratories are consistent and indicate an estimated peak acceleration of 20.3mill-g at the highest occupied level, which satisfies the national code requirements.

风舒适度分析

塔楼风洞试验分别由英国BMT公司和汕头大学风洞试验室完成，两个试验结果是一致的，显示本工程的最高住人楼层加速度为20.3mill-g，满足国家规范要求。

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Axial Shortening Analysis

Tall buildings will shorten under the gravity load, elastically as well as under the effect of shrinkage and creep. An initial construction program simulation analysis was carried out to estimate the amount of the axial shortening and evaluate the additional forces incurred. The internal forces of the mega braces were found to be increased due to the shortening of the mega columns which has been allowed properly in the member capacity checking.

轴向缩短分析

高层建筑在重力荷载下高度会有所缩短，并且在收缩和徐变效应下也会弹性化的变化。初步的建设方案模拟分析被用于估算轴向缩短量并评估额外产生的受力。其结果显示，巨型框架的内力由于巨型柱的缩短而增大，而这些巨型柱已被进行适当的受力能力检查。

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Elastic-Plastic Time-History Analysis of Level 3 Seismic

To achieve the seismic performance objective of no collapse undera severe earthquake, the design adopts the member plasticity development limits and analysis methods and procedures suggested in FEMA356 and ATC40. The non-linear seismic analysis was carried out with the general non-linear dynamic finite element analysis software LS-DYNA considering geometric non-linearity as well as material nonlinearity.

As for the composite steel plate shear wall, the steel plates and reinforced concrete shear walls are separately modelled as non-linear shell elements in space with common nodes, ensuring compatibility between the steel plates and reinforced concrete. Parameters such as overall mass and period of the elastic-plastic model under severe seismic activity are calibrated with the ETABS results to ensure the elastic compatibility of the dynamic properties.

Figure 12 indicates the inter-story drift response in the X and Y directions for the seven sets of time-history records under severe seismic activity, and each response satisfies the code requirement of 1/100.

罕遇地震弹塑性时程分析

为实现在罕遇地震作用下防倒塌的抗震设计目标，工程采用了美国FEMA356（建筑抗震修复预标准及其说明)和ATC40 所提供的结构构件弹塑性变形可接受限值，以及所建议的结构非线性地震分析方法与步骤。结构的非线性地震反应分析采用了通用非线性动力有限元分析软件LS-DYNA 进行计算，考虑了几何非线性与材料的非线性。

对于组合钢板剪力墙，把钢板和混凝土剪力墙分别建成共节点的非线性壳单元，保证钢板与混凝土协同作用。大震对弹塑性整体分析模型的质量及周期振型等信息与ETABS模型相比较，确保了弹性兼容性的动力特性。

7条时程波在弹塑性动力分析中，结构整体在X和Y方向上层间位移角的分布情况，均满足规范1/100的要求。

Overall inter-story drift under severe earthquake elastic-plastic time-history analysis
罕遇地震弹塑性动力时程分析结构整体层间位移角

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Design Study and Recommendations

Overall Stiffness Control and Selection of Structural Form

The structural height of the tower reaches almost 600 meters. The overall stiffness of the tower, therefore, was key to resisting the demanding wind and earthquake loads, and was driven by the stiffness-gravity ratio, shear-gravity ratio, inter-story drift, and peak acceleration of the top level under wind (comfort). The major design effort was focused on reducing the structure self-weight and to improve the structural efficiency. The steel-reinforced concrete composite structural system adopted for the tower maximizes the
technical advantages of a steel structure, provides superior structural stiffness and fire proofing resistance, while taking advantage of the relatively low cost of concrete. All of these characteristics are advantageous when compared to a pure steel structure, and ultimately provides an economical and reasonable structural form.

设计研究和建议

整体刚度控制与结构选型

塔楼结构高近600m，在风及地震作用下，整体刚度合理定量控制成为结构设计最重要的内容之一。因而刚重比、剪重比、结构层间位移角及风载顶点加速度（舒适度）这4项指标同时成为结构整体刚度的控制性因素，特别是超高层建筑“剪重比不能超越规范限值太多”的要求下，控制结构整体重量，采用更高效的抗侧力体系和构件布局成为设计的关键性因素。结构整体采用钢-混凝土混合结构，有效地将钢及混凝土进行组合，既具有钢结构的技术优势又具备混凝土造价相对低廉的特点，结构刚度大，防火性能好，与纯钢结构相比具有明显的优势，成为了塔楼最为经济合理的结构形式。

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Material Selection

Analysis revealed that 30% of the seismic mass originates from the concrete core, and that the shear wall is controlled by axial stress throughout the height of the building. Considering ductility requirements, the concrete grade was kept no higher than C60 for the shear wall. As a result, steel plates were added to provide composite action and to increase overall stiffness, shear resistance and ductility.

材料选择

经统计，结构地震质量的30％来源于混凝土核心筒，剪力墙轴压比成为核心筒全高的控制性指标。考虑一定的延性要求，混凝土材料等级被控制在C60，因此嵌入钢板的这种构造，提高了结构整体刚度、抗剪及延性等性能。

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Selection of Structural Form for External Frame

The overall stiffness of the external frame is significantly greater than the internal tube due to the cross mega brace configuration.

Similar flexural deformations for both the perimeter structure and the internal core occurred because of the increase of the external frame’s stiffness, which provided further confirmation that the external frame dominated the overall tower stiffness. Accordingly, outriggers were determined to be unnecessary due to this deformation consistency.

外框架结构形态选择

由于塔楼采用巨型框架＋交叉支撑的结构形式，外框架整体刚度明显大于内筒。

外筒刚度的增大，使得内外筒均呈现整体弯曲变形的特征，两者变形相对协调，伸臂桁架对协调两者变形的效能降低，对结构整体刚度几乎无贡献。

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Performance-Based Design

For seismic design of code-exceeding buildings in China, the codebased prescriptive method, or “seismic concept design”, is still the major design method used which is supplemented by the verification from a nonlinear elastic-plastic analysis and shake table test for the severe earthquake event. Important members were identified and designed
for the elevated design criteria. For example, different criteria in severe earthquakes have been considered for various components of the mega columns, transfer trusses, core walls and mega braces were designed to remain elastic under the fortification level earthquake. In the axial-moment analysis of mega columns under various internal force combinations, mega columns are in compression for the fortification earthquake event (1 in 475 years), the frequent earthquake event (1 in 50 years), and the 100-year return period wind event. Under severe earthquake, compression in the mega columns is overcome by axial tension induced by lateral action, and the mega columns are under a tension-bending state for most height. This phenomenon happens in high-rise buildings in high earthquake intensity regions after the seismic force magnification and would possibly become the controlling criteria for element design. The steel section and rebar have been checked to resist this tension force and relevant stiffness degradation is modelled in a non-linear analysis.

性能化设计

在规范体系框架下，采用抗震概念设计并辅以罕遇地震下弹塑性时程分析和整体模型振动台试验仍旧是中国对于复杂超限建筑抗震设计主要的方法，对于重要构件的强度要求则根据特点相应采用更高的抗震性能目标。例如本塔楼巨型柱、转换桁架要求满足大震性能，而核心筒（拉压弯）和巨型斜撑则按照中震性能进行复核。对于巨型柱的拉压弯构件校核，则分别考虑了小震、中震以及百年风作用不同的内力组合，而在大震下，结构自重不能平衡地震作用产生的轴拉力，因而使巨型柱在大部分高度范围内出现受拉工况。随着地震设计内力水准的显著提高，高震区超高层建筑中拉弯作用有可能成为相关构件设计的控制性因素，因而巨型柱的型钢和钢筋同时根据校核结果设计抵御此轴拉作用。此外在非线性分析中，同时考虑了巨型柱内由于混凝土受拉开裂构件刚度退化产生的相应影响。

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Conclusion

For the structural design of the slender tower of Tianjin Goldin Finance 117, the Chinese codes, together with the prescriptive performancebased design principles, guided the entire design process. Extensive linear and non-linear spectrum-based and time-history-based analyses have been carried out for different levels of earthquake events as well as wind events to ensure that the structure meets performance objectives. There are still obstacles within the code system and within the industry before a true performance-based design can be performed and accepted. However, we understand that the current approach is pragmatic in the current environment in China of fast-track construction of supertall buildings.

总结

对于天津高银117大厦这样一个高纤细建筑的结构设计，在中国规范基础上采用相应的抗震性能化设计贯穿了整个设计过程。基于大量的线性与非线性反应谱和动力时程进行的抗震分析与抗风工况分析确保了整个结构满足相应的性能目标。在现有中国规范体系下，实施并接受真正的性能化设计仍旧存在一些障碍。但考虑当前中国建造超高层建筑急速发展的环境，目前的设计方法是在现行规范下较为实际和稳妥的。

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Acknowledgements

The preliminary design of Goldin Finance 117 was approved by the National Review Panel for Seismic Design of Code-exceeding Buildings in October 2010. The authors would like to thank the local design institute ECADI for their support in the statutory submission process.

The authors are grateful to the following experts and parties involved in this design: experts of the National and Tianjin Code Exceeding Seismic Design Expert Panel, Xu Peifu, Wang Yayong, Dai Guoyin,Cheng Maokun, Chen Fusheng, Wu Xuemin, Ke Changhua, Lin Tong,Ling Guangrong, Ding Yongjun, Wen Libin, Huang Zhaowei, Zhou Yuming, etc; from RBS, Rong Baisheng, Li Shengyong, Li Zhishan; from ECADI, Wang Dasui, Lu Daoyuan; and the experts of wind engineering review: Zhang Xiangting, Gu Ming, Gu Zhifu, Lou Wenjuan.

致谢

天津高银117大楼的初步设计已于2010年10月通过了全国及天津市超限高层建筑工程抗震设防审查专家委员会的联合审查。
致谢：全国及天津市超限高层建筑工程抗震设防审查专家组徐培福、王亚勇、戴国莹、程懋堃、陈富生、吴学敏、柯长华、林桐、凌光容、王承春、丁永君、文礼彬、黄兆伟、周玉明以及广州容柏生建筑工程设计事务所容柏生、李盛勇、李志山，华东建筑设计研究院汪大绥、陆道渊，风工程审查专家组张相庭、顾明、顾志福、楼文娟等对本工程结构设计给予的大力帮助，并为工程设计提供了许多宝贵意见，在此表示忠心感谢！

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Mirko0223

好详细啊。。。。。。。。。