Revision of seismic design codes corresponding to building damagesin the “5.12” Wenchuan earthquake

A large number of buildings were seriously damaged or collapsed in the "5.12" Wenchuan earthquake. Based on field surveys and studies of damage to different types of buildings, seismic design codes have been updated. This paper briefly summarizes some of the major revisions that have been incorporated into the "Standard for classification of seismic protection of building constructions GB50223-2008" and "Code for Seismic Design of Buildings GB50011-2001." The definition of seismic fortification class for buildings has been revisited, and as a result, the seismic classifications for schools, hospitals and other buildings that hold large populations such as evacuation shelters and information centers have been upgraded in the GB50223-2008 Code. The main aspects of the revised GB50011-2001 code include: (a) modification of the seismic intensity specified for the Provinces of Sichuan, Shanxi and Gansu; (b) basic conceptual design for retaining walls and building foundations in mountainous areas; (c) regularity of building configuration; (d) integration of masonry structures and precast RC floors; (e) requirements for calculating and detailing stair shafts; and (f) limiting the use of single-bay RC frame structures. Some significant examples of damage in the epicenter areas are provided as a reference in the discussion on the consequences of collapse, the importance of duplicate structural systems, and the integration of RC and masonry structures.

Seismic resilience assessment of corroded reinforced concrete structures designed to the Chinese codes

The natural landscape in China exposes many existing RC buildings to aggressive environments.Such exposure can lead to deterioration in structural performance with regard to resisting events such as earthquakes.Corrosion of embedded reinforcement is one of the most common mechanisms by which such structural degradation occurs.There has been increasing attention in recent years toward seismic resilience in communities and their constituent construction;however,to date,studies have neglected the effect of natural aging.This study aims to examine the effect of reinforcement corrosion on the seismic resilience of RC frames that are designed according to Chinese seismic design codes.A total of twenty RC frames are used to represent design and construction that is typical of coastal China,with consideration given to various seismic fortification levels and elevation arrangements.Seismic fragility relationships are developed for case frames under varying levels of reinforcement corrosion,i.e.,corrosion rates are increased from 5%to 15%.Subsequently,the seismic resilience levels of uncorroded and corroded RC frames are compared using a normalized loss factor.It was found that the loss of resilience of the corroded frames is greater than that of their uncorroded counterparts.At the Rare Earthquake hazard level,the corrosioninduced increase in loss of resilience can be more than 200%,showing the significant effect of reinforcement corrosion on structural resilience under the influence of earthquakes.

Effect of URM infills on seismic vulnerability of Indian code designed RC frame buildings

Unreinforced Masonry (URM) is the most common partitioning material in framed buildings in India and many other countries. Although it is well-known that under lateral loading the behavior and modes of failure of the frame buildings change significantly due to infill-frame interaction, the general design practice is to treat infills as nonstructural elements and their stiffness, strength and interaction with the frame is often ignored, primarily because of difficulties in simulation and lack of modeling guidelines in design codes. The Indian Standard, like many other national codes, does not provide explicit insight into the anticipated performance and associated vulnerability of infilled frames. This paper presents an analytical study on the seismic performance and fragility analysis of Indian code-designed RC frame buildings with and without URM infills. Infills are modeled as diagonal struts as per ASCE 41 guidelines and various modes of failure are considered. HAZUS methodology along with nonlinear static analysis is used to compare the seismic vulnerability of bare and infilled frames. The comparative study suggests that URM infills result in a significant increase in the seismic vulnerability of RC frames and their effect needs to be properly incorporated in design codes.

Seismic fragility assessment of RC frame structure designed according to modern Chinese code for seismic design of buildings

Following several damaging earthquakes in China, research has been devoted to find the causes of the collapse of reinforced concrete （RC） building sand studying the vulnerability of existing buildings. The Chinese Code for Seismic Design of Buildings （CCSDB） has evolved over time, however, there is still reported earthquake induced damage of newly designed RC buildings. Thus, to investigate modern Chinese seismic design code, three low-, mid- and high-rise RC frames were designed according to the 2010 CCSDB and the corresponding vulnerability curves were derived by computing a probabilistic seismic demand model （PSDM）.The PSDM was computed by carrying out nonlinear time history analysis using thirty ground motions obtained from the Pacific Earthquake Engineering Research Center. Finally, the PSDM was used to generate fragility curves for immediate occupancy, significant damage, and collapse prevention damage levels. Results of the vulnerability assessment indicate that the seismic demands on the three different frames designed according to the 2010 CCSDB meet the seismic requirements and are almost in the same safety level.

Comparison of seismic actions and structural design requirements in Chinese Code GB 50011 and International Standard ISO 3010

This papcr presents a comparison between the Chinese Code GB50011-2001 and the International Standard ISO3010:2001(E),emphasizing the similarities and differences related to design requirements,seismic actions and analytical approaches.Similarities include:earthquake return period,conceptual design,site classification,structural strength and ductility requirements,deformation limits,response spectra,seismic analysis procedures,isolation and energy dissipation, and nonstructural elements.Differences exist in the following areas:seismic levels,earthquake loading,mode damping factors and structural control.

Seismic performance evaluation of typical dampers designed by Chinese building code

Adding dampers is a commonly adopted seismic risk mitigation strategy for modern buildings, and the corresponding design procedure of dampers has been well established by the Chinese Building Code. Even though all types of dampers are designed by the same procedure, actual seismic performance of the building may differ from one to the others. In this study, a nine-story benchmark steel building is established, and three different and typical types of dampers are designed according to the Chinese Building Code to realize structural vibration control under strong earthquake excitation. The seismic response of the prototype building equipped with a viscoelastic damper, viscous damper and buckling-restrained brace(BRB) subjected to 10 earthquake records are calculated, and Incremental Dynamic Analysis(IDA) is performed to describe progressive damage of the structure under increasing earthquake intensity. In the perspective of fragility, it shows that the viscoelastic damper has the highest collapse margin ratio(CMR), and the viscous damper provides the best drift control. Both the BRB and viscoelastic dampers can effectively reduce the floor acceleration responses in the mid-rise building.

基于公路与城市桥梁抗震设计规范反应谱的全非平稳地震动过程模拟

【目的】生成拟合公路与城市桥梁抗震设计规范反应谱的全非平稳地震动过程代表性时程集合。【方法】首先,结合非平稳地震动过程的强度-频率调制函数和平稳地震动过程的Clough-Penzien功率谱模型,建立全非平稳地震动过程的演变功率谱模型;其次,依据相关规范确定演变功率谱模型参数取值;然后,根据全非平稳地震动过程模拟的谱表示方法,编写MATLAB程序,生成全非平稳地震动过程代表性时程集合,计算其均值反应谱和规范反应谱拟合误差,并进行迭代修正。【结果】依据公路与城市桥梁抗震设计规范给出了不同场地类别和设计地震分组的演变功率谱模型参数取值;生成的代表性时程集合具有全非平稳地震动的典型特征,其均值反应谱和规范反应谱整体拟合程度较好,平均相对误差均在5%以内。【结论】基于演变功率谱模型,通过编写全非平稳地震动过程模拟谱表示方法的MATLAB程序,可生成满足公路与城市桥梁抗震设计规范要求的全非平稳地震动过程代表性时程集合,其均值反应谱与规范反应谱拟合一致,验证了所给方法和MATLAB程序的有效性,可为桥梁结构抗震性能评估提供可靠的地震动输入。

多高层木结构建筑抗震性能及设计方法研究进展

木结构作为中国传统建筑文化重要组成部分,具有低碳、绿色环保、抗震性能好等特点。随着装配式建筑的发展、“双碳”战略的提出,木结构的研究、木结构建筑在工程中的应用逐渐成为行业内热点。以木结构被动抗震领域为对象,从结构体系、抗震规范、抗震设计方法3个方面阐述,对最新抗震研究进展、发展趋势进行分析与总结。对常用结构的抗侧刚度、破坏模式、变形和耗能能力等进行具体的抗震设计文献调研;对不同国家和地区抗震规范基底地震力的计算进行对比和总结,结合目前已有的抗震设计方法研究,为木结构抗震领域的发展与工程应用提供参考。

Eurocode8与GB 50011—2010关于抗震设防目标、场地和地震作用等的比较

在结合2008年汶川地震震害经验的基础上,同时采纳了地震工程领域的科研新成果,我国新版《建筑抗震设计规范》(GB 50011—2010)于2010年12月1日起正式实施。主要从抗震设防目标、设计反应谱、场地类别、地震作用与抗震验算、性能化设计等方面对其与欧洲现行抗震设计规范(Eurocode8)2004版进行了对比分析,旨在为从事工程抗震设计和工程抗震研究的人员提供一定参考和借鉴。

湖北工人文化宫超限结构设计

湖北工人文化宫的主要功能为职工培训和展览等,主体结构采用框架-剪力墙结构,存在扭转不规则、偏心布置、楼板不连续、局部跃层柱等不规则项,属于复杂超限高层建筑。采用抗震性能化设计对主要构件进行复核,采用YJK和MIDAS Building软件对结构进行多遇地震弹性计算和弹性时程分析以及罕遇地震下的动力弹塑性时程分析和楼板应力分析等。分析结果表明,整体结构可以满足规范的要求,达到预定的性能目标。并根据分析结果采取抗震加强措施。在容易产生共振的大跨度预应力楼盖区域,以高阻尼橡胶减振垫作为减振材料,对楼盖在人行激励下和有节奏运动激励下的楼板舒适度进行分析。分析结果表明,楼板舒适度满足规范要求。

Eurocode8、CECS 160:2004与GB50011—2010中考虑土-结构相互作用效应的比较

我国新版《建筑抗震设计规范》(GB 50011—2010)于2010年12月1日起正式实施;从考虑土-结构相互作用效应方面,我国抗震规范与欧洲抗震设计规范(Eurocode8)2004版和我国建筑工程抗震性态设计通则(CECS 160:2004)进行了比较,旨在为从事工程抗震的设计和研究人员提供一定参考和借鉴。

某斜交网格筒中筒超限高层结构设计

某斜交网格筒中筒超限高层项目结构高度158m,采用钢筋混凝土核心筒与钢斜交网格外筒组成的筒中筒结构体系。外筒由钢斜柱和水平环梁组成,同时存在楼面开大洞、竖向刚度突变、斜柱、穿层柱等不规则情况。对内筒分别采用钢筋混凝土内筒、钢框架支撑内筒两种结构形式进行对比分析,对外筒钢斜柱分别采用箱形截面、圆形截面两种截面形式进行对比分析。结果表明,箱形截面钢斜交网格外筒-钢筋混凝土内筒结构体系施工操作更为简便,经济性更为优越,更能满足建筑要求效果。主要介绍了结构超限情况及超限措施、斜交网格关键节点有限元分析、罕遇地震动力弹塑性分析,验证了钢筋混凝土核心筒与钢斜交网格外筒组成的筒中筒结构体系具有良好的抗震性能。

FEMA P695-Quantification of Building Seismic Performance Factors简介

目前,各国建筑抗震设计规范对结构在"大震"下倒塌概率的评估尚不完善。FEMA P695以美国现行规范为基础,提出了一套用于标定其建筑抗震设计规范中关键设计参数的方法,用以保证结构在"大震"下的倒塌概率不超过某一可接受的值。介绍了美国建筑抗震设计规范的理论基础,说明了FEMA P695中关键参数的定义与美国现行抗震规范中设计参数的关系,详细介绍了该方法的基本内容、方法流程、关键细节、理论思路等,为了解美国抗震规范的发展方向及水平提供了参考。

恒申集团总部大楼结构方案比选及抗震超限设计

恒申集团总部大楼的建筑形体由四个体块穿插堆叠而成,结构上如何实现体块错动的效果,是该项目结构设计的关键点。为此,分析恒申集团总部大楼结构方案的比选过程,在综合评估空间利用率、结构受力性能、施工工艺等因素后,从中选择了最优方案即(少墙)钢框架结构体系。文中分析探讨了该项目抗震超限设计的过程,并提出长悬臂楼盖竖向振动舒适度的控制方案。

济南华润万象城抗震性能分析与设计

济南华润万象城为一栋结构高度412m的超限高层商业建筑,采用框架-剪力墙结构。结构中同时存在扭转不规则、平面开洞、大跨度结构、大悬挑结构、斜柱、桁架悬挑等多项平面及竖向不规则情况。采用多种计算程序进行了抗震性能分析,其结果均满足既定的抗震性能目标。对复杂商业中的各关键部位设计进行了多方案比选,确定了合理的结构布置和适当的构造措施,取得了良好的效果。

与桥梁抗震规范设计反应谱一致的地震动合成

工程上在对结构进行动力响应分析时,大多是在实测强震数据库中筛选出与规范设计反应谱相一致的实测强震记录作为地震动输入依据,然而,实测强震记录数量有限,需要系统地处理才可投入工程应用,且在对大型工程结构进行动力反应分析时无法体现地震动的空间变异性,因此,本文以《公路桥梁抗震设计规范》(JTG/T 2231-01-2020)中的设计反应谱为例,详细梳理了地震动向量过程的本征正交分解方法(POD)和复相干函数模型,并将反应谱转化功率谱法和调幅功率谱迭代法相结合,基于降维模拟方法,在概率层面上高效地生成了与设计反应谱相一致且具有空间变异性和非平稳性的人工地震动向量过程。数值算例表明,根据目标反应谱转化为调幅功率谱后,再根据功率谱迭代法迭代一次生成的地震动样本与目标反应谱对应良好,同时,降维方法生成的地震动样本具有显著的非平稳性和空间变异性,且统计特征与目标值对应良好。可以认为,本文为桥梁结构在地震作用下的地震激励输入提供了新的途径。

某2号综合楼结构抗震超限分析

某2号综合楼为钢筋混凝土框架-剪力墙结构。因二层多功能厅需要大空间,在三层楼板设置大开洞,在四层楼面处设置转换框架;结构竖向有两次体型收进,结构不规则项较多,属于超限高层,需对该楼进行抗震超限设计。对整体结构进行了小震弹性分析,采用两套软件进行对比计算,相互校核,并且采用弹性时程分析法进行补充计算,确保结构计算的准确性。对设防地震和罕遇地震时关键构件的各项验算,除保证在多遇地震时结构完全处于弹性状态外,还通过专项分析及采取加强措施后,使抗震设计达到应有的性能目标,确保结构的安全可靠。

某医疗超限高层建筑的结构设计

随着人民对医疗需求的提高,医疗建筑在近年来得到了快速的发展,医疗建筑呈现出了规模化、复杂化的特点,这对结构设计提出了更高的要求。论文结合工程实践简要概述大体量医疗建筑的结构布置,并针对其中一栋超限高层进行抗震性能化设计。结构的整体及局部分析主要采用 YJK、ETABS 以及 SAUSAGE 等软件,包括多遇地震反应谱法和弹性时程分析、设防地震及罕遇地震等效弹性分析和动力弹塑性时程分析以及楼板应力分析;主要计算结果表明,该单体的结构布置能满足性能目标 C 的设计目标。

武汉某超限多塔楼连体结构设计

武汉某超限多塔楼连体结构由6栋框架⁃核心筒高层塔楼及连接于各塔楼间不同高度处的6个钢结构连体组成,高层塔楼结构高度分别为139.5m和108.0m,钢桁架连体跨度分别为38.3m和32.7m,属于存在多项不规则的超限高位连体结构。针对此类复杂连体结构,为考察其抗震性能,提出了明确的分析思路,详细介绍了该项目结构方案、抗震性能设计、风洞试验及针对超限采取的加强措施;采用YJK和MIDAS Building两款软件对结构进行小震作用下的弹性整体计算分析,并进行弹性时程分析补充计算;采用SAUSAGE软件进行了罕遇地震动力弹塑性分析。结果表明,结构整体指标满足规范要求,能够达到预设的抗震性能目标。

Finite element modeling assumptions impact on seismic response demands of MRF-buildings

Recent seismic events have raised concerns over the safety and vulnerability of reinforced concrete moment resisting frame ＂RC-MRF＂ buildings. The seismic response of such buildings is greatly dependent on the computational tools used and the inherent assumptions in the modelling process. Thus, it is essential to investigate the sensitivity of the response demands to the corresponding modelling assumption. Many parameters and assumptions are justified to generate effective structural finite element（FE） models of buildings to simulate lateral behaviour and evaluate seismic design demands. As such, the present study focuses on the development of reliable FE models with various levels of refinement. The effects of the FE modelling assumptions on the seismic response demands on the design of buildings are investigated. the predictive ability of a FE model is tied to the accuracy of numerical analysis; a numerical analysis is performed for a series of symmetric buildings in active seismic zones. The results of the seismic response demands are presented in a comparative format to confirm drift and strength limits requirements. A proposed model is formulated based on a simplified modeling approach, where the most refined model is used to calibrate the simplified model.