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.

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.

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.

A Comparison of Saudi Building Code with 1997 UBC for Provisions of Modal Response Spectrum Analysis Using a Real Building

The study uses an actual building to compare the modal response spectrum analysis results of Saudi Building Code (SBC) and the 1997 Uniform Building Code (UBC) used in Saudi Arabia before the introduction of SBC. A sample of four buildings with reported analysis of comparison between IBC and UBC is taken for confirming the comparison. Eight sample places from SBC map for Saudi Arabia together with two sample places of high seismic activity in USA were taken for the comparisons. The study used software package ETABS in this study for modeling and analysis. The results are dissimilar from the comparisons reported for test places of USA. It is concluded that at most places SBC base shear is higher for both ELFP and MRSA. However, the results cannot be generalized and considered always right. The same is factual for overturning moments. Consequently, we cannot report that SBC is more conservative than UBC for all scenarios.

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.

An evaluation of force-based design vs.direct displacement-based design of jointed precast post-tensioned wall systems

The unique features of jointed post-tensioned wall systems, which include minimum structural damage and re-centering capability when subjected to earthquake lateral loads, are the result of using unbonded post-tensioning to attach the walls to the foundation, along with employing energy dissipating shear connectors between the walls. Using acceptance criteria defined in terms of inter-story drift, residual drift, and floor acceleration, this study presents a multiplelevel performance-based seismic evaluation of two five-story unbonded post-tensioned jointed precast wall systems. The design and analysis of these two wall systems, established as the direct displacement-based and force-based solutions for a prototype building used in the PREcast Seismic Structural Systems （PRESSS） program, were performed at 60% scale so that the analysis model could be validated using the PRESSS test data. Both buildings satisfied the performance criteria at four levels of earthquake motions although the design base shear of the direct displacement-based jointed wall system was 50% of that demanded by the force-based design method. The study also investigated the feasibility of controlling the maximum transient inter-story drift in a jointed wall system by increasing the number of energy dissipating shear connectors between the walls but without significantly affecting its re-centering capability.

A comparison of IBC with 1997 UBC for modal response spectrum analysis in standard-occupancy buildings

This paper presents a comparison of the seismic forces generated from a Modal Response Spectrum Analysis （MRSA） by applying the provisions of two building codes, the 1997 Uniform Building Code （UBC） and the 2000-2009 International Building Code （IBC）, to the most common ordinary residential buildings of standard occupancy. Considering IBC as the state of the art benchmark code, the primary concern is the safety of buildings designed using the UBC as compared to those designed using the IBC. A sample of four buildings with different layouts and heights was used for this comparison. Each of these buildings was assumed to be located at four different geographical sample locations arbitrarily selected to represent various earthquake zones on a seismic map of the USA, and was subjected to code-compliant response spectrum analyses for all sample locations and for five different soil types at each location. Response spectrum analysis was performed using the ETABS software package. For all the cases investigated, the UBC was found to be significantly more conservative than the IBC. The UBC design response spectra have higher spectral accelerations, and as a result, the response spectrum analysis provided a much higher base shear and moment in the structural members as compared to the IBC. The conclusion is that ordinary office and residential buildings designed using UBC 1997 are considered to be overdesigned, and therefore they are quite safe even according to the IBC provisions.

Development of seismic force requirements for buildings in Taiwan

This paper describes static and dynamic procedures to calculate seismic demand specified by the current seismic design code for buildings in Taiwan, which was issued in 2005. For design levels with a return period of 475 years, the design spectral response acceleration can be developed for general sites, near-fault sites and Taipei Basin. In addition, in order to prevent building collapse during extremely large earthquakes and yielding of structural components and elements during frequent small earthquakes, the required seismic demands at the maximum considered earthquake level （MCE, 2%/50 years） and operational level are also included in the new seismic design code.For dynamic analysis procedures, both the response spectrum method and time history method are specified in the new seismic design code. Finally, procedures to generate spectrum compatible ground motions for time history analysis are illustrated in this paper.

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.

Development of a “Space-Saving Model” for a One-Family Dwelling Case Study of Japanese Architecture with Space Limitations

The rapid globalization of building standards and codes in regards of contemporary housing and the growth of populations during this century demands an immediate response from designers in terms of space rationalizing to fulfill the forthcoming lack of architectural habitat on earth. The differences in culture imply a difference in the way of living, and the way of living indicates a contrast in the way of designing houses. A western house does not need an extra room covered with tatami mats for relaxation as a modern Japanese home would most likely do, as a separate living-like space. Organizations, among others, like CABO (Council of American Building Officials) and, in our specific case study, BCJ (Building Center of Japan) together with BRI (Building Research Institute) try to overcome these differences to provide better housing conditions to the world through the formulation of global designing and building standards. International publications like UBC (Uniform Building Code), IBC (International Building Code), OTFDC (One and Two Family Dwelling Code) and BSLJ (Building Standard Law of Japan) have also played an important role to globalize safety and design codes to better understand global housing under normal conditions. However, space limitations and concentration of human masses in mega cities result in a crucial new consideration: the urgent need of investigating the possibilities of rationally living within less space. Minimums provided by most codes do not take into account the space issue and overpopulation of large cities. Providing with some design recommendations for one-family dwellings has been the departure point and main motivation to carry out this case study based on actual buildings with the lack of space conditioning in a country where these conditions turn into reality.

基于建筑设计防火规范的高校课程设计实践研究

将建筑设计防火规范纳入课程设计教学过程中,是培养学生综合设计能力的重要教学任务,是工程认证体系(CDIO)的基本要求。文章结合燕山大学建筑学专业商业综合体课程设计,通过将建筑设计防火规范在不同设计阶段有针对性地引入课程设计过程中,让规范成为课程设计的重要内容,不仅对课程设计具有重要的指导作用,对学生树立消防安全和社会责任意识、保持对防火规范的敬畏感也具有重要现实意义,而且对于今后从事建筑设计工作都有深远的影响。

乡村历史建筑保护与更新设计研究——以黄屋大戏院修缮实践为例

乡村历史建筑见证着村落的发展,承载着村民的记忆,对其进行保护与更新既是时代发展所需也是村民期望所求。针对乡村历史建筑功能出现衰退、结构存在安全隐患、实践操作缺乏理论指导、公众保护意识淡薄和参与不足等问题,本文通过总结归纳诸多具体案例和设计团队的实践经验,从关注历史建筑本身拓展到关注建筑使用者的需求并将其融入乡村发展规划,提出旧材复用、大材小用、可复原、地域性、公众参与和修旧如故6项原则,从功能、体量、材料、技术4个方面建立保护与更新设计方法,并对广州市第六批历史建筑——黄屋大戏院进行实践设计,以期为乡村历史建筑的保护与更新提供理论支持和实践指导。

苏州太仓阿尔卑斯雪世界超限高层结构设计

苏州太仓阿尔卑斯雪世界结构形式为钢筋混凝土框架结构,屋盖采用平面桁架体系。存在扭转不规则、楼板不连续、偏心率大于0.15、错层等不规则项,为超限高层建筑。对基础形式、结构体系、荷载取值、性能目标等进行了介绍,并采用YJK、PMSAP、MIDAS Gen三种软件进行了弹性计算,应用Paco-Sap软件进行动力弹塑性分析;阐述了雪场结构设计中的关键问题,如层间位移角、长短柱、桁架关键节点、温度荷载等。计算结果表明,结构的周期比、层间位移角等指标均满足规范要求。采用性能化设计和动力弹塑性分析方法实现结构和构件在中震和大震作用下的既定性能目标,并对结构关键部位和构件采取了针对性的加强措施。

北京艺术中心绿色建筑设计实践

结合剧院功能特点和项目周边的绿色生态条件,北京艺术中心的绿色建筑设计建立了涵盖区域规划和建筑本体层面的绿色建筑技术体系,系统性集成开放共享、绿色外围护结构、可再循环材料应用、高效机电系统、室内空气品质、水资源利用、海绵城市等七大类别主要绿色建筑技术措施,全面提升项目的节能、节材、节水和减碳水平。结果表明,本项目年单位面积碳排放仅为75.87 kgCO_(2)/(m^(2)·a),较参照建筑碳排放降低比例约为16%,并获得绿色建筑三星级技术认定意见。

基于2021年版广东省高规的某含错层超限高层结构抗震性能化设计

2021年实施的广东省标准《高层建筑混凝土结构技术规程》(DBJ/T 15-92—2021)(简称广东省高规)在抗震计算和性能化设计方面做了一些调整。根据广东省高规相关要求,通过YJK软件对某含错层的超限高层结构作设防地震验算和抗震性能化设计,采用Perform-3D进行动力弹塑性分析以验证按广东省高规设计的错层结构在大震中的性能。结果表明,对于该项目错层处框架柱,按照广东省高规进行的性能化设计,相较于《高层建筑混凝土结构技术规程》(JGJ 3—2010),纵向钢筋用量平均节省约7%。

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。

江阴某超限高层住宅结构设计与分析

江阴某住宅建筑高度为140.95m,属于B级高度建筑,高宽比超限;采用剪力墙结构体系,属于超限高层建筑。针对结构超限情况,工程设计人员采用PKPM和MIDAS两种不同软件对工程建筑结构进行了多遇地震计算,采用PKPM软件进行多遇地震下弹性时程分析,同时还利用PUSH&EPDA软件对结构进行了罕遇地震静力弹塑性分析。分析结果表明,结构各项计算指标均满足规范要求,结构整体设计能达到预期的抗震性能目标,并针对结构超限采取了加强措施,以提高其结构承载能力和延性。

某部分框支剪力墙的错层高层结构设计及抗震性能分析

介绍深圳某部分框支剪力墙的错层超限高层的结构和性能化设计,通过建立对比模型,进行弹性和动力弹塑性分析,并从周期、位移、楼层剪力、关键构件等方面分析,以研究错层布置及框支转换对结构刚度和承载力的影响。结果表明:错层对结构的整体刚度影响较小,对剪力墙、楼板构件的内力影响较大,通过合理的设置拉通层以及相应的加强措施,能使结构满足设定的性能目标要求。

A prototype online database-enabled design framework for wind analysis/design of low-rise buildings

This study presents a development of an advanced cyberbased database-enabled design module for low- rise buildings （DEDM-LR） which provides estimation of the wind-induced responses for main wind force resisting frames by making direct use of pressure time histories measured at a large number of pressure taps over a suite of building models. These responses may be considered in lieu of code-specified load effects in which the overall accuracy may be influenced by the inherent simplifications in codes. In addition, this new automated approach is particularly attractive and advantageous as it allows a web-based online analysis/design via intuitive user-friendly interfaces for both the input and output in terms of familiar web-style forms that are nowadays very common in most of web-based services. Presently, the DEDM-LR hosts an aerodynamic database developed by the Tokyo Polytechnic University （TPU）, Japan for a variety of building configurations like flat, gable, and hip roofs under suburban terrain flow condition with immediate application to other databases. The paper shows the efficacy and validity of the DEDM-LR by walking through its details and examples on selected gable-roofed buildings. The architecture of DEDM-LR platform offers the ability to pool resources by hosting other databases that may become available in the near future.

基于均匀设计的海峡两岸高层建筑顺风向风荷载多因素分析

为明确海峡两岸高层建筑顺风向风荷载的异同,对两岸建筑风荷载标准进行了对标分析,并采用均匀设计方法进行了高层建筑顺风向风荷载多因素分析。研究表明:两岸风荷载标准中基本风速取样方法和极值分布参数取值方法存在明显区别,风压高度变化系数分布和不同重现期的设计风速转换系数大致相同,台湾地区标准给出的湍流强度建议值明显大于内地标准;台湾地区标准分类计算建筑物主体和围护结构的设计风压,内地标准采用统一表达式,两者给出的设计风荷载组合方式区别明显;以基底剪力和基底弯矩作为评价指标,H/(BL)(1/2)(高宽比)、α地面粗糙度指数)、C_(g)(脉动效应系数)、C_(p)(风荷载体型系数)和Iz(湍流强度),对高层建筑顺风向风荷载的影响程度依次减小,H/(BL)(1/2)和α为主要影响因素;随H/(BL)(1/2)的增大,C_(g)对顺风向风荷载的影响逐渐增强,当H/(BL)(1/2)增大到一定程度时,C_(g)成为主导因素。