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.

Design Methodology Research of the Floating Foundation for the Offshore MW-Rating Wind Turbine

With the rapid growth of the offshore wind industry, the innovative floating offshore wind turbine is chosen as the most feasible device to harvest the vast wind energy in deep water area. However there is no practical design guide for the floating wind turbine especially the floating foundation. In this paper, based on the investigation on the worldwide floating wind turbine and current available expertise on floating platforms accumulated in offshore O/G （oil and gas） industry, an integrated design methodology is presented according to the specialized characteristics of wind turbine, including the type selection of foundation and mooring system, design standard, design procedure, design conditions, key technologies involved. Finally a semi-submersible floating foundation is designed to support certain megawatt-rating wind turbine of Goldwind and also performance analysis and code checks are performed to validate the design. The design method of the floating foundation provided in this paper is proved feasible and can be adopted in practical engineering design.

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.

Integrating BIM and machine learning to predict carbon emissions under foundation materialization stage:Case study of China’s 35 public buildings

For the significant energy consumption and environmental impact,it is crucial to identify the carbon emission characteristics of building foundations construction during the design phase.This study would like to establish a process-based carbon evaluating model,by adopting Building Information Modeling(BIM),and calculated the materialization-stage carbon emissions of building foundations without basement space in China,and identifying factors influencing the emissions through correlation analysis.These five factors include the building function type,building structure type,foundation area,foundation treatment method,and foundation depth.Additionally,this study develops several machine learning-based predictive models,including Decision Tree,Random Forest,XGBoost,and Neural Network.Among these models,XGBoost demonstrates a relatively higher degree of accuracy and minimal errors,can achieve the RMSE of 206.62 and R2 of 0.88 based on testing group feedback.The study reveals a substantial variability carbon emissions per building’s floor area of foundations,ranging from 100 to 2000 kgCO_(2)e/m^(2),demonstrating the potential for optimizing carbon emissions during the design phase of buildings.Besides,materials contribute significantly to total carbon emissions,accounting for 78%e97%,suggesting a significant opportunity for using BIM technology in the design phase to optimize carbon reduction efforts.

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.

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。

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。

高层建筑结构设计探讨

介绍高层建筑中使用的新型墙体材料、保温材料等新型建筑材料,并分析新型建材在高层建筑中的发展优势,介绍混凝土结构、钢结构和钢混组合结构3种建筑结构形式并对它们的经济效益进行探讨,最后分析介绍方形桩地基系统的应用。

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。

“现代控制工程基础”课程蕴含思政元素分析与教学实践

“现代控制工程基础”是自动化专业的必修课,主要内容包括经典控制和现代控制两部分基础理论。课程理论性较强,在各个知识点中蕴含着丰富的思政元素,能够在潜移默化中实现对学生的思想政治教育,促进学生知识与能力、过程与方法、科学素养与价值引领的统一,从而充分发挥专业课教学的育人功能,做到了使专业课程与思想政治理论课同向同行,形成协同效应,使课程思政实现了全课程育人,达到润物无声的效果,实现对学生世界观、人生观、价值观的引领。

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%。

改进遗传算法在房建深基坑支护结构设计中的应用

住宅楼工程施工中经常采用复杂双排灌注桩且一桩两用的方式设计基坑支护结构,但工程实践中基坑施工具有明显的不确定性,各方面因素共同作用下导致数据模拟数值和理想数值之间通常存在鲜明差异。为此,以张家口宇鑫小区二期项目为例,研究基于改进遗传算法在深基坑支护结构设计中的应用,通过构建模型时取桩体嵌入地面的深度和桩体弯矩作为约束条件并设置惩罚函数,明确模型建立中的约束问题,同时结合施工现场基坑断面处理图形结构,通过在基坑中设置钢板桩支护结构以约束基坑变形等问题,并采用高压旋喷桩等方式确保基坑支护结构的防渗防水效果。实验结果显示,改进遗传算法的应用能够有效提高地表沉降、桩体的水平位移和地表沉降与理想数值之间的契合性,大幅度提高数值模拟可信度。

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。