复杂高层建筑抗震与消能减震研究进展

复杂高层建筑的震害在近来的历次地震中都有发生,其抗震分析和设计难度较大,提高其抗震性能是当前建筑抗震的难点之一。通过对近10年来国内在复杂高层建筑抗震方面的研究进行回顾和总结,重点介绍了组合剪力墙及筒体结构、钢管混凝土结构、结构模型振动台试验和三种消能减震方法。提出了采用新型高效的结构体系及高性能抗震部件或消能减震新技术改善复杂高层建筑抗震性能。这些研究工作与工程实践紧密结合,大部分研究成果已在实际工程中成功应用。图18参28     

Shaking table model test and numerical analysis of a long‐span cantilevered structure

This paper presents an earthquake‐resistance study program of a long‐span cantilevered story building. The program consists of a shaking table test study and nonlinear seismic analysis using finite element modeling technique. A 1/30 scale model of the prototype structure was designed and manufactured and then tested via the shaking table facility. Dynamic responses of the prototype structure under different earthquake excitation loadings were simulated. Dynamic properties, acceleration, and deformation responses of the scale down model under different intensity levels of earthquake were studied. The dynamic behavior, cracking pattern, and the likely governing failure mechanism of the structure were analyzed and discussed as well. The seismic responses of the prototype building were deduced and analyzed in terms of the similitude law. Furthermore, elaborate finite element models were established, and nonlinear numerical analysis of the prototype structure was conducted. The errors in the seismic response of the structure caused by structural simplification of scale down modeling are found small, and the dynamic behavior of the structure was not altered in the earthquake excitations. This test study provides a benchmark to calibrate the finite element model and a tentative guide in seismic design of such long‐span cantilevered story buildings.     

滚轴与橡胶垫隔震结构模型震动台试验研究

建筑物平移时已经具备了设置隔震消能装置的条件,平移时用的滚轴不再取出,在建筑物下设计安装隔震橡胶垫,使滚轴与橡胶垫共同承受上部结构传来的荷载,并且在地震作用下共同起减震作用.对滚轴与橡胶垫隔震结构模型进行了震动台试验研究,通过输入不同大小和类型的地震波,分析隔震上部结构和隔震支座的地震反应.分析结果表明,滚轴与橡胶垫隔震结构的隔震效果明显,试验结果可以为隔震设计和加固中使用这种隔震结构及进一步的理论分析提供重要依据.     

Large‐scale shaking table test on pile‐soil‐structure interaction on soft soils

The two large‐scale shaking table tests of tall buildings on soft soils in pile group foundations are performed to capture the effect of the seismic pile‐soil‐structure interaction (PSSI) on the dynamic responses of the pile, soil, and structure. The two different model conditions are observed, including a fixed‐base structure and a structure supported by 3‐by‐3 pile group foundation in soft soil, representing the situations excluding the soil‐structure interaction (SSI) and considering the SSI, respectively. In the tests, the superstructure is a tall building with 12‐story reinforced concrete frame. The pile‐soil‐structure system rests in a shear laminar soil container, which is designed to minimize the boundary effects during shaking table tests. The two models are subjected to various intensity seismic excitations of Shanghai bedrock waves, 1995 Kobe earthquake, and 1999 Chi‐Chi earthquake events. According to the experimental and analytical results, SSI systems have longer natural periods than the fixed‐base structure. In addition, soft soil has amplification effect under smaller seismic excitations and isolation effects under larger earthquake intensities. The strain amplitude at the top of pile is large, and the strain at the middle and tip is relatively small. Whereas the contact pressure is small at the top of pile and large at the middle and tip. From the dynamic responses of the superstructure, it is found that the PSSI amplifies the peak displacements and interstory drifts of the structures supported by pile group foundations by comparing with the fixed‐base structure. Whereas the peak acceleration and interstory shear force of the structure are reduced considering seismic PSSI. The results show that the seismic SSI is not always favorable, however, it may increase certain dynamic responses of the structure. Consequently, the seismic SSI should be considered reasonably, providing insight towards the rational seismic design of buildings rested on soft soils.     

Dynamic characteristics and seismic response of frame–core tube structures,considering soil–structure interactions

In order to study the dynamic characteristics and seismic response of high‐rise buildings with a frame–core tube structure, while considering the effect of soil–structure interactions (SSIs), a series of shaking table tests were conducted on test models with two foundation types: fixed‐base (FB), in which the superstructure was directly affixed to the shaking table, and SSI, consisting of a superstructure, pile foundation, and soil. To increase the applicability of the model to the dynamic characteristics of real‐world tall buildings, the superstructure of test models was built at a scale of 1/50. This simulated a 41‐floor high‐rise building with a frame–core tube structure. The mode shape, natural frequency, damping ratio, acceleration and displacement response, story shear, and dynamic strain were determined in each of the test models under the excitation of simulated minor, moderate, and large earthquakes. The SSI effect on frame–core tubes was analyzed by comparing the results of the two test models. The results show that the dynamic characteristics and seismic response of the two systems were significantly different. Finally, these results were verified by performing a numerical analysis on the differences in the seismic responses of the FB and SSI numerical models under various simulated seismic conditions.     

基于试验测量的高层结构整体抗震损伤评估

结构的损伤模型可以从材料、构件和整体三个层次研究。整体结构损伤模型主要以结构整体为研究对象,从结构的整体反应参数变化研究结构整体性能的变化规律,并对在地震作用下结构的损伤、抗震性能进行分析。结构损伤时物理参数的变化,必将引起动力参数的变化。因此可以通过动力测试来捕捉结构动力参数的变化,如:结构损伤前后固有频率、模态振型和阻尼的变化,可以进行结构损伤诊断。结合在同济大学土木工程防灾国家重点实验室做过的几十个模拟地震振动台试验测试结果,统计和总结地震作用下高层建筑结构自振频率与阻尼比的变化规律,提出了一种新的损伤模型与损伤指标。该损伤模型综合考虑了高阶振型、振型参与系数、结构自振频率、阻尼比等影响因素。最后,用该损伤模型和损伤指标对其中3个典型的高层建筑结构模型模拟地震振动台试验数据进行验证,结果表明:该损伤模型与试验现象基本吻合。可对既有工程结构快速准确地进行动力损伤识别与评估。     

Dynamic characteristics and viscous dampers design for pile‐soil‐structure system

A series of large‐scale shaking table tests are conducted on tall buildings with and without energy dissipation devices on soft soils in pile group foundations, representing pile‐soil‐structure interaction (PSSI) system and the corresponding fixed‐base situations. The superstructure is a 12‐story reinforced concrete (RC) frame. The dynamic characteristics of the test models show that the frequencies decrease and the damping ratio increase in PSSI system by comparison with the fixed‐base structures. The mode shapes of PSSI system are different from that under fixed‐base condition, and the mode shapes of structure without dampers change greater than that with energy dissipation devices under various white noises. An improved method for structural dynamic characteristics, considering the impedance function of piles, is developed to address the issue of modal parameters with PSSI effect. In addition, the structural dynamic parameters of the large‐scale shaking table tests are identified using the modification method and other regulation methods, demonstrating that the improved approach is highly accurate and effective. Subsequently, a design procedure for viscous dampers of structures with PSSI effect is presented based on the dynamic characteristics of the system. Finally, the dynamic responses of the structure with viscous dampers in the practical engineering are decreased effectively, indicating the good performance of designed viscous dampers. The numerical results also show that the damping efficiency of interstory drift is larger than the acceleration and interstory shear force. Therefore, the improved modal parameters method, validated through a series large‐scale shaking table tests, is applicable for identifying dynamic characteristics of pile‐soil‐structure with energy dissipation devices system. The design procedure of viscous dampers, proved by a reinforced concrete frame structure located on a practical Shanghai soft site, can be employed to design the viscous dampers considering seismic PSSI effect.     

Shaking table tests and numerical analysis of an over-track multi-tower building

This article aims to investigate the seismic performance of a four-tower (frame-shear wall) building with a large frame podium at bottom sitting on a metro depot through shaking table test and numerical simulations. Technical problems generally exist in this type of buildings due to irregularity in elevation and plan, tower offset, and structural transfer. These problems bring challenges to engineers when analysing and predicting dynamic responses under earthquakes which is crucial for structural safety. To evaluate the seismic performance of the building, a comprehensive study which includes a shake table test of the scaled model and time history analyses using a finite-element model is conducted. The shake table test model is designed based on the similitude law with a 1:40 scale. The dynamic characteristics, cracking pattern, failure mechanism, as well as maximum acceleration and deformation response are investigated. The corresponding finite-element analysis shows a good agreement with experimental results. It is concluded that this type of building can achieve the predefined performance objectives with well-behaved transfer floors. Shear failure at weak story is considered as a main failure mode of the structure. The whipping effect of stories on the top of structure is remarkable. There is no severe damage in steel reinforced concrete beams. Finally, some design suggestions are also proposed to improve the seismic performance of this type of buildings.     

Seismic analysis of the world’s tallest building

Taipei 101 (officially known as the Taipei Financial Center) with 101 stories and 508 m height, located in Taipei where earthquakes and strong typhoons are common occurrences, is currently the tallest building in the world. The great height of the building, the special geographic and environmental conditions, not surprisingly, presented one of the greatest challenges for structural engineers. In particular, its dynamic performance under earthquake or wind actions requires intensive research. The structure of the building is a mega-frame system composed of concrete filled steel tube (CFT) columns, steel brace core and belt trusses which are combined to resist vertical and lateral loads. In this study, a shaking table test was conducted to determine the constitutive relationships and finite element types for the CFT columns and steel members for establishing the finite element (FE) model of the tall building. Then, the seismic responses of the super-tall building were numerically investigated. An earthquake spectrum generated for Taipei Basin was adopted to calculate the lateral displacements and distributions of interior column forces. Furthermore, time-history analyses of elastic and inelastic seismic response were carried out using scaled accelerograms representing earthquake events with return periods of 50-year, 100-year, and 950-year, respectively. The computational results indicate that the super-tall building with the mega-frame system possesses substantial reserve strength, and the high-rise structure would satisfy the design requirements under severe seismic events. The output of this study is expected to be of considerable interest and practical use to professionals and researchers involved in the design of super-tall buildings.     

高层建筑钢-混凝土混合结构模型模拟地震振动台试验研究

本文对一典型的高层建筑钢 混凝土混合结构缩尺模型进行了模拟地震振动台试验研究,分析了混合结构的自振特性、结构的地震反应特征和破坏特征,并对混合结构的抗震性能进行了深入探讨,为提出高层混合结构体系抗震计算模型和设计理论提供了试验依据。     

Seismic performance of a frame-supported shear wall over-track building through shaking table test

This research deals with a frame-supported shear wall for urban over-track building of vehicle depot in Chisha, Guangzhou, China, which is characterized by its remarkable height of 160.8 m. Technical issues are commonly encountered in these kinds of buildings due to discontinuous vertical structural rigidity, large podium, and structural transition. These challenges significantly impact the engineering process, especially when the rigidity difference between transfer story exceeding the threefold, as well as the building height exceeds limit as in code. In this paper, a shaking table test was developed based on a 1:10 scaled model of the structure. Using similarity theory, the dynamic similarity relationship was established for the design of the model. Subsequently, the experimental model was constructed with the configuration of critical parameters such as mass design, sensor placement, and seismic test conditions. This was followed by in-depth analysis, recording component failures and investigating key aspects such as dynamic characteristics, that is, acceleration and displacement responses and shear force distribution under different earthquake intensities. A theoretical seismic response of the prototype structure was derived from the test results. The shaking table tests confirmed that the structure met the stringent seismic design requirements as prescribed in the Chinese standards, with no damage under minor earthquakes, repairability under moderate earthquakes, and collapse prevention under rare earthquakes. The results of the study provide valuable insights along with improvement measures for the design and development of similar urban over-track buildings, potentially contributing to more efficient land use in urban China.     

Study on seismic performance of a super‐tall steel–concrete hybrid structure

Many steel–concrete hybrid buildings have been built in China. The seismic performance of such hybrid system is much more complicated than that of steel structure or reinforced concrete (RC) structure. A steel–concrete hybrid frame‐tube super‐tall building structure with new type of shear walls to be built in a district of seismic intensity 8 in China was studied for its structural complexity and irregularity. Both model test and numerical simulation were applied to obtain the detailed knowledge of seismic performance for this structure. First, a 1/30 scaled model structure was tested on the shaking table under different levels of earthquakes. The failure process and mechanism of the model structure are presented here. Nonlinear time‐history analysis of the prototype structure was then conducted by using the software PERFORM‐3D. The dynamic characteristics, inter‐story drift ratios and energy dissipation conditions are introduced. On the basis of the comparison between the deformation demand and capacity of main structural components at individual performance level under different earthquake level, the seismic performance at the member level was also evaluated. Despite the structural complexity and code‐exceeding height, both experimental and analytical results indicate that the overall seismic performance of the structure meet the requirements of the Chinese design code. Copyright © 2012 John Wiley & Sons, Ltd.     

复杂高层建筑结构抗震与结构控制研究及其应用

结构抗震性能研究包括钢筋混凝土核心筒墙抗震伪静力试验、复杂高层建筑结构分析、用于指导工程结构设计的各种复杂高层和塔式建筑的振动台模型试验研究。结构控制方面包括一种新的组合基础隔震系统、一种新的组合耗能减震系统和采用流体阻尼器连接双塔结构减震研究。这些研究成果大多数已应用于工程实践,该文对一些成功例子作了介绍。     

Seismic behavior of tall buildings using steel–concrete composite columns and shear walls

For the seismic design of tall building structures, the behavior under severe earthquakes should be carefully considered and the upper limit of inter‐story deformations are often defined by the design codes. To improve the performance of structures under severe earthquakes, composite structural members, including steel reinforced column and steel plate reinforced shear wall, are often adopted. In the present work, the seismic behavior of tall buildings using steel–concrete composite columns and shear walls is investigated numerically. Fiber beam–column element models and multilayer shell models are adopted to establish the finite element model of structure, and the material nonlinearities are described by the plasticity and damage models. The accuracy of the developed models is verified by the experimental results of a single shear wall. Systematic numerical simulations are performed for the tall building structures subjected to different earthquakes. The comparative study indicates that the nonlinear redistribution of internal forces plays a very important role for the performance of tall buildings under severe earthquakes.     

建筑结构倒塌过程模拟与防倒塌设计

针对结构性能的数值模拟方法进行了综合分析,基于离散单元法提出了结构倒塌分析的理论模型。通过试验研究了混凝土块体间碰撞的力学行为,并结合扩展的数值分析建立了混凝土块体在不同碰撞形式下的计算模型。针对建筑物内的局部爆炸作用,在分析构件反应的基础上采用离散单元法对结构平面及空间倒塌过程进行了数值模拟。建立了适用于任意加载路径的材料弹簧力-位移本构关系,据此分析了地震作用下钢筋混凝土框架结构以及砌体结构空间倒塌过程。采用基于OpenGL的图形建模技术,实现了结构倒塌过程数值模拟结果的三维可视化。模拟结果与振动台模型试验结果及工程实测结果比较表明,所采用的离散单元法适合结构大变形阶段的分析。为提高计算效率和精度,有必要采用多尺度的模拟分析。另外,对不同荷载及作用下建筑结构抗倒塌设计方法进行了总结。并指出结构参数对抗连续倒塌性能的影响、结构倒塌机理、实用的防连续倒塌设计方法以及地震作用下结构防倒塌定量设计方法等方面尚待深入研究,以便建立相应的防倒塌设计规范。图15参21     

A modified friction damper for diagonal bracing of structures

In this paper, the dynamic behavior of a recently developed friction damper has been demonstrated. It is made from nine steel stripes and nine high strength steel bolts and is applied in the diagonal bracing of structures. This device has a square geometric shape and should be installed in the square spans. During this research work, a prototype of the modified friction damper was tested by a universal machine. Then the damper was installed inside a SDOF steel frame and tested by the shaking table under several earthquake excitations. For numerical assessment of the system, the model of SDOF frame was created in SAP2000 and analyzed under the same excitations which had been applied during the shaking table tests. By comparing the results obtained from SAP2000 to those of experimental tests, the validity of numerical modeling was proved. In order to assess the behavior of damper in multi-story buildings, the model of a four story frame, with and without the modified damper, was created in SAP2000 and analyzed under several seismic records. The results were indicating that the lateral displacements and the base shears of the multi-story building have been significantly reduced by the installation of this modified energy absorber and a considerable energy has been dissipated by the damping system.     

Measurement-based support for post-earthquake assessment of buildings

After a damaging earthquake, assessment of the residual seismic capacity is required for large parts of the building stock. Increased vulnerability of structures together with the threat of immediate aftershocks call for rapid and objective decision making. Structural identification has the potential to reduce parameter-value uncertainties of physics-based models through interpreting measurement data. Significant amounts of uncertainty are associated with the non-linear behaviour of structures during extreme events such as earthquakes. Therefore, a structural identification methodology that accommodates multiple sources of systematic modelling uncertainties is used. Error-domain model falsification (EDMF) enables structural identification through combining damage grades observed by visual inspection with fundamental frequencies that are derived from ambient vibrations. Parametric uncertainties of a hysteretic model are reduced with the two information sources in order to extrapolate the vulnerability of the building regarding future earthquakes. The applicability of the methodology is shown using measurements made on a mixed reinforced-concrete unreinforced-masonry building tested on a shaking table. Based on nonlinear time-history analyses involving single-degree-of-freedom models, EDMF leads to more precise, yet robust, vulnerability predictions of earthquake-damaged buildings when compared with prediction ranges that are obtained without data interpretation.     

超限高层建筑结构基于性能抗震设计的研究

基于性能的设计方法已引起工程界的关注 ,在超限高层建筑的结构抗震设计中 ,采用基于性能要求的抗震设计方法 ,有助于提高高层建筑工程抗震设计的可靠性、避免抗震安全隐患 ,同时又促进高层建筑技术发展。本义阐述基于性能抗震设计方法与常规抗震设计方法的比较 ;针对超限高层建筑结构的特点 ,提出结构的抗震性能目标、性能水准以及实施性能设计的主要方法 ,包括性能水准判别准则、性能目标的选用及结构计算和试验要求。文中还列举了应用性能设计理念和要求的部分工程实例。     

振动台试验对高层建筑结构设计的启示

2010年以后,我国高层、超高层建筑进入快速发展阶段,目前仍处于蓬勃上升期,我国已成为世界高层建筑发展的中心。抗震设计是我国高层建筑结构设计中的关键问题,而振动台模型试验是研究高层、超高层结构抗震性能的重要手段。通过科学、合理设计和精细模型加工,采用振动台试验可较准确测定结构的动力特性、动力响应和破坏形态,反映结构不规则性对抗震性能的影响,揭示薄弱部位。为此,以中国建筑科学研究院完成的28个实际工程模型振动台试验为基础,对试验结果和试验数据进行分类对比分析,研究阻尼比、整体刚度退化、连梁刚度折减系数、外框剪力比、加速度放大系数等影响高层建筑结构设计的参数和指标,并对有代表性和共性的结构薄弱部位及加强措施进行汇总,提出高层建筑结构设计相关的一些启示和设计建议。     

某型钢混凝土框架-混凝土核心筒结构的抗震性能评估

以某混合结构为研究对象,通过振动台试验和数值分析2种手段对该混合结构的抗震性能进行了相关研究.主要利用PERFORM-3D建立了整体结构的非线性计算模型,对结构进行了弹塑性时程分析.根据结构整体的位移响应和能量耗散以及构件的变形和塑性铰开展情况,来了解在不同强度地震作用下结构的地震反应特点,同时根据预定的性能指标限值对结构的抗震性能进行了评估,并将数值分析结果与试验结果进行了对比.试验与数值分析结果均表明,该结构具有良好的抗震性能.