砖混结构抗震加固实用计算方法

近年来,汶川地震后,中小学建筑的抗震安全问题引起全社会关注,中小学校舍安全工程已进入抗震加固的实施阶段。本文针对砖混结构抗震加固设计中存在的计算问题,依据提高砖墙折算抗剪及抗压承载力来达到建筑物抗震性能的原理,通过工程实例采用了行之有效的设计计算方法,供同类工程加固设计参考。     

大屯小学忠栋校舍耐震能力评估

有鉴于中小学校舍在1999年921集集地震中受损严重,近年来积极推动中国台湾地区中小学校舍的耐震补强。为确保学生及教职员在地震中的生命安全,台北市大屯小学亦针对其忠栋校舍进行结构耐震能力评估。由于忠栋校舍为石造建筑,而国内现有的建筑物耐震能力评估法仅适用于钢筋混凝土构造,因此无法以传统模式评估该建筑物的耐震能力。根据现行建筑物耐震设计规范的精神,并参考美国联邦紧急事务管理局所建议的建筑物耐震能力分析方法,对忠栋校舍进行有限元分析,藉以评估该建筑物在地震中的安全性,并为后续补强规划作参考。     

震损钢筋混凝土结构减震加固研究进展

震损钢筋混凝土结构如何考虑损伤影响以进行减震加固设计是值得研究的问题。本文介绍了国内外相关建筑加固与减震设计的系列标准规范,基于震损结构的各种加固工况探讨了减震加固技术的适用范围,概括了国内外有关消能减震加固技术的发展及其应用于震损结构加固的研究现状,简述了灾后震损结构进行减震加固的几种设计方法,并列出了部分典型的减震加固工程实例。最后,在已有研究的基础上,指出了现阶段震损结构减震加固研究中仍存在的一些问题。     

A protocol to assess the seismic criticality of existing small concrete dams

Dams are critical infrastructures whose failure would entail serious consequences for community safety. Although large dams represent the most dangerous items, small size dams may be critical, as a large number of these constructions are built in the proximity to inhabited zones. Earthquake is one of the hazards that may affect an existing dam. To assess safety and plan investments, dam owners need to create prioritisation sequences of interventions through a protocol considering technical, political and societal aspects. It is presented herein a specific procedure, based on a multi-criteria analysis with a rapid screening survey of the infrastructures, which addresses to classify the seismic criticality of dams considering the effects (in terms of loss of life and property) of a failure scenario subsequent to an earthquake. A protocol is used to define a prioritisation of interventions that mitigate the seismic risk. It has been applied to a group of 9 small concrete dams and 17 fixed weirs, built from 1920 to 1990 in Aosta Valley (Italy). As a result, about 30% of the existing dams, which are more vulnerable than fixed weirs, shows the highest level of seismic criticality, and needs to be retrofitted in accordance with the current standards.     

汶川地震农村中小学校舍典型震害分析

通过对5.12汶川地震区的郫县、彭州县,平武县、江油市、三台县、盐亭县等农村中小学校舍震害的调查,针对139幢典型校舍建筑的震害特征进行分析,总结了具有代表性的中小学教学楼抗震薄弱环节,提出了中小学教学楼建筑抗震概念设计的若干建议。可为中小学校舍的建设工程设计、施工以及抗震加固提供参考。     

汶川地震灾区学校建筑的震害分析

本文在对学校建筑震害调查的基础上,从结构体系、抗震构造措施及施工质量入手,分析了学校建筑破坏的原因。此外,本文对学校建筑的设计提出了建议。本项研究工作对今后既有学校建筑的加固改造以及新建学校建筑的设计施工,具有指导意义。     

既有砖混结构校舍隔震加固技术及其工程应用

结合我国抗震规范中的相关规定,分析校舍结构的结构特点和加固需求。针对其中多层砖混结构,介绍叠层橡胶基础隔震加固的计算分析方法、构造要求及相应的施工工艺。结合某7度抗震设防区一栋4层砖混结构教学楼的隔震加固实例,介绍其工程应用并分析技术经济指标。     

典型框架式学校建筑的抗震性能分析

本文在研究汶川地震灾区学校建筑震害的基础上,探讨了中小学校典型框架结构即外廊悬挑式单跨框架结构的抗震性能。基于静力非线性方法,用ETABS对典型框架结构进行弹塑性分析,对不同水准下结构的出铰顺序,出铰数量,侧向位移等进行对比,得出相应的抗震性能评价,本文还对该框架结构的薄弱部位进行分析,提出加固改造的相关建议。本文的研究工作对提高学校建筑的抗震能力具有实用价值。     

近场地震下混凝土框架考虑不确定性的#br# 抗震风险与恢复性评估

结构的抗震恢复性表征了结构震后维持和恢复其功能的能力,是近年来地震工程学界研究热点之一。文章以我国8度区典型中低层混凝土框架为例进行系统性的抗震恢复性评估。考虑结构设计参数以及震后修复行为的不确定性,探讨混凝土框架在远近场地震下的恢复性差异。通过增量动力分析的方法得到结构的易损性曲线,并在此基础上分析计算结构的经济损失、震后残余功能以及结构功能恢复过程。研究结果表明：相较于远场地震,近场地震对结构的破坏作用显著;近场地震显著增大了结构的易损性,同时造成更大的经济损失,更小的结构震后瞬时残余功能以及更长的功能恢复过程,降低结构的抗震恢复性;忽略结构不确定性会低估经济损失,一定程度上高估震后残余功能和结构抗震恢复性。研究结果可为考虑近场地震的混凝土框架结构的新建设计或者维护加固提供参考。     

Optimising portfolio loss reduction using a first-order reliability method sensitivity analysis

Advancements in loss estimation methodologies for building portfolios provide an opportunity for pre-disaster risk mitigation, particularly through structural retrofit. Budget constraints, however, limit which vulnerable buildings within a region are to be retrofitted to desirable levels of seismic resistance. This paper presents a new reliability-based approach to prioritise retrofit strategies to support regional earthquake risk mitigation efforts. The proposed framework uses the first-order reliability method (FORM) to evaluate a probability distribution of repair costs for a suite of spatially distributed buildings. Sensitivity measures computed within the FORM analysis are paired with retrofit costs. The proposed method is applied to a San Francisco neighbourhood building inventory, and results suggest which building categories should be upgraded to minimise estimated post-earthquake repair costs. The importance of spatial correlation as well as the level of loss to be minimised is investigated relative to cost-effective retrofit spending.     

基于建筑抗震韧性评价标准的某教学楼抗震韧性评价分析

对传统抗震设防目标和"可恢复功能"的抗震设计理念进行了介绍,采用新编国家标准《建筑抗震韧性评价标准》中的评价方法,对一栋新建小学教学楼进行了抗震韧性评价分析,对其修复费用、修复时间和人员损失进行了评估,以确定其抗震韧性等级。结果表明,抗震韧性评价可以对建筑物抗震性能进行量化分析,提供更易理解且更有价值的性能指标;同时,抗震韧性评价可以更加直观地验证"三水准"抗震设防目标,并发现非结构构件往往是造成人员伤亡和抗震修复代价的主要因素。     

Enhancing seismic risk mitigation decisions: a motivational approach

Implementing seismic risk mitigation is a major challenge in many earthquake-prone regions, despite the availability of a significant number of risk reduction measures such as technical design solutions and regulatory frameworks that include building codes, policies and regulations necessary to facilitate successful risk reduction activities. However, building owners have been found unwilling to retrofit their earthquake-prone buildings. The objective of this research is to investigate how to enhance buildings owners’ earthquake hazard preparedness decisions by adopting a motivational approach in order to reduce their vulnerability to earthquake risks. A multiple case studies approach was adopted and interviews conducted with the various stakeholders involved in seismic adjustments decisions. Significant intrinsic and extrinsic interventions such as intensifying and promoting the use of critical awareness motivators, financial and property market-based incentives necessary to enhance building owners’ decisions were revealed from the analysis of the qualitative data. These revealed intrinsic and extrinsic interventions offer plausible explanations regarding how human motivational orientation can be used to influence disaster preparedness decisions by increasing the salience of seismic risk issues.     

Quantitative evaluation and improvement of seismic resilience of a tall frame shear wall structure

Tall buildings are an important part of a city, and their earthquake-induced damage or collapse will lead to heavy losses, extended repair time, and casualties. Therefore, it is essential to quantify and improve the resilience of tall buildings. To this end, this paper develops a component damage-based metric to characterize tall buildings' functionality loss and then proposes a general quantitative evaluation process to evaluate tall buildings' resilience. Next, the evaluation process is applied to a 42-story reinforced concrete frame shear wall building to demonstrate its applicability. Finally, retrofit strategies on nonstructural components are discussed to enhance the building's resilience. It can be concluded that the proposed metric can be effectively used to evaluate tall buildings' functionality loss. The building being studied has great seismic resilience, with resilience values of 99.95%, 98.68%, and 88.69% at service level earthquake (SLE), design level earthquake (DBE), and maximum considered earthquake (MCE), respectively. The influence of nonstructural components on seismic resilience is greater than that of structural components at SLE and DBE levels. It is an effective alternative to enhance the seismic resilience of tall buildings under SLE and DBE by improving the performance of partition walls, ceilings, and equipment.     

体系不规则教学楼抗震鉴定及加固方法的探讨

简单介绍了教学楼的抗震鉴定,体系不规则结构的概念及其地震反应.针对体系不规则教学楼的震害提出多种抗震加固方案.在加固后教学楼的承载能力满足抗震验算要求的前提下,并对各方案的加固效果作了综合评价,为工程实际提供参考.     

防屈曲支撑加固钢筋混凝土框架拟静力试验设计

防屈曲耗能支撑由于兼具普通支撑和金属阻尼器双重功能,近年来在高抗震设防烈度地区的新建筑结构设计和既有结构抗震加固中得到越来越多的应用。本文以河北省图书馆抗震加固工程为依托,从图书馆原结构中选取单榀、单层、单跨钢筋混凝土框架的1/2缩尺模型作为试验模型,制作两榀钢筋混凝土框架试件,并对其中一榀框架用课题组自主研发的一种组合钢管混凝土式防屈曲耗能支撑进行加固。对两榀框架试件分别进行拟静力试验,来考察防屈曲支撑对钢筋混凝土框架的强度、刚度、延性和耗能能力等抗震性能的影响。有限元分析结果表明,未加固框架试件的强度和刚度低、耗能能力较差;防屈曲支撑加固的框架试件的强度和刚度显著提高,耗能能力较好;防屈曲耗能支撑具有很好的滞回性能。本文的试验设计可为相关抗震分析和试验设计提供参考。     

某校舍综合楼的抗震鉴定与加固设计

汶川地震以后,国务院成立全国中小学校舍安全工程领导小组,统一领导和部署中小学校舍安全工程。在全国范围实施校舍安全工程,全面改善中小学校舍安全状况,在全国中小学校开展抗震加固、提高综合防灾能力建设,使学校校舍达到重点设防类抗震设防标准。根据中小学校舍抗震鉴定加固工程委员会的要求,需对原结构按照新规范进行全面检测和抗震鉴定,本文结合某工程实例,采用一种较好的抗震加固方法—钢筋混凝土板墙加固法。它具有较大刚度、强度,有良好的变形和延性,对提高抗震能力有显著作用,施工快,综合效益好。对加固方法做了一个全面的论述,以供今后的类似工程参考。     

GB/T 38591—2020《建筑抗震韧性评价标准》与国际相关标准对比研究

建筑抗震韧性是指建筑结构在设定水准地震作用后维持和迅速恢复使用功能的能力。建立系统化的抗震韧性评价方法是建设抗震韧性建筑乃至韧性城市的重要组成部分。国际上从2012年起提出和发展了建筑抗震韧性评价方法,形成了多本韧性评价标准或指南。中国GB/T 38591—2020《建筑抗震韧性评价标准》于2020年3月31日发布,将于2021年2月1日起实行。为了对比GB/T 38591—2020与国际相关标准所评定的建筑抗震韧性水平,介绍了建筑抗震韧性评价方法的发展和基本流程,说明并比较了各标准计算韧性指标的不同策略,包括建筑修复费用、建筑修复时间和人员伤亡。采用算例说明了修复策略、次序和工人数量对建筑修复时间的显著影响,并对比了不同标准划定韧性建筑等级的判别标准。分析发现,GB/T 38591—2020在计算建筑修复时间、人员伤亡和判定抗震韧性等级方面与国际相关标准差别显著,且其所包含的不确信性范围小于国际相关标准。GB/T 38591—2020所评定的一星建筑的韧性水平约等同于或略高于REDi的银级建筑或USRC的4星建筑。     

Framework for city‐scale building seismic resilience simulation and repair scheduling with labor constraints driven by time–history analysis

A city‐scale time–history analysis‐driven framework is proposed for the quantitative evaluation of building seismic resilience and repair scheduling with repair resource constraints. First, a calculation method for the post‐earthquake residual functionality of buildings based on engineering demand parameters is proposed. Second, the repair‐scheduling unit (RSU) concept is proposed for city‐scale repair scheduling. Moreover, two repair priority indices are introduced to evaluate the repair priority of each RSU. Next, the concept of job block is proposed to compute the repair time of an RSU with insufficient repair resources. Subsequently, the workflow of repair simulation is presented to calculate the community recovery curve and resilience index quantitatively. Finally, 68,930 residential buildings of Beijing City's 16 administrative districts are simulated to demonstrate the proposed method. The outcomes of this work are expected to be a useful reference for building seismic resilience evaluation and repair scheduling of communities. Consequently, it could be an aid to pre‐earthquake disaster risk reduction planning and post‐earthquake rapid recovery of building functionalities.     

Seismic retrofit of a high‐rise steel moment‐resisting frame using fluid viscous dampers

The Tall Building Initiative project of Pacific Earthquake Engineering Research Center has been expanded to investigate the seismic performance and possible retrofit of existing tall buildings. A candidate 35‐story steel building with representative details from the early 1970s was analyzed following several guidelines, which revealed a wide range of potential inadequacies. Thus, a two‐level retrofit approach was examined that focused on achieving the collapse prevention limit state under the major basic safety earthquake (BSE‐2E) hazard level prescribed by ASCE 41. This paper focused on a Level‐2 retrofit that used fluid viscous dampers to augment Level‐1 retrofits. For this approach, feasible damper locations and overall effective damping ratios were first evaluated through a series of preliminary studies, and then a two‐phase design method was used to refine the distribution and mechanical properties of the dampers. Thorough assessments of the refined design were carried out following several design guidelines, including ASCE 41, FEMA 351, and FEMA P‐58. The results indicated that the proposed retrofit method of using fluid viscous dampers could achieve the retrofit goal and provide a cost‐effective means of improving the structural behavior and reducing economic losses in a major seismic event.     

震损建筑抗震鉴定加固中地震作用取值研究

在震损建筑抗震鉴定加固中,有关地震作用取值如何调整是值得深入研究的问题。以均匀Poisson过程描述地震的概率模型,以极值分布反映地震作用的概率分布,给出了地震烈度、地面峰值加速度与水平地震影响系数最大值之间的换算关系及其危险性曲线公式;阐释了等设防烈度原则、等超越概率原则和等重现期原则的基本原理;列出了震损建筑的几种分类方法及类别。基于震损建筑的后续使用年限,提出采用等重现期原则调整其地震作用取值的办法,并列出了具体的计算步骤。研究表明：相比等设防烈度原则和等超越概率原则,等重现期原则更为合理地反映了震损建筑在后续使用年限内遭遇相当设防烈度地震的风险概率,因此更适用于震损建筑抗震鉴定加固中地震作用取值的调整。